FR2812056A1 - Automobile parking brake electrical driven actuator has screw-nut mechanism in which rotational movement is translated into linear movement - Google Patents

Abstract

The nut retainer has an axial tip (72A) extending from the threaded part (70A) of the screw. The tip engages into a tapped hole (75A) in the nut (73A), when the screw is disengaged from the threaded section of the screw. The length of the tip is greater than the diameter of the threaded hole on the nut (73A). The nut is linked to means which prevent it from rotating around the screw (70) axis. The nut is fixed in translation to a connecting part (34) and is acted on by a spring (85A). The actuator has a housing in which is fitted: (a) an electric motor drive; (b) a coupling part (34) which moves in translation along an axis under the control of the motor, and; (c) between the motor and the coupling, a screw-nut fitting designed to transform a rotational movement into a translation movement. One of the screw-nut parts is driven by the motor and the other part is fixed to the coupler (34) and is linked to a part which stops rotation around the axis. The screw (70) has a threaded section (70A) and the nut has a tapped hole (75A) designed to cooperate with the threaded section of the screw. A nut retainer (72A) follows the screw axis, and holds the nut when the it is disengaged from the threaded section of the screw. A spring (85A) acts against to press the nut and the screw against each other so as to hold the nut against an end of the threaded section of the screw when its is disengaged from the threaded section.

Description

La zrresente nr..et.or_ crcrerne vr à D Ge S; a.ul i>, eJ IeFI ce, l, ei ,, ...

  -1 .-- D: in which are arranged: - an electric actuating motor; - A coupling member of an element to be actuated, which coupling member is movable in translation along an axis under the control of said motor; and - between said motor and said coupling member, a screw-nut arrangement suitable for transforming a rotational movement into a translational movement, one of the screw and the nut being rotated under the control of the motor and the other of the screw and the nut being integral in

  translation of said coupling member and associated with immobilizing means

  reading in rotation around said axis, the screw comprising a threaded section and the nut comprising a tapped conduit suitable for cooperating with the section

screw thread.

  In such an actuator, the screw-nut arrangement generally allows-

  ment to transform the rotational movement of the screw into a translational movement of the nut secured to the coupling member. So the nut

  is movable in translation along the length of the screw.

  The coupling member for example drives an actuating cable.

  jaws of a motor vehicle parking brake.

  The engine is started and stopped by a control unit. Under certain conditions, and in particular in the event of a malfunction of the control unit, the engine may run for too long when the parking brake is released.

  of the motor vehicle. In this case, the nut is then driven to the ex-

  free end of the screw from which it escapes.

  When an attempt is made to apply the parking brake, the screw is rotated in the opposite direction without, however, being able to drive

  the nut, which is no longer engaged with the threaded section of the screw.

  To re-engage the nut on the screw, it is then necessary to disassemble the

  actuator, open the actuator housing to access the nut and re-

  manually lock the nut around the screw.

  Ur De 'aeron! Me e cton r e; -est: - s: e es-

  L IV'-i, LI I d aim 'e to propose a thruster not presenting the drawback mentioned above and which in particular does not require the intervention of a qualified person when the nut of an arrangement to actuator screw-nut accidentally released from the threaded section of

I saw the commander.

  To this end, the invention relates to an actuator, in particular a motor vehicle parking brake, of the aforementioned type, characterized in that

  that it includes means for retaining the nut along the axis of the screw, when

  the nut is released from the threaded section of the screw, and elastic means for urging the nut and the screw towards each other to keep the nut applied against one end of the threaded section of the screw, when the nut is

  clear of the threaded section of the screw.

  According to particular embodiments, the actuator comprises one or more of the following characteristics:

  - Said nut retaining means comprise an axial pin

  skirting said threaded section of the screw, which stud is received in said threaded pipe of the nut, when the nut is released from the threaded section of the screw;

  - the length of said stud is greater than the diameter of the tarau duct-

of;

  - the nut is associated with means for its immobilization in rotation

  tion around the axis of rotation of the screw, the nut being integral in translation with the coupling member, and said elastic biasing means are applied to said nut;

  - said elastic biasing means are interposed between the

  coupling sleeve and housing; - The coupling member comprises a cable fixing yoke, and said elastic biasing means comprise a helical spring surrounding the cable, which spring bears on the yoke; - The nut is articulated relative to the yoke around an axis generally extending perpendicular to the axis of the screw;

  - esc;: s oovens c'irmcz, isation in rc-: - -

  coupling is guided in transiation and is kept fixed in rotation.

  The invention will be better understood on reading the description which will

  follow, given only by way of example and made with reference to the drawings, in which: - Figure 1 is a schematic top view of an actuator

  parking brake according to the invention installed in a motor vehicle

  bile; - Figure 2 is an exploded perspective view of the brake actuator according to the invention; - Figure 3 is a longitudinal sectional view of the actuator of Figure 2;

  - Figure 4 is a top view partially in section of the action -

Figure 2 neur; and

  - Figures 5 and 6 are partial top views of a solid nut

  of the actuator coupling member, respectively, in posi-

  tion engaged on the threaded section of the actuating screw and in the position

pledged from this threaded section.

  In Figure 1 is shown schematically a motor vehicle

  bile in which a parking brake is arranged incorporating an ac-

  brake actuator according to the invention.

  In this figure is schematically represented the vehicle body

  cule 10, its two front steering wheels 12 and its two rear wheels 14. Inside the passenger compartment delimited by the body 10 is provided a left front seat 18 for the driver of the vehicle and a bench seat 20 arranged

  transversely to the rear of the vehicle.

  The brake actuator according to the invention, designated by the general reference

  rale 22 and shown on a larger scale in Figure 1 for reasons of clarity, is arranged below the rear seat of the vehicle. The two actuator control outputs are movable along an X-X axis

  arranged transversely in the vehicle. Cables 24 slidably mounted

  sants in ducts are connected to the actuator control outputs.

  The ex: rem'es oposés es c.t es are connected aces.:es se fre t ace

es a.,. D ...-, W -? $ -A; -;, -

  More precisely, the brake actuator 22 comprises an electric motor.

  that of actuation 26 of axis Y-Y. The engine output is connected by a mechanical transmission 32 to two movable members 34 for coupling the

  cables 24. These coupling members 34 are movable along the axis X-

  X and constitute the control outputs of the actuator 22.

  The mechanical transmission 32 includes a mechanism for transforming

  mation of the rotational movement of the motor output in one movement

  of translation of the coupling members 34.

  The drive motor 26 has its axis YY disposed transversely to the axis of movement XX of the coupling members 34. Thus, the axis YY of the motor 26 extends along the longitudinal axis of the vehicle when the axis of displacement of the coupling members 34 extends transversely. Preferably, the actuator is installed in the vehicle, so that the plane

  defined by the axes X-X and Y-Y extends along the running plane of the vehicle

  cule, that is to say substantially the horizontal plane.

  In addition, the mechanical transmission 32 includes a bevel gear allowing the transformation of the rotational movement of the output shaft of the motor 26 around the axis Y-Y into a rotational movement around

the X-X axis.

  The actuator 22, shown in detail in FIGS. 2 to 4, comprises a housing 50 formed by two half-shells 50A, 50B assembled according to a

  median plane corresponding substantially to the section plane of FIG. 4.

  The engine 26, the transmission 32 and the coupling members 34

  are arranged inside the housing.

  The motor 26 is an electric motor which can be supplied from the battery of the motor vehicle. An engine control unit 52 is arranged in the housing 50 behind the engine. This unit regulates the power supply to the motor. It also manages the engine operating time for tightening and loosening the

braking means.

  The mc-: er 26 has a rotating shaft 54 e es, - e

  the control unit 52 through a passage 57. This end is accessed

  visible from the end of the housing 50 and constitutes an auxiliary drive end piece of the actuator in the absence of electrical power to the motor 26. The other end of the shaft 54, denoted 58, constitutes a rotary output end of the motor. The latter is connected directly to the angular gear noted 60 via a coupling sleeve 62. The angular gear 60 comprises an endless screw 64 arranged coaxially with the shaft of

  outlet 58 and integral with it. The worm 64 has a helical thread

coïdal.

  In addition, the bevel gear 60 has a wheel 66 with a helical thread.

  gear adapted to cooperate with the thread of the worm 64. The wheel

  66 is rotatably mounted around the axis Y-Y of movement of the actuating members

  coupling 34. It is supported in a yoke 68 forming a bearing received

in a housing 50 obviously.

  The wheel 66 is integral in rotation with a screw 70 extending on either side

across the Y-Y axis.

  The screw has two opposite sections 70A, 70B having threads

  reverse letters. These two threaded sections extend on either side of the wheel 66. In its intermediate section disposed between the two threaded sections 70A, 70B, the screw 70 has a rotation drive profile, such

  that a drive hex received sliding in a passage 71 (fig.

  gure 3) of complementary section formed along the axis of the wheel 66. Ain-

  if, the screw 70 and the wheel 66 are integral in rotation while the screw 70 is

  free to slide along the X-X axis of the wheel 66.

  One end of the screw 70 is shown on a larger scale on

  Figures 5 and 6, this end being associated with a coupling member-

ment 34.

  At each end of the screw, the threaded sections 70A, 70B are pro-

  each bordered by an axial stud 72A, 72B having a smooth cylindrical wall. The diameter of each nipple is substantially equal to or less than the

  diameter mr'ie Cj s - rnrj. LINE: é 70A, 70B corresc-: -es -

Fiets.

  Each coupling member 34 is integral in translation with a

  nut 73A, 73B adapted to cooperate with a threaded section 70A, 70B.

  The nuts have threaded conduits 75A, 75B complementary to the threaded sections 70A and 70B. The threaded conduits provided in

  the nuts are through at both ends.

  The pins 72A, 72B advantageously have a length greater than the diameter of the threaded conduits 75A, 75B, this length being however less than the length of the conduits. This length is such that each stud provides retention of the associated nut along the axis of the screw when the nut is completely unscrewed, as illustrated in FIG. 6, and the stud

  is received in the threaded pipe, the nut then being pressed against the end

mite from the threaded section 70A, 70B.

  Each coupling member 34 has a yoke 76A, 76B.

  Each nut has two opposite pins 77 laterally

  putting the articulated connection of a yoke 76A, 76B. These pins are received in lights made in each of the two branches of each yoke. The yokes 76A and 76B have a general U shape and are

  notched at their base by a notch 80A, 80B for passage and rete-

  bare of a projecting head 82A, 82B provided at the end of the cables 24 assu-

  rant the connection to the wheel braking means.

  The half-shell 50B of the housing has, along the axis X-X,

  84A, 84B guides in rectilinear translation of the yokes 76A, 76B.

  The yokes 76A, 76B are slidably mounted in these channels 84A, 84B along the axis X-X and are immobilized therein in rotation. The immobilization in rotation of the yokes ensures the immobilization in rotation around the axis XX of the nuts 72A, 72B relative to the housing 50, the nuts being secured

  to the yokes at two points spaced from the X-X axis by the lugs 77.

  Finally, a coil spring 85A, 85B is disposed inside the box.

  tier 50 around each cable 24. These springs, arranged along the axis XX, bear at one end on the base of each yoke 76A, 76B and at their other extremJi: é sar se ocre f xe 86A, 86B of the box; er 53. ces ar3- A_

  crossed by zas caecS C -n. naque ressoert ooa Bse s. ..

  on a bias towards the screw 70 of the associated coupling member 34 and

  therefore of the corresponding nut 73A, 73B.

  In particular, each spring 85A, 85B maintains a nut 73A, 73B pressed against the end of the associated threaded section 70A, 70B, the nut being retained along the axis of the threaded section by being engaged around

  a pin 72A, 72B, as illustrated in FIG. 6.

  The half-shell 50B has, along the axis XX, a bearing 87 in which is received a cylindrical end of the endless screw 64. In addition, a ball 88 is received in an axial recess formed at the free end of the worm screw 64, this ball bearing on an end surface 90 of the housing 50 formed at the end of the bearing 87. The ball 88 thus provides support for the worm screw on the housing and constitutes a ball stop allowing recovery axial forces applied to the worm 64, while retaining

satisfactory performance.

  When the electric motor 26 is supplied with electric current, the motor turns in one direction or the other, depending on the direction of the current. The

  rotational movement of the output shaft 58 of the motor prints a mo-

  rotation of the screw 70 thanks to the angle gear 60. The arrangement with

  screw-nut formed of threaded sections 70A, 70B and nuts 73A, 73B as-

  on a conversion of the rotational movement of the screw 70 into movements

  translation elements in opposite directions of the nuts 73A, 73B and the cha-

associated pes.

  Thus, the cables 24 are simultaneously pulled or released depending on the direction of rotation of the motor. This pulling or loosening

  imposed on the cables ensures a tightening or a release of the braking means

  swimming. Due to the possible sliding of the screw 70 relative to the wheel 66,

  load balancing on the two cables is carried out continuously.

  As illustrated in Figure 5, during normal operation of the ac-

  the nut 73A moves along the length of the threaded section 70A of

the opinion.

  E, case te '.sfc ccnnement, and for example c-s of a function

  lert garlic rmaemeT.or, & -. i'pacem- r.

  large from nut 73A towards the free end of the screw, nut 73A is completely free from the threaded section 70A, as illustrated in the figure

6.

  In this case, under the action of the partially compressed spring 85A, the yoke 76A maintains the nut 73A in abutment on the end of the threaded section A. In this position, the stud 72A is engaged inside the tapped conduit 75A , thus ensuring that the axis of the conduit 75A is maintained along the axis XX of the screw 70. Thus, even after the actuator has operated for too long, causing the nut to move towards the free end

  of the screw, the nut 73A remains in position around the pins.

  When ordering the screw 70 in the opposite direction, the nut 73A

  is automatically screwed back onto the threaded section 70A, due to the stress

  permanent position of spring 85A which tends to engage the complete threads

  of the threaded section 70A and the threaded conduit 75A.

  The pin 72A ensuring the alignment of the threaded section 70A and the

  75A threaded conduit facilitates engagement of complementary threads.

  It will be understood that with an actuator as described here, even in the event of a malfunction tending to cause a nut to come out of the associated threaded section of the screw, no human intervention is necessary to engage the nut again on the threaded section, when the screw is driven in the opposite direction. In order to facilitate the automatic restoration of the actuator, the motor control unit 52 is advantageously fitted with a button.

  reset allowing, when pressed, to cause the shift

  cementing of the screw in a direction allowing the reintroduction of the nut around the threaded section. This button can be used in case of detection of a

actuator malfunction.

  However, recourse to this command may be superfluous, insofar as, during a normal command of the actuator intended to cause

  applying the parking brake of the motor vehicle, the screw is

  drag in the direction causing the re-engagement of the nut around the section

  çor, fie; _ L e, a v ,. that which has a reaction-e-: r "a: e ce Liiu, s sB I eaL sa - .;

  momentary of which the actuator may have been a victim.

  Alternatively, the motor rotates the nut which is fixed in translation. On the contrary, the screw cooperating with the nut is movable in translation and fixed in rotation. It drives a coupling member. In this case, the axial biasing means are interposed between the screw and the housing

  to keep the screw pressed against the nut even when they are loose

  committed following a malfunction of the control unit.

RPEENDICAT1O.NS

  i.- Ac, inner compriseare unl Dooier ,, 3 / ca tn> rQ: l s eqeH; sc; ,, cl; s-9s

aun -o - eH r * -

  - an electric actuating motor (26);

  - a member (34) for coupling an element to be actuated, which or-

  coupling gane (34) is movable in translation along an axis under the control of said motor (26); and

  - Between said motor (26) and said coupling member (34), a device

  screw-nut cement suitable for transforming a rotational movement into a

  translational movement, one of the screw and the nut being rotated

  tion under the control of the motor (26) and the other of the screw and the nut being integral in translation with said coupling member (34) and associated with immobilization means in rotation about said axis, the screw ( 70) comprising a threaded section (70A, 70B) and the nut comprising a threaded conduit (75A, B) capable of cooperating with the threaded section (70A, 70B) of the screw, characterized in that it comprises means ( 72A, 72B) for retaining the nut (73A, 73B) along the axis of the screw (70), when the nut (73A, 73B) is released from the threaded section (70A, 70B) of the screw, and elastic means (85A, 85B) for biasing the nut (73A, 73B) and the screw (70) towards each other to hold the nut (73A, 73B) applied against one end of the threaded section (70A, 70B) of the screw, when the nut (73A, 73B) is released from the

threaded section of the screw.

  2.- actuator according to claim 1, characterized in that said

  nut retaining means include an axial stud (72A, 72B)

  managing said threaded section (70A, 70B) of the screw, which stud (72A, 72B) is

  received in said threaded conduit (75A, 75B) of the nut, when the nut is released

  guaranteed by the threaded section of the screw.

  3.- Actuator according to claim 2, characterized in that the lon-

  of said stud (72A, 72B) is greater than the diameter of the threaded pipe

(75A, 75B).

  4.- Actuator according to any one of the preceding claims.

  tes, characterized in that the nut (73A, 73B) is associated with means for immobilizing it in rotation about the axis of rotation of the screw (70), the nut (73A, 73B) being integral in translation of the coupling member (34 '. and in this Bue esc, s rm, oyers [elastic of sc i' tais [- .: click on ec: ec:, u 7 3.ai 5.- Actuator according to claim 4, characterized in that said elastic biasing means (85A, 85B) are interposed between the coupling member (34) and the housing (50) 6.- Actuator according to claim 5, characterized in that l 'coupling member (34) comprises a yoke (76A, 76B) for fixing a cable (24), and in that said elastic biasing means comprise a helical spring (85A, 85B) surrounding the cable (24) , which comes out (85A,

  85B) press on the yoke (76A, 76B).

  7.- actuator according to claim 6, characterized in that the nut (73A, 73B) is articulated relative to the yoke (76A, 76B) about an axis

  generally extending perpendicular to the axis (X-X) of the screw (70).

  8.- Actuator according to any one of claims 4 to 7, ca-

  characterized in that said means for immobilizing the nut in rotation (73A, 73B) around the axis of the screw (70) comprises a channel (84A, 84B) defined in said housing (50), and in which the coupling member (34) is guided

  in translation and is kept fixed in rotation.