FR2535805A1 - Device for taking up the play of an automobile vehicle drum brake using a ratchet - Google Patents

Abstract

Device for taking up the play of an automobile drum brake, comprising a brace 15 interposed between two jaws 1, 2 and a toothed nut 20 for adjusting the length of the brace by the intermediary of a ratchet 22. The ratchet 22 is mounted pivotably on one jaw 1 about an axis Y-Y perpendicular to the brace and orthogonal to the axis X-X of the drum 6, and interacts with a portion of the nut 20 situated between the brace 15 and the axis X-X of the drum 6. This arrangement makes it possible to house the ratchet entirely under the brace, freeing the zone lateral to the latter.

Description

2535 05

  The present invention relates to a play take-up device for a motor vehicle drum brake. It is known that the drum brakes commonly used in motor vehicles advantageously include a device for taking up the existing play, when the brake is at rest, between the friction surfaces of the drum and of two internal jaws, this play tending to increase with wear. friction linings

equipping the jaws.

  The invention relates to such a device, in which the two jaws, returned to one another by at least one spring, are kept apart, when the

  brake is at rest by a spacer of adjustable length

  ble, orthogonal to the axis of the drum and arranged between a

  drum hub and a hydraulic actuating cylinder

only brake.

  The spacer generally consists of two parts which can slide one inside the other, and whose relative position is adjustable by means of a nut, on the one hand screwed onto a threaded rod secured to one of the parts and on the other hand in axial support on the other part These two parts are each connected to one of the jaws, or to a control lever articulated on one of the jaws, by a means preventing rotation of the spacer around of the axis of the threaded rod, but allowing a slight sliding of the spacer on at least one of the jaws when the latter deviate by

hydraulic brake actuation.

  So that backlash is automatic

  periphery of the nut is circular and toothed, and coo-

  father with a pivoting ratchet on one of the jaws

  in response to any movement of separation thereof.

  The teeth and the pawl are arranged so that, when this movement reaches a determined amplitude reflecting an excessive radial clearance between the drum and the jaw linings, the pivoting of the pawl becomes sufficient to hook a next tooth from the periphery of the nut , therefore to cause a rotation thereof in the direction corresponding to the elongation of the spacer and as a result of a reduction in the radial clearance 1 The pawl usually pivots about a geometric axis Io parallel to the axis of the drum , and cooperates laterally with the nut, that is to say that it oscillates in a zone lateral to the nut situated in the vicinity of a plane perpendicular to the axis of the drum tangent to the periphery of the nut This implies that this area is not occupied by another part The pivoting of the pawl can be done simply by engagement

  of a narrow portion of the pawl in a suitable light

prayed from the jaw.

  The pawl is driven by a spring tending to rotate it in the aforementioned direction This spring is advantageously constituted by a thin portion of the pawl

  itself, made for this purpose from an elastic metal.

  The angular position of the pawl on the jaw is determined by cooperation of a portion of the pawl with one face of the spacer or with another part

  which moves relative to this jaw when this one

this deviates from the other.

  The object of the invention is to produce a play take-up device of this type, in which the pawl is particularly simple and does not occupy the area.

lateral to the nut.

  According to the invention, the device is characterized in that the pawl is pivotally mounted about an axis perpendicular to the spacer and orthogonal to the axis of the tanlour, and

  cooperates with a portion of the nut located between the

height rod and drum axis.

  It is understood that such an assembly makes it possible to house the pawl entirely between the hub of the drum and the spacer, outside of the zone lateral to the nut which is thus

  Indeed, the portion of the toothed nut with the-

  which cooperates the end part of the pawl, is located in the vicinity of a plane perpendicular to the axis

  of the drum and containing the axis of the threaded rod.

  IO According to one embodiment of the invention, the

  ratchet, which is provided with an elastic end part

  only in engagement with the teeth of the nut, constitutes a first arm of an elastic clamp having a general shape approximately in U, having a central part I 5 which crosses the core of the associated jaw by a light formed in said core , and a second

  arm folded in elastic support on the core.

  Thus, the pawl is limited by the part of the clamp located between its central portion and the end engaged with the nut, and can pivot on the support jaw around an axis orthogonal to the axis of the drum and passing

  para central portion It follows that the displacement of 1 the extreme

  half of the pawl, when it appears a radial play, is

parallel to the axis of the drum.

  According to another feature of the invention, the light provided in the core or flange of the jaw of

  support for the clamp, is delimited by two parallel edges

  lines substantially perpendicular to the general direction

  spacer, which materialize the pivot axis of the pawl and hold the central part between them

of the pliers.

  The opposite edges of this central part advantageously have notches in which the soul of the jaw can fit, and which therefore ensure

  retaining the central part of the clamp perpendicular to

  the soul of the jaw.

  Other features and advantages of the invention

  will appear during the description which follows,

  made with reference to the accompanying drawings which illustrate

  an embodiment by way of nonlimiting example.

  Fig 1 is a side elevational view of a drum brake equipped with a take-up device

game according to the invention.

  IO Fig 2 is a sectional view along the line

II-II of Fig 1.

  Fig 3 is a vertical cross-sectional view

  shim along line III-III of Fig 1.

  Fig 4 is an exploded perspective view of

  I 5 the adjustable spacer forming part of the device shown

felt in Figs 1 to 3.

  Fig 5 is a perspective view on an enlarged scale showing the elastic clamp of the device

Fig 1 to 3.

  Referring to Figs 1 to 3, there is seen a control mechanism of two jawsl, 2 of a drum brake, placed on a plate 3 and intended to be applied, by means of friction linings 4,5 of which

  they are equipped, against the internal friction surface

  of a drum 6 provided with a hub 7.

  The jaws 1,2 cooperate respectively by their upper ends 1a, 2a with two sliding pistons

  in a cylinder 8 for hydraulic actuation of the brake, fixed to the

  upper tie of the plate 3 Two springs 9,10 whose ends are subject to the jaws 1,2, tend to bring those: -cm apart from each other, making a radial clearance J appear between the linings 4,5 and the drum 6, when the brake is not

not activated.

  A manual control lever 11 is pivotally mounted

  both at one of its ends on an axis 12 integral with the jaw 2, and is connected at its other end 11a to a cable not shown A notch 13 formed in the edge of the lever 11 receives one end of a spacer horizontal 15 of adjustable length, disposed orthogonally to the axis XX of the drum 6, this spacer being located

  radially between the hub 7 and the cylinder 8.

  Each end of the spacer 15 cooperates with IO a jaw so as to keep the jaws 1,2 apart when the brake is at rest, and the spacer is formed of two parts 17,40 slidably mounted one inside the other The first part 17 comprises a threaded rod 19 provided with a nut 20 in axial support

I 5 against the second piece 40.

  The part 40 is, in this embodiment,

  a bar whose cross section is sensitive-

  ment larger in a direction parallel to the axis X-X of the drum than in the radial direction, and which therefore has a generally flattened shape This bar-40-comprises,

  on the side of its bearing face for the nut 20, an

  moth in the fork 16 with two branches 25,26 with internal edges

  parallel laughers The nut 20 is freely engaged between these edges, and a grooved head 18 of the first part 17 can slide between the branches 25, 26 by taking

support on the edges of these.

  The bar 40 has a second fork end 14, opposite the part 17 and which receives, between its two branches 53, 43, the notch 13 of the lever 11 o The space between the two branches 25, 26 of the end 16 is widened near the support face 21, in order to reserve a housing 29 for the nut 20, ensuring the axial stop of the latter The support face 21

  constitutes the edge of a semi-cylindrical housing 41

  that, formed in the bar 40 to receive coaxially a part of the rod 19 The external surface 30 of the housing 41 constitutes a relief preferably also semi-cylindrical. Two lateral grooves 23, 24 are formed in the head 18 parallel to the rod 19, to receive the corresponding inner edges of the branches 25, 26 of the end 16 On the other hand, on the side opposite to the rod

  19, a groove 27 is formed in the head 18 perpendicular

  cularily to the rod 19, to receive the core or flange

  10 lb of the corresponding jaw 1.

  The central part 42 of the bar 40 is offset in the direction of the cylinder 8 relative to its fork ends 14 and 16, so as to have a convexity

  turned towards the cylinder 8 (Fig 5).

  I 5 A pawl 22, articulated on the jaw 1, cooperates with the circular peripheral toothing 20a of the nut to ensure automatic take-up of the radial clearance J. The pawl 22 is pivotally mounted about a vertical axis YY orthogonal to l axis XX of the drum 6, and cooperates with a portion of the nut 20 located between

  the spacer 15 and the X-X axis (Fig 1 and 3).

  The pawl 22, provided with an end portion 140 in resilient engagement with the teeth 20 a, constitutes a first arm of an elastic clamp 100 having a general shape approximately in U The clamp 100 has a central portion 32 which passes through the core or flange 1b of the associated jaw 1, by a slot 33 formed in this flange 1b, and a second arm 34 folded in elastic support on the flange 1b The lumen 33 is delimited

  by two parallel edges 35,36 substantially perpendicular to

  in the general direction of the spacer 15 The edges 35, 36 materialize the axis Y-Y of pivoting of the pawl 22, and hold the central part between them

32 of clamp 100.

  The central part 32 is provided with a projection or tab 38, spaced from the flange 1b and pressing against

  a terminal face 39 of the spacer 15 (Fig 2), mo-

  bile with respect to the flasqẻ lb when the jaws 1 and 2 move apart or move towards each other More

  specifically, the bearing face 39 belongs to the part 17.

  The tongue 38 limits the pivoting of the pawl 22 by "displaying" on the latter the position of the face 39 of the spacer 15 relative to the flange lb. Io The nut 20 protrudes from the side of the flat fork end 16 facing the axis X-X, and there clamps

  elastic 100 is placed in its entirety on this side.

  The edges 35, 36 of the light 33 are extended

  by the edges 35 a, 36 a of an enlarged and inclined portion

  I 5 born of the light (Fig 1) This enlarged portion is arranged to allow the clamp 100 to be introduced and then to tilt it to its position of use,

  in which it is kept immobilized by fitting

  the flange lb in two notches 37 of the portion

central 32.

  The clamp 100 is made of an elastic metal, from a cut and folded sheet- Its tongue 38 and its end 140 which cooperates with the teeth a are thus formed by folded edges of this

pliers.

  The operation of this game take-up device is similar to that of devices of the same

  type, comprising between the two jaws 1,2 a

  height rod in two sliding-parts stopped in rotation by their connection with the jaws 1,2, and adapted to be separated by screwing the toothed nut 20 actuated by the pawl 22 pivoting on one 1 of the jaws, in

  response to a movement of separation thereof.

Z 535805

  However, unlike known devices,

  the pawl 22 provided by the invention pivots on the jaw

  re 1 around a vertical axis YY and orthogonal to the axis XX of the drum 6 As a result, the displacement of the end'140 of the pawl 22 is parallel to the axis XX, and that the portion of the nut 20 with which it cooperates

  is located in the vicinity of a plane P (Fig 3) perpendicular to

  laire to the axis X-X of the drum 6 and containing the axis of the

  threaded rod 19, preferably on the side of the

IO height chart 15 facing the X-X axis.

  This arrangement is particularly suitable for brakes in which the spacer, such as a bar like the bar 40 of the example described above, is flat at its end comprising the adjusting nut 20, I 5 which emerges therefrom. on the side of the axis XX and of the hub 7 of the drum 6 This makes it possible to have the whole of the pawl 22 and of its pivoting and elastic return means entirely between the spacer and the hub 7 of the drum 6, with a low footprint In particular, in the

  direction parallel to, the axis X-X of the drum 6, this assembly

  ble does not significantly exceed the width of the spacer

  se 15, as seen in Fig 3.

  This play catching device occupying a particular

  significantly less space between the hub 7 and the cylinder 8, these two elements can be largely dimensioned, so as to provide the brake with maximum efficiency and reliability. Furthermore, the device according to the invention, in which the assembly of the pawl 22 and its pivoting and elastic return means consists of a single piece 100, is of a particularly low cost price.

  The invention is not limited to the embodiment

  tion described and may include alternative embodiments.

  In particular, the spacer 15 described can be replaced

  created by any other equivalent means.

Claims (6)

- CLAIMS -   1. Backlash device for a motor vehicle drum brake, provided with two jaws   interior (1,2), comprising a spacer (15) inter-   placed between them in a general direction orthogonal to the axis (X-X) of the drum (6) and -a nut (20) l toothed periphery, mounted in the spacer (15) and   suitable for adjusting the length of the latter when   appears an excessive radial clearance (J) in the brake, by cooperation of its peripheral toothing with a pawl (22) pivotally mounted on one (1) of the jaws (1,2), characterized in that the pawl (22 ) is pivotally mounted around an axis (YY) perpendicular to the spacer and orthogonal to the axis (XX) of the drum (6), and cooperates with a portion of the nut (20) located between the spacer ( 15) and the axis Is 5 (XX) of the drum 2. Device according to claim 1, characterized in that the pawl (22), provided with a terminal part (140) in resilient engagement with the teeth (20a) of   the nut (20) constitutes a first arm of an elastic clamp   tick (100) having a general shape approximately in a U, having a central part (32) which passes through the core (lb) of the jaw (1) associated by a light (33) formed in said core (lb), and a second arm (34)   folded in elastic support on the core (lb).   3 Device according to claim 2, characterized in that the light (33) is delimited by two parallel edges (35,36) substantially perpendicular to the   general direction of the spacer (15), which materiali-   feels the pivot axis (Y-Y) of the pawl (22) and   hold the central part (32) of the pliers between them (100)   4, Device according to one of claims 2 and   3, characterized in that the central part (32) of the clamp (100) is provided with a tongue (38) spaced from the core (lb) of the jaw (1), and pressing against a   end face (39) of the spacer (15) movable relative to   wear to the core (lb) when the jaws (1,2) move apart or approach each other, the tongue (38) limiting the pivoting of the pawl (22) by "displaying"   on the latter the position of the face (39) of the   height rod (15) relative to the core (1b).   5. Device according to one of claims 2 to   IO 4, in which the spacer (15) comprises a part (40)   provided with a flat end (16), the cross section of which   versal is larger in a direction substantially   parallel to the axis (X-X) of the drum (6) only in the direction   radial tion of the latter and forms a fork between the I 5 branches (25,26) from which the nut (20) is held axially, which protrudes from the side of the flat end (16) in fork turned towards the axis (XX) of the drum (6), characterized in that the elastic clamp (100) is   placed in its entirety on this side, and the face (39)   which is supported by the tongue (38> from -   the clamp (100) belongs to a part (17) mounted at neck   smooth between the branches (25,26) of the furnace end-   che (16) and provided with a threaded thread (19) carrying the nut (20).   6. Device according to one of claims 2 to 5,   characterized in that the edges (35,36) of the lumen (33) are extended by those (35a, 36a) of an enlarged and inclined portion of the lumen, arranged to allow the clamp (100) to be inserted therein ) then to tilt it to its position of use, the opposite edges of the central part (32) of the clamp (100) having notches (37) in which the core (lb) of the jaw (1) and which immobilize   the central part (32) perpendicular to the core (lb).