AU427669B2 - Automotive disc brake - Google Patents

Description

27,67 6171 This invention is generally concerned with a

hydraulic brake system of a motor vehicle and has a

particular reference to a disc brake for use in the brake system.

The disc brake in which the improvements according

to this invention are to be incorporated is disclosed in

United States Patent No. 3,245,500.

The disc brake of the disclosed type uses a

braking disc which is rotatable with a wheel of the motor

vehicle and a hydraulic cylinder and which is secured to a

stationary part adjacent to one side of the braking disc.

Two opposed pistons are axially slidably fitted in the cylinder bore of the hydraulic cylinder, defining a fluid

chamber therebetween. The fluid chamber communicates with a brake pedal operated master cylinder or other source of

pressurized fluid and, when the brake pedal Is depressed, the fluid under pressure is supplied to the fluid chamber for urging the pistons apart. A pair of friction pad assemblies are provided, one of which is interposed between the hydraulic cylinder and the adjacent face of the braking

disc and the other is positioned

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2767 6 /7 adjacent the opposite face of the braking disc. The two pistons are respectively associated with the two friction pad assemblies in such a manner that one piston is in abutting engagement with one friction pad assembly to directly move the assembly toward the braking disc and the other piston is mechanical- ly connected to the other friction pad assembly so as to move this assembly through the mechanical connection toward the disc. Such mechanical connection is provided by a yoke which is connected to the indirectly actuated friction pad assembly and on which the piston associated with the indirectly actuated friction pad assembly bears when moved by the pressurized fluid supplied into the fluid chamber. The yoke is provided with a central opening which is adapted to accommodate an adjacent arcuate portion of the braking disc and to form spaced side edges which are parallel to the axis of the braking disc. Two opposed grooves are formed in the sides of an extension of the stationary hydraulic cylinder and receive the respective side edges of the opening in the yoke for slidably guiding the yoke in a direction parallel to the axis of the-disc.

The friction pad assemblies are forced against both faces of the braking disc when the pistons are

3- 427 669 fluid and, moved apart by means of the pressurized is exerted,/O the this occurs a braking torque when when this occurs, traction applied- due to the tracti friction pad assemblies torque on instance, the braking thereto. In this is friction pad assemblies the indirectly actuated in turn, transfers the taken by the yoke which, hydraulic cylinder. The torque to the stationary of only to carry the movment yoke is thus used not friction pad indirectly actuated the piston to the exerted At ssembly but to bear the braking torque S this pad assembly. and to stream- For simplicity of construction it is evidently the operation of the brake, however, line bearing be freed of a duty of desirable that the yoke serve the and permitted to solely the braking torque piston to the the movement of the purpose of carrying friction pad assembly. indirectly actuated the side edges which are n iprovision, moreover, of of in the opposed grooves in the extension received by a hydraulic cylinder is reflected the stationary diameter of the hydraulic relatively large outside which are encountered cylinder and by restrictions the yoke during production. in bending or press-machining of this invention It is, therefore, a primary object -ncrid 4 inwhiCh- to provide a disc brake

4 6 receiving the braking the yoke is freed of the duty of pad assemblies and torque on either of the friction the purpose of accordingly permitted to solely serve the pistons to the carrying the movement of one of The disc indirectly actuated friction pad assembly. thus features a brake according to this invention operation. simplified construction and streamlined the As a means to achieve this particular object, support invention proposes to incorporate a stationary hydraulic cylinder structure which is connected to the or to any me~aib-el stationary member of the The support structure is provided ,.motor vehicle. side with an opening defining opposed internal directly and faces which confront side edges of the which indirectly actuated friction pad assemblies against the consequently bear at their side edges structure when the opposed side faces of the support the faces friction pad assemblies are forced against on the of the braking disc. The braking torque transferred friction pad assemblies are in this manner to the stationary support structure. The stationary hydraulic cy- support structure may be secured to the linder where the hydraulic cylinder is f -the-ype motor 4e4a-4-is fast on a stationary member of the bottom vehicle. Where the hydraulic cylinder having a

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27,676171 wall is movable, the support structure may be secured directly to the stationary member of the motor vehicle. In this instance, means may be provided which is adapted to support and guide the hydraulic cylinder. A secondary object of this invention is to provide a disc brake ef the deseribcd tse from which the cooperating side edges and grooves provided for slidably guiding the yoke can be removed where desired thereby to reduce the outside diameter of the hydraulic cylinder and to facilitate beiding or press-machining of the yoke during production. A further secondary object of this invention is to provide a disc brake in which arrangement¢ are made so that an easy access to the friction pad assemblies is provided to facilitate inspection and replacement of the friction pad assemblies. This will prove advantageous for timely and easy maintenance and servicing of the disc brake. Some practical forms of the disc brake in accordance with this invention are illustrated by way of example in the accompanying drawings 3 in which: Fig. I is a view illustrating in section in the left.half and in plan in the right half one form of the disc brake according to the invention; Fig. 2 is a plan view, partly in sectionja portion

6- 427.669

216i467I of the disc brake shown in Fig.l; Fig. 3 is a cross sectional view of the disc brake shown in Fig. 1; Fig. 4 is similar to Fig. 1 but shows another form of the brake according to the invention; Fig. 5 is a/ccz~t3a view of the disc

brake shown in Fig. 4;and Fig. 6.is also similar to Fig. 1 but shows still another form of the disc brake according to the in- vention.

Reference is now made to the drawings and par-

ticularly to Figs. 1 to 3 showing a first preferred

embodiment of this invention in which the improve-

ments are made over the disc brake disclosed by the previously named issued United States Patent No.* 3,245,500. Though not shown, the disc brake is

used in conjunction with a brake-pedal operated master cylinder or other suitable source of fluid under pr essure so as to apply brakes to the %whexels of a motor vehicle. As illustrated, the disc brake includes a rota- table braking disc 10 which is mounted for rotation with the wheel through mechanical connections in- cluding, for instance, a member 11, bolts 12 and 13,

a wheel disc 14 and a rim .15 of the wheel. Adjacent

7 ~427. 669 br~r~6617 an inner face 9r. the br isc 10 is positioned a hydraulic cylinder 16 which, in this embodiment, is held stationary through rigid connection with a stationary structural member 11, through suitable fastening means such as a bolt 12. This Is best-seen in Fig. 3. As best seen in Fig. 1, the stationary hydraulic cylinder 16 is open at both ends and positioned to have its axis substantially parallel to the axis of the braking disc 10. An inner piston 17 an d an outer piston 18, respectively, are axially slidably fitted in the cylinder bore of the stationary hydraulic cylinder 16. The pistons 17 and 18 have opposed walls 17,a and 18a, respectively, so as to define a fluid chamber 19 therebetween. The fluid chamber 19 communicates with the master cylinder (not shown) so that fluid under pressure Is supplied thereto when the brake pedal is depressed, whereby the pistons 17 and 18 are urged apart from each other.

Directly and indirectly actuated friction pad assemblies are positioned adjacent the faces of the braking disc 10. The directly actuated friction pad assembly Is Interposed between the braking disc 10 and the stationary hydraulic cylinder 16 and comprises a friction pad 20 and a backing plate 21 to which the friction pad is bonded or otherwise

427. 6 69 is thus in abutting secured. The inner piston 17 plate inner face of the backing engagement with the -assembly actu ated friction pad 21. The indirectly the the opposite side of is positioned adjacent pad 22 and comprises a friction braking disc 10 and thereto.., The backing a backing plate 23 secured areas preferably have larger plates 21 and 23 may 22, as friction pads 20 and than the respective illustrated.- and the friction pad The stationary cylinder generally in a yoke 24 which is assemblies are housed at 24a is partly raised as a flat plate and which portion the adjacent arcuate (Fig. 3) to accommodate a suitably 10. The yoke 24 has of the braking disc forms a generally rectangular shaped opening 24b which to be received tongue 24c. Thca tongue 24c is adapted 18a- s0 that the bottom wall in the outer piston 18 end of the against the forward of the piston bears on- member 25 is mounted tongue 24C. An interlocking 23 to the backing plate the yoke 24 and connected friction pad assembly, of the indirectly actuated yoke 24. interlocked with the which is consequently are numerals 26 and 261 Designated by reference. between the hydraulic sealing rings which are-mounted -ist0ons -17. -and- 18.- cylinder 16 and the -two-

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2i,67 6v' When, now, the brake pedal is depressed and the

fluid under pressure is supplied from the master cy-

linder into the fluid chamber 19 between the opposite walls 17a and 18a of the inner and outer pistons 17 and 18, respectively, then the pistons are moved

apatt from each other by means of the fluid pressure. The inner piston 17 thus presses upon the backing plate 21 of the directly actuated friction pad assembly, forcing the friction pad 20 against the braking disc 10. The outer piston 18, on the other hand, -is moved away from the inner piston 17 and bears upon the forward end of the tongue 24c of the yoke 24. The yoke 24 is accordingly moved in the

direction of movement of the outer piston 18 with the result that the indirectly actuated friction pad assembly is moved toward the braking disc The braking disc 10 is in this manner powerfully

gripped by the two friction pads 20 and 22, to apply

brake to the wheel. According to this invention, now, a support structure 27 is provided, which is securely mounted

on the stationary hydraulic cylinder 16 by suitable fastening means such as bolts 28 and 28'. The sup-

port structure 27 has formed therein an opening 29 which is so configured as to substantially follow

427,6 69 the out line of tkhe Iricticn 7a aa014 to meae therein the Pad as2b~Ies as CI~yse in 11 1g. 2.

The opening 29 mzay isiclcde tuoc~ae 011d Prc Ov

29a and 29b receiving tte side ed~es Gf the brazng

plates 21 and 23 of the dilrectly gad imdirectly ata friction pad aSSezblieS, rL-ective1ly, so that the pad assemblies are guideed t~e z-,ed tG-Wzrd ad WaY

fromn the braking disc 10.- ft~e sullmrt structure 27

may also have forn-ed tbereim a Slnt zo W-hichi s adapted to acceo Dlate the ajjazent zarccate ;crticfl of th6 braking disc Vfnen the friction Pad e fcrced 01slis

against the faces of the bTra:,-dM dln- Z=I" !aki3d-

action, the pad asse--blies are s-ubjectzd tv IC-Mntlm due to the braking torque ELppLie-d t!2Tzt0 nrc the

braking disc and, as a result, t~h~z 7Lates 21

and 23 are forced againsx eithezr of thO stcff ledges

forming the opening 29- The- t7ra-I-nZ tar -e is thu

taken by the support structUre 2' an:d is ~se therethrotlgh to the stationary hydra--lac zeylizfzr f the yoke 2Yisolated frc= the tzarq-e -Ay instant. The yoke 24 is in tthis e Zzzr tted to

lend itself to solely carryizg the =zv=-t Of e

outer piston 18 to the imdizectly zete itizn

pad assemnbly.

axial having a width -in an if desired. a slot 31 thickness of the the combined axial direction related to may be disc_ and the two friction pad assemblies braking provide a visual in the support structure 27 so as. to formed of the pad assemblies to facilitate inspection access to the are found When the friction pads pads and backing plates. the friction become deteriorated, to have worn out or simply by replaced with new ones pad assemblies can be the support unscrewing the bolts 28 and 28' to remove cylinder 16. structure 27 from the to this disc brake according Another form of the modified in Figs. ~4and 5. This Invention is -illustrated to the essentially similarly disc brake functions the disc brake. previously described.from 4iand 5 thus also includes The disc brakeoof Figs. assemblies actuated friction pad directly and indirectly disc of a rotatable braking surmounting both sides comprises a friction pad assembly The directly actuated the indirectly backing plate 21, while friction pad 20 and a friction pad assembly comprises a actuated friction pad of 23, similarly to the counterparts 22 and a backing plate 32 is passed 1 to 3. A guide pin the disc brake of Figs. 21 in the backing plates through apertures formed

427. 6 6 9

0 1r and 23, guiding the friction pad assemblies when the pad assemblies are moved toward and away from the. brak-

ing disc.

In this modified form of the disc brake, a hy-

draulic cylinder which is now represented by numeral

33 is positioned adjacent to/inner face of the back-

ing plate 21 of the directly actuated friction pad assembly. Working in the cylinder 33 is the piston, which is sealed by a sealing ring 37 housed in an annular groove in the cylinder bore and which is in abutting engagement with the backing pla~te 21. Be- tween the bottom wall of the cylinder 33 and an outer fdce of the 4iner piston 35 is defined a fluid chamber 36 which communicates with the master cylinder to receive therefrom fluid under pressure when the brake pedal is depressed. The pressurized fluid supplied into the fluid chamber 36 acts upon the cy- linder 33 and the piston which are consequertly moved apart from each other. A s-lln; ing 37 may be rnunted betw~cn the cylinder

Md t6he wall of the inner pitOn

Designated by reference numeral 38 is dust-proofing seal means which may be provided at the innermost ends of the cylinder 33 and the 4+er piston 35 so as to preclude entrance of dust into the cylinder.

-13 427.6 69 friction pad assemblies The cylinder and the sub- 39. The yoke 39 is are encased in a yoke edges opened to form lQngthwise stantially centrally outer face of the bottom 39a and 39b facing the of the 33 and the outer face wall 34 of the cylinder indirectly actuated friction back plate 23 of the when the cy- pad assembly. With this arrangement, from the piston linder 33 is moved away chamber drawn into the fluid by the fluid pressure edge 36/bears at its outer face upon the lengthwise 0 the as to move the yoke in 39a of the yoke 39 so at its yoke 39, in turn, presses same direction. The 23 of the upon the backing plate lengthwise edge 39b pad assemnbly. The indirectly actuated friction pad assiemibly is con- indirectly actuated friction the outer fage of the sequently forced against friction pad braking-disc 10. The directly actuated braking hand, is moved to the assembly, on the other ine exerted thereto by the disc 10 by the pressure by toward the braking disc piston 35 which is forced the fluid chamnber 36. the fluid pressure in 4 and 5 pow further The disc brake of Figs. 33 by which the cylinder includes a support structure moved. is supported and guided when A stationary The support structure comprisea

:14 14 427.-6 69

27,67 6/71 support member 40 having formed therein recesses

41 and 41'. The recess 41 not only accommodates the arcuate portion of the braking disc 10 but-receives

therein the friction pad assemblies in a manner to

permit the pad assemblies to move in a direction

parallel to the axis of the braking disc 10.- The

recess 41', on the other hand, accommodates therein

the cylinder 33. More specifically, the recess 41

defines a pair of opposite side edges 41a and 41b

for abutting engagement with the sides of the

directly actuated friction pad assembly and a pair of

opposite side edges 41c and 41d for engagement with

the sides of the indirectly actuated friction pad

assembly, as shon./An +a is secured to the sup- port member 40 and extend$ toward the hydraulic cy-

linder 33. /l arm 42 has formed in its free end portion an aperture (not numbered) into which a guide

pin 43 is slidably inserted through a bushing 44

which may be made of elastic material such as rubber.

The guide pin 43 is directed in parallel.to the

direction of movement of the, cylinder 33. and rigidly

connected thereto. The pin 43 is herein illustrated as secured to the cylinder 33 through limbs 45 and

extending from the cylinder. The support member is rigidly secured to a suitable stationary member

15 427669

2167 6/71 suitable fastening 46 of the motor vehicle through 47 as seen in Fig. means such as for instance a bolt

in this With the support structure arranged forced manner, when the friction pad assemblies are brakes, the against the braking disc 10 to apply to bear against either pad assemblies are caused and 41d of the the side edges 41a and 41c or 41b

support member 40 depending-on the direction of

rotation of the braking disc. The braking torque

imparted to the friction pad assemblies due to

traction by the braking disc 10 is taken by the

support member 40 which, in turn, transfers the torque

motor vehice. to the stationary member 46 Lof the a duty The yoke 39 is therefore liberated from

of taking such braking torque during the braking

operation and is permitted to solely contribute to 33 to the in- carrying the movement of the cylinder

directly actuated friction pad assembly. the The use of the rubber bushing 44 to retain for efficient guide pin 43 will prove beneficial

movement of the cylinder 33 because of its elasticity direction that urges the guide pin 43 to return in.a guide pin has opposite to the direction in which the

been moved with: the cylinder by the fluid -pressure.

v

47 6 9 S'16

2*767 67 The space over the friction pad assemblies/e joei in the disc brake shown in Figs. 4 and 5 to

provide an easy access to the pad assemblies, the facilitating inspection and replacement of pad assemblies.- the pad assemblies can be removed and replaced with new ones simply by removing the such guide pin. 32 from the assemblies. Provision of open space over the pad assemblies will also prove advantageous for the purpose of dissipating the heat evolved in the friction pads and the braking disc due to friction therebetween. It will now be appreciated from the foregoing description that the first and second forms of the disc brake according to this invention are useful especially where a simplified construction and a streamlined smooth operation of the disc brake is a matter of concern. With the arrangements of the disc brake hereinbefore described, it is no longer necessary that the cylinder 16 or 33 be provided

with a guide groove to-engage the longitudinal in side edge of the central opening which is formed the yoke. This is advantageous not only for reduc- ing the outside diameter of the hydraulic cylinder outlines but for simplifying the. internal and extbrnal of the yoke. The yoke-thus features a compact

17 42 7. 6 69 construction and is adapled for being bent -or press- machined during production.

A primary feature of the disc brake according

to this invention is, as previously discussed' that

the yoke is not required to take the braking torque

on the friction pad assemblies. This feature can

be maintained even in a disc brake using a yoke which

slides on a stationary member because no: torque is

transferred to the yoke through the sliding engagement

between the yoke and the stationary member. An

example of/Athe disc brake of this character is illust-

rated -in Fig. 6.

The disc brake shown in Fig. 6 is shown, by way

of exannple, as a modification of the disc brake of

Figs. I to 3 and, as such, like reference numerals

are assigned to corresponding members.

In the disc brake herein shown, the outer piston

18 is shown to be inverted to define the fluid chamber

19 between its cavity and the opposite wall of the

inner piston 17 and to-bear against the internal

lengthwise edge of the yoke 24 at 'its outermost wall

18a. The support structure 27 is now provided with

a guide groove 49 which extends in a direction sub-

stantially parallel to the axis of the braking disc

Likewise, tlie yoke 24 has formed on its external

18 427-669

27,671,1 side edge a straight sliding surface 50 which is received in the guide groove 49. The yoke 24 is thus guided by the groove 49 when moved in a direction parallel to the axis of the braking disc 10w In this instance, the braking torque on the friction pad assemblies is transferred to the stationary hydraulic cylinder 16 through the support structure 27 arid, as a consequence, the yoke 24 is completely isolated from such torque.

-19-427.6 69

Claims (1)

1. 27.,7 6/71 The claims defining the invention are as follows:

   i. A disc brake for a motor vehicle hydraulic brake

   system, comprising a braking disc rotating with a wheel of

   the motor vehicle, a hydraulic cylinder having an inner

   piston and an outer piston slidable in opposite directions

   which are substantially parallel to an axis of said braking

   disc, said pistons defining a fluid chamber into which

   pressurized fluid is supplied when a braking action is to

   be initiated, directly and indirectly actuated friction pad

   assemblies positioned adjacent to both faces of said braking

   disc, said directly actuated friction pad assembly being in

   abutting engagement with said inner piston and thereby

   forced against said braking disc when the inner piston is

   moved by said pressurized fluid, a yoke movable in a direction

   parallel to said axis of the braking disc and carrying the

   movement of said outer piston to said indirectly

   actuated friction pad assembly for forcing the indirectly

   actuated friction pad assembly against said braking:dise

   when said outer piston is moved by said pressurized fluid,

   and a stationary support structure associated with said

   hydraulic cylinder and having opposed internal side faces

   facing side edges of said friction pad assemblies, said

   427.6 69

   21~6 r, .6'll their side edges friction pad assemblies bearing at passing a braking against one of said side faces for to said stationary torque on said friction pad assemblies are forced support structure when the assemblies against said braking disc. 1, wherein 2. A disc brake as claimed in Claim stationary and said said hydraulic cylinder is held hydraulic cylinder.- support structure is secured to the 2, wherein 3. A disc brake as claimed in Claim in said side faces said support structure has formed of said side edges. grooves receiving at least portions of said friction pad assemblies. 2, wherein 4. A disc brake as claimed in Claim an aperture said support structure has formed therein for provid- located over said friction pad assemblies ing a visual access to the pad assemblies. 2, wherein A disc brake as claimed in Claim a guide said hydraulic cylinder has formed therein substantially groove extending in a direction said braking disc for Parallel t o said axis of edges of said yoke. slidably receiving external side 6. A disc brake as claimed in Claim 2, connected to said wherein said support structure is least one bolt. hydraulic cylinder by means of at wherein 7. A disc brake as cl.aimed in Claim 1,

   2 1 427. 66 9

   27,67 61',7 said hydraulic/is combined with said outer piston

   into an integral structure. 8. A disc brake as claimed in Claim 7, wherein

   said suppprt-structure comprises a stationary support member secured to a stationary member of the motor .vehicle, an arm secured to said support member

   and having an aperture formed at its free end portion, and a guide pin secured to said integral structure

   and extending in a directidn parallel to the direction of movement of said integral structure, said guide pin being slidably passed through said aperture in said arm for supporting and guiding said integral

   structure when said outer piston is moved.

   9. A disc brake as claimed in Claim 8, wherein

   said support structure further comprises a rubber

   bushing which is secured in said aperture in said arm. lop A disc brake as claimed in Claim 8, wherein

   said yoke is open over said friction pad assemblies. 11. In a disc brake for a motor vehicle by-

   draulic brake system including a braking disc rotatable with a driving wheel of the motor vehicle, a hydraulic cylinder having/ i _d outer pistonsslidable in opposite directions which are parallel to an axis of said braking disc, said pistons being moved in said'

   22- 427,66 9

   Z6 7 6 f7 directions by pressurized 'fluid supplied therebetween, directly and indirectly actuated friction pad assemblies which are positioned adjacent to both faces of said braking disc, said directly actuated friction pad assembly being in abutting engagement with said inner piston and thereby forced against said braking disc when the inner piston is moved by said pressurized

   fluid,. and a yoke movable in a direction parallel to said axis of said braking disc and carrying the movement of said outer piston to said indirectly r_ ,actifated frict ion pad assembly for forcing the indirectly actuated friction pad assembly against said braking disc when said outer piston is moved

   by said pressurized fluid, the improvement com- prises provision of a stationary support structure /p~it~n~drcltiv t~said hydraulic cylinder and having opposed internal side faces facing side edges of -said friction pad assemblies, said friction pad

   assemblies bearing -at their side edges against one of said side faces for passing a braking torque on said friction pad assemblies to said stationary sup- port structure when the pad assemblies are forced against said-braking disc. 12. A disc brake as constructed and arranged substantially as described herein with reference

   427. 6 69

   276 7671 to the accompanying drawings.

   DATMD this 14th day of April, 1971.

   iIsS~Iq4 13T3"R C01M?-ItNY LII-T7D

   Patent Rttorneys for the Ao-oicant: F. B. RIC- CO.

   427. 6 9

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   427. 669

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   A27669