GB2125127A - Improvements relating to disc brakes - Google Patents

Improvements relating to disc brakes Download PDF

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Publication number
GB2125127A
GB2125127A GB08320475A GB8320475A GB2125127A GB 2125127 A GB2125127 A GB 2125127A GB 08320475 A GB08320475 A GB 08320475A GB 8320475 A GB8320475 A GB 8320475A GB 2125127 A GB2125127 A GB 2125127A
Authority
GB
United Kingdom
Prior art keywords
brake
disc
friction pad
pad assembly
annular
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB08320475A
Other versions
GB2125127B (en
GB8320475D0 (en
Inventor
Carl Meyer
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ZF International UK Ltd
Original Assignee
Lucas Industries Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Lucas Industries Ltd filed Critical Lucas Industries Ltd
Publication of GB8320475D0 publication Critical patent/GB8320475D0/en
Publication of GB2125127A publication Critical patent/GB2125127A/en
Application granted granted Critical
Publication of GB2125127B publication Critical patent/GB2125127B/en
Expired legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D65/00—Parts or details
    • F16D65/02—Braking members; Mounting thereof
    • F16D65/04—Bands, shoes or pads; Pivots or supporting members therefor
    • F16D65/092—Bands, shoes or pads; Pivots or supporting members therefor for axially-engaging brakes, e.g. disc brakes
    • F16D65/095—Pivots or supporting members therefor
    • F16D65/097—Resilient means interposed between pads and supporting members or other brake parts
    • F16D65/0973—Resilient means interposed between pads and supporting members or other brake parts not subjected to brake forces
    • F16D65/0974—Resilient means interposed between pads and supporting members or other brake parts not subjected to brake forces acting on or in the vicinity of the pad rim in a direction substantially transverse to the brake disc axis
    • F16D65/0975—Springs made from wire
    • F16D65/0976—Springs made from wire acting on one pad only
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D55/00—Brakes with substantially-radial braking surfaces pressed together in axial direction, e.g. disc brakes
    • F16D55/02—Brakes with substantially-radial braking surfaces pressed together in axial direction, e.g. disc brakes with axially-movable discs or pads pressed against axially-located rotating members
    • F16D55/22—Brakes with substantially-radial braking surfaces pressed together in axial direction, e.g. disc brakes with axially-movable discs or pads pressed against axially-located rotating members by clamping an axially-located rotating disc between movable braking members, e.g. movable brake discs or brake pads
    • F16D55/224—Brakes with substantially-radial braking surfaces pressed together in axial direction, e.g. disc brakes with axially-movable discs or pads pressed against axially-located rotating members by clamping an axially-located rotating disc between movable braking members, e.g. movable brake discs or brake pads with a common actuating member for the braking members
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D65/00—Parts or details
    • F16D65/0006—Noise or vibration control
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D65/00—Parts or details
    • F16D65/02—Braking members; Mounting thereof
    • F16D65/04—Bands, shoes or pads; Pivots or supporting members therefor
    • F16D65/092—Bands, shoes or pads; Pivots or supporting members therefor for axially-engaging brakes, e.g. disc brakes
    • F16D65/095—Pivots or supporting members therefor
    • F16D65/097—Resilient means interposed between pads and supporting members or other brake parts
    • F16D65/0971—Resilient means interposed between pads and supporting members or other brake parts transmitting brake actuation force, e.g. elements interposed between brake piston and pad

Landscapes

  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Braking Arrangements (AREA)

Abstract

The brake has a caliper member 16 which straddles a brake disc 10 and is supported on a carrier member 2 so as to be movable transversely of the brake disc 10; an actuating piston 20 in the caliper member 16 acts on a first friction pad assembly 26 arranged between the actuating piston 20 and the brake disc 10; on the other side of the brake disc a second friction pad assembly 28 is supported on an annular abutment formed by a Belleville washer 44 which, when unloaded, abuts the second friction pad assembly 28 with one annular edge only. As shown, Belleville washer 44 is received in an annular groove 42 and even in completely flattened condition (upon the actuating piston 20 being subjected to a pressure of the order of 20 to 40 bar) projects slightly from groove 42 towards friction pad assembly 28. <IMAGE>

Description

SPECIFICATION Improvements relating to disc brakes The present invention relates to a disc brake, for use in a motor vehicle.
In particular, the present invention relates to a disc brake comprising a caliper member which straddles a brake disc and is supported on a carrier member so as to be movable transversely of the brake disc. An actuating piston is slidably supported on one side of the brake disc in the caliper member, to act upon a first friction pad assembly which is arranged between the actuating piston and the brake disc. A second friction pad assembly which is arranged on the other side of the brake disc, is supported on an annular abutment on the caliper member at least approximately coaxially with the actuating piston.
The caliper member of a disc brake of this type can be supported on the carrier member in such a manner that it is slidable in a straight line transversely of the brake disc in parallel with its original position; this may also be referred to as a sliding caliper disc brake. The caliper member, however, can also be pivotable around an axis, which is at least approximately parallel to the brake disc, in order to carry out movements to and from the brake disc. Brakes of this type are also termed as swivel caliper disc brakes. In both embodiments of disc brake of the generic type, only the friction pad assembly arranged on the one side of the brake disc is pressed directly against the brake disc upon braking by the actuating piston.The caliper is displaced by the reaction force thus acting upon it in such a manner that the second friction pad assembly is also pressed against the brake disc.
In contrast with such sliding or swivel caliper disc brakes, fixed caliper disc brakes have a stationary caliper which has actuating devices on both sides of the disc brake, said actuating devices acting directly on one friction pad assembly each.
When vehicles with sliding or swivel caliper disc brakes are braked gently from a high speed of, for example, 200 km/h, low frequency braking noise can occur, also described as judder, which makes itself noticeable to passengers in the interior of the vehicle as unpleasant vibration or throbbing. The cause of judder is not yet clear; however, it is certain that this phenomenon, often observed in sliding caliper disc brakes, either does not occur in fixed caliper disc brakes or at the most occurs to a considerably lesser and not particularly disturbing degree. It was therefore obvious that the cause of judder be sought in that area in which the sliding caliper is slidably carried on the carrier member. However, up until now, those measures which have been applied in this area have not effectively combated judder.In those cases where the cause for judder in sliding or swivel caliper disc brakes of the type described at the outset, has been sought in the area of the friction pad assemblies, it was thought that it lay in an asymmetry of the forces acting upon the mutually averted braking surfaces of the brake discs. Asymmetry of this kind can, for instance, be caused by uneven resilient deformation of the friction pad assemblies, especially when the actuating piston acts upon the one friction pad assembly with an annular end face while the other friction pad assembly is supported over a large area on the caliper.
In order to avoid the differing support given to the opposing friction pad assemblies in a known disc brake of the type described at the outset (DE-OS 25 16 323), whose actuating piston has an annular end face abutting the one friction pad assembly, an abutment is arranged on the caliper member, being coaxial with and having the same form and surface area as the annular end face; this abutment acts as support for the other friction pad assembly. However, at best only certain noises could be reduced but not judder which occurs above all when a vehicle is gently braked from a high speed, for instance on leaving a motorway, so that the pressure acting upon the actuating piston over a long period of time does not exceed 1 5 bar.
Another disturbing vibration phenomenon which often occurs in disc brakes of different types and which has a considerably higher frequency than judder is brake squealing. In order to counteract this, intermediary members of the most diverse kind have been arranged between actuating piston and the adjacent friction pad assembly, which members are able to absorb high-frequency vibrations at least to a certain degree. Thus, a fixed caliper disc brake is known (FR-PS 13 30 418, Fig. 8) in which a cylindrical, resilient block is embedded in each actuating piston such that the piston does not directly touch the adjacent friction pad assembly and the actuating forces are transmitted exclusively via this block to the friction pad assembly.Instead of a uniform resilient block of this type, a resilient cushioning element can be arranged between each actuating piston and the adjacent friction pad assembly (FR-PS 13 30 418, Fig. 9), said resilient cushioning element having a rubber layer vulcanised between two metal plates. Attempts to prevent judder in sliding or swivel disc brakes with such assemblies were less successful.
An aim of the present invention is therefore to more effectively counter judder in a disc brake of the type described at the outset, that is to prevent or at least considerably moderate low-frequency vibrations during long continuous and light brake actuation.
According to the present invention there is provided a disc brake for motor vehicles comprising a caliper member which straddles a brake disc and is supported on a carrier member so as to be movable transversely of the disc brake, an actuating piston being arranged on one side of the brake disc in the caliper member to act upon a first friction pad assembly which is arranged between the actuating piston and the brake disc, a second friction pad assembly being arranged on the other side of the brake disc and being supported on an annular abutment which is located on the caliper member at least approximately coaxially with the actuating piston, the abutment being formed by a Belleville washer which, when loaded, abuts the second friction pad assembly with an annular edge only.
Just as the causes of judder are still unclear, neither is it yet completely clear why a Belleville washer arranged in accordance with the present invention as an abutment for the second friction pad assembly, should prevent judder or at least it to an extent which is no longer disturbing, while elastomeric elements and other resilient intermediate layers between the second friction pad assembly and the caliper member should remain without any substantial influence on judder. It is to be assumed that the typical degressive spring characteristic of the Belleville washer is at least partially responsible for the success of the measure according to the present invention.
In a preferred embodiment of the present invention, the Belleville washer is embedded in an annular groove in the caliper member and even in completely flattened condition, projects slightly from this towards the second friction pad assembly.
Preferably, the Belleville washer in unloaded condition is considerably flatter than the normal commercial Belleville washers of the same diameter. In disc brakes of usual passenger vehicle size, a Belleville washer which has a travel from unloaded to fully flattened condition in the order of between 0.10 and 0.15 mm has been particularly effective.
Preferably, the Belleville washer has a characteristic such that it is completely flattened when the actuating piston is subjected to a pressure in the order of 20 to 40 bar, preferably 28 to 32 bar.
it is also expedient if the Belleville washer, when unloaded, abuts the second friction pad assembly with one annular outer edge of larger diameter and the caliper member with one annular inner edge of smaller diameter.
If the brake is a disc brake whose actuating piston - in a manner known per se - has an annular end face facing the brake disc, then in accordance with a particularly advantageous development of the present invention, the diameter of the annular edge of the Belleville washer abutting the second friction pad assembly when unloaded corresponds at least approximately to the outer diameter of the annular face of the actuating piston and the diameter of the annular edge abutting the caliper member corresponds at least approximately to the inner diameter of said annular face.
The present invention will now be further described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a sliding caliper disc brake in crosssection along the axis of the corresponding brake disc, Fig. 2 is the view of the brake in axial direction corresponding to the arrow II in Fig. 1, and Fig. 3 is the part section Ill-Ill in Fig. 2.
According to Fig. 1, a carrier member 12 is fixed adjacent to a motor vehicle brake disc 10 on the inboard side - with respect to the vehicle of said brake disc. Two parallel guide pins 14 are mounted on the carrier member 12, which extend at right angles to the braking surfaces of the brake disc 10. The guide pins 14 carry a caliper member 1 6 which overlaps the brake disc 10 and has an hydraulic actuating cylinder 1 8 with an actuating piston 20 on the vehicle-inboard side. The actuating piston 20 has the form of a cup opening towards the brake disc 10 with a plane annular end face 22.
On both sides of the brake disc 10, in the carrier member 12 and on the caliper member 16 respectively, a pair of friction pad assembly guides 24 are formed which carry between them a first vehicle-inboard friction pad assembly 26 and a second vehicle-outboard friction pad assembly 28 respectively. Each of the friction pad assemblies 26 and 28 has a stiff backing plate 30, made for example of steel, which is slidably guided by means of laterai shoulders 32 which engage on the upper side of corresponding friction pad assembly guides 24, allowing for movement in the direction of the axis A of the actuating cylinder 1 8.
A pad 34 of friction material is mounted on each backing plate 30 so as to leave the shoulders 32 and an upper portion of the backing plate free of friction material. A depression spring 36 is fixed pivotably on this upper portion on a rivet 38. The depression spring 36 engages upwardly against the caliper member 1 6 and thereby presses the shoulders 32 of the corresponding friction pad assembly 26 or 28 respectively from above against the corresponding friction pad assembly guides 24.
On the vehicle-outboard end of the caliper member 16, two limbs 40 are formed which extend parallel to a radius of the brake disc and which have on their vehicle-inboard side a part annular groove 42 in which a Belleville washer 44 is inserted as an abutment for the second friction pad assembly 28.
When unloaded, the Belleville washer 44 has a rhombic cross-section which deforms to a square when the Belleville washer is completely flattened -- which is the case when the brake fluid pressure in the actuating cylinder 1 8 is approximately 30 bar. In Figs. 1 and 3 the rhombic form of the cross-section of the unloaded Belleville washer 44 is grossly exaggerated; in reality, the angles at the four corners of the rhombic crosssection are only two to three degrees larger or smaller than a right angle. Thus, the Belleville washer 44, having for example an outer diameter of 48 mm, will already be completely flattened after an axial deformation in the order of 0.10 to 0.15 mm.
The thickness of the Belleville washer 44 is rather greater than the depth of the annular groove 42; the Belleville washer 44 thus still projects slightly from the groove 42, even when it is in completely flattened condition so that, in every load condition, it forms an annular abutment for the backing plate 30 of the second friction pad assembly 28. In each case, the Belleville washer 44 bridges the gap between the two limbs 40 and combines them into a unit with the effect of absorbing vibration. The diameter of the circular outer edge 46 of the Belleville washer 44 conforms at least approximately with the outer diameter of the actuating piston 20; in corresponding manner, the diameter of the circular inner edge 48 of the Belleville washer is at least approximately the same as the inner diameter of the actuating piston.
The greater the outer diameter of the Belleville washer 44, the greater its thickness. In the following, several examples of usual commercial actuating pistons 20, whose outer diameters are represented by 'DK', are listed alongside suitable Belleville washers 44 whose outer diameters are represented by 'Dt' and whose thicknesses are represented by's': Dk Dt s 48 48 2.5 mm 54 54 3.2 mm 60 62 5.0 mm In each case, the Belleville washer 44 is constructed such that, at a pressure in the actuating cylinder 18 of 1 5 bar, it deforms by about 0.05 mm and at a pressure of 30 bar achieves a deformation of 0.1 mm, being thus completely or almost completely flattened.

Claims (8)

1. A disc brake for motor vehicles comprising a caliper member which straddles a brake disc and is supported on a carrier member so as to be movable transversely of the brake disc, an actuating piston being arranged on one side of the brake disc in the caliper member, to act upon a first friction pad assembly which is arranged between the actuating piston and the brake disc, a second friction pad assembly being arranged on the other side of the brake disc and being supported on an annular abutment which is located on the caliper member at least approximately coaxially with the actuating piston, the abutment being formed by a Belleville washer which, when loaded, abuts the second friction pad assembly with an annular edge only.
2. A disc brake as claimed in claim 1, in which the Belleville washer is embedded in an annular groove of the caliper member and, even in completely flattened condition, projects slightly from this towards the second friction pad assembly.
3. A disc brake as claimed in claim 1 or 2, in which from unloaded to completely flattened condition the Belleville washer has a travel in the order of 0.10 mm to 0.15 mm.
4. A disc brake as claimed in claims 1 to 3, in which the Belleville washer is completely flattened when the actuating piston is subjected to a pressure in the order of 20 to 40 bar.
5. A disc brake as claimed in claim 4, in which the Belleville washer is completely flattened when the actuating piston is subjected to a pressure of 28 to 32 bar.
6. A disc brake as claimed in any one of claims 1 to 5, in which the Belleville washer, when unloaded, abuts the second friction pad assembly with one annular outer edge of larger diameter and the caliper member with one annular inner edge of smaller diameter.
7. A disc brake as claimed in claim 6, whose actuating piston has an annular face facing the brake disc, in which the diameter of the annular edge of the Belleville washer abutting the second friction pad assembly, when unloaded, corresponds at least approximately to the outer diameter of the annular face of the actuating piston and the diameter of the annular edge abutting the caliper member corresponds at least approximately to the inner diameter of said annular face.
8. A disc brake for motor vehicles constructed and arranged substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.
GB08320475A 1982-07-30 1983-07-29 Improvements relating to disc brakes Expired GB2125127B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19823228602 DE3228602A1 (en) 1982-07-30 1982-07-30 DISC BRAKE

Publications (3)

Publication Number Publication Date
GB8320475D0 GB8320475D0 (en) 1983-09-01
GB2125127A true GB2125127A (en) 1984-02-29
GB2125127B GB2125127B (en) 1985-09-25

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ID=6169777

Family Applications (1)

Application Number Title Priority Date Filing Date
GB08320475A Expired GB2125127B (en) 1982-07-30 1983-07-29 Improvements relating to disc brakes

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DE (1) DE3228602A1 (en)
GB (1) GB2125127B (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3621507A1 (en) * 1986-06-27 1988-01-14 Teves Gmbh Alfred Brake shoe for a spot-type disc brake

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4140279C1 (en) * 1991-12-06 1993-04-29 Mercedes-Benz Aktiengesellschaft, 7000 Stuttgart, De
FR2709522B1 (en) * 1993-09-02 1995-10-20 Peugeot Braking device for motor vehicle.

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3621507A1 (en) * 1986-06-27 1988-01-14 Teves Gmbh Alfred Brake shoe for a spot-type disc brake

Also Published As

Publication number Publication date
DE3228602A1 (en) 1984-02-02
GB2125127B (en) 1985-09-25
GB8320475D0 (en) 1983-09-01

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PCNP Patent ceased through non-payment of renewal fee