Abstract:
The invention involves a spring for a floating caliper disc brake with a frame jaw caliper which, in the middle section of its axial outer edge, has a side window and on both sides of this window openings for an axial bracket of a fixed brake anchor plate. The caliper is displaceably and axially mounted on the bracket of the brake anchor plate. Brake linings are attached on both sides of the disc brake to the bracket of the brake anchor plate in an axial, displaceable manner and are also overlapped by the frame jaw caliper. The invention includes a onepiece curved wire holding spring, the middle section of which is releasably attached to the axial outer brake lining and which has two springs arms that are essentially placed in a contrary tangential direction to the middle section. The holding spring biases the frame jaw caliper radially against the brake anchor plate and biases the axial outer brake lining axially against the inside of the outer edge of the frame jaw caliper.

Description:
TECHNICAL FIELD 
     This invention generally relates to disc brakes and more particularly relates to a spring configuration for a floating-caliper disc brake. 
     BACKGROUND OF THE INVENTION 
     A spring configuration of a floating-caliper disc brake is known from DE 33 36 302 A1 where the floating caliper is a fist-type caliper without frame. A retaining spring bent in one piece from wire is riveted to the back side of the axially outer brake pad and is moreover secured against twisting in the plane of the brake disc. Two free spring arms support themselves axially on the outside of the fist leg and secure with bias the brake pad axially relative to the fist leg. One sole spring arm designed as parallel spring extends tangentially towards one side and supports itself on a carrier arm of the brake carrier in order to secure with bias the brake pad radially relative to the brake carrier. The radial securing with bias of the fist-type caliper relative to the brake carrier is done indirectly in that the outer brake pad is coupled to the fist leg of the fist-type caliper by means of a catch. 
     Regardless of the fact that such a spring configuration cannot be used with a floating-caliper disc brake with a fist-and-frame-type caliper there are further disadvantages. The fact that there is provided but one sole spring arm for the radial securing with bias involves the introduction of a torque into the brake pad in the plane of the brake disc whereby the brake pad located on the side opposite the sole spring arm tends to lift off from the carrier arm of the brake carrier. Efficient control of clattering noises will thus not be achievable. Moreover, the retaining spring is undetachably connected to the brake pad and will therefore have to be exchanged together with the worn brake pad. 
     Another spring configuration of a floating-caliper disc brake with a fist-type caliper without frame is known from DE 43 31 633 A1. A retaining spring bent in one piece from wire is detachably connected with the axially outer brake pad and secures with bias the brake pad radially relative to the brake carrier by means of two lateral spring arms. The fist-type caliper is also indirectly secured with bias relative to the brake carrier thanks to the fact that the brake pad is coupled with the fist leg of the fist-type caliper via two axially projecting catches. Projecting on the back side of the carrier plate of the brake pad are two notched nails disposed at a certain distance on top of each other which receive a lozenged looping formed in the central area of the retaining spring. For assembly and disassembly, the retaining spring must be twisted by 90 degrees in the plane of the brake disc so that the retaining spring can be moved over the heads of the notched nails thanks to the bigger distance between the respective corners of the lozenged looping of the retaining spring. Regardless of the fact that it does not become evident from DE 43 31 633 A1 whether or not the spring configuration also secures with bias the outer brake pad axially relative to the outer floating-caliper leg, this spring configuration cannot be used with a type of floating-caliper disc brakes equipped with a fist-and-frame-type caliper. 
     It is an object of this invention to provide a suitable spring configuration for a floating-caliper disc brake equipped with a fist-and-frame-type caliper. 
     The spring configuration of the present invention provides a retaining spring which is bent in one piece from wire and which includes a central section, detachably connected with the axially outer brake pad, and two spring arms essentially projecting from the central section in opposite tangential directions and which both secure with bias the fist-and-frame-type caliper radially relative to the brake carrier and secure with bias the axially outer brake pad axially relative to the inside of the outer fist-and-frame-type-caliper leg. Such a spring configuration is particularly suited for a floating-caliper disc brake with a fist-and-frame-type caliper 
     In a preferred embodiment, a spring configuration is disclosed which is beneficial for a floating-caliper disc brake with a fist-and-frame-type caliper which, in the central area of its axially outer fist-and-frame-type-caliper leg, comprises a leg window and which, on both sides of this leg window, comprises apertures for an axial carrier arm each of the brake carrier stationarily connected with the chassis and which features a symmetrical design, particularly so with regard to a central plane extending transversely to the brake disc. In this embodiment the central section of the retaining spring is provided to be arranged essentially within the leg window of the outer fist-and-frame-type-caliper leg and the two spring arms of the retaining spring are provided to be disposed essentially on the outside of the outer fist-and-frame-type-caliper leg and each to reach with their outer end sections axially through the apertures provided in the fist-and-frame-type caliper for the carrier arms of the brake carrier and moreover to support themselves slidingly with radial bias on the undersides of the carrier arms of the brake carrier. 
     An advantageous embodiment of the spring configuration is disclosed having an easily manufactureable detachable connection of the retaining spring with the outer brake pad and the latter&#39;s axial pull support against the inside of the fist-and-frame-type-caliper leg. To this end, the central section of the retaining spring comprises a central part which is bent like a hairpin and the legs of which reach behind an enlarged, preferably axially outwards tapering head of a pin disposed on the outer brake pad and axially projecting therefrom into the leg window. Moreover, via corresponding connecting sections, the central part of the retaining spring is connected under axial tensile stress with a spring arm each of the retaining spring which axially support themselves on the outer fist-and-frame-type-caliper leg. To produce this detachable connection between the retaining spring and the brake pad, the central part of the retaining spring which is bent like a hairpin will just be slid with its open side in the radial direction onto the pin and engage the head from behind. An axially tapering shape of the head also enables another kind of assembly, with the hairpin-shaped central part axially being snapped onto the pin of the brake pad and with the legs of this hairpin-shaped central part temporarily being resiliently straddled apart. 
     An embodiment of the spring configuration is disclosed which provides the two legs of the hairpin-shaped central part each to pass over into a second leg bent like a hairpin into the opposite direction which passes over into an outer spring arm of the retaining spring by way of an essentially axially extending portion. This design enhances the elasticity of the central section of the retaining spring both in the tangential and axial directions, thereby facilitating both assembly and disassembly of the retaining spring. 
     Another variant of the spring configuration is disclosed which aims at a further facilitation with regard to the assembly of the retaining spring and permits a simpler configuration of the retaining spring. Here, the central section of the retaining spring is provided to have a tangentially extending central part whence, on both sides, a leg extends against the radial direction, with these two legs again each passing over into the spring arms of the retaining spring via an essentially axially extending portion. The two axial portions are designed so as to support themselves each with a section, preferably punctually, on the bottom side of the leg window and thus are connected with the spring arms of the retaining spring so that there is a tilting moment in the central section of the retaining spring which will pull the central part of the retaining spring outwards. 
     Also disclosed is an embodiment which provides the tangential central part of the central section of the retaining spring to be hung up behind a metal tongue which is fastened to the back side of the outer brake pad and is open preferably downwards, opening with a step-like expanded section. When mounting the retaining spring, in this case, the central tangential part of the retaining spring is inserted from below and disposed behind the metal tongue, with the retaining spring being swiveled around its longitudinal axis so that it supports itself with the respective sections on the bottom side of the leg window while simultaneously its tangential central part is moved in the radial direction on the back side of the metal tongue. The step-like expanded section of the metal tongue facilitates the assembly of the retaining spring in that it provides the retaining spring with a temporary support in a suitable intermediate position during its assembly. 
     An additional embodiment enables the retaining spring to be given a shape as simple as possible while its function is fully ensured although the predetermined geometrical conditions are relatively complicated due to the special type of a floating caliper. It is provided that the two spring arms of the retaining spring each support themselves in their central area against the radial direction and with their inner spring leg, which points to the central section, in the radial direction on an axial projection or recess provided on the frame of the fist-and-frame-type caliper. 
     Again, there are two beneficial variants in this respect. One embodiment provides that the central areas of the two spring arms of the retaining spring each are designed as spiral looping and each are supported on a cylindrical axially projecting pin disposed on the frame of the fist-and-frame-type caliper and that the inner spring legs of the two spring arms of the retaining spring support themselves on the upper side of an axially open groove-like recess in the frame of the fist-and-frame-type caliper. This design ensures a very reliable fitting of the retaining spring. On the other hand, it requires the existence of axially projecting pins on the frame of the fist-and-frame-type caliper which may be a disadvantage if the constructional space available in the axial direction is but of minimum size. 
     In a preferred design the central areas of the two spring arms of the retaining spring are designed as vertices pointing against the radial direction and being the vertices of two spring legs extending at an obtuse angle in respect of each other which support themselves on the bottom side, i.e. on the side pointing in the radial direction, of an axially open groove-like recess of the frame of the fist-and-frame-type caliper. Simultaneously, the respective inner spring legs of the two spring arms each support themselves on the upper side of this groove-like recess, i.e. on the side of the groove-like recess which points against the radial direction. The particular advantage of this design is that it needs less constructional space in the axial direction of the disc brake and that, moreover, the shape of the retaining spring is less complicated and thus easier to manufacture. 
     To ensure a reliable locking of the retaining spring in the axial direction of the disc brake in all situations an embodiment is disclosed wherein the free ends of the retaining spring which adjoin the outer end sections of the spring arms which reach through the apertures of the fist-type frame are bent so that they engage the inside of the frame of the fist-and-frame-type caliper from behind, thus locking the retaining spring axially on the fist-and-frame-type caliper. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a view of a spring configuration for a floating-caliper disc brake with a fist-and-frame-type caliper; 
     FIG. 2 is a view of a retaining spring; 
     FIG. 3 is a top view of the retaining spring of FIG. 2; 
     FIG. 4 is a side view of the retaining spring of FIG. 3; 
     FIG. 5 is a detail of an embodiment of a detachable connection of brake pad and retaining spring; 
     FIG. 6 is sectional representation of a detail of the spring configuration of FIG. 1; 
     FIG. 7 is a view of another embodiment of a spring configuration for a floating-caliper disc brake with a fist-and-frame-type caliper; and 
     FIG. 8 is a perpendicular cross-section along line VIII—VIII of FIG.  7 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The floating-caliper disc brakes represented in FIG. 1 as well as in FIGS. 7 and 8 comprise a brake carrier  1  which is to be fastened to the vehicle so as to be stationarily connected with the chassis and whereon, by means of two bolt guides  2 , a floating caliper having the design of a fist-and-frame-type caliper  3  is supported axially displaceably. The fist-and-frame-type caliper  3  straddles the brake disc  4  and receives two brake pads  5  composed of friction lining and backing plate. Out of these brake pads  5 , the inner brake pad is directly applicable to the brake disc  4  via a hydraulic actuating device  6  while the outer brake pad is applicable to the brake disc  4  indirectly via the outer fist-and-frame-type-caliper leg  7  of the fist-and-frame-type caliper  3 . The brake pads are axially displaceably supported and guided in carrier arms  8  of the brake carrier  1  which axially reach across the brake disc  4 . The fist-and-frame-type caliper  3  is characterized in that it has a frame  9  to enhance its stability and torsional strength. The frame  9  surrounds the lower edge of the fist-type caliper like a frame and is connected therewith. The fist-and-frame-type caliper  3  is designed so that there are disposed a leg window  10  centrically in the axially outer fist-and-frame-type-caliper leg  7  and, on either side of this leg window  10 , an aperture  11  each for the carrier arms  8  of the brake carrier  1 . 
     The inventive spring configuration further comprises a retaining spring  12  essentially extending parallel to the brake disc  4 . This retaining spring  12  has a central section  13  essentially arranged within the leg window  10  and detachably connected with the axially outer brake pad  5 . The central section  13  of the retaining spring  12  is adjoined by the two spring arms  14  which, each proceeding from the central section  13 , extend in opposite tangential directions. The spring configuration, with the retaining spring  12  being the essential component thereof, is designed so that both the outer brake pad  5  is secured with bias in the axial direction relative to the inside of the outer fist-and-frame-type-caliper leg and the fist-and-frame-type caliper  3  is secured with bias against the radial direction R relative to the brake carrier  1  and the axial carrier arms  8  thereof in order to essentially avoid clattering noises of the disc brakes during operation of the vehicle. 
     A first embodiment of a spring configuration results from FIGS. 1 through 6. The retaining spring  12  is arranged essentially parallel to the brake disc  4 . Like the entire disc brake it is symmetrically constructed with respect to a central plane running transversely to the brake disc. The central section  13  of the retaining spring  12  is essentially arranged within the leg window  10  of the fist-and-frame-type caliper  3  and is moreover detachably connected with the backing plate of the axially outer brake pad  5 . To this end, a pin  15  is disposed on the backing plate of the brake pad  5 . This pin  15  projects axially into the leg window  10  and includes an enlarged head  16  at its free end. This head is designed so as to taper conically towards the free end. This pin  15  with head  16  may be formed by an axial bulge of the material of the backing plate of the brake pad  5  or, also, by a notched nail disposed in the backing plate of the brake pad  5 . 
     On the other hand, the central section  13  of the retaining spring  12  has a central part  17  shaped like a hairpin. The legs of this central part extend in the radial direction R and are open in this direction R. The legs of the hairpin-shaped central part  17  receive the pin  15  between them and engage the head  16  of this pin  15  from behind to thus form an easy-to-achieve detachable connection. This detachable connection is simply brought about by pressing the hairpin-shaped central part  17  in the axial direction onto the conically tapering head  16  of the pin  15  so that the legs of the hairpin-shaped central part  17  slide onto the conical head  16  and are temporarily straddled apart in the way of an elastic spring until they snap over the head  16  and, behind the same, back into their initial position, receiving the pin  15  between them. The enlarged head  16  thus forms a stop for the central part  17  of the retaining spring  12  in the axial direction. The elasticity of the central section  13  of the retaining spring is increased in the tangential direction of the brake disc  4  in order to ensure that the forces required for straddling the hairpin-shaped central part  17  apart will not be excessive. This increase in elasticity is achieved in that the ends of the two legs of the hairpin-shaped central part  17  each pass over into a second leg  18  by means of a further hairpin bend running against the radial direction R. Each of the second legs  18  essentially extends against the radial direction R and is adjoined by an axially extending portion  19  of the retaining spring  12  which leads up to the outside of the outer fist-and-frame-type-caliper leg  7  and is connected there with a spring arm  14 . 
     A major part of the spring arms  14  which, proceeding from the central section  13 , each extend in opposite tangential directions is disposed in a groove-like recess  20  which is worked into the frame  9  of the fist-and-frame-type caliper  3  and which is open axially outwards. The two spring arms  14  support themselves in the axial direction on the bottom of this groove-like recess  20 . As can be seen from FIG. 4, in the relaxed state of the retaining spring  12 , the hairpin-shaped central part  17  is bent axially outwards relative to the second legs  18  by an acute angle {acute over (a)} of approximately 5 degrees in order to secure with bias the outer brake pad  5  axially on the inside of the fist-and-frame-type-caliper leg  7 . This will ensure that the legs of the hairpin-shaped central part  17  reach behind the head  16  of the pin  15 , disposed on the brake pad  5 , with axial tensile stress. 
     It can also be noticed that, in their central area, the spring arms  14  each comprise a spiral looping  21  whereby each time an inner spring leg  22  and an outer spring leg  23  are formed, with the inner spring legs  22  being connected with the axially extending portions  19  of the central section  13 . The inner spring legs  22  and outer spring legs  23  connected with each other via the looping  21  each time form a torsion spring supported with the looping  21  on a cylindrical pin  24 . The cylindrical pins  24  are disposed within the groove-like recess  20  and project axially outwards from the bottom of the groove-like recess  20 . These cylindrical pins  24  are advantageously manufactured by casting and thus are an integral component of the frame  9  or rather of the fist-and-frame-type caliper  3 . 
     The inner spring legs  22  of the spring arms  14  are disposed in the groove  20  of the frame  9  and support themselves in the radial direction R on the upper side of the groove  20 . Knob-like projections  25  are integrally formed on the upper side of the groove  20  in the area where the groove  20  passes over into the leg window  10  so as to achieve a punctiform support of the inner spring legs  22 . These projections project into the groove  20  against the radial direction R. The end sections of the spring arms  14  or rather of the outer spring legs  23  are bent axially inwards and each reach through an aperture  11  in the fist-and-frame-type caliper  3  in order to support themselves with appropriate spring elasticity in the radial direction R on the undersides of the carrier arms  8  of the brake carrier  1 . This secures with bias the fist-and-frame-type caliper  3  evenly radially relative to the brake carrier  1  without any torque being introduced into the brake pad  5  in the plane of the brake disc  4  as in the case of a known spring configuration with but one lateral spring arm. Besides, assembling the spring is made easier, for each of the two spring arms  14  has to generate only half of the total elastic force required for the proper securing with bias of the fist-and-frame-type caliper  3  relative to the brake carrier  1 . 
     The retaining spring  12  of this first example of an embodiment of a spring configuration is also equipped with an additional means for locking the retaining spring  12  on the frame  9  of the fist-and-frame-type caliper  3  in the axial direction. This means consists in that the free ends  26  of the spring arms  14  or rather of the outer spring legs  23  which adjoin each time the end section  25  are bent so that they reach behind the inside of the frame  9  of the fist-and-frame-type caliper  3 . To achieve that the retaining spring  12  is reliably locked in the axial direction, the free ends  26  are in part obliquely directed axially outwards in order to achieve that the retaining spring is axially secured with bias on the frame  9  of the fist-and-frame-type caliper  3 . This additional locking of the retaining spring  12  is of particular importance if for space reasons the cylindrical pins  24  whereon the loopings  21  of the spring arms  14  are supported only can have a relatively small axial extension. This additional axial locking by means of the bent free ends  26  will prevent the loopings  21  of the retaining spring  21  from snapping off from the cylindrical pins  24  under respective stress conditions. The last-mentioned complex becomes particularly clear in FIG.  6 . FIG. 6 also reveals how retaining spring  12  supports itself with its end section  25  slidingly on the underside of the carrier arm  8  of the brake carrier  1 . 
     Another example of an embodiment of a spring configuration for a fist-and-frame-type caliper disc brake is revealed by FIGS. 7 and 8. Again, a retaining spring  12  is an essential component of this spring configuration. Retaining spring  12  comprises a central section  13  essentially disposed within the leg window  10  of the fist-and-frame-type-caliper leg  7 . From this central section  13 , there extends a spring arm  14  each in opposite tangential directions. Riveted to the backing plate of the outer brake pad  5  is a metal tongue  27  which is open against the radial direction R and moreover projects axially into the leg window  10 . The central section  13  of the retaining spring  12  comprises a straight central part  28  which extends tangentially and reaches behind the metal tongue  27  fastened on the brake pad  5 . From the two ends of the tangential central part  28  there extends a leg  29  each parallel to the brake disc  4  and against radial direction R. These legs  29  each pass over into an essentially extending portion  30 . These axial portions  30 , again, are connected with the two spring arms  14  of the retaining spring  12 . 
     The central section  13  of the retaining spring  12  is designed to ensure that a tilting moment will pull the tangential central part  28  axially outwards in order to secure the outer brake pad  5  with axial tensile stress relative to the inside of the fist-and-frame-type-caliper leg  7 . To achieve this the two essentially tangentially extending legs  29  each support themselves on a supporting point  31  on the bottom of the leg window  10 . As, moreover, the legs  30  do not extend parallel to the bottom of the leg window  10  but slightly ascend, proceeding from the supporting point  31 , it becomes possible to bias the central section  13  so as to ensure that a permanent tilting moment will pull the tangential central part  28  axially outwards. This biased condition of the central section  13  will be achieved in that the spring arms  14  each support themselves in the area of the inner spring legs  22  against the radial direction R on the upper side of the axially open, groove-like recess  20  in the frame  9  of the fist-and-frame-type caliper  3 , particularly on the knob-like projections  32  projecting from above into the groove-like recess  20 . Further, the two spring arms  14  support themselves axially on the outside of the fist-and-frame-type-caliper leg  7  and, thus, on the bottom of the groove-like recess  20 . 
     FIG. 8 also reveals that the metal tongue  27  comprises a section  33  which, step-like, expands downwards. This step-like section  33  facilitates the assembly of the retaining spring  12  in that it at first is hung up in this step-like section  33  and thus already will reliably be held in a temporary intermediate position before it reaches its final position. 
     From FIG. 7 it can be seen that the two spring arms  14  of the retaining spring  12  ensure an even radial securing with bias of the fist-and-frame-type caliper  3  on the brake carrier  1  without introducing any troublesome torque into the brake pad  5 . The spring arms  14 , again, each have an inner spring leg  22  and an outer spring leg  23  connected with each other at an obtuse angle in a vertex  34 . The vertices  34  of the spring arms  14  each support themselves on the bottom side of the groove-like recess  20  against the radial direction R while, in the radial direction R, the inner ends of the inner spring legs  22  support themselves on the knob-like projections  32  projecting from above into the groove-like recess  20 . 
     Further, the retaining spring  12  of this embodiment is designed towards its ends in the same way as the retaining spring  12  of the embodiment represented in FIGS. 1 through 6. This means that, on each of its outer spring legs  23 , the retaining spring  12  comprises end sections  25  which are bent in the axial direction and, as shown in FIG. 6, reach through the apertures  11  and support themselves slidingly in the radial direction R on the underside of the carrier arms  8  of the brake carrier  1 . Moreover, as likewise shown in FIG. 6, the free ends  26  of the retaining spring  12  are bent so as to reach behind the inside of the frame  9  of the fist-and-frame-type caliper  3 , thus reliably securing with bias the retaining spring  12  in the axial direction on the frame  9  of the fist-and-frame-type caliper  3 . 
     Further, it can be seen from FIG. 8 that the rivet pin  35  whereon the metal tongue  27  is riveted is advantageously made from a bulge of the material of the backing plate of the brake pad  5 . 
     LIST OF REFERENCE NUMERALS 
       1  brake carrier 
       2  bolt guide 
       3  fist-and-frame-type caliper 
       4  brake disc 
       5  brake pad 
       6  hydraulic actuating device 
       7  fist-and-frame-type-caliper leg 
       8  carrier arm 
       9  frame 
       10  leg window 
       11  aperture 
       12  retaining spring 
       13  central section 
       14  spring arm 
       15  pin 
       16  head 
       17  central part 
       18  second leg 
       19  portion 
       20  groove-like recess 
       21  looping 
       22  inner spring leg 
       23  outer spring leg 
       24  cylindrical pin 
       25  end section 
       26  free end 
       27  metal tongue 
       28  central part 
       29  leg 
       30  portion 
       31  supporting point 
       32  projection 
       33  section 
       34  vertex 
       35  rivet pin 
     α angle 
     R radial direction