Abstract:
A disc brake comprises pads, a support member, elastic members, and a caliper. The pads include first engaging portions having first slanted surfaces with a first distance therebetween. The support member straddles the rotor and is supported on a body. The support member includes a pair of second engaging portions having second slanted surfaces. The second slanted surfaces have a second distance therebetween. The elastic member, disposed on the pads, presses the pads in a direction which shortens a third width defined by an adjacent pair of the first and second slanted surfaces, respectively. The first and second distances change gradually along the first and second slanted surfaces. Engaging protrusions are provided to one of the pairs of the first and second engaging portions, each including a first width. Engaging grooves are provided to the other of the pairs of the first and second engaging portions, each including a second width.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a disc brake for a vehicle. More particularly, the invention relates to a structure of the disc brake which is capable of preventing an abnormal sound from being generated, when the disc brake is operated, at an engaging portion where a pad and a support portion, which are assembled into the disc brake, engage with each other. 
     2. Description of the Related Art 
     A disc brake having a structure as shown in FIGS. 6 and 7 is known as a disc brake for a vehicle. The disc brake is disclosed in JP-A-9-79296. As shown, a support member  2  is disposed close to a part of a rotor  1 , which rotates together with a wheel (not shown) of the vehicle. The support member  2  is firmly supported on a suspension device (not shown) provided on the vehicle body side. The support member  2  supports a caliper  3  in a state that the caliper  3  is movable in the axial directions of the rotor  1  (the axial direction is back-and-forth direction, in other words, direction vertical to the drawing surface of FIG. 6, or is vertical direction when viewed in FIG.  7 ). A pair of run-in and run-out side support portions  4  and  5  are located at both ends of the support member  2 , while being spaced apart from each other in the circumferential direction of the rotor  1 . The top ends of those support portions  4  and  5  are each bent to be shaped like U. Each of the support portions  4  and  5  is disposed astride the outer peripheral portion of the rotor  1  in the vertical direction in FIG. 6 (in other words, vertical direction when viewed in FIG.  7 ). The first ends of pads  6  are supported by the run-in side support portion  4 , while being slidable in the axial direction of the rotor  1 . The second ends of those pads  6  are supported by the run-out side support portion  5 , while being also slidable in the axial direction. The run-out side support portion  5  receives brake torque, which is generated, when the braking is effected, by friction of the pads  6  against the side surfaces of the rotor  1  and act on those pads  6 . In the embodiment, the run-out side support portion  5  is located at the run-out side end (in other words, left end in FIGS. 6 and 7 when the rotor  1  is rotated from the right side to the left side, in the direction “a” of an arrow in FIGS.  6  and  7 ). 
     Engaging protrusions  8  are protruded from both ends of a back plate  7  of each pad  6 . Engaging grooves  9  are formed in the inner side surfaces of the run-in side and run-out side support portions  4  and  5 , respectively. The engaging protrusions  8  are respectively brought into contact with the engaging grooves  9  such that the engaging protrusions  8  are movable in the axial direction of the rotor  1 , and the engaging portions will be referred to as a run-in engaging portion and a run-out engaging portion. Thus, the pads  6  are respectively movable to and from the side surfaces of the rotor  1 , while being supported on the support member  2 . 
     The caliper  3  is supported by the support member  2  while straddling the pair of the pads  6 . The caliper  3  is provided with cylinder portions  10  and caliper claws  11 . The cylinder portions  10  include pistons for pressing the pads  6  against the rotor  1 . 
     Pad clips  12 , which is formed with an elastic metal plate, for example, a stainless steel plate, are provided at the portions of the support member  2  where the support member supports both ends of the pads  6 . The pad clips  12  elastically press the pads  6  to thereby prevent unsteady motions of those pads, which is caused by rattling during the vehicle running. Each of the pad clips  12  partly covers the inner surface of the corresponding engaging groove  9 . In this case, a small clearances  13  exist between the part of the pad clip  12  where the pad clip covers the inner surface of the engaging groove  9  and the corresponding engaging protrusion  8 . The clearances  13  are dimensionally selected so as to secure smooth displacement of the pads  6  in the axial direction of the rotor  1  in a normal state, and further even when the back plates  7  and/or the support member  2  are varied in dimension. The back plates  7  are formed with stainless steel plates and the support member  2  is made of cast iron. Accordingly, those component parts become rusty. In this case, the resultant products somewhat vary the dimensions of those and related component parts. For example, the corrosive products formed on the back plates  7  yield slight dimension increase of the back plates  7  or the outside dimensions of the engaging grooves  9  are also somewhat varied. 
     In the conventional disc brakes having the structure shown in FIGS. 6 and 7, the clearances  13  are selected to be wide enough to allow the pads  6  to smoothly displace in the axial directions of the rotor  1  even when the outer periphery edge of the back plates  7  and/or the support member  2  made of cast iron are rusted, and as a result, the back plates  7  increase their dimensions and the engaging grooves  9  decrease their dimensions. With use of such clearances  13 , the pads  6  sometimes rapidly moves with respect to the support member  2 . When the disc brake is operated for braking the vehicle, the pads  6  come into frictional engagement with the rotor  1 , and are displaced in the circumferential direction of the rotor  1 . At this time, the clearances  13  associated with the run-out side support portion  5  disappear, while at the same time the back plates  7  impact against part of the pad clips  11 , to thereby generate a beat sound, called a cronk sound. Also when the disc brake is not operated, the pads  6  displace while resisting the elastic force by the pad clips  12 , to sometimes generate noisy vibrations called rattle sounds. Increasing the elastic forces of the pad clips  12  may prevent generation of such noisy vibrations. However, this approach is not desirable for the following reasons. The elastic force increase makes the assembling work of the disc brake complicated, and further restricts movements of the pads  6 , and hence a drag resistance increases between the pads  6  and the rotor  1  in a non-braking mode. 
     SUMMARY OF THE INVENTION 
     Accordingly, an object of the present invention is to provide a disc brake which ensures reliable displacement of the pads with respect to the support member and eliminates the unsteady motions of those pads with respect to the same. The object of the present invention is attained by a disc brake for braking with a rotor rotating together with a wheel, and the disc brake comprises pads, a support member, elastic member, and a caliper. The pads respectively includes a pair of first engaging portions having first slanted surfaces. The first slanted surfaces have a first distance therebetween in a direction parallel to a rotating direction of the rotor. The support member straddles the rotor and is supported on a body. The support member also includes a pair of second engaging portions respectively having second slanted surfaces. The pair of second engaging portions has a second distance therebetween in the direction parallel to the rotating direction of the rotor. The elastic member is disposed on the pads and presses the pads in a direction which shortens a third width defined by an adjacent pair of the first and second slanted surfaces, respectively. The caliper is guided by the support member and includes at least one piston which moves the pair of the pads. The first and second distances are gradually changed along the first and second slanted surfaces. Engaging protrusions are provided to one of the pairs of the first and second engaging portions, each of the engaging protrusions includes a first width in a direction parallel to a line connecting a center of the rotor and a center of each of the pads, and includes one of the first and second slanted surfaces. Engaging grooves are provided to the other of the pairs of the first and second engaging portions, each of the engaging grooves includes a second width in the direction parallel to the line connecting the center of the rotor and the center of each of the pads, the second width is wider than the first width, and includes the other of the first and second slanted surfaces. 
     It is also preferable that the elastic member urges the pad in the direction parallel to the line connecting the center of the rotor and the center of each of the pads. 
     Moreover, it is also preferable that the first and second slanted surfaces are slanted at about 30 degrees with the line connecting the center of the rotor and the center of each of the pads. 
     Further, it is preferable that the pad further includes a back plate and the first engaging portions are provided to the back plate. 
     Moreover, it is also preferable that the first and second slanted surfaces are slanted at an angle within the range of 5 to 30 degrees with respect to the line connecting the center of the rotor and the center of each of the pads. 
     The disc brake of the invention operates for braking as the conventional one does. In the disc brake, the support member supports the pads in a state that such unsteady motions of the pads as to generate noisy sounds are removed, and that even when the corrosive products are formed and as a result, the dimensions of the support member and the back plates of the pads are somewhat varied, the pads are reliably displaceable. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front view showing an embodiment of a disc brake according to a first example of the present invention, some component members of the disc brake being omitted; 
     FIG. 2 is a diagram showing a part of a left end portion of the disc brake in FIG. 1, which is a second example of the embodiment; 
     FIG. 3 is a diagram showing a part of a left end portion of the disc brake in FIG. 1, which is a third example of the embodiment; 
     FIG. 4 is a diagram showing a part from a center portion to a left end portion of disc brake, which is a fourth example of the embodiment; 
     FIG. 5 is a cross sectional view taken on line A—A in FIG. 4; 
     FIG. 6 is a plan view showing a structure of a conventional disc brake; and 
     FIG. 7 is a bottom view of the disc brake shown in FIG.  6 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 shows a first example of an embodiment of a disc brake according to the present invention. One of the major features of the present invention resides in an improvement of a structure of the disc brake, which is provided for supporting both ends of a back plate  7   a  of each pad  6   a  on a support member  2   a . The remaining structure and operations of the disc brake are substantially the same as those of each of the conventional disc brakes as shown in FIGS. 6 and 7. Therefore, embodiment description will be given while placing emphasis on the structure essential to the invention. 
     The support member  2   a  is provided straddling a rotor  1  (not shown in FIG. 1, see FIGS.  6  and  7 ), which rotates together with a wheel of the motor vehicle, and a run-in side support portion  4   a  and a run-out side support portion  5   a  are provided on the support member  2   a . Engaging grooves  9   a  are formed in the run-in side support portion  4   a  and the run-out side support portion  5   a , respectively. Engaging protrusions  8   a  are respectively protruded horizontally and outwardly from both ends of the back plates  7   a  of the pads  6   a . The engaging protrusions  8   a  are brought into engagement with the engaging grooves  9   a  such that it is slidable in the axial directions (in other words, direction vertical to the drawing surface of FIG. 1) of the rotor  1 . A pair of pads  6   a  (only one pad is illustrated in FIG. 1) are provided astride the rotor  1 . Pad clips  12   a  as elastic members are provided respectively between the run-in side support portion  4   a  and the back plates  7   a , and between the run-out side support portion  5   a  and the back plates  7   a . The pad clips are made of stainless spring steels and formed by bending. 
     In the disc brake of this embodiment, the back end faces  14  of the engaging grooves  9   a  are not parallel to each other. Those back end faces  14  are oblique to the direction of a force, which is imposed on each pad  6   a  as the result of its friction against the corresponding side surface of the rotor  1 . More specifically, the back end faces  14  are slanted at an angle α(≈30°, for example) with respect to a phantom line “x” which extends in the diameter direction of the rotor  1  and passes through the center of the pad  6   a . The slanting directions of the back end faces  14  are slanted such that the distance between the back end faces  14  increases from the outer side of the rotor  1  to the inner side as viewed in the diameter direction. Incidentally, the direction in which the force acts on the pad is substantially perpendicular to the phantom line “x”, and is denoted as “y” in FIG.  1 . The end faces  15  of the engaging protrusions  8   a  are slanted in parallel with the back end faces  14  of the engaging grooves  9   a , as shown. 
     A width W 9a  of each engaging groove  9   a  (when viewed in the up-and-down direction in FIG. 1) is larger than a width W 8a  of each engaging protrusion  8   a . Accordingly, each engaging protrusion  8   a  is movable within the corresponding engaging groove  9  in the up-and-down direction in FIG.  1 . In this embodiment, the width W 9a  of the engaging groove  9   a  is selected to be somewhat larger than the sum of the width W 8a  of the engaging protrusion  8   a  and a value two times as large as the thickness T 12a  of the metal plate of each pad clip  12   a  (W 9a ≈W 8a +2 T 12a +0.7 mm). 
     An elasticity of each pad clip  12   a  is selected to be large enough to press the pads  6  in such a direction as to cause the back end face  14  and the end face  15 , which are associated with the pad clip, to move to each other. In other words, the pad clip  12   a  presses the pads  6  in a direction such that width W 16  between the back end face  14  and the end face  15  becomes narrower. (In this embodiment, pressure owing to the pads  6  actually causes little change of the width W 16  because the pad clip  12   a  is made of spring steels, for example.) To this end, in this embodiment, the inner terminals (the lower end portions thereof in FIG. 1) of the pad clips  12   a  as viewed in the diameter direction of the rotor  1  are formed as elastic pieces  16  of which the elastic forces are directed outward (upward in FIG.  1 ). The tips of the elastic pieces  16  are brought into contact with the inner end edges of the back plates  7   a  of the pads  6   a . The pads  6   a  are resiliently urged outward as viewed in the diameter direction of the rotor  1  with respect to the support member  2   a . Accordingly, when no external force acts on the stricture, each back end face  14  and the corresponding end face  15  sandwich the part of the pad clip  12   a  in a state that no or a little gap (for example, 0 to 0.2 mm) is present between those adjacent contact surfaces thereof. 
     The thus constructed disc brake of this embodiment can support the pads  6   a  on the support member  2   a  in a state that the pads  6   a  are reliably displaceable with respect to the support member  2   a  even in the following situations: when a measure is taken to eliminate such an unsteady motions of the pads as to generate noisy sound, and as the result of yielding the corrosive products, the outside dimensions of the back plates  7   a  of the pads  6   a  are somewhat increased or the inside diameters of the engaging grooves  9   a  are somewhat reduced. 
     An initial mode of the disc brake will first be described. In this mode, no corrosive products are present on the end faces  15  of the engaging protrusions  8   a , which are provided at both ends of the back plates  7   a  and the back end faces  14  of the engaging grooves  9   a . In other words, the back plates  7   a  have the smallest outside dimensions, and the back end faces  14  have the largest clearances therebetween. Further, in the initial mode, the disc brake is not operated. In the initial mode, the pads  6   a  are most displaced outward as viewed in the diameter direction of the rotor  1  by the elasticity of the pad clips  12   a . In this state, as already stated, each back end face  14  and the corresponding end face  15  sandwich the part of the pad clip  12   a  in a state that no or a little gap is present between those adjacent contact surfaces thereof. Further, the back end face  14  and the corresponding end face  15  are coupled with each other in a wedging fashion by the elasticity of the pad clips  12   a . With this structure, the elasticity of the pad clips  12   a , which is set to be not large, is capable of preventing the unsteady motions of the pads  6   a  with respect to the pads  6   a  and the generation of the noisy sound called rattle in the non-braking state. 
     Next, a state of the disc brake when it is operated for braking will be described. When the disc brake is operated, a friction of the friction member of each pad  6   a  against the corresponding side surface of rotor  1  imposes a force having a direction “y” of an arrow (FIG. 1) on the pad  6 . The force presses the end face  15  of the pads  6   a  against the back end face  14  on the left side in the drawing of FIG. 1 where the run-out support portion  5   a  is located. It is noted that those end faces  14  and  15  are slanted with respect to the line of the force action (indicated by the arrow head line or vector “y”). As a result of relative sliding movement between the end faces  14  and  15 , a force acting in the diameter direction of the rotor  1 , namely, a component of the force represented by the vector “y”, is generated in the pad  6   a . Specifically, the direction of the component force is directed to the inner side as viewed in the diameter direction (downward in FIG.  1 ). By this force, the pads  6   a  displace while elastically deforming the elastic pieces  16 , and at an inner location as viewed in the diameter direction of the rotor  1 , their displacing motions are restrained by the inner surface of the engaging groove  9   a  and the back end face  14  thereof. Thus, if the back plates  7   a  are fixed by its rusting, their fixing is removed when the pads  6   a  move, namely, with progress of the braking operation. In this state, the side surfaces of the rotor  1  are in strong frictional engagement with the friction members of the pads  6   a . Therefore, there is no chance that the pads  6   a  displace in the diameter direction of the rotor  1 . On the run-out side of the disc brake, a gap between the back end face  14  of engaging groove  9   a  and the corresponding end face  15  of the engaging protrusion  8   a  is extremely small, 0 to 0.2 mm, as referred to above. Therefore, it never happens that the outer side of the engaging protrusion  8   a , which includes the end face  15 , forcibly collides with the inner side of the engaging groove  9   a , which includes the back end faces  14 , to thereby generate noisy sounds. When the pads  6  displace to the inner side as viewed in the diameter direction of the rotor  1 , the outer side of the engaging protrusion  8   a  collides with the inner side of the engaging groove  9   a  relatively gently. Therefore, the collision is hard to generate the noisy sounds. 
     Description will be given about a case where corrosive products are formed on the outer surface of the engaging protrusion  8   a  and/or the inner surface of the engaging groove  9   a  of the support member  2   a , and the outside dimension of the back plate  7   a  of the pad  6   a  (namely, an overall length L 7a  of the overall back plate  7   a  as measured in the longitudinal direction (right-and-left direction) in FIG. 1) or a width W 8a  of the engaging protrusion  8   a  is increased, or the inside dimension of the engaging groove  9   a  is reduced. When the overall length L 7a  is increased or the distance between the pair of the back end faces  14  is reduced, the end face  15  of the engaging protrusion  8   a  mutually and forcibly presses the back end face  14  of the engaging groove  9   a . When in the braking mode, the rotor  1  is rotating in the direction “b” of an arrow, a pad couple force (indicated by a line M of an arrow in the figure, and is a force, based on a brake torque for causing the pad to rotate) acts on the pad portion  6   a , and hence the pad  6   a  will rotate. The sliding engagement of the end faces  14  and  15  generates a component of force, which is directed to the inner side as viewed in the diameter direction of the rotor  1  (downward in FIG.  1 ), and the pad  6  displaces to the inner side as viewed in the diameter direction of the rotor  1  while resisting the elasticity of the pad clip  12   a . As a result, the gap between the outer surface of the engaging protrusion  8   a  and the engaging groove  9   a  tends to increase, and hence the engaging protrusion  8   a  smoothly displaces on the inner surface of the engaging protrusion  8   a  irrespective of presence of the corrosive products. Also when the width W 8a  of the engaging protrusion  8   a  is increased or the width W 9a  of the engaging groove  9   a  is reduced, and the pad  6  displaces to the inner side as viewed in the diameter direction of the rotor  1  while resisting the elasticity of the pad clip  12   a , whereby the smooth displacement of the engaging protrusion  8   a  is secured. As seen from the above description, it is required that the angle α is selected to have a value large enough to generate a component of force which can displace the pad  6   a  while resisting the elasticity of the pad clip  12   a  when the pad  6  is rusted. In the stage of design, the value of the angle α is selected in consideration of a coefficient of friction of the sliding portion. In an example where the back plates  7   a  are formed with steel plates and the pad clips  12   a  are formed with stainless steel plates, the angle α is selected to be about 50° to 40°. 
     Turning now to FIG. 2, there is shown a second example as a modification of the above-mentioned embodiment. In this example, the end face  15   a  of the engaging protrusion  8   b  and the back end face  14   a  of the engaging groove  9   b  are slanted to the side opposite to that to which those corresponding faces are slanted in the embodiment shown in FIG. 1 with respect to the phantom line “x” (see FIG.  1 ). Also in the disc brake having such a structure, the pads  6   b  may be supported on the support member  2   b  while securing reliable displacement of them even when the great unsteady motions of those pads large enough to generate noisy sounds is removed, and the dimensions of the back plates  7   b  of the pad  6   b  and the support member  2   b  are somewhat varied as the result of formation of corrosive products. The remaining structure and operations of the first modification are substantially the same as of the embodiment shown in FIG.  1 . Hence, no further description of them will be given. 
     FIG. 3 shows a third example as a modification of the embodiment shown in FIG.  1 . The third example, unlike the embodiment shown in FIG.  1  and the second example, is arranged such that the engaging protrusions  8   c  are formed on the support member  2   c , and the engaging grooves  9   c  are formed in the back plates  7   c  of the pads  6   c . The end face  15   b  of the engaging protrusion  8   c  and the back end face  14   b  of the engaging groove  9   c  are slanted to the same side as of the corresponding ones in the embodiment shown in FIG.  1 . Also in the disc brake having such a structure, the pads  6   c  may be supported on the support member  2   c  while securing reliable displacement of them even when the great unsteady motions of those pads large enough to generate noisy sounds is removed, and the dimensions of the back plates  7   c  of the pad  6   c  and the support member  2   c  are somewhat varied as the result of formation of corrosive products. Further, also in this example, the end face  15   b  and the back end face  14   b  may be slanted to the same side as of the corresponding ones in the example shown in FIG.  2 . The remaining structure and operations of the first modification are substantially the same as of the embodiment shown in FIG.  1 . Hence, no further description of them will be given. 
     FIGS. 4 and 5 show a fourth example as a modification of the embodiment shown in FIG.  1 . In this example, a pad clip  12   b  is placed at a mid position of a support member  2   a  in connection with the related pad  6   a , as shown. The pad clips  12   b  urge the pads  6   a  outward in the diameter direction of the rotor  1  (see FIGS.  6  and  7 ). The pad clips that are respectively provided at the run-in and run-out sides of the disc brake (as described in the first to third examples) are not used in this modification. Also, in the thus constructed disc brake, the pads  6   a  are reliably displaced with respect to the support member  2   a , and the unsteady motions of the pads  6   a  are effectively removed. 
     As seen from the foregoing description, the disc brake thus constructed and operated is capable of reliably displacing the pads with respect to the support member, and effectively removing the unsteady motions of the pads. In this respect, the present invention succeeds in realizing a brake structure that is reliable free from generation of noisy sounds. 
     While only certain embodiments of the invention have been specifically described herein, it will be apparent that numerous modifications may be made thereto without departing from the spirit and scope of the invention. 
     The present invention is based on Japanese Patent Application No. Hei. 10-313532 which is incorporated herein by reference.