Disc brake

Abstract

In a disc brake, a pair of pads are disposed on opposite sides of a disc. A caliper body extends over the disc. A piston is slidably held in the caliper body on a side opposite to the disc relative to the corresponding pad. In the caliper body, a prepared hole for a bore into which the piston is slidably fitted and a recess extending from a bottom portion of the prepared hole outwardly in a radial direction of the prepared hole are formed by means of a core during casting. A linear passage opening is formed by cutting from an exterior surface of the caliper body so as to communicate with the recess. In this disc brake, an opening for forming a brake fluid passage can be easily formed by machining, resulting in high production efficiency. The position of the opening can be determined with a high degree of freedom of design.

1 . A disc brake comprising: 
 a pair of pads disposed on opposite sides of a disc;    a caliper disposed so as to extend over the disc, the caliper being adapted to be mounted on a vehicle body; and    at least one piston slidably held in the caliper, the piston being located on a side opposite to the disc relative to the corresponding pad,    the caliper including:    a prepared hole to be machined to form at least one bore into which the piston is slidably fitted,    a recess extending from a bottom portion of the prepared hole outwardly in a radial direction of the prepared hole, the prepared hole and the recess being formed by means of a core when the caliper is cast, and    a linear passage opening formed so as to extend from an exterior surface of the caliper to the recess.    
   
   
       2 . A disc brake according to  claim 1 , wherein: 
 the caliper includes a plurality of said bores arranged in a spaced relationship in a direction of rotation of the disc and a communication passage for communication between each pair of adjacent bores, the communication passages being formed in the caliper by means of said core when the caliper is cast:    said recess is formed at a position corresponding to the top of the uppermost bore of said plurality of bores when the caliper is mounted on the vehicle body; and    said passage opening is formed so as to extend from the exterior surface of a portion of the caliper that is located at an upper position when the caliper is mounted on the vehicle body.    
   
   
       3 . A disc brake according to  claim 2 , wherein: 
 said plurality of bores are disposed on each of the opposite sides of the disc in an axial direction of the disc; and    a linear communication opening is formed so as to extend from the exterior surface of the caliper and to intersect said passage opening, the communication opening being adapted to form a part of a connection passage for allowing communication between the bores disposed on the opposite sides of the disc in the axial direction of the disc.    
   
   
       4 . A disc brake according to  claim 1 , wherein: 
 the caliper includes an inner-side cylinder portion and an outer-side cylinder portion, each having the bore into which the piston is slidably fitted, the inner-side and outer-side cylinder portions being formed as a one-piece member by casting; and    all the bores are formed by machining from portions thereof on a side of a space between the inner-side cylinder portion and the outer-side cylinder portion, to thereby maintain a closed state of bottom portions of all the bores obtained by casting.    
   
   
       5 . A disc brake according to  claim 4 , wherein: 
 the prepared holes to be machined to form the bores have inmost recess portions located at the bottom portions of the bores and having a larger diameter than inner-diameter portions of the bores and, wherein, said prepared holes, said inmost portions and said recesses extending from the inmost recess portions outwardly in a radial direction thereof, are formed by means of the core when the caliper is cast; and    the inner-diameter portions of the bores are formed by machining said prepared holes from portions thereof on a side of the space between the inner-side cylinder portion and the outer-side cylinder portion.    
   
   
       6 . A disc brake according to  claim 1 , wherein said prepared hole has an inmost recess portion located at a bottom portion of the bore and having a larger diameter than an inner-diameter portion of the bore and wherein, said prepared hole, said inmost recess portion and said recess extending from the inmost recess portion outwardly in a radial direction thereof, are formed by means of the core when the caliper is cast.  
   
   
       7 . A disc brake according to  claim 1 , wherein: 
 the caliper includes a plurality of said bores arranged in a spaced relationship in a direction of rotation of the disc and each bore has an inmost recess portion located at bottom portion of the bore and having a larger diameter than an inner-diameter portion of the bore; and    the prepared holes to be machined to form the bores, inmost recess portions, the recess extending from at least one of the inmost recess portions outwardly in a radial direction thereof as well as a communication passage for communication between the inmost recess portions of the adjacent bores, are formed by means of the core when the caliper is cast.    
   
   
       8 . A disc brake according to  claim 1 , wherein said recess extends from part of the circumference of the bottom portion of the corresponding prepared hole.  
   
   
       9 . A disc brake according to  claim 5 , wherein said recess extends from part of the circumference part of the corresponding inmost recess portion.  
   
   
       10 . A disc brake according to  claim 1 , wherein said passage opening is communicated with a distal end of the recess extending from the prepared hole outwardly in the radial direction thereof.  
   
   
       11 . A disc brake according to  claim 6 , wherein said passage opening is communicated with a distal end of the recess extending from the prepared hole outwardly in the radial direction thereof.  
   
   
       12 . A disc brake according to  claim 8 , wherein a proximal end of the recess extends, outwardly in a radial direction of the disc along the circumference of the bottom portion, from a position corresponding to the center axis of the corresponding bore or a position located inwardly from the center axis of the corresponding bore as viewed in the radial direction of the disc.  
   
   
       13 . A disc brake according to  claim 9 , wherein a proximal end of the recess extends, outwardly in a radial direction of the disc along the circumference of the inmost recess portion, from a position corresponding to the center axis of the corresponding bore or a position located inwardly from the center axis of the corresponding bore as viewed in the radial direction of the disc.  
   
   
       14 . A disc brake according to  claim 1 , wherein a bleeder mount opening for mounting of a bleeder valve for release of air is formed in the passage opening on a side opposite to the recess.  
   
   
       15 . A disc brake according to  claim 2 , wherein a bleeder mount opening for mounting of a bleeder valve for release of air is formed in the passage opening on a side opposite to the recess.  
   
   
       16 . A disc brake according to  claim 1 , wherein the passage opening extends between a mounting bolt opening extending in a radial direction of the disc and a pad-mounting space.  
   
   
       17 . A disc brake according to  claim 6 , wherein the passage opening extends between a mounting bolt opening extending in a radial direction of the disc and a pad-mounting space.  
   
   
       18 . A disc brake according to  claim 8 , wherein a distal end of the recess is located outwardly from a region occupied by the corresponding bore bottom portion as viewed in a direction of rotation of the disc, while being located radially outwardly from the center axis of the corresponding bore as viewed in a radial direction of the disc.  
   
   
       19 . A disc brake according to  claim 9 , wherein a distal end of the recess is located outwardly from a region occupied by the corresponding inmost recess portion as viewed in a direction of rotation of the disc, while being located radially outwardly from the center axis of the corresponding bore as viewed in a radial direction of the disc.  
   
   
       20 . A disc brake according to  claim 8 , wherein a proximal end of the recess extends, outwardly in a radial direction of the disc along the circumference of the bottom portion, from a position located on a gravity line drawn from the center axis of the bore in a direction parallel to the direction of gravity when the caliper is mounted on a vehicle, wherein the intersection of the gravity line and the circumference of the bore near an inner end of the linear passage opening communicating with the recess is closer to the center of the disc than an intersection of a radius line drawn from the center of the bore to the inner end of the linear passage opening and the circumference, or on the same side of said line as the center of the disc.