Abstract:
A brake caliper for a disk brake, in particular for motorcycles and/or bicycles, includes a housing ( 30 ) in which a disk space ( 39 ) for receiving a brake disk and a brake cylinder ( 35 ) for receiving a brake piston ( 25 ) are formed. The brake cylinder ( 35 ) is connected to the disk space ( 39 ) and has, on its side opposite to the disk space ( 39 ), an assembly opening ( 50 ) through which the brake piston ( 25 ) can be inserted into the brake cylinder ( 35 ). A closure element ( 10 ) closes the assembly opening ( 50 ) after the insertion of the brake piston ( 25 ) into the brake cylinder ( 35 ). A securing element ( 21 ) secures the closure element ( 10 ) in the assembly opening ( 50 ) against forces in the direction of the main axis of the brake cylinder ( 35 ).

Description:
CROSS REFERENCE 
     The present invention is a division of U.S. application Ser. No. 11/031,988 filed Jan. 7, 2005, now U.S. Pat. No. 7,610,997. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a brake caliper and a method for the production of a housing of a brake caliper. 
     2. Description of the Prior Art 
     In the case of known brake calipers, at least one brake cylinder in the housing is formed for receiving a brake piston. Usually, the brake cylinders are formed by machining. In general, two brake cylinders which are located on opposite sides of a disk space for receiving brake linings and a brake disk are formed in one operation. Such brake calipers and their function are known to a person skilled in the art. As a result of the method of production, at least one of the brake cylinders of a pair of brake cylinders is formed in such a way that a continuous hole is formed from the disk space through the housing to the outside. During assembly of the brake caliper, the brake pistons are inserted through this open brake cylinder from the outside into the brake caliper, and the assembly opening is closed by a closure element. Usually, the assembly opening, i.e. the end of the open brake cylinder is formed with an internal thread, and the closure unit is formed with an external thread. For closing the open brake cylinder, the closure element is screwed into the assembly opening using an appropriate tool. 
     Such a known brake caliper is shown, for example, in the article “Intensiv-Test, Yamaha XJR 1300” [Intensive test, Yamaha XJR 1300”, Motorradfahrer [Motorcycle rider] magazine, November 2003 issue, pages 28 to 30. 
     The German Laid-Open Application DE 22 163 162 A describes a cast brake caliper in which the open side of the hole in which the brake piston is held is closed by means of a stopper which is inserted into the hole from the inside. This has the disadvantage that the assembly is very complicated, particularly because at least one piston can be used only after insertion of the stopper. 
     The German Laid-Open Application DE 25 27 700 A1 describes a cast brake caliper in which the open side of the hole is closed by means of a closure disk. A securing ring prevents the closure disk from falling out in an outward direction. The securing ring is accessible from the outside and can be removed in order to provide access to the closure disk for removal. This has the disadvantage that the brake caliper can accidentally be opened by the driver during repair or maintenance of the vehicle. 
     European Patent EP 1 256 740 A1 describes a brake caliper in which the open side of the hole is closed by means of a closure element. For securing the closure element, either the housing or the closure element is refashioned after the closure of the closure element. This has the disadvantage that assembly is very complicated and difficult. 
     The known brake calipers have the disadvantage that mounting of the closure element is complicated. Moreover, in some known brake calipers, there is the disadvantage that the brake caliper is opened accidentally by the driver during repair or maintenance of the vehicle or opens during operation due to the loads caused by the pressure changes in the system. 
     SUMMARY OF THE INVENTION 
     It is therefore the object of the invention to provide a brake caliper in which the closure element can be mounted easily and simply from the outside. 
     It is also the object of the invention to provide a brake caliper in which the closure element cannot be accidentally removed or preferably cannot be removed. 
     According to the invention, the brake caliper for a disk brake, in particular for motorcycles and/or bicycles, includes a housing in which a disk space for receiving a brake disk and a brake cylinder for receiving a brake piston are formed. The brake cylinder is connected to the disk space and has, on its side opposite to the disk space, an assembly opening through which the brake piston can be inserted into the brake cylinder. A closure element closes the assembly opening after insertion of the brake piston into the brake cylinder. A securing element secures the closure element in the assembly opening against forces in the direction of the main axis of the brake cylinder, the housing and the closure element enclosing the securing element. 
     This brake caliper has the advantage that the mounting of the closure element is substantially simplified and therefore more economical compared with the prior art because no screwing in and no torque monitoring during screwing in of the closure element are required. Moreover, there is the advantage that the closure element can no longer become detached by itself as a result of the loads caused by the pressure changes in the system. A further advantage is that the closure element can no longer be removed, and the brake caliper cannot be accidentally damaged. 
     According to a preferred embodiment of the invention, the securing element is a circlip. By this embodiment, it is possible to achieve a particularly simple design. Assembly, too, is very simple because the circlip need only spring into its place in order to secure the closure element. 
     A groove for receiving the securing element is preferably provided in the assembly opening. Accordingly, the closure element may have a groove for receiving the securing element. 
     According to an embodiment of the invention, a shoulder for supporting the closure element is provided in the housing, in the region of the assembly opening. A seal may be provided between the shoulder and the closure element. In this way, the sealing of the pressure space of the brake cylinder can be realized in a simple and safe manner. 
     According to an embodiment of the invention, a further brake cylinder which is intended for receiving a further brake piston which is arranged coaxially with the other brake cylinder is provided on that side of the disk space which is opposite to the assembly opening. During assembly, all brake pistons (and seals) are preferably inserted through the assembly opening before the assembly opening is closed by the closure element. 
     For safety reasons, it is advantageous if the closure element and the securing element are no longer removable after mounting of the closure element in the housing. 
     According to a preferred embodiment of the invention, a further brake cylinder for receiving a further brake piston which is arranged next to the other brake cylinder is provided, a closure element and a securing element according to the invention being provided. 
     The brake caliper according to the invention preferably has a plurality of pairs, in particular preferably two pairs, of brake cylinders, in each case a closure element and securing element according to the invention being provided on one side of the brake caliper for each pair of brake cylinders. 
     Advantageously, the housing of the brake caliper according to the invention is a forged part. Compared with housings of cast or milled parts, this has the advantage that the brake caliper can be made smaller while having the same strength. In particular, sufficient strength can be achieved in the region of the assembly opening for receiving the securing element (circlip), in order to absorb the forces occurring during braking. 
     WO 02/064991 A1 describes a brake caliper which is formed without cutting and has a shaft for receiving the brake linings, which is a cast or forged part. Housings for brake calipers having at least two shafts for receiving the brake linings are, on the other hand, usually cast or milled parts. It is not known to a person skilled in the art that housings for brake calipers of disk brakes having at least two shafts for receiving the brake linings can be formed as a forged part. Particularly in the case of housings having at least two shafts for receiving the brake linings, a person skilled in the art will assume that finishing of the shafts for the formation of the contact surfaces for the brake linings is required because the housing has to be removed from the forging dies in such a way that the forging dies are withdrawn simultaneously from both shafts in one direction, although the contact surfaces for the brake linings in the two shafts are differently oriented in order to ensure optimum contact. Due to the method, formations of undercuts are not possible in forging, because the forging dies can then no longer be removed for removing the housing from the die. In order to produce the housing for a brake caliper with at least two shafts as a forged part, finishing of the shafts by machining is therefore necessary for creating the optimum contact surfaces. This has the disadvantage that the production is very complicated and expensive. Moreover, the hardness and surface quality of the finished contact surfaces deteriorate. 
     It is therefore the object of the invention to provide a method for the production of a housing for a brake caliper as a forged part, which method is simple and economical. 
     According to the invention, the method for the production of a housing of a brake caliper for a disk brake, in particular for motorcycles and/or bicycles, having a plurality of shafts for receiving brake linings, which in each case comprise at least one contact surface with which the brake linings come into contact on braking of the vehicle for absorbing braking forces, includes the following steps: 
     a) formation of a pair of forging dies in such a way that the contours of the two forging dies define the contours of the housing to be produced, and the two forging dies define partitions in the shafts, in which excess material remains during forging, 
     b) introduction of material into the first forging die, 
     c) forging of the material using the pair of forging dies, and 
     d) demolding of the housing by removal of the pair of forging dies, 
     e) removal of the excess material of the partitions, the partitions in the shafts lying obliquely to the take-off direction of at least one of the forging dies. 
     It would also be possible to say that, according to the invention, the partitions in the shafts are inclined relative to the plane which is defined by a normal vector whose direction corresponds to the take-off direction of at least one of the forging dies. 
     As a result of the oblique position of the partitions, it is possible to form the contact surfaces in the desired optimum orientations in a forging process without producing undercuts. A one-part housing having a plurality of shafts can therefore be produced. 
     According to the invention, the partitions may also be curved, provided that no undercuts which prevent the removal of the forging dies are formed. 
     According to an embodiment of the method according to the invention, the partitions are advantageously formed outside the contact surfaces for the brake linings. Consequently, no burrs form on the contact surfaces as a result of removal of the partitions, with the result that there is the advantage that, on braking, the brake linings rest against a forged, burr-free contact surface which has not been finished. To this extent, on operation of the brake, the brake linings can easily move in the axial direction (on braking in the direction of the brake disk and on release of the brake away from the brake disk). Troublesome burrs need not be removed because the partitions are located outside the contact surfaces. This feature is particularly important during braking of the forward-moving vehicle, because high loads occur thereby. 
     The parting planes in the shafts are preferably at an angle of 1-45°, preferably 5 to 40°, particularly preferably 10 to 39°, particularly preferably 20 to 38°, particularly preferably 30 to 37°, and particularly preferably about 36°, relative to a plane which is defined by a normal vector whose direction corresponds to the take-off direction of at least one of the forging dies. 
     According to a preferred embodiment of the invention, the housing has two shafts. The parting planes are preferably arranged with mirror symmetry. 
     According to an embodiment of the invention, brake cylinders or pairs of brake cylinders for receiving brake pistons are formed in the housing after step d) and before step e) or after step e), preferably by turning, milling or drilling. The first alternative has the advantage that part of the partition is already removed during this processing step. This facilitates the subsequent step e). 
     The combination of forming the brake caliper according to the invention with a housing which is formed by a method according to the invention is particularly advantageous. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Below, the brake caliper according to the invention and the method according to the invention are described in more detail with reference to an embodiment of the invention which is shown in the figures. 
         FIG. 1  shows a section through the brake caliper according to the invention, along the line I-I of  FIG. 5 , 
         FIG. 2  shows a section through the closure element of the brake caliper of  FIG. 1 , 
         FIG. 3  shows a side view of the closure element of  FIG. 1 , 
         FIG. 4  shows a side view of the brake caliper according to the invention, of  FIG. 1 , 
         FIG. 5  shows a view of the brake caliper according to the invention from the front, 
         FIG. 6  shows a view of the brake caliper according to the invention from above, 
         FIG. 7  shows a section through the brake caliper according to the invention, of  FIG. 1 , along the line VII-VII of  FIG. 6 , the position of the partitions formed during forging in the two shafts being indicated, and 
         FIG. 8  shows a schematic side view of the housing for a brake caliper according to  FIG. 7  before the formation of the brake cylinders. 
         FIG. 9  shows a schematic view of the method for the production of the housing for a brake caliper according to the invention. 
         FIG. 10  shows a schematic cross sectional view of the forging process for the housing for a brake caliper according to the invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  shows a section through a housing of a brake caliper according to the invention, along the line I-I of  FIG. 5 . The housing  30  has a disk space  39  for receiving a brake disk which is not shown. The disk space  39  is part of a shaft which passes through the housing  30  and in which brake linings  27  and  28  are arranged in the side regions  37  and  38 . Brake linings  27  and  28  are inserted into the shaft from the right side of  FIG. 1 , i.e. from the outside in the direction of the center of the brake disk which is not shown, and secured with a bolt  29 . The housing  30  has two brake cylinders  35  and  36 , in each of which a brake piston  25 ,  26  is arranged. The brake pistons  25 ,  26  are arranged on opposite sides of the disk space  39  and are subjected to pressure in a known manner during braking, in order to press the brake linings  27  and  28  against the brake disk. The cylinder walls are provided with grooves  33 ,  34  which hold square seals  23 ,  24  which seal the disk space  39  from the brake cylinder  35  and  36  and cause the brake pistons to return after braking in a known manner. 
     The housing of the brake caliper shown in  FIG. 1  is a forged part. The brake cylinders  35  and  36  are formed by machining. The upper wall in  FIG. 1  remains as an end wall of the brake cylinder  36 . The brake cylinder  35  is open to the outside as a result of the machining. After insertion of the brake pistons  25  and  26 , the brake cylinder  35  was closed by the closure element  10 . The closure element  10  has a groove  13  in which a securing element  21  in the preferred form of a circlip is arranged. The housing  30  has a recess  31  which is partly engaged by the securing element  21 . The securing element  21  secures the closure element  10  in the housing  30 , in particular during braking, if a pressure which presses the closure element  10  in  FIG. 1  downward is built up in the cylinder  35  by the brake fluid. Furthermore, a shoulder  32  in which the closure element  10  is supported by a seal  22  is formed in the housing  30 . The seal  22  seals the pressure space of the brake cylinder  35  from the outside. 
       FIG. 2  shows a sectional view according to  FIG. 1 , of the closure element  10 . The closure element  10  has a recess  11  on its outside. The recess serves for reducing the weight and can alternatively also be otherwise formed or omitted. Compared with the known closure elements, it has the advantage that it has a more appealing appearance and there is no danger of confusion owing to the fact that engagement sections for assembly tools are not necessary. The closure element  10  has a groove  13  for receiving the securing element  21 , which groove is formed between an outer wall  12  and a section  14 . The external diameter of the outer wall  12  corresponds to the internal diameter of the opening in the housing  30  into which the closure element  10  is inserted. It is therefore not possible to remove the closure element  10  from the outside because the securing element  21  is not accessible from the outside. The section  14  corresponds in its external diameter substantially to the external diameter of the outer wall  12 . The external diameter of the section  15  is slightly smaller than the external diameter of the section  14 . The external diameter of the section  15  corresponds substantially to the internal diameter of the opening in the housing  30  against which the closure element  10  rests after mounting. After mounting of the closure element  10 , it is therefore also not possible to actuate the securing element  21  from the inside. Thus, after assembly is complete, the closure element  10  cannot be removed from the brake caliper. Since the pistons  25  and  26  are designed for a duration of operation which is substantially greater than the duration of operation of the vehicle, there is also no need to remove the closure element  10  again after assembly is complete. The closure element  10  furthermore has a recess  16  for receiving the seal  22 . 
       FIG. 3  shows a side view of the closure element  10  of  FIG. 1 . The description of  FIG. 3  substantially corresponds to that of  FIG. 2  and will not be repeated here. 
     For mounting of the closure element  10 , the closure element  10  is introduced together with the securing element  21  via a funnel device into a sleeve whose internal diameter corresponds to the internal diameter of the assembly opening  50 . The sleeve is placed on the housing  30  and the closure element  10  is pushed with the securing element  21  into the assembly opening  50  until the closure element  10  comes into contact with the seal  22 . At the same time, the securing element  21  reaches the region of the recess  31 . The securing element  21  is a circlip which is prestressed and snaps into the recess  31 . Half of the securing element  21  is arranged in the recess  31  and the other half in the groove  13  of the closure element  10 . The closure element  10  is secured in the assembly opening  50  by the securing element  21 . 
       FIG. 4  shows the housing of the brake caliper according to the invention from the side. The housing  30  has two pairs of brake cylinders. The two closure elements  10  are shown in  FIG. 4 . 
       FIG. 5  shows the brake caliper according to the invention from the front. The arrow  40  indicates the direction of rotation of the brake disk during the forward travel of the vehicle. The housing  30  has two shafts  51  and  52  for receiving pairs of brake linings which are not shown. 
       FIG. 6  shows a view of a housing of the brake caliper according to the invention from above. 
       FIG. 7  shows a section through the housing of the brake caliper according to the invention, along the line VII-VII of  FIG. 6 . The housing has two shafts  49 A and  49 B, each of which holds a pair of brake linings which is not shown. The shaft  49 A has a contact surface  47  on which the brake lining is supported during braking of the vehicle if the forward-moving vehicle is to be braked. The shaft  49 B has a corresponding contact surface  43 . During backward movement, the brake linings which are not shown are supported on the contact surfaces  44  and  46  during braking. 
       FIG. 7  shows the housing  30  in a processing state in which the cylinders  35 A and  35  have already been formed in the housing  30 . The partitions  41  and  42  from the forging method have not yet been removed. The partition  41  has an angle of 36° relative to the direction in which one forging die is withdrawn, i.e. the forging die which is withdrawn in the direction of the center of the brake disk. The partition  41  runs from that end of the contact surface  47  which faces away from the brake disk to that end of the contact surface  46  which faces the brake disk. The partition  42  is formed with mirror symmetry relative to the partition  41  in the shaft  49 B. It runs from that end of the contact surface  43  which faces the brake disk to that end of the contact surface  44  which faces away from the brake disk. 
     The partitions  41  and  42  are removed from the housing in a manner known to a person skilled in the art. Since the partitions are located outside the contact surfaces  43  and  47 , it is not necessary to finish the contact surfaces. Owing to the oblique arrangement of the partitions  41  and  42 , it is possible to arrange the contact surfaces  43  and  47  at various angles to one another and at the same time to permit demolding of the housing  30  after the forging process. Owing to the oblique arrangement of the partitions  41  and  42 , no undercuts which would make the demolding process impossible form. 
       FIG. 8  shows a sectional view, corresponding to  FIG. 7 , of the housing according to the invention of the brake caliper according to the invention in an earlier processing step immediately after the forging process shown in  FIG. 10 . Process steps for the formation of the brake cylinders and of the disk space and the passage for bolts and attachments have not yet been formed. Particularly, first and second forging dies  60  and  62  are used having contours  60 A and  62 B which define contours of housing  30  to be produced. Material introduced into one of the forging dies  60  and  62  is forged in the first and second forging dies  60  and  62 , with excess material forming the partitions  41  and  42  in the shafts  49 A and  49 B of the housing  30 . The housing  30  is demolded by removing the first and second forging dies in a take-off direction  70 . The section of  FIG. 8  shows the continuous partitions  41  and  42  which remain after the forging process. By the formation of the brake cylinders  35  and  35 A shown in  FIG. 7 , the partitions  42  and  41  are partly removed. The remaining parts of the partitions  41  and  42  are then removed. Alternatively, the partitions  41  and  42  could also be completely removed before the formation of the brake cylinders  35  and  35 A.