Abstract:
A brake apparatus includes a caliper with two housing members secured together by an E-section cage. The housing members straddle a rotor, so as to be able to urge one or more pistons disposed therein to apply brake pads against the rotor, thereby effectuating a braking force on the rotor. The E-section cage provides support for the housing members and reduces the clam shell effect generated by application of the breaking force.

Description:
CLAIM OF PRIORITY  
       [0001]     This application is a Continuation in Part of application Ser. No. 11/108,425, filed Apr. 18, 2005. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     This invention relates generally to a vehicular disk brake apparatus and more particularly to the brake caliper thereof, having a reinforced cage for reducing load.  
         [0003]     In general, a vehicular or automotive brake operates on a hydraulic system, in which the depression of a brake pedal causes a plunger in the master cylinder to push hydraulic fluid to a braking unit at the wheels. A disk brake is one kind of braking unit. In a conventional opposed caliper disk brake, a fixed caliper straddles a rotor, which is attached to the wheel. In a floating caliper disk brake, the caliper urges piston or pistons on one side of the rotor to apply a pad, while at the same time pushing the caliper housing away from the rotor, drawing the outboard pad up to the rotor. In either case, when fluid from the master cylinder is introduced into the caliper, it urges one or more pistons in the caliper to apply brake pad(s) against the rotor, thereby effectuating a braking force on the rotor and causing the wheel to slow down or stop.  
         [0004]     A typical caliper is formed in the shape of a clam for straddling the rotor. Current designs either utilize a one member housing, or two member housing, straddling over the top of the rotor and held together by bolts. In straddling the rotor, one member is disposed on the inboard side of the rotor and the other member is disposed on the outboard side of the rotor. The members have piston(s) disposed therein.  
         [0005]     A basic problem in calipers of this type is that they are subject to high shearing and bending forces, with the load bearing on the bridge section. When such forces are transmitted through the caliper, they act to spread the caliper apart like a clam, a phenomenon often referred to as the “clam shell” effect. The result is decreased braking efficiency, as some of the force generated by the master cylinder is lost in the spreading of the caliper, and there is also the consequent effect of increasing pedal travel, tapered pad wear, spongy pedal and loss of modulation.  
         [0006]     To minimize this deflection, caliper designs have typically utilized either a monoblock or a bolting design. For example, in a monoblock caliper, the caliper is formed from a solid body with a bridge section integrally joining the inboard and outboard members of the caliper housing. This type of caliper requires a rather massive bridge section to effectively reduce the clam shell effect that causes the caliper to open at the bottom. A massive bridge is undesirable, however, as it gets in the way of maximizing the rotor diameter.  
         [0007]     In a caliper where the members are connected by bolts, as shown in  FIG. 1 , there is still a clam shell effect, resulting in the pad cocking with respect to the rotor face, which causes an increase in pad drag and wear, and a decrease in braking efficiency. The key stress area of a caliper is typically within the pad boundaries, within the pistons. Although the use of a bolting connection may limit the growth of the outer portion of the caliper, it does nothing to stop the deflection below. In other words, the bottom of the caliper is free to open, and when subjected to high pressures will still clamp back down on the rotor causing the pad to attempt to wedge into the rotor, thereby causing taper.  
         [0008]     For the foregoing reasons, there is a need for a disk brake assembly having a brake caliper that is sufficiently stiff to reduce the clam shell effect.  
       SUMMARY OF THE INVENTION  
       [0009]     The present invention is directed to an improved brake caliper that satisfies the need for reducing the clam shell effect. A disk brake apparatus having the features of the present invention comprises a rotor and a brake caliper for applying braking force to the rotor. The brake caliper is basically comprised of a first housing member and second housing member straddling the rotor, with the first and second housing members connected by a bridge. The caliper housing members have actuating pistons disposed therein, with brake pads associated therewith for engaging the rotor.  
         [0010]     The bridge is generally comprised of a cross member and associated anchors. For example, in an embodiment as shown in  FIG. 3 , the bridge is formed in the shape of the letter “C” with a cross member and two anchor members. As shown in the embodiment, the anchor members are downward turning arms. This type of bridge is generally referred to as a C-section bridge because of its shape. In this type of bridge, the arms can be integrally formed with respect to the cross member, or they can be separate members fixedly connected to the cross member.  
         [0011]     Further, the bridge can take a variety of form and shape that incorporates the basic combination of cross member and associated anchors. As an example, the bridge can be comprised of a cross member and anchor plates. As another example, the bridge can take the shape of the letter “Y” with two anchor arms spread at an angle and joined by a vertical member. Moreover, the cross member can take various shape, such as tubular or, as shown in figure  FIG. 3 , rectangular.  
         [0012]     The bridge, as such, provides structural support for the caliper housing members. The caliper housing is commonly made of low tensile strength materials in order to reduce weight, as the weight of the caliper, which tends to be relatively heavy, can affect the operation and suspension of the chassis. However, a low strength caliper will have low load capacity and low structural stiffness. The C-bridge provides structural rigidity by using high tensile strength materials, creating a “bending moment” situation, which improves support to the low strength caliper housing members. By using high strength materials only where needed, the strength of the caliper can be maximized while still minimizing weight.  
         [0013]     One key advantage of the present invention to be noted is the use of high tensile strength anchors (i.e. the downward turning arms) in between the pistons of the caliper, especially as assembled to the center portion of the caliper. The use of high strength downward turning arms allows for a stronger bridge design to reduce deflection.  
         [0014]     Structurally, the first and second members each have at least one channel provided therein respectively for receiving the anchor members of the bridge, and at least one hole formed therein respectively in substantial alignment with the channels. The bridge has at least two holes formed in the anchor members. The bridge anchor members are capable of fitting flush in the channels of the first and second members, such that the holes in the bridge anchor members coaxially align with the holes in the first and second members. A securing means, such as a bolt, capable of passing through the holes in the first and second caliper housing members and engaging the holes in the bridge, acts to secure the first member and second member to the bridge.  
         [0015]     In another embodiment of the brake caliper, the first and second members are secured by a plurality of bridges. Accordingly, the first and second members include a plurality of channels therein for receiving the anchor members of the bridges and a plurality of holes and securing means for connected the bridges to the first and second members.  
         [0016]     In yet another embodiment of the invention, first and second members of the brake caliper do not have channels formed therein. Instead, the outside face of the bridge abuts the inside face of the first and second members, such that the holes in the bridge coaxially align with the holes the in first and second members. In this embodiment, the bridge extends into the pad area between the housing members. As such, the bridge could provide additional pad support and retention. This would increase the center rigidity by increasing the cross-section thickness.  
         [0017]     An advantage of using a bridge such as the C-section is that it provides superior rigidity, which correspondingly would require less master cylinder volume to fill the pistons since deflection in the caliper is reduced.  
         [0018]     In a preferred embodiment of the invention as shown in  FIG. 5 , an E-section cage connects the first and second housing members. In contrast to a C-section bridge, this type of bridge can be referred to as an E-section cage because of its profile. The E-section cage as shown has a top rectangular frame that includes two side members joined at the midpoint by a one cross member, with the respective ends of the side members connected by endplates. The profile of the rectangular frame with the two endplates and the midpoint anchor can be described as forming an E-section. At the midpoint of each respective side member where the cross member is connected, each side member is connected to a downward anchor. The two respective downward anchors are not unlike the anchors on the C-section bridge in that each anchor has at least one hole formed therein to be in substantial alignment with corresponding holes on the first and second housing members. Similarly, integral to the outside face of each respective endplate is a recessed shoulder block having at least one hole formed therein to be in substantial alignment with corresponding holes on the first and second housing members. The center portion of each endplate is cut-out to reduce weight, with the endplate tabbed on the bottom edge as shown.  
         [0019]     In the preferred embodiment shown in  FIG. 5 , the inboard surface of each respective housing member is recessed in relation to the raised shoulders of the housing member. The recessed inboard surfaces of the first and second housing members are such that the endplates and anchors on the rectangular frame of the E-section cage fit between the recessed surfaces when first and second housing members are assembled. When the E-section cage is fitted between the first and second housing members, the recessed shoulder blocks on the endplates fit with the raised shoulders on the first and second housing members. Securing means, such as bolts, capable of passing through the holes in the first and second housing members and engaging the corresponding holes in the anchors and shoulder blocks of the E-section cage, act to secure the first and second housing members to the E-section cage as shown in  FIG. 5 .  
         [0020]     In other contemplated embodiments of the invention, the rectangular frame may include more than two side members or multiple cross members. For example, the rectangular frame may include two side members joined by two cross members with or without endplates. In yet another alternative embodiment, the rectangular frame may include two side members connected by endplates but without a cross member. However, the preferred embodiment is as shown in  FIG. 5 .  
         [0021]     An advantage of the E-section cage is that it provides even greater structural rigidity than the C-section bridge because of the rectangular frame. The shoulder blocks on the rectangular frame allow the first and second housing members to be connected at the shoulders in addition to being connected at the anchors at the midpoint of the rectangular frame, resulting in greater overall rigidity. Hence, the E-section cage allows the mechanical stress to be spread over the body of the cage, with much of the load taken by the shoulder blocks on the rectangular frame, thereby further reducing deflection in the caliper. The greater rigidity of the cage is achieved without sacrificing efficient heat ventilation because of the frame structure and the cut-out in the endplates. 
     
    
     DRAWINGS  
       [0022]      FIG. 1  is a perspective view of a prior art brake caliper.  
         [0023]      FIG. 2  is a perspective view of a brake caliper according to an embodiment of the invention.  
         [0024]      FIG. 3  is a partially exploded perspective view of the break caliper according to an embodiment of the invention.  
         [0025]      FIG. 4  is a cross-section view of an embodiment of the invention.  
         [0026]      FIG. 5  is a partially exploded perspective view of the break caliper according to a preferred embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0027]     An embodiment of a brake caliper is shown in  FIGS. 2 and 3 . Referring to  FIG. 2 , the brake caliper  10  has first member  12  and second member  14  straddling the rotor (not shown), with first and second members  12 ,  14  connected by a bridge  16 .  FIG. 2  shows brake caliper  10  with bridge  16  connected to first and second members  12 ,  14 .  FIG. 3  shows a partially exploded view of brake caliper  10  with bridge  16  unconnected to first and second members  12 ,  14 . It is to be noted that although  FIGS. 2 and 3  show a C-section bridge  16 , the bridge can take a variety of form and shape that incorporate the basic combination of cross member and associated anchors.  
         [0028]     Referring to  FIG. 3 , C-section bridge  16  is generally comprised of a cross member  16   a  and associated anchor arms  16   b  and  16   c . The C-section bridge  16  has at least one hole  16   d  in arm  16   b  and at least one hole  16   e  in arm  16   c . The first member  12  has at least one channel  18  provided therein for receiving arm  16   b  of C-section bridge  16 , and at least one hole  20  formed therein in substantial alignment with channel  18 . Likewise, second member  14  also has at least one channel  22  provided therein for receiving arm  16   c  and also at least one hole  24  (as shown in  FIG. 4 ) formed in substantial alignment with channel  22 . Referring to  FIGS. 3 and 4 , the anchor arms  16   b ,  16   c  of C-section bridge  16  are capable of fitting flush in channels  18 ,  22  of first and second members  12 ,  14 , such that holes  16   d ,  16   e  in C-section bridge  16  coaxially align with holes  20 ,  24  in first and second members  12 ,  14 . A securing means  26  passing through holes  20 ,  24  and engaging holes  16   d ,  16   e  secures first member  12  and second member  14  to C-section bridge  16 .  
         [0029]     First and second members  12 ,  14  can also be secured by a plurality of C-section bridges  16 . Accordingly, first and second members  12 ,  14  would include a plurality of channels  18 ,  22  therein for receiving anchor arms  16   b ,  16   c , and a plurality of holes  20 ,  24  for securing means  26  to connect C-section bridges  16  to first and second members  12 ,  14 .  
         [0030]     In another embodiment of the invention, first and second members  12 ,  14  of brake caliper  10  do not have channels  18 ,  22  formed therein. Instead, the outside face of C-section bridge  16  abuts the inside face of first and second members  12 ,  14 , such that holes  16   d ,  16   e  in C-section bridge  16  coaxially align with holes  20 ,  24  in first and second members  12 ,  14 .  
         [0031]     The preferred embodiment of the invention is shown in  FIG. 5 . Referring to  FIG. 5 , an E-section cage  30  connects the first and second housing members  12 ,  14 . In contrast to the C-section bridge  16  shown in  FIG. 3 , this type of cage can be described as an E-section because of its profile. The E-section cage  30  has a top rectangular frame  32  which includes two side members  34 ,  36  joined approximately at the midpoint by a cross member  38 . At the midpoint of each respective side member  34 ,  36  where the cross member  38  is connected, each side member  34 ,  36  is connected to a downward anchor  40 . The two respective downward anchors  40  are not unlike the anchors on the C-section bridge  16  in that each anchor  40  has at least one hole  40   a  formed therein to be in substantial alignment with holes  20  on the first and second housing members  12 ,  14 . The respective ends of the side members  34 ,  36  are connected by endplates  42 . It should be noted that the center portion of each endplate  42  can be cut-out to reduce weight as shown in  FIG. 5 , with the endplate  42  tabbed on the bottom edge as shown. Integral to the outside face of each respective endplate  42  is a shoulder block  44  that is recessed with respect to the side edges of endplate  42 . Each shoulder block  44  has at least one hole  44   a  formed therein to be in substantial alignment with holes  44   b  on the first and second housing members  12 ,  14 .  
         [0032]     In the preferred embodiment as shown in  FIG. 5 , the inboard surface of each respective housing member  12 ,  14  is recessed in relation to the raised shoulders of housing member  12 ,  14 . The recessed inboard surfaces of first and second housing members  12 ,  14  are such that the endplates  42  and anchors  40  on rectangular frame  32  of E-section cage  30  fit between the recessed surfaces when first and second housing members  12 ,  14  are assembled. When rectangular frame  32  of E-section cage  30  is fitted between the recessed surfaces of first and second housing members  12 ,  14 , the recessed shoulder blocks  44  on endplates  42  fit with the raised surfaces of the shoulders on first and second housing members  12 ,  14 . A securing means, such as a bolt, capable of passing through holes  20  in first and second housing members  12 ,  14  and engaging holes  40   a  in anchors  40 , acts to secure first and second members  12 ,  14  to E-section cage  30 . In addition, other securing means, capable of passing through holes  44   b  in first and second housing members  12 ,  14  and engaging holes  44   a  in shoulder blocks  44  of E-section cage  30 , act to further secure first and second members  12 ,  14  to E-section cage  30 .  
         [0033]     The embodiments described herein demonstrate an improved brake caliper having a reinforced cage. This brake caliper design will reduce the clam shell effect. Although the present invention has been described in considerable detail with reference to certain preferred versions thereof, other versions are possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the preferred versions contained herein.