Abstract:
A disc brake tool to assist brake maintenance by forcing retraction of a brake piston. Two plates are inserted into the open area of a brake caliper while a third central member is forced between the plates. A crank-rotatable threaded shaft engages the central member to control central member movement along the shaft. The plates engage the caliper directly or indirectly and force pressure on the outside of a piston to cause it to retract back into the caliper. A method is also disclosed for retracting a brake piston by placing plates within the open area of a caliper. The method includes rotating a shaft to cause a third member to press apart the plates so as to force pressure on a piston.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to automobile brake maintenance. More particularly, the invention relates to servicing disc brakes including the replacement of disc brake pads. 
       BACKGROUND OF THE INVENTION 
       [0002]    Disc brake devices slow and stop the rotation of a wheel. Automobiles generally to come standard with two different braking systems, drum and disc brakes on alternating axles. Disc brakes are often utilized on the front axle of a car or motorcycle, and provide substantial braking power when applied to a wheel. In use, disc brakes operate to stop the wheel, by forcing brake pads (friction material mounted on the brake caliper) against both sides of a brake disc (also known as a “rotor”). Friction causes the disc, or rotor, to stop. The rotor being attached to the wheel controls the velocity of the vehicle. 
         [0003]    A brake caliper is an assembly which houses the brake pads and piston(s). Calipers may be fixed or floating. A single-piston “floating” (or sliding) caliper is generally self-centering and self-adjusting. The floating caliper changes position relative to the disc along a line parallel to the axis of rotation of the rotor. A piston on one side pushes the inner brake pad until it makes contact with a braking surface, then pulls the caliper body with the outer brake pad so that pressure is applied to both sides of the disc. The caliper is free to float back and forth on the wheel brake to ensure that the brake is centered on the wheel. There is generally no spring to pull the brake pads, which contact the disc, so the pads stay in light contact with the disc. Furthermore, the piston will adjust to extend to contact the disc so as to allow a more consistent requirement of brake fluid flow to apply a consistent braking power. 
         [0004]    The most common caliper design uses a single hydraulically actuated piston within a cylinder, however higher braking power needs can lead to use of as many as a dozen pistons arranged singly or paired on both sides of the disc. Disc brakes come in all sizes and number of pistons. Brake pads are designed for high-friction with brake pad material embedded in the disc. Brake pads must usually be replaced regularly due to wear. 
         [0005]    When replacing brake pads, it is usually required to disconnect the caliper from the wheel. Brake pads may then be free to slide out, however sometimes there may be a clip or spring holding the pad. Once the pads are out, it is necessary to push the piston(s) back into the caliper. Many methods have been designed to accomplish this task. For instance, a C-clamp may be used with one end positioned inside the caliper and the other on the outside of the caliper to compress the piston. This method is cumbersome and risks placing unwanted pressure on the outside of the caliper. Another method comprises putting an oval shaped tool into the caliper, and rotating this device until the long end holds the piston back. This method is dangerous for it requires much applied and specific force to accomplish. Other methods have been designed for single-piston brakes. Certain specific methods use a shaft inserted from the open end of the caliper to press on the piston and a second surface inside the caliper, for example see U.S. Pat. Nos. 5,018,261 to Markous and 6,523,238 to Priddy (requiring entry both from the open end and through an aperture in the caliper back wall, thus incapable of use with a dual-piston caliper). These methods are inadequate when direct access from a single direction is not easily attained. 
         [0006]    Another known method includes access only through the open end, without requiring access from an aperture, however this method suffers from many drawbacks, including a lack of proper support or strength to properly manipulate these tools have proven less popular. 
         [0007]    Other methods rely on a tool inserted into a region of the brake pads. Most of these methods use a very small contact area to engage the piston, and retain many of the drawbacks of other methods known in the art. 
       OBJECTS OF THE INVENTION 
       [0008]    It is therefore an object of the present invention to provide a tool to assist in positioning a caliper piston for replacement of brake pads whereby the user is free to enter at any direction. 
         [0009]    It is a further object to provide piston retraction with access only through an open end of a caliper. 
         [0010]    It is a yet further object of the present invention to provide a brake piston retraction tool that may be used on single as well as dual-piston systems. 
         [0011]    It is yet another object to provide piston retraction with enough leverage power. 
         [0012]    It is another object of the present invention to provide a tool with dual-plates to engage a caliper piston and a second surface. 
         [0013]    It is yet another object of the present invention to provide a tool with plates broad enough to easily engage at least a caliper piston. 
         [0014]    It is still another object of the present invention to provide a tool for easy piston retraction. 
         [0015]    It is still yet another object of the present invention to safely retract or separate a misplaced item. 
         [0016]    These and other objects of the present invention will become more apparent to those skilled in the art as the description of the present invention proceeds. 
       SUMMARY OF THE INVENTION 
       [0017]    According to one aspect of the present invention, an apparatus is provided for pushing back a disc brake caliper piston. A pair of arms are thin enough to be inserted within a disc brake caliper, whereby at least one of said pair of arms can engage the end of a brake piston, and the other arm can engage a second surface. The arms are loosely coupled to one another. A crank is provided to cause the pair of arms to separate when the crank is rotated in a single direction. 
         [0018]    According to another aspect of the present invention, an apparatus is provided for pushing back a disc brake caliper piston. A pair of arms are thin enough to be inserted within a disc brake caliper, whereby at least one of said pair of arms can engage the end of a brake piston, and the other arm can engage a second surface. The arms are loosely coupled to one another at their bases so as to allow them freedom to move apart and closer to one another and also to rotate relative to one another about an axis, or axes defined between the two arms. The arms may be described so as to each have an interior surface and an exterior surface, whereby the exterior surfaces are for engaging surfaces of the disc brake caliper. One, or both, of the arms may be tapered so that the ends away from the bases have a gradual opening. The preferred embodiment may also contain a central member, preferably a wedge, set between the two arms, and the central member is adapted to move between the arms back and forth, from base to tip. One of the arms surface may also contain a dove-tail feature to secure the central member in place, and the central member has a complimentary surface to interact with the dove-tail. 
         [0019]    A threaded shaft may be disposed through the central member, whereby rotating the threaded shaft causes the central member to move relative to the shaft. A crank can be attached to the threaded shaft for rotating the shaft. A connection plate, preferably with an aperture for receiving and maintaining the shaft, may loosely couple the pair of arms. 
         [0020]    The present invention also provides an apparatus for retracting at least one piston of a disc brake caliper. A top finger and a bottom finger each have an interior surface, an exterior surface, a base at one end, and a tip at an opposing end. A central member is set between the top and bottom fingers for engaging the interior surfaces. The central member may be wedge-shaped with a broad portion of the wedge positioned towards the tip of at least one of the fingers. The central member may also include a threaded aperture to engage the threaded member. 
         [0000]    The top and bottom fingers have substantially parallel longitudinal axes formed along each tip and base; and the central member is adapted to move between the arms, longitudinally back-and-forth, substantially parallel along the axes. A threaded member engages the central member wherein rotation of the threaded member forces contact between the central member and both of the top and bottom fingers. A crank may be coupled to the threaded member to rotate it. In the preferred embodiment, at least one of the top and bottom fingers has a dove-tail to fit with a complimentary surface on the central member to form a dove-tail joint. 
         [0021]    The present invention also provides and apparatus for retracting at least one piston of a disc brake caliper, the caliper having at least one piston and a second surface disposed opposite the piston, wherein the caliper piston moves in a linear fashion defining a plane perpendicular to the movement of the caliper piston. The apparatus is a threaded shaft disposed substantially along the plane perpendicular, whereby the shaft is initially free to rotate substantially within the plane perpendicular. A central member receives the shaft through its threaded aperture so that rotation of the shaft forces the central member to move along the shaft and by doing so, forces the piston to retract. The apparatus may have a top and bottom arm, each having a tip at one end and a base at an opposing end, and having an interior surface and an exterior surface, the interior surfaces facing one another with the shaft positioned there between, and wherein rotation of the shaft forces the central member to engage the arms&#39; interior surfaces. It may do so by causing the central member to force a portion of the top and bottom arms apart from one another, causing their exterior surfaces to engage the caliper piston. 
         [0022]    The present invention also provides a method of controlling a caliper piston position. Two plate members are inserted between an exposed caliper piston and a second surface. A central member is forced there between in order to force the plate members to engage the caliper piston and the second surface by forcing the plate members apart form one another so as to cause at least one of the plate members to push on the caliper piston. This method may include forcing two caliper pistons back simultaneously. The method may also be performed via activating and rotating a rotating a threaded member and may pull the central member towards a base of the two plate members. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]    The present invention may more readily be understood by reference to the accompanying drawings in which: 
           [0024]      FIG. 1  is a perspective view of an embodiment of the invention; 
           [0025]      FIG. 2  is an elevational view along Line  2 - 2  showing the cross-section of  FIG. 1 ; 
           [0026]      FIG. 3  is a partial cross-sectional view along Line  3 - 3  of  FIG. 2 ; 
           [0027]      FIG. 4  is an exploded partial view of the apparatus of  FIG. 1 ; 
           [0028]      FIG. 5  is a cross-sectional view along Line  5 - 5  of  FIG. 1 ; 
           [0029]      FIG. 6  is a top view along Line  6 - 6  of  FIG. 5 ; 
           [0030]      FIG. 7  is a cross-sectional view along Line  7 - 7  of  FIG. 5 ; 
           [0031]      FIG. 8  is an enlarged partial view of area  8  of  FIG. 5 ; 
           [0032]      FIG. 9  is a perspective view of an alternate embodiment of the invention; 
           [0033]      FIG. 10  is a partial exploded view of the apparatus shown in  FIG. 9 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0034]    Referring first to  FIGS. 1-4 , an embodiment of the invention is shown as a brake tool. In the preferred embodiment, brake tool  1  has top plate  10  positioned directly over bottom plate  20 . Top plate base  14  is aligned with bottom plate base  24 . Top plate interior surface  11  and/or bottom plate interior surface  21  may be tapered towards top and bottom plate tips  13  and  23  so as to create a broadening opening towards the tips. Central member  60  is preferably set between plates  10  and  20 . Central member  60 , also referred to and shaped as a “wedge” in the preferred embodiment, may be free-floating, out of contact with either of the plates. Wedge  60  is positioned with narrow portion  62  pointing towards plate bases  14  and  24  and connection plate  40 . Broad portion  61  of the wedge  60  points away from connection plate  40 . Shaft  30  may serve to support wedge  60 . In the preferred embodiment, shaft  30  is a threaded screw member with threads  34  to engage wedge  60 , whereby rotation of shaft  30  causes a force on wedge  60  to move the wedge longitudinally along the shaft&#39;s length. 
         [0035]    Top plate  10  has exterior surface  12  to engage a portion of the brake caliper (not shown), such as a piston head. Exterior surface  12  is preferably large and flat to maximize the surface area contact with the caliper. Bottom plate  20 , also has exterior surface  22  for similar purpose. 
         [0036]    Connection plate preferably fits perpendicularly along bases of top and bottom plates  10  and  20 . Connection plate  40  has slots  44  to accept complementary coupling fasteners  41 . Coupling fasteners are attached directly or indirectly to the top and/or bottom plates through the connection plate. This loosely couples the connection plate to the plates, allowing the top and bottom plates to move relative to one another. Generally, slots  44  allow vertical movement of coupling fasteners  41 . Aperture  42  is preferably at or near the center of the connection plate. Aperture should be wide enough to accept shaft  30 . Supports  15  and  25  may be added to further secure top and bottom plates  10  and  20 , respectively. Support fasteners  16  and  26  serve to preferably permanently secure supports to the top and bottom plates. 
         [0037]    Shaft  30  is preferably fitted with hex base  33  for mounting crank  50 . Hex base is preferably on a first side of the connection plate. Shaft extends through aperture  42  to other side of the connection plate. Threads  34  extend along a portion of shaft  30 , but preferably only on the front end  31 . Crank  50  has fitting  51  to mate with shaft  30 . Crank  50  uses bar  52  to provide leverage enough to convert power along shaft  30  to promote movement of wedge  60 . Further, handle  53  allows for manipulation of crank  50 , to facilitate rotation of shaft  30 , thus causing central member  60  along shaft  30  to force plates  10  and  20  against caliper surfaces. Handle  53  may be perpendicular to bar  52  and may be a separate piece that is pivotally connected to bar  52  for allowing manipulation of crank  50 . Handle  53  can include other embodiments wherein the handle is permanently affixed to bar  52 , or any other way known in the art for handles. 
         [0038]    Wedge  60  has wide portion  61  directed towards tips  13  and  23  of plates  10  and  20 , and narrow portion  62  towards the base. Top and bottom plates  10  and  20  are preferably tapered so that they provide a large opening towards the tips for placement of a wedge or like structure. Threads  34  engage complementary surface within torque zone  65 . As shaft  30  turns, mechanical forces pull or push wedge  60  longitudinally along shaft. Wedge top surface  67  engages the top plate and bottom surface  68  engages bottom plate. Movement of wedge  60  in between the top and bottom plates surfaces causes top and bottom plate interior surfaces  11  and  21  to move relative to one another and thus force piston back. When central member  60  is wedge shaped, the thickness of the wedge may at some point become thinner than shaft  30 . For this reason, open area  64  is built into wedge  60  to allow for shaft  30 . Top and bottom plates  10  and  20  therefore contain recesses, grooves, or pass-throughs  19  and  29  formed towards bases  14  and  24 , on interior surfaces  11  and  21 . 
         [0039]      FIGS. 5-8  demonstrate the interior mechanisms of the preferred embodiment. Shaft  30  preferably extends longitudinally along the entire length of the plates. Top and bottom plates are tapered to allow a larger opening away from connection plate  40 . Torque region  65  of wedge  60  is the portion of the wedge that contains complementary or even threaded interior surface to allow rotation of mated shaft to cause the wedge to move longitudinally along shaft  30 . Clip  43  may be provided along shaft  30  and nearby or around connection plate  40 , to secure shaft and crank to the connection plate and altogether hold the apparatus together. 
         [0040]    Referring to  FIG. 6 , open area  64  of the central member is shown. Open area does not contain the complementary surface to contact threads  34  of the shaft. Bottom plate  20  is equipped with pass-through recess  29  to allow tapering of the bottom plate without interference with the shaft. 
         [0041]    Referring to  FIG. 7 , top plate  10  and bottom plate  20  surround a central member, preferably a wedge-shaped piece, or wedge  60 . Shaft  30  fits between the plates and within recesses  19  and  29  along open area  64 . 
         [0042]    Referring to  FIG. 8 , connection plate  40  allows shaft  30  through. Clips  43  are provided to secure longitudinal position of shaft  30  in relation to connection plate  40 . Hex base  33  of the shaft is over-fitted with crank fitting  51 . In the preferred embodiment, fitting  51  surface complements hex base configuration, however, any permanent or temporary fitting or attachment mechanism may be used, as are known in the art. 
         [0043]      FIGS. 9 and 10  demonstrate another preferred embodiment of the invention. Brake tool  100  has top plate  110  with support bar  183  at its base. Support bar  183  may be used instead of supports or may be included for aesthetic purposes. Connection plate  140  is positioned at the base of the device and may or may not remain in this preferred embodiment, or may be part of a crank support. Shaft base  135  here is of a round shape, rather than a hex shape, and may form any structure complementary to fitting  151 . Crank  150  attached to shaft  130  such that rotation in a first direction causes shaft to rotate in a first direction, thus pulling wedge  160  in towards the base. Such pulling action forces wedge  160  between the plates and forces plates  110  and  120  apart from one another. When plates are forced apart, top exterior surface  112  and bottom exterior surface  122  (not shown) engage parts of a brake caliper, and may force a piston back. Rotating crank  150  in a second direction forces wedge  160  away from the base and allows plates to resume a position closer relative to one another. 
         [0044]    Crank  150  has handle  152  to provide leverage. Crank handle  153  is useful to rotate the crank and is preferably large enough for manipulation by the hands or fingers of a mechanic. Handle  153  should be long enough to be gripped with enough force such that no counter pressure, or twisting is required. It is preferred that the brake tool will be held in place by either a second hand, or by pressures within the caliper such that a single hand may be used to run the crank. 
         [0045]    Either or both exterior surfaces  112  or  122  (bottom mot shown) may be forced against a piston, and the invention is intended to be used right side up or upside down without any difference as to which of the top and bottom plates are positioned within the caliper. 
         [0046]    Referring to  FIG. 10 , an alternate embodiment of the central member is shown. Shaft  130 , with hex base  133  is shown. Shaft  130  enters through open area  164 , into the aperture and emerges near the front panel  166 . To accommodate dove-tailing, wedge complimentary surface  170  may include tapered joint wings  172 , with support beam  173  placed there between. Joint wings  172  are complimented by dove-tails  184 . Joint wings  172  are preferably tapered with maximum extension towards front surface  166 , receding towards the base to a particular reflex point  174 . At the reflex point, support beam  173  is inverted, along with the removal or reversal of the joint wings. This occurs relative to cross-line  185  to work with tapered region  182  of plate  180 . Reflex point allows wedge  160  with dove-tailing joint wings to be inserted further in between plates, towards the base, so as to cause some or further separation of the plates. Central member  160  although preferably shaped as a wedge, may function in alternative shapes. 
         [0047]    Plate  180  is identical on top and bottom of the device, therefore, for this embodiment, only one plate is demonstrated. Plate  180  preferably uses pass-through  129  to allow for placement of shaft  130  with enough room for shaft to freely rotate within pass-through. Plate has flat surface  181  on its interior for mating with another plate flat surface. At rest, with central member affixed towards tips or not affixed at all, surface  181  may be free to contact with its complement on a second plate. Wedge  160  fits into dove-tails  184  so that wedge complementary surface  170  engages plate  180  by its dove-tails. Dove-tails  184  recede along tapered region  182  and may end at or before cross-line  185 . 
         [0048]    Another aspect of the present invention relates to a method for engaging a brake caliper. Two plates  10  and  20  are inserted into the open end of a single or multiple pistoned disc brake caliper. No access should be required through a secondary aperture. Plates  10  and  20  are set to engage with at least one piston, that may have extended into the caliper give the wear of brake pads, or release of counter-pressure during maintenance, etc. One plate engages at least one piston, and the opposite plate is set against another surface of the caliper, or a surface placed within the caliper. Shaft  30  is manipulated, preferably by crank  50 , to cause central member  60  between the plates  10  and  20 . Interior surfaces  11  and  21  of plates  10  and  20  engage the exterior surfaces  67  and  68  of central member  60 . As shaft  30  further causes central member  60  between plates  10  and  20 , plates  10  and  20  are forced apart. Plates  10  and  20  then exert pressure on a piston, causing the piston to retract. 
         [0049]    The present invention has been described in terms of selected specific embodiments of the invention incorporating details to facilitate the understanding of the principles of construction and operation of the invention. Such reference herein to a specific embodiment and details thereof is not intended to limit the scope of the claims appended hereto. It will be apparent to those skilled in the art that modifications may be made in the embodiments chosen for illustration without departing from the spirit and scope of the invention.