Abstract:
A disk brake kit including a pair of brake pads disposed on opposite sides of a brake disc and carried from calipers suspended from a kit frame indexed to predetermined land marks on the wheel housing.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to the field of retrofitting parking brakes on high performance sports automobiles.  
         [0003]     2. Description of the Prior Art  
         [0004]     Sports automobile enthusiasts often seek to modify their vehicles to test the limits of their capacity. In search of drawing the highest performance possible out of their cars, these enthusiasts realize that many of the support components also require modification or outright replacement to withstand the increased rigors of high performance. Knowledgeable sports car enthusiasts often increase the horsepower and acceleration of sports car engines beyond what the original engineering specifications. Consequently components such as the braking system should be upgraded to meet the higher demands for stopping power. Also, many aging models of sports cars incorporate worn components which are out of production and for which no parts are available for replacement.  
         [0005]     One particular popular high end automobile that that lends itself to modification is the Porsche Model 914. Enthusiasts of the Porsche 914 often seek to increase the horsepower output of this rear wheel drive platform where rear wheel braking is critical. The original brake system for the Porsche 914 employed a combination main brake incorporating a parking brake function. While these original equipment manufacturer (OEM) brakes were sufficient for the performance of the stock model sold, modified versions of the Porsche 914 require higher braking performance which often leads to greater heat generation thus requiring more efficient heat dissipation.  
         [0006]     Age, deterioration, improved braking requirements and unavailability of replacement OEM brakes often force the enthusiast to employ special manufactured disc-braking systems capable of achieving improved braking performance. The better performing disc brake systems for sports cars employ main brakes with hydraulically actuated action calipers and a floating spot-type caliper design for the parking brake. One of the primary advantages of the spot-type floating caliper disc brake is the ability to resist warping that is typically associated with non-spot-type caliper brakes from uneven engagement of the disc. The braking horse power necessary to slow down these modified sports cars on the main brake requires a large braking surface that already covers a large portion of the rotor arc. This is evident where OEM main brakes utilize only two pistons to actuate the calipers compared to the four or six pistons used by upgraded main brakes. Consequently, the main braking system does not have room for an additional parking brake.  
         [0007]     A shortcoming of high performance braking systems is that they typically do not incorporate a separate parking brake system. Using a special manufactured main brake leaves the sports car modification enthusiast with three alternatives for a secondary brake. Either a parking brake function can be incorporated into the main brake or an entirely separate parking brake assembly can be mounted or a parking brake can be omitted altogether.  
         [0008]     Most replacement main brakes require a hydraulic system and are already too large to incorporate a separate parking brake function. When retrofitting a separate parking brake (often called secondary or emergency brake), typically a drum brake requiring its own bulky mechanical subassembly is used. Most parking brakes use drum systems because there is no room to fit another hydraulic system on the wheel housing for the parking brake so drum brakes use existing mechanical components for actuation. However, using a drum brake as a parking brake requires separate tools for changing the brake shoes, requires a lengthy process for mounting the brake assembly and changing brake linings, and provides inferior braking power than a disc brake system. High performance automobiles require high performance braking. High performance braking usually requires a disk braking system that is not typically available in secondary brake systems. Secondary brakes must achieve two important functions in high end automobiles.  
         [0009]     The first function is to assist in keeping the car in place while it is not in gear. This function lessens the strain placed on transmissions when the car is not moving or idling. It is very important to apply the secondary brake when a car with standard transmission is parked on an incline. Without it, the car is free to roll down the hill. Oftentimes one can recognize an automobile in which the OEM brake has been replaced since the consequent lack of a brake dictates the placement of a brick or other obstruction on the down hill side of a hill.  
         [0010]     The second function of a parking brake is to serve as a secondary brake or emergency back up brake should the main brake fail. Without a secondary brake, failure of the main brake usually spells disaster since the motorist must then downshift to decelerate placing him or her at risk of failing to stop before disaster. As most sports car enthusiasts know, employing an OEM secondary brake to decelerate from high speeds runs the risk of the parking brake exceeding the capacity of the mount to withstand stress. While drum brakes are typically sufficient for use in non-sports cars, their weaker braking power and bulkiness detracts from the braking required in high end sports cars. I have discovered that by employing a spot-type disc brake for an emergency brake, braking power is improved and reliability of the brake mount is improved.  
         [0011]     As one skilled in the art of modifying sports autos knows, seldom is the framework of an automobile conducive to non-OEM parts since the automobiles were designed as complete systems with many hours of design and engineering exerted in the elaborate interconnection of components to achieve ease of assembly and performance efficiency. Consequently, non-OEM parts often do not lend themselves to ready and convenient mounting from a wheel or wheel hub thus requiring the framework itself to be modified for receipt of the new part. Modification of the framework typically involves mutilating the components by welding and cutting metal. Disc brake systems are typically subject to these constraints and sports car enthusiasts wishing to employ high performance disc brakes on, for example, the Porsche 914 are forced to modify the components surrounding the suspension near the wheels requiring undesirable expenditures of time, money, and risk in the damage of the suspension components.  
         [0012]     In recognition of the need for auxiliary brakes, it has been proposed to attach non-OEM disc brakes to automobile wheels. One proposed mount is observed in the U.S. Pat. No. 6,478,120 to Runkel et al. The patent to Runkel discloses an actuating apparatus with automatic clearance adjustment for vehicles using a disc brake system. The actuating apparatus uses a spot-type brake having a floating caliper. A lever is fastened to the outer end of the shaft and connected to a parking brake lever or pedal for switching the operation of the brake from main brake to parking brake mode. For attachment to the suspension, the caliper is guided onto the brake carrier so as to be in a conventional manner displaceable parallel to the axis of a brake disc. Brakes of such design suffer from a lack of secured and convenient mounting means to the suspension. While they can be guided into place, their attachment requires the modification of OEM suspension components or an OEM design that incorporates the brake in its current form. Additionally, combination brakes such a Runkel&#39;s are bulky and do not fit onto the suspension and rotor of a high end sports car wheel where two separate brakes are necessary.  
         [0013]     U.S. Pat. No. 5,038,895 to Evans discloses a disc brake assembly that can function as both a hydraulically operated main brake and a mechanically actuated parking brake. Like Runkel&#39;s brake, the brake to Evans suffers from bulkiness and even more importantly, should the main brake pad fail, the secondary brake system is likely to also fail since they operate using the same brake pads. To the further detriment of one using Evans&#39; brake, the system lacks a convenient and simple retrofit mounting structure that can be mounted onto an existing automobile wheel housing.  
         [0014]     These proposed solutions in the prior art require modifying or mutilating the wheel assembly or are designed as their own OEM brake systems uncooperative for retrofitting. These solutions lack ease of installment and readiness to a preexisting wheel housing. Other related art may suggest means for mounting to a wheel housing but does not take advantage of preexisting bores outside of the wheel hub where it is less complex to mount on. Also, while the prior art references teach combining a parking brake to a main brake, many fail to suggest using separate brake pads for the main and secondary braking functions in the event the main brake should fail.  
         [0015]     Therefore, it can be seen that a need exists in the art for a brake kit that is readily mountable to existing automotive wheel structure to provide high performance secondary braking.  
       SUMMARY OF THE INVENTION  
       [0016]     Briefly and in general terms, the present invention is directed to a parking brake kit that uses a known disc brake system to readily mount onto the pre-existing components of an automobile. The parking brake kit includes a frame with a mounting bore to act as a first mounting point to a wheel structure and a second mounting point which may be an edge to abut against a boss structure to support against rotation of the frame about a bolt through bore.  
         [0017]     One embodiment may use a spot-type floating caliper brake system. To mount the parking brake kit to the suspension, one of the halves of the caliper, typically the action half, and the kit frame is mounted onto the control arm and mounting bore. A through bore on a flange of the brake kit frame is aligned with a preexisting mounting bore on the control arm of the suspension. A contoured flange edge is placed abutting in fit with the contours of the surface of the control arm. A bolt is inserted through the two bores and the brake housing may be secured to the wheel assembly by a locking nut threaded onto the bolt. is over the position of the brake disc until the brake kit frame and action caliper half are aligned for functionality of the brake. After the brake disk is mounted into place on the wheel assembly, the floating caliper half of the is attached to the rest of the brake kit frame assembly.  
         [0018]     The brake system may use a mechanically actuated driver to displace the brake pads towards the opposite side of a brake disk. A brake cable is actuated by a lever or similar means in the automobile driver&#39;s compartment. The kit may use an extension or connector arm to connect the parking brake cable to the actuation driver. When the cable is actuated, an actuation driver displaces the action caliper half brake pad toward the brake disc by using a cam action to push against a brake pad support engaging the brake pad to the disc. The reaction caliper half pad on the other side of the brake disc is displaced by reactionary forces associated with the action caliper half moving toward the disc. The reaction caliper half then moves toward the other side of the disc to engage a brake pad on its end with the surface of the disc.  
         [0019]     Other features and advantages of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings which illustrate, by way of example, the features of the invention 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]      FIG. 1  is a right side perspective view of the high performance retrofit brake kit of the present invention;  
         [0021]      FIG. 2  is a left side perspective view of the brake kit shown in  FIG. 1 ;  
         [0022]      FIG. 3  is a right hand of the brake kit shown in  FIG. 1  mounted to a wheel assembly;  
         [0023]      FIG. 4  is a broken sectional view of the kit taken along the line  4 - 4  of  FIG. 3 ;  
         [0024]      FIG. 5  is a transverse sectional view taken along the line  4 - 4  of  FIG. 4  showing the connection structure of the actuation arm;  
         [0025]      FIG. 6  is a longitudinal sectional view taken through the connection structure of the actuation arm shown in  FIG. 5 ;  
         [0026]      FIG. 7  is a sectional view taken along the line  7 - 7  of  FIG. 6  showing the inclined surface of the rotary cam;  
         [0027]      FIG. 8  is perspective view, in reduced scale, and partially broken away of the brake kit shown in  FIG. 3 , mounted on an OEM brake disk wheel assembly;  
         [0028]      FIG. 9  is a top view, in enlarged scale, of the brake kit shown in  FIG. 8 ;  
         [0029]      FIG. 10  is a front view, in enlarged scale, of the wheel and brake kit shown in  FIG. 9 ; and  
         [0030]      FIG. 11  is a partial top view, in enlarged scale, of the wheel and brake kit shown in  FIG. 10 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0031]     Referring to  FIGS. 8-10 , the high performance replacement brake kit  20  of the present invention may be configured with a frame  22  to mount on a wheel housing defined by a control arm  23  formed with an axial boss  26  whose exterior is defined by an abutment surface  27  and a mounting bore  34 . The frame mounts a pair of pads  33  and  35  to act on a brake disk  28  carried from the wheel. A brake disk  28  is receivable on an axle  24  and mounted over a wheel hub  22  (not shown) A parking brake cable  30  may be pulled to draw the pads into contact with the disk.  
         [0032]     Sports car enthusiasts often upgrade the performance of an automobile engine allowing the car to rapidly accelerate to high speeds but leave the standard braking mechanism on the automobile thus failing to account for the greater kinetic energy that must be counteracted to provide a safe rate of deceleration. Even when more robust brake pad systems are installed, the driver is left without an operating hand or emergency brake system to apply when the car is parked or to actuate as a back-up should the hydraulic brakes fail. Furthermore, within a relatively short period after a model year, production of OEM parts is often discontinued thus making them unavailable to the owners of older or vintage automobiles thereby leaving the owner with the expense of custom made components for a replacement braking system. It is desirable to have a replacement brake installation kit which will be available to the customer and can conveniently be installed relatively rapidly and without need for high skilled mechanics.  
         [0033]     Automobile wheel construction typically incorporates an axel, wheel housing and disk brake which maybe acted on by OEM disk pads. It is desirable to have a replacement kit which will hang directly from and index to the wheel housing in a manner which will position the brake calipers directly over the brake disk and which may be coupled with the parking brake cable for actuation thereof when the automobile is in a parked position or in the event the hydraulic brakes fail thus providing a secondary backup deceleration system.  
         [0034]     Brake disks are typically coupled to axels which may be driven by the vehicle drive train and may be covered by a dust cover or the like. In any event, by removing certain components from a wheel housing, such disk may be made accessible for installation in the housing of an auxiliary or replacement brake mechanism, in the form of brake pad calipers, to be actuated by a parking brake cable or the like.  
         [0035]     One high performance sports car on which the replacement brake system of the present invention may be mounted is a Porsche automobile which includes a wheel housing in the form of the control arm  23  having a cylindrical boss  26  projecting axially therefrom and typically configured with a mounting flange  32  ( FIG. 4 ) which is formed with a mounting bore  34  conventionally utilized to mount OEM equipment such as a dust cover from the control arm. The OEM brake disk  28  ( FIGS. 8 and 9 ) is disposed in a vertical plane parallel to and spaced axially outwardly an inch or so from the control arm mounting flange  32 . I have discovered that the mounting flange  32  constitutes a convenient attachment point for the OEM high performance replacement brake of the present invention. Generally, the brake kit includes a frame  22  mounted to the flange  32  to bring a pair of brake pads  33  and  35  on opposite sides of the disk to be a actuated by a brake cable  30 .  
         [0036]     The frame  22  is vertically elongated and, in top plan view ( FIG. 1 ), is configured with a vertically mounting flange  40  ( FIG. 4 ) to be oriented parallel with the brake disk, spaced axially inwardly therefrom and formed centrally with a mounting bore  42  to be aligned with mounting bore  34  in the flange  32  ( FIG. 4 ). Such flange is configured at its rear extremity with a somewhat C-shaped contoured abutment surface  44  to compliment vertical profile of the boss  26  to thus cooperate with the mounting bolt  46  through the bore  42  to mount the frame cantileverly from the flange  32 . The frame  22  is viewed in top plan view ( FIG. 4 ), is configured with an orthogonal axially inwardly projecting offset plate  48  and an orthogonal rearwardly projecting support plate  50  which is formed at its rear extremity with a pair of vertically spaced bores to receive securing bolts  60  and  62 . The plates  48  and  50  are supported at their intersections by gussets  52  and  53  ( FIG. 11 ). The arms  41  and  47  are formed rearwardly with axially projecting legs  43  and  45 , respectively, and include respective laterally spaced part, rearwardly projecting legs  37  and  39  mounting the brake pads on the confronting rearward extremities thereof. Sandwiched between the confronting ends of the legs  43  and  45  are a pair of spacer blocks  49  and  51  ( FIG. 1 ). The securing bolts  60  and  62  secure the arms and spacers together and are receivable through the bores of the plate  50 . Capping the upper and lower rear corners of the frame  22  are right angle strips  54  and  56 , respectively. The free extremities of the strips  54  and  56  are tapered at their edges providing wheel clearance while the other extremities are rigidly fixed to the support plate  50  ( FIG. 11 ). Within the right angle strips are male guides for receipt of female grooves formed in the rearward extremities of caliper legs  43  and  45 , ( FIGS. 1 and 3 ). The rear extremity of the caliper arm  47  is formed with an enlarged in diameter axial bore mounting a cup shaped piston housing, generally designated  64  ( FIGS. 4 and 6 ). The piston housing  64  is formed with an inwardly opening piston chamber  66  which receives a cylindrical piston  75  therein. The housing  64  is formed at its closed end with an axial, threaded bore  74  which receives as an adjustment stud  76  having a lock nut  79  received thereon. Referring to  FIGS. 2 and 5 - 7 , such housing  64  is also formed in its peripheral wall with a circumferential clearance slot  78 .  
         [0037]     A control lever, generally designated  80  projects radially through the slot  78  and is formed intermediately with a blind axial mounting bore  82  ( FIG. 6 ) that receives the distal end of the adjustment stud  76  and is configured on one end with an axially outwardly projecting cylindrical cam driver  88 . Sandwiched between the distal end of such driver and the piston is a wedge shaped axial cross section, circular cam follower  70  housing an inclined surface  71  such that pivoting of the arm about the stud  76  causes the piston  75  to be selectively driven toward the brake pad support and confronting brake pad  33  ( FIG. 6 ).  
         [0038]     The free extremity of the control arm  80  is formed with a through bore for receipt of connector pin  90  connecting one extremity of connector fitting, generally designated  92  therewith to connect with the brake cable  30 . The arm  80  is formed intermediately with a through bore  94  to which is hooked one end of a coil return spring  96  drawing the arm clockwise as viewed in  FIG. 5 .  
         [0039]     It will be appreciated that an automobile may include a conventional hydraulic brake caliper, generally designated  100  ( FIG. 8 ) mounted from the wheel housing and embracing the forward periphery of the brake disk  28 . In practice the parking brake  20  of the present invention may be mounted from the brake housing to the rear side of the disk  28  diametrically opposite the hydraulic brake caliper  100 . The replacement kit of the present invention will typically be packaged with all components together in a replacement kit package. If a workman desires to install the present replacement kit, he or she will remove the bolt mounting the dust cap (not shown) and any other parts not necessary to operation to provide clearance for installation of the present kit. The kit of the present invention can be withdrawn from the packaging and the dust cap bolt removed from the mounting flange  32  of the brake arm ( FIG. 4 ) for access thereto.  
         [0040]     The brake kit will typically be preassembled with the components generally in the configuration shown in  FIG. 1  and the installer need only to align the bore  42  of the frame flange  40  with the bore  34  in the mounting flange  32  abutting the semicircular abutment surface  44  with the periphery of the boss abutment surface  27  shown in  FIG. 4  to insert the bolt  46  to act as an anchor to the flange  32  and maintain the abutment surface  44  abutted in firm contact with the surface  27  to thereby suspend the frame  22  in position with the caliper arranged disposing the disk pads  33  and  35  on the opposite sides of the disk  28  ( FIGS. 4 and 8 ). The mounting bolt  46  will then be inserted and tightened and the cable adaptor  92  connected between the free extremity of the actuation arm  80  and the cable to ready the replacement brake kit for operation. The screw thread components at the end of the connector  92  may be adjusted to adjust the length thereof to provide the desired travel for the free extremity arm to provide the desired cam effect for control of the piston  68  and consequent engagement of the spot pad with the brake disk.  
         [0041]     In operation of the automobile it will be appreciated that in normal stopping conditions, the hydraulic brakes may be actuated to actuate the hydraulic caliper  100  to slow the vehicle. In other instances, as for instance where the hydraulic brakes are inadequate or in the event they should fail, it will be possible for the driver to pull the emergency brake lever to draw the emergency cable and rotate the lever  80  ( FIG. 5 ) clockwise to drive the cam driver  88  across the surface of the wedge cam follower  70  to the thick side to drive the piston  75  outwardly in the housing  64  driving the brake pad  35  into contact with the near side of the brake disk  28  with adequate force to apply sufficient frictional drag to the disk to positively slow the vehicle. The reaction caliper half  41  and brake pad  33  will displace towards the brake disk as reactionary forces caused by the contact of pad  35  to the disk cause the pad  33  to contact the opposite side of the brake disk. This then provides a braking function that would otherwise not be available and enhances the safety of operation of the vehicle.  
         [0042]     When the brake pad calipers are actuated to close the pads on the disk  28  such pads will provide frictional drag force to the disk  28  to resist rotation thereof. As for example, assuming the automobile wheels are rotating in the forward direction to rotate the disk  28  in the counterclockwise direction as viewed in  FIG. 8 , application of the brake pads will tend to resist that rotation with the reactive forces thereof being applied to the free end of the cantileverly mounted frame  22  upwardly tending to also rotate in a counterclockwise direction about the mounting bolt  46 . This braking force will be resisted by the frame as dictated by the fact that mounting bolt  46  is subjected to shear forces and rotation of the mounting flange  40  about such bolt will be resisted by the contact of the contoured abutment surface  44  of that flange with the abutment surface  27  of the boss  26 .  
         [0043]     As will be appreciated of those skilled in the art, the frame  22  may take many different forms and shapes, it being important that it index to the wheel housing in such a manner that when so indexed and oriented, the brake pads are in position on opposite sides of the disk for operation thereof. For the purposes of this description it is intended that the mounting flange  40  will include at least two attachment points, one being the bore  42  which receives the mounting bolt  46  and the other being, for instance, a second mounting bore or other abutment arrangements such as the contoured abutment surface  44  which engages the abutment surface  27  on the boss  26  to limit rotation of the frame about the bolt  46  to thereby carry the weight of the frame and calipers, as well as to provide robust resistance to the frictional forces applied to the brake pads when they are actuated against the brake disk  28 . By providing for the mounting of such flange to known landmarks, such as the mounting bore  34  on the flange  32  ( FIG. 4 ) and abutment against another anchor point, to position the frame  22  so as to properly orient the brake pads and to position the control arm  80  to be drawn by the cable  30 , quick efficient and reliable mounting is assured.