TECHNICAL FIELD

[0001] The invention herein resides in the art of industrial brake equipment and, more particularly, to a disc brake assembly for implementation with mill equipment and the like. The invention particularly relates to spring-applied caliper disc brakes of a basic structure and configuration that are adaptable to accommodate any of a wide variety of standard caliper sizes and orientations, reducing the need to inventory a multiplicity of parts and assemblies while still meeting industry specifications.

BACKGROUND OF THE INVENTION

[0002] Technical Report #1 1 of the Association of Iron and Steel Technology (AIST), formerly known as the Association of Iron and Steel Engineers (AISE), covers drum brakes for mill motors and has defined the standard for spring-applied brakes in the U.S. steel industry for more than half a century. Many other industries, such as crane manufacturers for applications outside of steel mills, have also adopted the steel industry standard as their de facto standard.

[0003] In 1997 the AIST recognized the advantages of caliper disc brakes and established a new standard that included six separate sizes interchangeable with the same torque ratings and mounting dimensions as the six existing drum brake sizes, adding one additional size. However, all of the drum and caliper brakes suffer from a lack of interchangeable parts between sizes. Each size has a unique set of parts, including brake pads, spring actuators, release mechanisms, and mounting arrangements. Thus, original equipment manufacturers and facilities that use a variety of sizes must inventory a wide range of costly parts and assemblies. Facilities that are in the process of upgrading to the higher performance capabilities of caliper brakes must stock spare parts and assemblies of up to 13 different sizes of brakes.

[0004] In light of the foregoing, there is a great need in the industry for a caliper disc brake design and a method of providing spring-applied braking that can reduce the need to inventory multiple parts and assemblies. Furthermore, there is a need for a caliper brake that can be easily modified to accommodate the spring-applied brake needs of equipment with disc brake diameters and thicknesses, along with torque requirements, that do not align with the AIST standards.

DISCLOSURE OF INVENTION [0005] In light of the foregoing, it is a first aspect of the invention to provide an adaptive caliper disc brake wherein the caliper is adjustably positionable with regard to the discs to accommodate any of numerous applications.

[0006] Another aspect of the invention is the provision of an adaptive caliper disc brake in which the variably positionable caliper substantially reduces the need for the stocking of spare parts and assemblies for various and different sizes of brakes.

[0007] Still another aspect of the invention is the provision of an adaptive caliper disc brake that can be easily modified to accommodate the spring-applied brake needs of equipment with brake disc diameters and/or thicknesses and/or torque requirements that do not align with AIST standards. [0008] Yet a further aspect of the invention is to provide an adaptive caliper disc brake that is basic in construction, adaptive for implementation in various braking systems, easy to service, and reliable and durable in operation.

[0009] The foregoing and other aspects of the invention that will become apparent as the detailed description proceeds are achieved by an adaptive caliper disc brake assembly, comprising a brake disc of an AIST standard disc size having a shaft aperture passing through the center thereof; a caliper having a first end secured to a caliper base plate, said caliper base plate being secured to an adapter base plate; a support arm removably interconnecting a second end of said caliper to said caliper base plate and angularly positioning said caliper with respect to said brake disc in satisfaction of a first industry standard; and a selectable and replaceable spring cup assembly received by said caliper and impacting a force on said caliper consistent with a selected brake torque setting in satisfaction of a second industry standard.

[0010] Other aspects of the invention that will become apparent herein are achieved by a method for constructing and servicing a caliper brake for a disc rotating with a shaft, comprising selecting an adapter base plate according to an associated AIST standard disc size; attaching a caliper base to the adapter base plate to locate the caliper base in compliance with a shaft-to-floor dimension of the AIST standard; selecting a support arm to locate the caliper angularly to the disc according to the required AIST standard brake size; selecting a replaceable spring cup assembly to supply the force required to meet the brake torque according to the AIST standard brake size and disc selection; and placing said spring cup assembly within said caliper and securing said support arm between said caliper and said caliper base.

DESCRIPTION OF DRAWINGS [0011] For a complete understanding of the various aspects, structures and methods of the invention, reference should be made to the following detailed description and accompanying drawings wherein:

[0012] Fig. 1 is a side-elevational view of a first embodiment of the invention;

[0013] Fig. 2, comprising Figs. 2A-2F, shows the concept of the invention in employment with various AIST brake sizes and orientations;

[0014] Fig. 3 is an assembly diagram of the caliper assembly of the invention;

[0015] Fig. 4 is a cross-sectional view of the spring assembly of the caliper of Fig. 3;

[0016] Fig. 5 is a perspective view of an adaptive caliper disc brake according to the invention, along with its control unit; and [0017] Fig. 6 is the hydraulic circuit of the hydraulic unit of the control unit shown in Fig. 5.

DESCRIPTION OF PREFERRED EMBODIMENT

[0018] Referring now to the drawings and more particularly Fig. 1, it can be seen that an adaptive caliper disc brake assembly made in accordance with the invention is designated generally by the numeral 10. Included in the assembly 10 is a brake disc 12 having an aperture 14 passing through the center thereof for receipt of an appropriate axle or shaft upon which the brake disc 12 rotates. An appropriate keyway 16 is provided within the aperture 14 for purposes of locking the brake disc 12 to the axle or shaft. [0019] An adapter base plate 18 is provided with a mounting hole pattern and a bolt hole pattern to attach a universal caliper base plate 20. According to the invention, the mounting hole and bolt hole patterns are those of the Association of Iron and Steel Technology (AIST) as is known and understood by those skilled in the art. A caliper assembly 22 is secured to the caliper base plate 20 with a universal caliper 24 sandwiching the brake disc 12 in standard fashion. A housing 26 of the caliper 24 is secured to the caliper base plate 20 by means of an appropriate pin connection 28. A caliper support arm 30 is secured at one end to the housing 26 by means of an appropriate pin 32, while being secured at the opposite end by an appropriate pin 34 to the caliper base plate 20. [0020] Appropriate bolts 36 secure the caliper assembly 22 to the adapter base plate 18 according to the appropriate AIST protocol, taking into account the AIST rotor diameter and shaft-to-floor dimension. The lower hole in the caliper housing 26 is pinned to the front hole of the caliper base plate 20 by means of the pin 28 while the caliper support arm 30 is connected to the top hole of the housing 26 and the rear-most hole of the base plate 20 by means of respective pins 32, 34, the length of the support arm 30 being selectable to position the universal caliper 24 in the correct angular orientation to the rotor 12, according to the AIST standard for a given brake size. By simply selecting a caliper support arm 30 of an appropriate length, the caliper assembly 22 can be configured to accommodate the AIST standard for any of a wide variety of brake sizes. Indeed, as shown in Fig. 2, comprising Figs. 2A-2F, various sizes of caliper support arms 30 are employed to achieve a wide variety of AIST caliper brake configurations. Six such configurations are shown in Fig. 2. The only differences in the caliper assemblies 22 being the length of the caliper support arm 30. The correlations between the figures and the AIST standard are: 2A - 0812; 2B - 1014; 2C - 1317; 2D - 1621 ; 2E - 1924; and 2F - 2329.

[0021] According to the invention as described thus far, pins 28, 32 and 34 provide respective pivotal connections when any one of the other pins is removed. A triangular or truss-type relationship is in place when the three pins are interconnected as shown in Fig. 1, but removal of any of pins 28, 32, 34 allows the caliper 24 to be moved with respect to, or totally removed from, its juxtaposition with the brake disc 12. Serviceability, such as replacement of brake pads and the like, is greatly enhanced by this feature. [0022] In the preferred embodiment of the invention, the pins 28, 32 are carried in self-aligning bushings such as to enable axial movement to accommodate a self-aligning feature. Preferably, the self-aligning bushings are spherical bearings such that the caliper 24 has alignment compliance relative to the brake disc 12. The spherical bushings may have spring-actuated halves to stabilize the caliper. If desired, additional bushings and springs may be interposed between the split halves of the spherical bushings, the additional bushings frictionally gripping the associated pin tight enough for the springs located on both sides of the bushing to push on the spherical half bushings and move the caliper back from the disc to center it upon caliper release, while being frictionally loose enough for the clamping force of the caliper to reposition it as the friction plates wear. Hence, there is a rudimentary brake wear adjuster.

[0023] The adapter base plate 18 is specific for the AIST standard. There are two bolt patterns in each plate, one for the AIST mounting, and a second for attaching the caliper base plate 20. In other words, by selecting the appropriate adapter base plate 18 and arm 30, the caliper can be adapted to any AIST size.

[0024] With reference now to Fig. 3, the detailed structure of the universal caliper 24 can be appreciated. As shown, the caliper 24 comprises a spring assembly 42 adapted to interconnect with an active caliper half 44 adjacent a fixed or passive caliper half 46, the same being secured together by means of appropriate bolts 48. Appropriate shims 50 and bushings 52 may be employed at the interconnection between the active and passive caliper halves 44, 46 as may be necessary. As shown, friction pads 54 are attached to each of the caliper halves 44, 46 and are adapted to be positioned on either side of the disc 12 when in operation. While the bolts 48 secure the caliper halves 44, 46 together, the bolts 56 serve to secure the spring assembly 42 to the active caliper half 44, completing the universal caliper assembly.

[0025] An appreciation of the spring assembly 42 may be attained by reference to the cross-sectional view of Fig. 4. As seen, spring assembly 42 includes a housing 60 defining a cavity receiving one or more springs 62, 64 therein. It will be appreciated that the nature of the springs can vary extensively as being die, coil, disc, or a combination of spring elements as by the showing of two such springs in the embodiment if Fig. 4. A spring-restricting cylinder 66 is provided and may contain therein a spring such as the spring 64, and/or retain thereabout a spring such as the spring 62. As shown, the spring 62 is interposed between the housing 60 and the cylinder 66, while the spring 64 is retained between the cylinder 66 and a spring pin 70. The spring pin 70 passes through a thrust washer 68, capping an end of the cylinder 66, and through a thrust plate 74 at an opposite end of the cylinder 66. The spring pin 70 is secured to the thrust plate 74 by means of an appropriate connector such as a pin retainer 72. At the opposite end of the spring pin 70, an adjuster screw 76 is slidingly received. The adjuster screw 76 has external threads received by mating threads in the housing 60 and has a head configured for receiving an appropriate adjustment tool such as a wrench. When assembled to the caliper, rotating of the screw 76 urges the thrust washer 78 further against the springs 62, 64 to a final point of desired pre-compression.

[0026] It can be appreciated that the spring assembly 42 comprises a preloaded spring assembly of springs 62, 64 that are pre-compressed by the length of the spring pin 70 between the thrust plate 74 secured to one end thereof and the thrust washer 68 retained near the other as a consequence of restricting engagement between the flanged inner end of the screw 76 and the shoulder of the spring pin 70 leading to its enlarged head. There is thus defined a pre-compressed spring cup assembly. The type of springs employed and the amount of preset compression is based upon the force required by the associated AIST standard brake/rotor combination. The pin retainer 72 attaches to the end of the spring pin 70 to establish a preloaded compressed length of the spring elements 62, 64. Adjuster screw 76, threaded into the housing 60, such that when the spring assembly 42 is assembled into the caliper 24, the thrust plate 74 mates to the back of the caliper piston to translate the spring force into braking force through the caliper. The adjuster screw 76 may then be tightened until the end of the pin 70, which may serve as a wear indicator, is flush with the end of the adjustment screw 76, as shown. This establishes the final spring element compressed length required to create the associated AIST brake torque standard for the brake size and rotor combination. Thrust washer 68 holds the spring compression through adjuster screw 76 to thrust plate 74.

[0027] Assembly, servicing and repair of the caliper brake itself, and particularly the spring cup assembly 42, is a simple matter. Removal of the pair of bolts 56 accommodates separation of the spring assembly 42, and removal of the retainer pin 72 allows access to the interior for removal, replacement or original construction of the assembly 42 with the necessary springs to satisfy a desired AIST torque setting. Of course, spring cup assemblies 42 may be premanufactured with the appropriate springs, pre-compressed as described above, so only final adjustment of the spring compression by turning screw 76 is necessary upon installation.

[0028] Referring now to Fig. 5, there is shown a caliper brake system 80 employing the adaptive caliper disc brake structure presented and described above. The caliper brake system 80 includes a brake control unit 82 containing the hydraulic system for control of the caliper 24 and interconnecting that hydraulic system to the caliper by means of a hydraulic hose 84.

[0029] The hydraulic circuit for control of the caliper 24 is shown in detail in Fig. 6 and designated generally by the numeral 86. There it can be seen that a motor 88 drives a hydraulic pump 90 to draw hydraulic fluid from a reservoir 92. The hydraulic fluid is driven through a check valve 94, and through a line to the hydraulic hose 84 connected to the caliper 24. An accumulator 96 is positioned in communication with the system, as shown. A pressure switch 98 is interconnected between the motor 88 and the pressure lines of the system to monitor the system pressure. As will be apparent directly below, when the system pressure reaches a preset level, the pressure switch 98 turns off the motor 88. Thereafter, the solenoid valve 104 and check valve 94 hold the system pressure at or near that preset level. In the event that the pressure drops below that level, the pressure switch 98 turns the motor 88 on again to cause the pump 90 to re-pressurize the system to that level. The pressure level of the switch 98 is such as to act against the spring assembly 42 of the caliper 24 to keep the caliper brake pads 54 open and off of the brake disc 12.

[0030] It will be appreciated that actuation of the caliper disc brake assembly 80 is achieved by releasing the hydraulic pressure to the caliper 24 such that the spring biasing of spring assembly 42 forces the brake pads 54 into engagement with the disc 12. To this end, a needle valve 100, shunted by a bypass shunt 102, is in series interconnection with the solenoid valve 104. The solenoid valve 104 is normally open such that when power is disconnected from it, the solenoid valve 104 reverts from its closed position to its normally open position to allow hydraulic fluid to return to the hydraulic fluid reservoir 92. A pressure relief valve 106 is provided for safety purposes across the pump 90 to the reservoir 92. [0031] In operation, the motor 88 drives the pump 90 until reaching a preset pressure as sensed by the pressure switch 98, at which time operation of the motor 88 is terminated. The preset pressure level is sufficient to overcome the spring biasing of the spring assembly 42 to keep the caliper 24 "off with the brake pad 54 being separated from the disc 12. During this time, the solenoid valve 104 is closed by the application of an appropriate voltage. The system remains pressurized between the check valve 94 and the closed solenoid valve 104 and the caliper brake is "off. Should leakage occur such that the hydraulic pressure drops below a preset level, the pressure switch 98 causes the motor 88 to again activate to pressurize the system to the threshold at which the switch 98 turns the motor 88 off. Accordingly, the caliper 24 stays disengaged from the disc 12 until such time as an emergency or other situation signals to the solenoid valve 104 that the voltage thereto should be released such that the solenoid valve 104 returns to its normally open position. At this time, the hydraulic pressure in the system, and particularly in the line 84 to the caliper 24, begins to drop. When the pressure drops below the holding level of the spring assembly 42, the spring assembly causes the active one of the brake pads 94 to be urged toward the passive one, braking the disc 12 therebetween. The braking action can be instantaneous, if desired. In such a case, the needle valve 100 may be opened to full flow. However, in many instances, and particularly due to safety considerations, there needs to be a controlled release of the hydraulic pressure and, for those reason, the needle valve 100 with bypass shunt 102 may be employed. The needle valve 100 is preferably adjustable such that the rate of flow therethrough can be controlled. The purpose of the shunt valve 102 is to ensure that even if the needle valve 100 were adjusted to a total turnoff, there would be a path for bypass pressure through the shunt 102.

[0032] Thus, it can be seen that the various aspects of the invention have been achieved by the invention presented and described above. While in accordance with the patent statutes, only the best mode and preferred embodiment of the invention has been presented and described in detail, the invention is not limited thereto or thereby. Accordingly, for an appreciation of the scope and breadth of the invention, reference should be made to the following claims.