Abstract:
A apparatus for forming a brake actuator that includes a flange case defining a peripheral groove circumscribing a push rod movable axially in relation to the flange case whereby the push rod presents a push rod guide bushing on the bearing surfaces of the push rod guide bushing being in contact with a seal. An automatic manipulator of the apparatus moves in multi-axial directions relative the flange case. A tucking tool of the automatic manipulator holds the seal. The tool includes at least two members movable relative to one another. First member rotates around the axis of the tucking tool and presents a tucking surface for forcing the seal into the peripheral groove of the flange case. Second member gradually injects the seal into the peripheral groove and pushed the seal into the back wall of the peripheral groove.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to an improved diaphragm-type pneumatic brake actuator for vehicle braking apparatus and more particularly to a method of installing a seal into a flange case of the brake actuator. 
       BACKGROUND OF THE INVENTION 
       [0002]    Pneumatic brake actuators form part of the pneumatic braking apparatus of commercial vehicles having a large gross vehicle weight, including trucks, buses and trailers requiring a braking apparatus which responds rapidly with substantial braking power. A typical diaphragm-type pneumatic brake actuator includes a housing having cup-shaped housing members including opposed rim or flange portions, a flexible diaphragm which is cup-shaped in its relaxed condition including a central portion, a generally conical side wall which surrounds the central portion and a generally radial rim portion which extends between the rim portions of the housing members. A brake actuator further includes a piston having a contact surface which engages the central portion of the diaphragm and which reciprocates with the central and side wall portions of the diaphragm in response to pneumatic pressure changes on opposed sides of the diaphragm from a first position. In response, the diaphragm is extended to a cup-shape, to a second inverted position to actuate the vehicle braking apparatus. The brake actuator is connected by pneumatic lines to the pneumatic braking apparatus of the vehicle to actuate the brake actuator. The piston is operably connected to the braking apparatus of the vehicle to actuate the vehicle brakes. 
         [0003]    The brake actuator apparatus includes an emergency or spring chamber having a power spring which actuates the braking apparatus of the vehicle when the pneumatic pressure of the vehicle falls below a predetermined minimum or the parking brake is actuated by the vehicle operator. In a spring brake chamber, a power spring is located in the housing between the end wall and the piston. During normal operation of the vehicle, the pneumatic pressure from the vehicle is received in the power spring chamber on the side of the cup-shaped diaphragm opposite the power spring and piston, normally compressing the power spring. When the pneumatic pressure in the spring chamber falls below a predetermined minimum, the power spring expands and actuates the braking apparatus of the vehicle. 
         [0004]    The spring and service chambers may be combined in a “piggyback” assembly as disclosed, for example, in U.S. Pat. No. 5,311,809 assigned to the assignee of this application. In this design, the assembly includes a central generally H-shaped flange case and the opposed ends of the flange case are enclosed by cup-shaped housing members to define a service chamber on one side of the flange case and a power spring chamber on the opposed side of the flange case. A central opening in the web portion of the flange case receives a pushrod having a head portion biased against the central portion of the diaphragm in the service chamber opposite the piston and power spring, such that the pushrod is driven against the piston in the service chamber to actuate the vehicle braking apparatus when the pressure in the spring chamber falls below a predetermined minimum pressure. 
         [0005]    Currently, the seals are installed manually. Manual installation of the seals is not cost effective and presents a high likelihood of human error. To solve these problem, a prior art apparatus manufactured by Automated Industrial Apparatus, a company based in Erie, Pa., were used to install O-rings and seals of the type using automation apparatus to eliminate need of manual installation. To the extent practicable, these apparatus keep the seals on the same plane with the seal groove thereby shrinking the outside diameter of the seal by pushing the seal through the funnel. This method negatively impacts formation of perfect “seat contact” between the seal and the groove in which the seal is installed, which may result in voids between the seal groove and the seal creating opportunities for leakage of fluids, lubricants, and the like. 
         [0006]    There has, therefore, been a longstanding need to improve methods and apparatus of seal installation. These and other problems have been solved by the improved apparatus and method described below. 
       SUMMARY OF THE INVENTION 
       [0007]    An apparatus of the present invention installs a seal into a generally H-shaped flange case of a brake actuator (not shown). The flange case includes a central web portion, an outer wall and radially extending flanges. A cover or head portion of the brake actuator includes an end wall, a side wall and a flange or a skirt portion. A flexible diaphragm extends between the flange case and the cover thereby forming a lower pneumatic chamber and an upper pneumatic chamber on opposed sides of the diaphragm. The flange case defines an opening in the web portion extending into a peripheral groove also defined in the web portion. The diameter of the peripheral groove is larger than the diameter of the opening wherein both the peripheral groove and the opening are coaxially aligned with one another. The peripheral groove and the opening circumscribe a push rod (not shown) movable axially in relation to the flange case. 
         [0008]    An automatic device installs the seal into the peripheral groove through the opening defined in the web portion. Those skilled in the art will appreciate that the automatic device may be used in any applications that require installation of seals, O-rings, and the like and is not intended to limit the scope of the present invention. The automatic device presents an arm adaptable for multi-axial movement. A terminal portion of the arm includes a shaft extending through the terminal portion to a terminal end. 
         [0009]    A seal holding element or guide is cooperable with the terminal end. A seal deflector is connected to the seal holding guide. A plunger includes a center pin and other seal engaging elements to be discussed below. The plunger is located inside the seal holding guide and is movable relative the seal holding guide. In the initial stage of seal installation, the seal is placed in position to be pushed upwardly into the seal holding guide. The seal is pushed by a lever and pneumatic cylinder. As the seal moves upwardly, the seal passes the seal deflector having an angled portion, which forces the upper portion of the seal towards of the center pin. A mandrel presenting a seal engaging surface or a mandrel surface is placed to abut the central web portion to capture the seal in the opening. 
         [0010]    Alluding to the above, the seal holding guide is lowered toward the opening to insert the seal into the peripheral groove. The upper portion of the seal is biased by the back portion of the center pin while the lower portion of the seal is biased by the mandrel surface thereby causing the seal to fold. As the seal folds, the lower portion extends generally perpendicular to the upper portion thereby extending into the back side of the peripheral groove as the seal folds over on itself. 
         [0011]    As the seal is driven into the peripheral groove, the center pin forces the seal to fold over itself. The seal guide is retracted relative the center pin to allow the plunger to enter the flange case. The plunger is raised to a point wherein the center pin is clear of the seal to allow the upper portion of the seal to flip into a generally perpendicular position relative the plunger. The plunger then moves to a seal engaging position to insert the pin in the middle of the seal. 
         [0012]    Alluding to the above, the plunger includes a neck portion extending to an eccentric wiper or a tucking portion. The neck portion includes a peripheral wall. The peripheral wall presents the diameter being smaller than the diameter of the eccentric wiper. The bottom surface of the eccentric wiper presents a pocket portion defined therein for receiving and retaining the upper portion of the seal as the seal is forced by the plunger into the peripheral groove. The aforementioned center pin is located in the center of the bottom surface. The pocket portion is designed to guide the upper lip of the seal to pass the upper edge of the peripheral groove. The plunger is then lowered to drive the remaining portion of the seal in to the peripheral groove. The seal is then placed in its entirety into the peripheral groove. 
         [0013]    To prevent any potential leaks and deformations of the seal that may result in response to the seal not being properly seated in the peripheral groove, it is important to ensure that proper “seal to groove” or “seat contact” is formed, whereby no void portions are formed between the peripheral groove and the seal. The plunger is placed in the position to spin about the axis thereby forcing the seal into the distal portion of the peripheral groove. The plunger is then moved upwardly enough to extend the edge of the eccentric wiper is between the upper edge of the peripheral groove and the upper lip of the seal. The plunger is then rotated to force the seal toward the mandrel surface. The seal is now properly seated in the peripheral groove of the web portion and the plunger is moved upwardly. 
         [0014]    A seal installation device is cooperable with the automatic device. A pair of elements of the seal installation device is movable about respective axis and relative the automatic device. A first element slides along a second element for holding the seal between the elements as the seal installation device is moved adjacent the automatic device for inserting the seal into the holding guide. One of the elements is defined by a first slide having terminal ends. One of the terminal ends extends to a lip portion and another terminal end presents one of the respective axes. A support tower presents a plate defining a groove of a non-planar configuration for receiving the axis of the first slide thereby allowing the first slide to move along the groove as the first slide moves relative the automatic device. A second slide rotates about the other of the respective axis and moves along the first slide to and away from the lip portion to limit the distance between the lip portion and the second slide thereby trapping the seal between the first and second slides. A lever is cooperable with the first and second slides to insert the seal into the guide as the first and second slides are moved into a seal inserting position with the seal being trapped between the first and second slides. 
         [0015]    An advantage of the present invention is to provide an improved apparatus and method for installing a seal into a seal groove defined in a flange case thereby eliminating need for manual installation. 
         [0016]    Another advantage of the present invention is to provide an improved apparatus and method for installing the seal into the seal groove that is not cost effective and eliminates likelihood of human error. 
         [0017]    Still another advantage of the present invention is to provide an improved apparatus and method for installing the seal into the seal groove that forms a perfect “seat contact” between the seal and the groove wherein the seal is installed, thereby eliminating problems of fluid leakage. 
         [0018]    Other advantages and meritorious features of this invention will be more fully understood from the following description of the preferred embodiment, the appended claims, and the drawings; a brief description of which follows. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    Other advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: 
           [0020]      FIG. 1  illustrates a fragmental view of a tucking tool of the present invention for installing a seal into a flange case of a brake actuator wherein the seal is in position by a seal installation device to be pushed upward into a seal guide of the tucking tool; 
           [0021]      FIG. 2  illustrates the seal installation device with the seal, shown in phantom, in its moving position, before the seal is inserted into the flange case; 
           [0022]      FIG. 3  illustrates the seal installation device in its seal insertion position, wherein the seal is inserted into the tucking tool; 
           [0023]      FIG. 4  illustrates a fragmental view of the tucking tool wherein the seal is inside the seal guide and oriented to be inserted into the flange case defining a seal groove; 
           [0024]      FIG. 5  illustrates yet another fragmental view of the tucking tool of the present invention wherein the seal is driven to the peripheral wall of the seal groove and a center pin of the tucking tool forces the seal to fold over itself; 
           [0025]      FIG. 6  illustrates enlarged fragmental view of  FIG. 5 ; 
           [0026]      FIG. 7  illustrates enlarged fragmental view of a plunger; 
           [0027]      FIG. 8  illustrates a fragmental view of the web portion and the seal positioned in the seal groove wherein a wiper portion of the plunger spins around the seal to seat the seal into the bottom of the seal groove before “seal to groove” contact is formed; 
           [0028]      FIG. 9  illustrates yet another fragmental view of the tucking tool wherein the seal is already installed in the seal groove and the wiper portion of the plunger spins around the seal to seat the seal into the bottom of the seal groove before the tucking tool retracts from its tucking mode; 
           [0029]      FIG. 10  illustrates cross sectional view of the tucking tool of the present invention as shown in  FIG. 9  in various rotational modes; and 
           [0030]      FIG. 11  illustrates a schematic view of seal engaging members of the seal installation tool in various positions. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0031]    Referring to the Figures, wherein like numerals indicate like or corresponding parts, an apparatus of the present invention is generally shown at  10 . The apparatus  10  installs a seal  12  into a generally H-shaped flange case, generally indicated at  14 , of a brake actuator (not shown). However, it should be understood to those of skill in the art that other case configuration requiring a seal are also contemplated by the inventor. The flange case  14  includes a central web portion  16 , an outer wall or peripheral wall  18  and radially extending flanges  20  and  22 . The brake actuator also includes other components (not shown) required to actuate the brake. A cover or head portion of the brake actuator includes an end wall, a side wall and a flange or skirt portion. A flexible diaphragm extends between the flange case and the cover thereby forming a lower pneumatic chamber and an upper pneumatic chamber on opposed sides of the diaphragm. 
         [0032]    The flange case  14  defines an opening or aperture  24  in the web portion  16  having a peripheral wall  25  extending into a peripheral groove  26  also defined in the web portion  16 . The diameter of the peripheral groove  26  is larger than the diameter of the opening  24  and peripheral wall  25 . Both the peripheral groove  26  and the opening  24  are coaxially aligned. The peripheral groove  26  and the opening  24  circumscribe a push rod (not shown) movable axially in relation to the flange case  14 . The groove  26  retains the seal  12  in a known manner to seal the pneumatic chamber of the brake actuator. 
         [0033]    Referring to  FIGS. 1 through 6 , an automatic device, generally indicated at  30 , installs the seal  12  into the peripheral groove  26  through the opening  24  defined in the web portion  16 . Those skilled in the art will appreciate that the automatic device  30  may be used in any applications that require installation of seals, O-rings, and the like and is not intended to limit the scope of the present invention. The automatic device  30  presents an arm  32  adaptable for multi-axial movement. The arm  32  actuates in a vertical direction via pneumatic pressure. However, the arm  32  may also be actuated by way of hydraulic or servo motor as desired. 
         [0034]    A terminal portion  34  of the arm  32  retains a shaft  36  ( FIG. 5 ) that actuates in a vertical direction with the arm  32 . A tucking tool  40  is formed from seal holding member (first member) or guide  43  for holding the seal  12  and is cooperable with a terminal end (second member)  38  that is a lower terminal end of the shaft  36 . The second member  38  of the tucking tool  40  has a distal surface  45  that includes a center pin  44  and other seal engaging elements to be discussed below. The second member  38  acts as a plunger and telescopically extends through the guide  43  to insert the seal  12  into the aperture  24  as will become more evident below. In the initial stage of seal installation, the seal  12  is placed in position to be pushed upwardly into the seal holding guide  40 . The seal  12  is pushed by a seal installation device, generally shown at  41  in  FIGS. 1 through 3 . The seal installation device  41  and its functional and mechanical aspects will be discussed in great details further below. The automatic device  30  is cooperable with the terminal portion  34  present at least two gears  35  and  37  and belts  39  and  43  encircling the gears  35  and  37 , respectively, to rotate the holding guide  40 . The gear  35  is rotated by a main shaft (not shown) extending from the automatic device  30 . The type, configuration, layout, and arrangement of the gears  35  and  37  and belts  39  and  43  as illustrated in  FIG. 5  are shown for illustrative purposes and are not intended to limit the scope of the present invention. Those skilled in the mechanical art will appreciate that other mechanical devices may be used in the present invention to rotate the holding guide  40 . 
         [0035]    As best seen in  FIGS. 1 and 2 , a mandrel  52  presenting a seal engaging surface or a mandrel surface  54  is placed to abut the central web portion  16  to cover the opening  24  defined in the web portion  16  on an opposite side of the web portion  16  from the tucking tool  40 . During installation, the seal holding guide  40  is lowered toward the opening  24  to insert the seal  12  into the peripheral groove  26 . 
         [0036]    When the seal is ready for installation, the upper portion of the seal  12  is received by a pocket  50  in the distal surface  45  of the second member  38  and the lower portion of the seal  12  is biased toward the mandrel surface  54 . The seal  12  is retained inside the first member or seal holder  43  in a distorted configuration by center pin  44 . As best shown in  FIGS. 5 and 6 , the distorted seal  12  fits into the aperture  24 , which has a narrower inside diameter than the outside diameter of the seal  12  due to the seal&#39;s  12  distorted configuration. Upon installation, the lower portion of the seal  12  is folded generally perpendicularly to the upper portion  48  as deflected by the mandrel surface  54  into the back side of the peripheral groove  26 . The seal  12  is thus forced into the peripheral groove  26  as the center pin  44  forces the seal  12  to fold over upon itself. The seal guide  40 , which is spring biased retracts relative the center pin  44  as the distal end  45  of the second member  38  telescopes to enter the aperture  24 . The center pin  44  is spring loaded to bias outwardly from the distal surface  45  and compresses to allow the second member  38  to continue to force the seal into the aperture  24  and into the groove  26 . A pocket  50  retains the seal  12  against the distal surface  45  of the second member  38  in a desired orientation while the center pin  44  retracts. 
         [0037]    As best seen in  FIGS. 7 and 8 , the second member  38  includes a neck portion  70  extending to an eccentric wiper or a tucking portion  72 . The neck portion  70  includes a peripheral wall  74  presenting a diameter that is smaller than the diameter of the eccentric wiper  72 .  FIG. 8  presents a cross sectional view of the tucking tool  40 . The shaft  36  is located inside the guide  43  and present a first axes Y. The second member  38  is disposed inside the shaft  36 . The second member  38  presents a second axes X being offset from the first axes Y. The second member  38  defines a cavity  73  to receive the center pin  44  and a spring  75  thereby allowing the center pin  44  to retract into the cavity  73 . The offset defined between the axis X and the axis Y allows the eccentric wiper  72  to rotate about the axis Y and to drive the remaining portion of the seal  12  completely into the seal groove  26  to ensure that proper “seal to groove” or “seat contact” is formed between the peripheral groove  26  and the seal  12 . 
         [0038]    The complete installation of the seal is best explained when referring to  FIGS. 6 through 9 . The center pin  44 , now having released the seal  12  is retracted into the cavity  73  defined in the second member  38 . The pocket portion  50  now guides the upper lip of the seal  12  to past the upper edge  84  of the peripheral groove  26 . The second member  38  is lowered to drive the remaining portion of the seal  12  in to the seal groove  26 . The seal  12  is then placed in its entirety into the peripheral groove  26 . 
         [0039]    To prevent any potential leaks and deformations of the seal  12  that may result in response to the seal  12  not being properly seated in the peripheral groove, it is important to ensure that proper “seal to groove” or “seat contact” is formed between the peripheral groove  26  and the seal  12 . 
         [0040]    The eccentric wiper  72  is positioned between the upper edge  84  of the peripheral groove  26  the seal  12 . The second member  38  is then rotated to force the seal  12  toward the mandrel surface  54  so that the eccentric wiper is located inside the groove  26  as best seen in  FIGS. 9 and 10 . The mandrel surface  54  provides space necessary to flex the seal  12  fully into the groove  26  with the eccentric wiper  72 . The seal  12  is now properly seated in the peripheral groove  26  of the web portion  16  and the second member  38  is withdrawn. The second member  38  rotates on an axis that is offset from an axis defined by the aperture  24 . The mandrel  52  is then disengaged from the H-shaped flange case  14 . The apparatus  10  of the present invention may be integrated into an assembly line (not shown) or be utilized as a separate unit. 
         [0041]    Another aspect of the inventive apparatus  10  is the delivery of the seal  12  to the tucking tool  40 . This is best explained by referring again to  FIGS. 1 through 3  and  11 . The seal installation device or arm  41  includes a first element  90  and a second element  92 . The second element  92  has terminal ends  96  and  98 . One of the terminal ends  96  extends to a key portion  100 . The opposing terminal end  98  includes a pin  102 . A support tower  104  presents a plate  108  defining a groove  110  of a non-planar configuration, as best shown in  FIG. 11 . The groove  110  is designed to receive the pin  102  of the second element  92  thereby allowing the second element  92  to move along the groove  110  as the second element  92  moves relative the automatic device  30 . The key portion  100  presents an angled seal contact  112  to deflect the seal  12  as the seal is inserted into the seal holding guide  43 . The seal holding guide  40  defines a keyway  120  to receive the key portion  100  having the angled seal contact  112  as the seal  12  is inserted into the seal holding guide  40  to deform the seal around the center pin  44  as explained above. 
         [0042]    The first element  90  is positioned just below the second element  92  and pivots generally at the tower  104 . The first element  90  includes terminal ends  124  and  126 . The first terminal end  124  includes a first pivot pin  128 . The second terminal end  126  presents a pocket  130  to receive and retain the seal  12  before the seal  12  is inserted into the guide  40 . The seal  12  is placed into the pocket  130  manually or by an automatic insertion device or mixing bowl (not shown). As best shown in  FIG. 11 , the first element  90  is rotatable about the axis defined by pin  128 , between a seal receiving or first position ( FIG. 1 ) and a seal installation or second position ( FIG. 3 ). Because the first element pivots at pivot pin  128  and the second element pivots in groove  110  the distal ends  126  and  96  very relatively between the first position and the second position of the arm  41 . In the seal receiving or first position ( FIG. 1 ) the key portion  100  is retracted from the pocket  130  providing access to insert a seal  12  into the pocket. When the arm is located in the seal installation or second position ( FIG. 3 ) the key is position over the pocket  130  and is received in the keyway  120  to deflect the seal when lifted by lever  132 . As the seal  12  is positioned below the seal holding guide  40 , the lever  132 , pivots upwardly to lift the seal  12  into the guide  40 . 
         [0043]    The apparatus  10  of the present invention provides numerous advantages over prior art apparatus and methods. The apparatus  10  of the present invention eliminates need of manual installation of the seal  12  into the peripheral groove  26  defined in the flange case  14  reducing manufacturing costs of the brake actuator and eliminates likelihood of human error. The apparatus  10  ensures that a perfect “seat contact” is consistently formed between the seal  12  and the peripheral groove  26  wherein the seal is installed eliminating problems associated with fluid leakage. 
         [0044]    While the invention has been described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.