Abstract:
A piston pulling apparatus constructed like a mandrel; having top and bottom ends and a cylindric periphery body defined by an array of piston bowl gripping segments having tops and bottoms and lying longitudinally between the top and bottom ends. The top end and the proximate tops of segments are held to each other with a fixed radius and circumference. The bottom end and its proximate array of bottoms are coupled to enable the radial expansion of the array from its bottoms. A threaded shaft lies axially within the body and is coupled to the bottom end to move it vertically upward axially, to displace the segment array bottoms radially, to increase the effective circumference of this apparatus near its bottom end; which, during the expansion, can be positioned to grip the inner sides of a piston bowl.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]    This application claims the benefit of U.S. Provisional Application Ser. No. 60/262,671, filed Jan. 22, 2001.  
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    This invention concerns apparatus for aiding the maintenance and repair of engines, such as diesel engines; the subject apparatus being employed for pulling the piston out from its associated cylinder.  
           [0004]    2. Background and Prior Art  
           [0005]    The repair and/or maintenance of reciprocating engines, having pistons or piston rods moving back and forth linearly within cylinders, often requires the removal of a piston from within its respective cylinder. The removal of a piston usually presents minimal effort/problem with respect to small engines, having small diameter cylinders and associated pistons, as with passenger automobiles. However, larger reciprocating engines, especially diesel engines, can present a difficult task in the removal of a piston, without damage to the piston, its cylinder and adjacent components. A common method for removing pistons has been to drive them out manually, as with a mallet, from one end of the cylinder, out through the opposite end. Such manual/mallet method often is physically difficult, too time consuming, and can damage the piston, cylinder, cylinder liner, bearings, crank shaft, connecting rod, piston cooler nozzle, etc. Some very large diesel engines, such as for railroad and ocean liners, construct the top of the piston to receive a large eye bolt or chain, which is attached to the piston at the time for its removal. At such removal time, a pulling mechanism, such as a block and tackle, is connected to the eyebolt; and the piston is pulled from the cylinder. One problem with this pulling approach is the need for supporting the upper end of the block and tackle. Another problem is that the top surface of the piston has to be threaded to receive the eyebolt. It is neither practical nor time effective to thread the top surface at time of pulling. Also, the piston body could be weakened if the piston diameter and length are relatively small, as with diesel engines, for various classes and types of marine, automotive, truck and stationary engine applications.  
           [0006]    As well known, a piston slides tightly within the cylinder liner, its cylinder or engine block. Usually, the top of a piston of a diesel engine is formed with a combustion or compression bowl, having a generally vertical interior side. Often, the bowl has a base diameter smaller or larger than the diameter at its upper top lip; thus, not providing any good clamping surfaces for a tool pulling the piston from the cylinder liner, engine block and/or cylinder.  
           [0007]    The prior art does teach a piston puller to L. Gregg 4,019,235 useable after the cylinder liner is removed. Thereupon, a sleeve of the tool is inserted in the annular space vacated by the liner and has a bottom end which surrounds the exterior bottom of the piston. The tool then is pulled upward to remove its sleeve and the piston it is grasping. Another piston puller uses a turnbuckle for pulling a piston from a cylinder. The turnbuckle is placed into the combustion bowl, with the turnbuckle&#39;s two ends pointed towards opposite interior sides of the bowl. Then, a short rod is placed manually into the center of the turnbuckle, or a small wrench clamps over it, and is pivoted through a plurality of small accurate motions, with the rod or wrench moved away from the longitudinal axis of the piston, to tighten the turnbuckle ends into the combustion bowl. The turnbuckle continues to lie at right angle to the longitudinal axis of the piston. Next, the turnbuckle is pulled vertically along the longitudinal axis of the piston, to pull the piston from the cylinder liner. This turnbuckle apparatus and method is slow, inconvenient, if not impossible, to use. For example, some compression bowls, such as for the Caterpillar and Cummins 5½″ and 5⅜ bores, have an upward projection—cone shaped—in the center of the bowl. Hence, a turnbuckle-like device could not lie across the interior diameter of the bowl. At best, it is difficult to provide sufficient grip upon the interior side of the combustion bowl; whereupon, the apparatus can slip out of the bowl, damaging the bowl, the cylinder liner, etc. and the hand of the user.  
         SUMMARY OF THE INVENTION  
         [0008]    The present invention is an apparatus easy to use manually, applies a significantly sufficient force quickly upon the entire interior side surface of the combustion bowl, and is safe to use. This apparatus has a radially expanding mandrel comprised of a plurality of gripping segments. The radially exterior surfaces of these segments are arcuate and are wedged or cammed outwardly against the entire interior surface of the circular sidewall of the combustion bowl by the axial lifting of a wedge shaped base member against the interior surface of the mating mandrel segments. The lifting of the wedge shaped base member is achieved by the manual rotation of a threaded shaft, which is coaxial with the expanding mandrel and the piston. The mechanical force ratio of the invention is significant, such that turning of the threaded shaft, as by a handle, is done easily and quickly, with high mechanical leverage/force and a resulting very positive fit of the mandrel segments against the inside of the combustion bowl. 
       
    
    
     BRIEF DESCRIPTION OF THE FIGURES  
       [0009]    [0009]FIG. 1 is a side elevational view, partly in section, of one of the embodiments of the invention;  
         [0010]    [0010]FIG. 2 is a perspective view of the internal components of the FIG. 1 embodiment;  
         [0011]    [0011]FIGS. 3 a ,  3   b  and  3   c  are side views of three versions of one of the gripping segments;  
         [0012]    [0012]FIG. 4 is a bottom view of the segment shown in FIG. 3 a ;  
         [0013]    [0013]FIG. 5 is a front view of the segment shown in FIG. 3 c ;  
         [0014]    [0014]FIG. 6 is a partial side view of the embodiment shown in FIG. 1, with the expansion base member elevated, so as to wedge the lower portion of the gripping segments outward radially;  
         [0015]    [0015]FIG. 7 is a fragmentary side elevational view, showing the lower portion of the gripping segments oriented as in FIG. 6, seated into a combustion bowl, with the piston partly pulled from the cylinder liner;  
         [0016]    [0016]FIG. 8 is a side view of a preferred embodiment of one of the gripping segments; and  
         [0017]    [0017]FIG. 9 is a view, similar to FIG. 1, of a preferred embodiment of the invention. 
     
    
     DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0018]    With reference to the side elevational view in FIG. 1 and the perspective view of the internal components in FIG. 2, the piston pulling apparatus  10  of this invention primarily comprises an expandable mandrel  12  mounted around a shaft  14 , a portion of which is threaded, as at  16 . Secured near the top of the shaft  14  is a head member  18 , having a generally circular periphery  20  and a plurality of facets  22 , such as eight. The facets can be inclined, as shown in the left sides of FIGS. 1, 2 and  6 , or they can be vertical, as shown, at the right sides of FIGS. 1, 2 and  6 . The head member  18  can be fixed to the shaft, whereby rotation of the shaft will not cause the head member to be threaded up or down the shaft. Or, the head member can be mounted to rotate around the shaft, but at a non-threaded portion; so that relative rotation between the shaft  14  and the head member  18  will not cause the head member to move up or down the shaft.  
         [0019]    A base member  24 , also having a generally circular periphery  26  and the same number of facets  28  as the head member  18 , is mounted around the threaded portion  16  of the shaft  14 . A nut  29  is mounted on the shaft  14 , below the base member  14 ; whereby, rotation of the shaft will cause the nut  29  to move up or down along the shaft, depending upon the direction of shaft rotation, and push the base member upward, as shown in FIG. 6, or let it slide downward to a bottom position, as shown in FIG. 6, or the alternative, as shown in FIG. 7, the base member  24  can be threaded, so as to move up or down the shaft threads  16 , without need of the nut  29 . The facets  28 , as shown in the lower left of FIGS. 1 and 2, are inclined inwardly, so that the upper surface  30  of the base member has a smaller diameter than the bottom surface  32  of the base member. The inclined surface or face  34  of each facet  28  defines a ramp, wedge or camming surface, the function of which is discussed further below. Alternately, as shown in the lower right of FIGS. 1 and 2, the facets  34 ′ can be vertical.  
         [0020]    As shown in FIGS. 6 and 7, the bottom of the shaft  14  is formed with a stop element  36 , which will prevent the nut  29  or the threaded base member  24  from being threaded off from the bottom of the shaft and thus prevents the base member  24  front falling off the shaft  14 . At the top of the shaft  14  there is a projecting portion  40 , for receiving a handgrip  42 . Or, as shown in the broken away area of FIG. 1 at the top of the shaft  14 , there can be a socket  38 , over which a mating shaft  40  can be removably mounted. The handgrip  42  can be of any suitable configuration. If there is insufficient vertical space for the shaft, the handle  40  and the users hand, a wrench (not shown) can be applied to the socket  38 , at right angle to the axis of the shaft, for rotation of the shaft.  
         [0021]    As shown in FIG. 1, a plurality of gripping segments  44 , equal to the number of facets  22 ,  34 , are arranged around the periphery of the head and base members  18  and  24 . The segments  44  can be held in relative position by more than one suitable manner. FIGS. 1 and 3 a  show notches  46 ,  48  in the exterior side  50  of each segment, near its top and bottom, respectively. A pair of bands  52 ,  54  seat into the notches  46 ,  48 , respectively, like O-rings, to hold the segments  44  against the generally circular peripheries  20  and  26  of the head and base members  18  and  24 . The upper band  52  is of constant size; however, the lower band  54  is elastic, to permit the adjacent portions of the array of the segments of the mandrel  12  to be forced radially inward or outward, to have an effective diameter and circumference less than or greater than that at the upper band  52 . The lower band can be a tightly wound coil spring.  
         [0022]    A preferred embodiment of the gripping segments  44  is shown in FIG. 8 and is different from that shown in FIG. 3 a  in that the notch  46  is replaced by a hole  46 ′. The top, inelastic band  52  passes through each hole  46 ′ of the gripping segments which thereby cannot fall away from the head member  18 , when the apparatus  10  is in the non-expanded condition. When initially fabricating the piston puller  10  of this preferred embodiment, the band  52  can be of a length of metal, which is threaded through the holes  46 ′ and welded at its ends to form a ring. Such band  52  need not be round in cross section.  
         [0023]    As shown in FIGS. 3 c  and  5 , the gripping segment  44 ′ has a curved interior side  56  near its top and a notch  58 , which is vertically elongated and extends into a passageway  60 , through which a pivot pin  62  can pass and seat into the facet  22  of the head member  18 . Thereupon, the bottom end of the segment  44 ′ can pivot radially outward around the pivot pin  62 , to achieve the same increase in diameter and circumference of the mandrel  12  as the same portion of the segment  44  of FIGS. 3 a  and  3   b , adjacent the elastic band  54 .  
         [0024]    To force the bottom of the segments  44  and  44 ′ radially outward, as shown in FIGS. 6 and 7, from a generally vertical orientation, as shown in FIG. 1, the shaft  14  is rotated clockwise to cause the nut  29  in FIG. 6 to thread upward and push the base member  24  upward; or, the threaded base member in FIG. 7 to thread up. This causes its inclined facet faces  34 ,  34 ′ to move upward against the interior surfaces  64 ,  64 ′ of the segments  44 ,  44 ′ to force those surfaces radially outward. The face  34  need not be inclined, as shown in the lower left of FIG. 1 and in FIG. 2. The facet face can be vertical, as shown in the lower right of FIGS. 1 and 2, as element  34 ′. If both the facet face  34  and the interior lower surface  64  are inclined or sloped similarly, the radial expansion of the gripping segments is more smoothly, incrementally achieved than if only one of these pairs of surfaces ( 34 ,  64 ′; or  34 ′,  64 ) is inclined, or none are inclined.  
         [0025]    As shown in FIGS. 6 and 7, the gripping segments  44  (or  44 ′), of which two of many are illustrated, are splayed to form an outward surface, like the surface of a cone, with the bottom portions of the segments firmly backed by the faces  34  (or  34 ′) of the facets  28  of base member  24 . The bottoms of the segments are held in this new position by the elastic band  54 . The top ends of the segments are held in place by the top band  52 , against the periphery  20  of the head member  18 . If, as shown in FIG. 7, the interior side  66  of the combustion bowl  68  of the piston  69  is sloping so that the lip  70  of the bowl has a smaller diameter than the bottom  72  of the bowl, then the splayed gripping segments  44  can be forced tightly into being somewhat parallel with the interior  66  of the bowl. A condition which would be most effective to hold the piston pulling apparatus  10  firmly in place while it is pulled upward relative to the cylinder liner  74  and cylinder  76 , to disengage the piston  69  therefrom.  
         [0026]    The embodiments shown in FIGS. 1, 2,  6  and  7  have a limitation best understood by a comparison of FIGS. 6 and 7. As now should be understood, to cause the base member  24  to rise and thereby cam against the interior surface  64  of the gripping segments  44 , the threaded shaft  14  will be advanced downward into the piston bowl  68 . If the diameter of the piston bowl  68  was significantly greater than shown in FIG. 7, then the stop element  36  on the bottom of the shaft  14  would hit the bottom  72  of the bowl, before the base member  24  could be raised sufficiently to force the exterior sides  50  of the gripping segments  44  firmly against the interior side  66  of the bowl. The preferred embodiment of FIG. 9 avoids such a problem. As shown in FIG. 9, seated in the head member  18  is a nut  78 , which is threaded on the threads  16  of the shaft  14 . When the expansion mandrel  12  of the tool  10  is in its relaxed, non-expanded orientation, as shown in FIG. 9, the lower end of the shaft  14  at its stop element  36  is close to the bottom surface  32  of the base member  24  and would be safely above the surface  72  (not shown) of the bowl  68 . Thereupon, threading the shaft counterclockwise (assuming conventional thread) will cause the shaft  14  to move upward. Since the nut  78  is seated in the head member  18 , which itself cannot move vertically, the only relative vertical movement can be the upward movement of the entire shaft  14 , with its bottom located stop element  36 . Hence, the stop element  36  also will move upward and raise the base member  24  upward and force its facets  34  against the surfaces  64  of the segments  44 ; to thereby expand the lower end of the mandrel  12  against the interior side  66  of the piston bowl  68 ; whereupon, the apparatus  10  can be pulled axially upward and carry with it the piston bowl  68  and its piston  69 .  
         [0027]    If the interior side  66  of the combustion bowl is more perpendicular, it would be better if the gripping segments were more parallel to each other in the expanded/gripping orientation, than as shown in FIG. 7. This can be accomplished if the head and base members  13  and  24  are further apart (hence the segments  44  are longer) and/or their diameters and circumferences more closely approach that of the interior of the combustion bowl, so that radial expansion by the mandrel  12  is relatively small.  
         [0028]    If the interior  66  of the compression bowl  68  has a larger base diameter  72  than its lip  70 , the head member  18  can have a diameter larger than that of the base member  24 , so that the exterior sides  50  of the gripping segments  44  are inclined slightly v-shaped as they expand outwardly against the generally mating surface  66  of the bowl. This would be a reverse orientation that that shown in FIGS. 6 and 7. Yet also, if the interior side  66  of the bowl  68  was of some unique shape (not shown in FIG. 7) then the surface  50  of the segments  44 , proximate the notches  43  and the bottom band  54 , could be formed to have similar, unique shape (also not shown in the Figs.)  
         [0029]    To achieve a firm, splayed orientation, as shown in FIGS. 6 and 7, a piston having a five inch (12.70 cm.) combustion bowl maximum interior diameter, as shown in FIG. 7, can be pulled safely and effectively by the apparatus according to this invention, when the mandrel  12  is expanded by about one inch (2.54 cm.) in diameter. Such a piston puller  10  would have gripping segments about four inches long (10 cm.). Hence, a relatively small, easily portable, very efficient piston pulling apparatus can be made according to this invention. To accommodate a large range of piston diameters, and combustion bowl profiles, at least a few different of this novel piston puller apparatus, or interchangeable parts, could be needed. Such differences and other possibly needed variables would be well within the skill in the art, in view of the teachings of the present patent specification and its Figures, without departing from the scope of the invention, as defined by the appended claims.