Abstract:
A piston pin puller adaptor tool, which includes a body, a puller screw attached to the body and a number of interchangeable adaptor sleeves, which attach to the body. The interchangeable adaptor sleeves include at least a short skirt adaptor sleeve and a full skirt adaptor sleeve. Also, an adaptor sleeve for use with a pin puller tool, which has been configured to interface with the contours of a short skirt piston.

Description:
The following is a non-provisional patent application which claims priority to provisional application 61/229,841 filed Jul. 30, 2009 to the same inventor. 
     TECHNICAL FIELD 
     The present invention relates generally to tools for working on piston repair and more particularly to tools for detaching piston pins for removal of pistons. 
     BACKGROUND ART 
     Most internal combustion reciprocating engines use pistons as a means of providing motive power. The pistons are each located in a cylinder, and are made air-tight by piston rings. Its purpose is to transfer force from expanding gas in the cylinder to the crankshaft by piston rods or connecting rods. The head of the piston is exposed to repeated bursts from compressed ignited gasoline and air in the cylinder, and therefore become worn with time and periodically require replacement. The pistons are connected to the piston rods by piston pins, and when the pistons are to be removed, the pins are pulled to allow the piston to be removed and then replaced by new or refurbished pistons. 
     Pistons currently come in two main varieties, the “full skirt piston” and the “short skirt piston”, also know as a “slipper piston”.  FIGS. 1-2  show isometric views of the full skirt piston  20  with the major elements indicated. The piston assembly  1  includes a rod  2 , which is attached to the piston  3  by a pivot joint  4  using a pin  5  (shown in both figures as being partially drawn). The pin  5  seats in a socket  6 , which extends through the piston  3  into the rod  2 , and back into the piston  3 . The exterior of the socket  6  is referred to as the piston pin boss  7 . The piston  3  includes rings  8  which seat in ring lands  9 . The full skirt  21  extends down over the pin boss  7  and a portion of the rod  2 . 
       FIGS. 3-4  show isometric views of the short skirt piston  30  and  FIG. 5  shows a cut-away of the short skirt piston  30  with the major elements indicated. The major elements are referred to by the same reference numbers as when referring to the full skirt piston above, where appropriate, so again, the piston assembly  1  includes a rod  2 , which is attached to the piston  3  by a pivot joint  4  using a pin  5 . The piston  3  includes rings  8  which seat in ring lands  9 . The pin  5  seats in a socket  6 , which is surrounded by piston pin boss  7 . The short skirt  31  can be compared to the full skirt  21  of  FIGS. 1-2 . It can be seen that the short skirt  31  is shorter on the sides than the full skirt  21 , and extends only to just below the ring lands  9  at the front and back near the pin boss  7 . It can also be see that the pin  5  is hollow and includes a pin bore  12 . 
     The cross-sectional view of the short skirt piston  30  in  FIG. 5  shows the pin  5  partially withdrawn from the socket  6  within the pin boss  7 . Clips  10  are held in clip grooves  11  which are fashioned in the pin boss  7 . These clips  10  serve to help retain the pins  5  in the pin bosses  7 , and must be removed in order to remove the pins  5 . The ring lands  9  are showed with the rings  8  removed. 
     Short skirt pistons are being used more and more commonly as a means of reducing internal friction in the cylinder and to reduce weight, both of which increase engine performance. 
     As the piston becomes worn, the piston pin boss often becomes deformed and sometimes includes burrs or other formations that resist the extraction of the pins. Thus, a considerable amount of force may be required to draw the pin and to allow the piston to be removed. Therefore piston pin puller tools have been devised to forcibly draw the pins. Prior piston pin pullers are generally configured for working with the traditional full skirt piston, and are fashioned with a sleeve that has a full circular end-section. This works well with the full skirt piston, where the end of the sleeve easily abuts the side of the skirt portion surrounding the pin socket. However, when this configuration is used with a short skirt piston, most of this skirt area surrounding the pin socket has been removed so that a sleeve with a full circular end-section does not rest evenly on the side of the piston. 
     As seen in  FIG. 6  (prior art), the full circular end  42  of the pin puller sleeve  40  thus rests mainly on the area including portions of the piston ring lands  9 . This can cause a number of problems, including damage to the rings and ring lands. If the ring lands are damaged the piston cannot be reused. 
     Also, since the circular end  42  of the prior art sleeve  40  is supported only at a portion of its circumference, which includes the skirt  31 , but not the piston pin boss  7 , when force  50  is applied to draw the pin  5 , the sleeve  40  tends to pivot at this support point, resulting in a rotational moment  51 . The pin  5  is thus not retracted in a straight line, but tends to also pivot. This can cause damage to the pin  5 , and can gall the pin socket  6  as well. 
     Thus, there is need for a pin puller with a sleeve that conforms to the contours of a short skirt piston. Further, there is a need for a pin puller that has interchangeable sleeves that can accommodate both full skirt pistons and short skirt pistons. 
     DISCLOSURE OF INVENTION 
     Briefly, one preferred embodiment of the present invention is a piston pin puller adaptor tool, which includes a body, a puller screw attached to the body and a number of interchangeable adaptor sleeves, which attach to the body. These interchangeable adaptor sleeves include at least a short skirt adaptor sleeve and a full skirt adaptor sleeve. 
     Also disclosed is an adaptor sleeve for use with a pin puller tool, which has been configured to interface with the contours of a short skirt piston. 
     An advantage of the present invention is that it is usable on both short skirt pistons and full skirt pistons. 
     Another advantage of the present invention is that it is usable on short skirt pistons without risking damage to the rings and ring lands. 
     A further advantage of the present invention is one tool includes replaceable sleeves, which are configured for both full skirt and short skirt pistons. 
     And another advantage of the present invention is that it includes a number of pin adaptors, which work with various sized pins 
     Yet another advantage of the present invention is that it is can be less expensive than buying separate tools for full skirt and short skirt operations. 
     A further advantage of the present invention is that it minimizes the number of tools that a mechanic may have to keep in his kit. 
     These and other objects and advantages of the present invention will become clear to those skilled in the art in view of the description of the best presently known mode of carrying out the invention and the industrial applicability of the preferred embodiment as described herein and as illustrated in the several figures of the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The purposes and advantages of the present invention will be apparent from the following detailed description in conjunction with the appended drawings in which: 
         FIGS. 1-2  show isometric views of a full skirt piston; 
         FIGS. 3-4  show isometric views of a short skirt piston; 
         FIG. 5  shows a cross-sectional view of a short skirt piston; 
         FIG. 6  shows a cross-sectional detail view of a pin puller of the prior art used on a short skirt piston; 
         FIG. 7  shows a cross-sectional detail view of a pin puller of the present invention used on a short skirt piston; 
         FIG. 8  shows an exploded isometric top view of the piston puller adaptor tool of the present invention with a short skirt adaptor sleeve; 
         FIG. 9  shows an exploded isometric top view of the piston puller adaptor tool of the present invention with a full skirt adaptor sleeve; 
         FIG. 10  shows cross-sectional view of the piston puller adaptor tool of the present invention with a short skirt adaptor sleeve, pulling a piston pin; and 
         FIG. 11  shows a cross-sectional view of the piston puller adaptor tool of the present invention with a full skirt adaptor sleeve, pulling a piston pin. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention is a pin puller adaptor tool, which will be referred to by the reference number  100 , and thus shall be referred to as pin puller adaptor tool  100 . A preferred embodiment of the pin puller adaptor tool  100  and its elements are illustrated in  FIGS. 7-11 . 
     As discussed above, as a piston becomes worn, the piston pin boss often become deformed and sometimes include burrs or other formations that resist the extraction of the pins. Thus, a considerable bit of force may be required to draw the pin and to allow the piston to be removed. Therefore piston pin pullers have been devised to forcibly draw the pins. 
     Prior piston pin pullers are generally configured for the traditional full skirt piston, and are fashioned with a sleeve that has a full circular end-section. This works well with the full skirt piston, where the end of the sleeve easily abuts the side of the skirt portion surrounding the pin hole. However, when this configuration is used with a short skirt piston, most of this skirt area surrounding the pin socket has been removed so that a sleeve with a full circular end-section does not rest evenly on the side of the piston. 
     As seen in  FIG. 6  (prior art), the full circular end of the pin puller sleeve  40  thus rests mainly on the area including portions of the piston ring lands  9 . This can cause a number of problems, including damage to the rings and ring lands. If the ring lands are damaged the piston cannot be reused. 
     Also, since the end of the sleeve  40  is supported only at a portion of its circumference, which includes the skirt  31 , but not the piston pin boss  7 , when force  51  is applied to draw the pin  5 , the sleeve  40  tends to pivot at this support point, resulting in a rotational moment  51 , and the pin  5  is not retracted in a straight line, but tends to also pivot. This can cause damage to the pin  5 , and can gall the pin socket  6  as well. 
     In answer to these problems, the present pin puller adaptor tool  100  has been invented.  FIGS. 7-11  show the present pin puller adaptor tool. Referring now particularly to  FIGS. 8 and 9 , the pin puller adaptor tool  100  with a short skirt adaptor sleeve  150  is shown in exploded view in  FIG. 8 , and  FIG. 9  shows a full skirt adaptor sleeve  160  in exploded view. Both have an adaptor assembly  102 , including a body  104 , a puller screw  106 , and an adaptor sleeve  108 , of which there are two varieties, the short skirt adaptor sleeve  150  and the full skirt adaptor sleeve  160 . There is also a puller screw adaptor  110 , which screws onto threads  112  at the end of the puller screw  106 . A nut  114  is provided at the other end of the puller screw  106 , which is configured to be gripped and turned by a wrench or by hand. The body  104  includes an end plate  116 , which includes female threads  118 , through which male threads  120  on the puller screw  106  are mated (see  FIGS. 10 and 11 ). It is noted that in the present embodiment as shown, the end plate  116  and the body  104 , is actually composed of two separate parts which are pressed together. However, this is not to be taken as a limitation, and it is presently preferred that the body  104  and the end plate  116  be a single unitary member. 
     Cross-sectional views of the pin puller adaptor tool  100  with short skirt adaptor sleeve  150 , and a full skirt adaptor sleeve  160  are shown in  FIGS. 10 and 11  respectively, and  FIG. 7  shows a detail cross-sectional view, which can be compared with  FIG. 6  (prior art). 
     The replaceable short skirt adaptor sleeve  150  has a unique shape that contacts the piston  3  on the piston pin boss  7 . Since the area around the pin boss  7  is very strong and does not touch the cylinder wall, it is a much better place to apply pressure while removing the pin  5 . 
     It is noted that in the present embodiment as shown, the puller screw  106 , is actually composed of two smaller screws, which are threaded together. However, this is not to be taken as a limitation, and it is presently preferred that the puller screw  106  be a single unitary member. 
     The puller screw adaptors  110  come in a variety of sizes to match the sizes of the piston pins  5  and diameters of pin sockets  6 . 
     In practice, when a pin  5  is to be pulled, the clips  10  are removed. The pin puller adaptor tool  100  is assembled with the correct adaptor sleeve  150 ,  160  in place. Both adaptor sleeves  150 ,  160  are preferably configured with a male step socket member  122  which fits with a corresponding female step socket member  124  formed in the body  104  of the pin puller adaptor tool  100 . The puller screw  106  is inserted through the pin bore  12  of the pin  5 , and a puller screw adaptor  110 , which is of greater diameter than the pin bore  12 , is screwed onto the threads  120  of the puller screw. For a short skirt piston, the sleeve adaptor  150  is positioned abutting the pin boss  7 . The nut  114  is rotated, causing the male threads  120  of the upper puller screw  106  to withdrawn through the female threads  118  in the end plate  116 . The entire puller screw  106  thus backs up, pulling the puller screw adaptor  110  and the captured pin  5  with it from its socket  6 . When the pin  5  is withdrawn, the piston  3  is free to be removed from the rod  2 . 
     For a full skirt piston, the procedure is much the same, with a full skirt adaptor  160  being installed, which then abuts the side of the full skirt piston. It is noted that the contact end of the full skirt adaptor  160  is slightly contoured to securely fit the cylindrical side of the full skirt piston  3 . As before, the nut  114  is then rotated to withdraw the puller screw adaptor  110  and the pin  5 . 
     While various embodiments have been described above, it should be understood that they have been presented by way of example only, and not limitation. 
     INDUSTRIAL APPLICABILITY 
     The present piston pin puller adaptor tool  100  is well suited generally for removing a variety of piston pins of varying configurations. It accomplishes this by providing two or more adaptors, which interface with the various configurations of pistons better than previous pin pullers. 
     Pistons currently come in two main varieties, the “full skirt piston” and the “short skirt piston”. Short skirt pistons have some portion of the skirt area removed as a means of reducing internal friction in the cylinder and to reduce weight, both of which increase engine performance. Consequently, short skirt pistons are being used more and more commonly. 
     Prior piston pin pullers are generally configured for the traditional full skirt piston, and are fashioned with a sleeve that has a full circular end-section. This works well with the full skirt piston, where the end of the sleeve easily abuts the side of the skirt portion surrounding the pin hole. However, when this configuration is used with a short skirt piston, most of this skirt area surrounding the pin socket has been removed so that a sleeve with a full circular end-section does not rest evenly on the side of the piston. 
     Consequently, the full circular end of the pin puller sleeve thus rests mainly on the area including portions of the piston ring lands. This can cause a number of problems, including damage to the rings and ring lands. If the ring lands are damaged the piston cannot be reused. 
     Also, since the end of the sleeve is supported only at a portion of its circumference, which includes the skirt, but not the piston pin boss, when force is applied to draw the pin, the sleeve tends to pivot at this support point, resulting in a rotational moment, and the pin is not retracted in a straight line, but tends to also pivot. This can cause damage to the pin, and can gall the pin socket as well. 
     The present pin puller adaptor presents a solution to these problems. The pin puller adaptor tool  100  can have either a short skirt adaptor sleeve  150  or a full skirt adaptor sleeve  160 . Both have an adaptor assembly  102 , including a body  104 , a puller screw  106 , and an adaptor sleeve  108 , of which there are two varieties, the short skirt adaptor sleeve  150  and the full skirt adaptor sleeve  160 . There is also a puller screw adaptor  110 , which screws onto threads  112  at the end of the puller screw  106 . A nut  114  is provided at the other end of the puller screw  106 . This nut  114  is configured to be gripped and turned by a wrench or by hand. The body  104  includes an end plate  116 , which includes female threads  118 , through which male threads  120  on the puller screw  106  are mated. 
     The replaceable short skirt adaptor sleeve  150  has a unique shape that contacts the piston  3  on the piston pin boss  7 . Since the area around the pin boss  7  is very strong and does not touch the cylinder wall, it is a much better place to apply pressure while removing the pin  5 . 
     The puller screw adaptors  110  come in a variety of sizes to match the sizes of the piston pins  5  and diameters of pin sockets  6 . 
     In practice, when a pin  5  is to be pulled, the clips  10  are removed. The pin puller adaptor tool  100  is assembled with the correct adaptor sleeve  150 ,  160  in place. Both adaptor sleeves  150 ,  160  are preferably configured with a male step socket member  122  which fits with a corresponding female step socket member  124  formed in the body  104  of the pin puller adaptor tool  100 . The puller screw  106  is inserted through the pin bore  12  of the pin  5 , and a puller screw adaptor  110 , which is of greater diameter than the pin bore  12 , is screwed onto the threads  120  of the puller screw. For a short skirt piston, the sleeve adaptor  150  is positioned abutting the pin boss  7 . The nut  114  is rotated, causing the male threads  120  of the upper puller screw  106  to withdrawn through the female threads  118  in the end plate  116 . The entire puller screw  106  thus backs up, pulling the puller screw adaptor  110  and the captured pin  5  with it from its socket  6 . When the pin  5  is withdrawn, the piston  3  is free to be removed from the rod  2 . 
     For a full skirt piston, the procedure is much the same, with a full skirt adaptor  160  being installed, which then abuts the side of the full skirt piston. It is noted that the contact end of the full skirt adaptor  160  is slightly contoured to securely fit the cylindrical side of the full skirt piston  3 . As before, the nut  114  is then rotated to withdraw the puller screw adaptor  110  and the pin  5 . 
     Thus, the present pin puller adaptor tool  100  is usable on many types and sizes of pistons, of both full skirt pistons and short skirt pistons. 
     For the above, and other, reasons, it is expected that the pin puller adaptor tool  100  of the present invention will have widespread industrial applicability. Therefore, it is expected that the commercial utility of the present invention will be extensive and long lasting.