Abstract:
A spring-loaded pin-guided magnetic tool which is particularly well adapted for the lifting of hydraulic valve lifters from their bores in an OHV engine. An elongated tube has a magnet affixed to one end and is inserted into the engine block. The magnet is guided into place with spring-loaded, retractable guide pin. By extending the guide pin into the bore and guiding it into a recess on the top of a valve, the magnet can be placed very close to the center of the lifter. The placement of the magnet improves the precision of the tool because a user can be reasonably certain the magnet end of the tool is located at the bottom of a recess in a lifter. An collar is positioned along the tube allowing it to rest against the head and hold the magnetic end of the tool at a proper height.

Description:
PRIORITY 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application number 61/529,924 filed Sep. 1, 2011 by the same inventor entitled “Magnetic Lifting Tool” which is hereby incorporated by reference as if fully set forth herein. 
     
    
     BACKGROUND 
       [0002]    Conventional automotive and truck engines are constructed with a valve actuating camshaft located in a bore in an engine block. Typically, these engines use the overhead valve principle, with the valves being actuated by pushrods extending upwardly from the camshaft lobes and acting on rocker arms atop the cylinder head to actuate the valves. Originally lifters were of mechanical (solid) design that required the maintenance of proper clearances in the valve train to accommodate expansion of the components when heated during normal engine operation. Modern engines also use hydraulic (or tappets), flat, and roller lifters. The lifters ride on the cam lobes to actuate the valve pushrods. The hydraulic lifter was designed to ensure that the valve train always operates with zero clearance, leading to quieter operation and eliminating the need for periodic adjustment of valve clearance. 
         [0003]    The hydraulic lifter may consist of a hollow expanding piston situated between the camshaft and valve. It is operated either by a rocker mechanism, or for overhead camshafts, directly by the camshaft. Often the lifter is filled with engine oil intermittently from an oil gallery via a small opening. When the engine valve is closed, the lifter is free to fill with oil. When the valve is opening and the lifter is being operated by the camshaft, the oil feed is blocked and the lifter acts just as a solid one would, oil being incompressible. 
         [0004]    From time to time it is generally necessary to remove the camshaft from the engine to effectuate repairs or improvements. Conventionally the labor required for such a job was relatively extensive because of the need to remove the cylinder head(s) in order to access the lifters before removing the camshaft. If the lifters are not removed the lifters will drop down past the cam lobes and bearings when the camshaft is removed. As the camshaft continues to be withdrawn, the succeeding cam lobe or bearing encounters the dropped lifter from the adjacent valve in the adjacent cylinder, which blocks further withdrawal of the camshaft from the block. Conventionally a mechanic is required to spend the additional time and labor to remove the cylinder head(s) from the engine to gain access to the lifter bores, and then remove the lifters from their bores. 
       SUMMARY 
       [0005]    Disclosed herein is a solution to the above problem in the form of a spring-loaded pin-guided magnetic tool which is particularly well adapted for the lifting of hydraulic valve lifters from their bores in an overhead valve (OHV) gasoline or diesel engine. An elongated tube has a magnet affixed to one end and is inserted into the engine block. The magnet is guided into place with spring-loaded, retractable guide pin. By extending the guide pin into the bore and guiding it into a recess on the top of a valve, the magnet can be placed very close to the center of the lifter. The tube has indicia indicating depth of the bore. The precise placement of the magnet improves the precision of the tool because a user can be reasonably certain the magnet end of the tool is located at (or close to) the bottom of a recess in a lifter. 
         [0006]    An adjustable collar is positioned along the shank of the tube allowing the tube to rest against the head and hold the magnetic end of the tool at a sufficient height to maintain the lifter clear of the cam lobes. 
         [0007]    The construction and method of operation of the invention, however, together with additional objectives and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  illustrates an embodiment of a magnetic lifting tool. 
           [0009]      FIG. 2  shows an embodiment of a magnetic lifting tool. 
       
    
    
     DESCRIPTION 
       [0010]    Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. 
       DETAILED DESCRIPTION 
       [0011]      FIG. 1  illustrates a first embodiment of a magnetic lifting tool  100 . In  FIG. 1  a guide pin  110  has a knurled knob  112  affixed to one end. The guide pin  110  is disposed in a cylindrical tube  114  such that the guide pin  110  extends completely through the tube  114 . The guide pin  110  has threading at the top end for attaching the knurled knob  112 . The guide pin  110  may be tapered (not shown) at the end opposite the knurled knob  112 . 
         [0012]    A bushing  116  is inserted into the tube  114 . The tube  114  may have multiple inner diameters to allow for receiving the bushing  116  and securing it in place. The bushing  116  is sized to compress against the inner diameter of the tube  114  thus keeping it secure. Attached to the guide pin  110  is a lower retainer (or “push nut”)  118 . The lower retainer  118  acts to keep the guide pin  110  from sliding past the bushing  116 . 
         [0013]    As shown in  FIG. 1  the cylindrical tube  114  may have two different interior diameters, however, one have skill in the art will recognize that the inner diameter of the tube need not be effectuated this way. In addition, while the inventor contemplates making the tube  114  from aluminum, the tube  114  may be made from any material capable of holding the necessary components and operating appropriately. Similarly, other components such as the guide pin  110  and retainers may also be manufactured from a variety of materials. 
         [0014]    A spring  120  is placed around the guide pin  110  and positioned to abut the bushing  116  on the side of the bushing  116  opposite the lower retainer  118 . An upper retainer  122  is placed around the guide pin  110  and positioned to retain the spring over a portion of the guide pin  110 . In some embodiments the retainer  122  may be held in place by tapering the tube  114  at the end closest to the retainer  122 . 
         [0015]    A magnet  124  is placed in the lower end of the tube  114 . The magnet  124  may extend slightingly beyond the edge of the tube  114 . The magnet  124  has a hole through the center and the guide pin  110  is aligned to pass through the center of the magnet  124 . The magnet  124  may be disposed inside the tube  114  or attached on to the end of the tube  114 . The size of the magnet  124  may be determined based on the expected carrying capacity of the tool. 
         [0016]    In operation, a user would push the knob  112  thus extending the guide pin  110  out the bottom of the tube  114 . In pushing the guide pin  110 , the spring  120  will be depressed between the bushing  116  and the upper retainer  122 . When the user releases the knob  112 , the force of the spring retracts the guide pin  100  back into the tube  114 . One having skill in the art will appreciate that the lengths of the spring  120 , guide pin  110 , and tube  114  operate together to determine the length of extension of the guide pin  110  from the bottom of the tube  114 . 
         [0017]    One having skill in the art will recognize that the shaft  114  may be formed using two shafts, an inner and an outer shaft. If the inner shaft is cut to the correct length, it may provide for a lip to hold bushing  116  and a lip to hold the magnet  124 . 
         [0018]    References in the specification to “one embodiment”, “an embodiment”, “an example embodiment”, etc., indicate that the embodiment described may include a particular feature, structure or characteristic, but every embodiment may not necessarily include the particular feature, structure or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one of ordinary skill in the art to effect such feature, structure or characteristic in connection with other embodiments whether or not explicitly described. Parts of the description are presented using terminology commonly employed by those of ordinary skill in the art to convey the substance of their work to others of ordinary skill in the art. 
         [0019]      FIG. 2  shows an alternate embodiment of a magnetic lifting tool  200 . In  FIG. 2  the tool  200  is shown in a cut-away perspective view of an engine block  210 . The tool  200  has indicia  212  along the edge allowing a user to know the depth of the tool when it is inserted into the engine block  210 . The indicia may be displayed with one or more standard measurement units such as inches or centimeters. A stop-collar  214  is placed around the central shaft  220  of the tool  200  and may be locked onto the shaft  220  using a threaded set screw  216  (shown in the figure with a knurled knob for easy adjustment). 
         [0020]    A guide pin  218  is shown partially extended from the bottom of the tool  200 . The guide pin  218  is fed from a bore in the center of the shaft  220 . At the opposite end of the shaft  220  there is a push-button control  222  coupled to the guide pin  218 . By operating the push-button control  222 , a user may extend the guide pin  218  beyond the end of the shaft  220 . At the end of the shaft  220  is a magnet  226  attached to the shaft  220  such the guide pin extends from the center of the shaft  220 . The magnet  226  is positioned such that the magnetic field affects the outer edge of the shaft  220  and the surrounding area. 
         [0021]    The engine block  210  encloses a lifter  224 . Conventional lifters have a concave recess (or indentation) on one surface as shown by the dotted lines in  FIG. 2 . In operation, the user extends the guide pin  218  beyond the end of the shaft  220  and into the recess on the lifter  224 . While the guide pin  218  is extended and positioned into the recess, the tool  200  may be lowered down through the engine block  210  such that the guide pin  218  enters into the recess of the lifter  224 . Once lowered in place, a user gently releases the guide pin  218  while pushing the tool  200  further down into the engine block  210 . When the tool  200  is inserted as far as it will go, the magnet  226  will be located substantially about the center of the recess and will adhere to the lifter using magnetic force. 
         [0022]    During the insertion process the guide pin  218  acts to prevent the lifter from being forced up to the magnet  226  because the guide pin  218  forces the lifter  224  away. The guide pin  218  also prevents the magnet  226  from moving laterally and attaching to the sides of the recess on the lifter  224 . Thus, the diameter of the tool  200  does not affect positioning of the magnet on the lifter  224 . The use of the guide pin  218  for positioning the magnet area into the recess allows for more accurate positioning of the magnetic lifter tool  200  on the lifter  224 . With the magnet positioned into the recess, the user is reasonably assured of the tool&#39;s position, thus the depth indicia  212  is more accurate and positioning the tool  200  (or similar tools) may be done repetitively for each cylinder in the engine. Once the tool  200  is positioned at the appropriate height, the stop-collar  214  may be tightened in place using the set screw  216 . 
         [0023]    To remove the tool  200 , a user extends the guide pin  218  by operating the push-button  222  thus separating the magnet  226  from the lifter  224  by breaking the magnetic hold on the lifter  224  and releasing the tool  200 . One having skill in the art will recognize that the strength of the magnet and the strength and length of the guide pin are determined by the intended operation of the magnetic tool  200 . 
         [0024]    In operation, the tool  200  may be applied in each pushrod passage to hold all of the lifters simultaneously during camshaft removal and installation. One having skill in the art will recognize that the tool  200  may be modified to provide other functions as well, by forming a square, hexagonal, or other shaped receptacle at the magnetic end to grip a square drive socket, an interchangeable tool bit, or other component as desired. 
         [0025]    The guide pin  218  may be constructed from a hollow tube (not shown). A hollow tube of sufficient diameter allows for liquids such as oil to be injected down the tube and on to the lifter thus allowing the valve to be properly oiled before starting the engine. 
         [0026]    The above illustration provides many different embodiments or embodiments for implementing different features of the invention. Specific embodiments of components and processes are described to help clarify the invention. These are, of course, merely embodiments and are not intended to limit the invention from that described in the claims. 
         [0027]    Although the invention is illustrated and described herein as embodied in one or more specific examples, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention, as set forth in the following claims.