Abstract:
A grasping tool for removing and reinstalling a valve from within a valve guide in an internal combustion engine. The grasping tool includes a securing loop of cable extending from a grasping head. The length of the securing loop can be adjusted such that the valve is entrapped between the securing loop and the grasping head. Specifically, the length of cable that forms the securing loop is fixed at one end relative to the grasping head and includes a locking member attached to a second end to fix the length of the cable between the first end and the locking member. The grasping tool includes a handle movably mounted to an elongated shaft through which the cable passes. The handle is rotatable relative to the elongated shaft to adjust the length of the cable that forms the securing loop.

Description:
BACKGROUND OF THE INVENTION 
     The present invention generally relates to a hand tool for use in the maintenance of an internal combustion engine. More specifically, the present invention relates to a tool for removing and reinstalling a valve from within a valve guide in an aircraft internal combustion engine. 
     Aircraft engines, like many other types of internal combustion engines, include a valve positioned in each cylinder of the internal combustion engine that opens and closes to provide access to an exhaust port. The exhaust port allows the volume of exhaust gases contained within the cylinder to be discharged after combustion has occurred within the cylinder. Each valve generally includes a valve head connected to an elongated valve stem. The valve stem is guided through its reciprocating movement by a valve guide having an inner diameter slightly larger than the external diameter of the valve stem. 
     After extended periods of use of an internal combustion engine, airborne carbon particles entrained within the exhaust discharged from the cylinder through the exhaust port begin to build up on the inner diameter of the valve guide. The carbon build up on the inner diameter of the valve guide reduces the tolerance between the valve guide and the valve stem. Eventually, the carbon build up on the inner diameter of the valve guide can cause the exhaust valve to freeze up and no longer function properly. The freeze up of the valve stem within the valve guide can cause the internal combustion engine to malfunction and possibly shut down. 
     Since complete shut down of an internal combustion engine in an aircraft can have disastrous consequences, the engine manufacturers suggest that the individual valve guide for each cylinder in the internal combustion engine should be cleaned after a predetermined number of hours of operation of the internal combustion engine. For example, some aircraft manufacturers suggest that the valve guides be cleaned after 400 hours of operation of the aircraft engine. 
     During the maintenance and cleaning of the valve guides, the valve itself must be removed from the valve guide and the inner diameter of the valve guide is cleaned and re-bored by a conventional boring tool. Although the actual maintenance performed on the valve guide is rather simple and quick, a substantial obstacle in cleaning the valve guides is the removal and insertion of the valve from the valve guide prior to and after the cleaning. 
     Currently, two common methods are used for cleaning the valve guides of an internal combustion engine. The first method requires completely disassembling the engine and removing each valve by pushing the valve into the hollow cylinder of the engine. Once the valve has been removed from the valve guide, a cleaning device can be used to re-bore the valve guide. This type of maintenance on an internal combustion engine can require up to 24 hours of labor, and thus be extremely expensive for the aircraft owner. 
     Alternatively, a method of cleaning the valve guides has been suggested in which the retainer attached to the end of the valve stem is removed and the entire valve is pushed into the cylinder. Once the valve has been pushed into the cylinder, the valve guide can be bored and cleaned as discussed. After the valve guide has been cleaned, individual finger-like grippers can be used to reach into the cylinder through the exhaust port and grasp the valve within the cylinder. Once grasped, the end of the valve stem must be guided into the opening of the valve guide. However, this method of removing and replacing the valve has proven to be extremely difficult and very time-consuming due to the tedious process of attempting to grasp the valve once it has fallen into the cylinder of the internal combustion engine. In practice, this method of removing and replacing the valve has proven impractical, since it can often require ten or more hours to clean each valve guide of the internal combustion engine. 
     Therefore, a need exists for an improved method of removing the valve from within the exhaust port of an internal combustion engine without either disassembling the entire engine or requiring the engine mechanic to fish the valve out from within the open cylinder. Further, it is an object of the present invention to provide a tool that can be used to securely grasp the valve prior to the valve being removed completely from the valve guide. Additionally, it is an object of the invention to provide a tool that securely grasps the valve such that the valve can be removed and repositioned within the valve guide without losing positive control of the valve. 
     SUMMARY OF THE INVENTION 
     The present invention is a grasping tool for securely holding a valve such that the valve can be removed and reinstalled from within a valve guide. The grasping tool maintains a secure hold on the valve such that the valve can be removed and the valve guide cleaned by appropriate methods. Once the valve guide has been cleaned, the grasping tool can be used to guide the valve back within the valve guide. 
     The grasping tool of the present invention includes a hollow, elongated shaft extending between a first end and a second end. The hollow, elongated shaft includes an open passageway extending between the first and second ends. The elongated shaft includes an angled section to permit the tool to be inserted into the cylinder through the exhaust port. 
     A grasping head is attached to the first end of the elongated shaft. The grasping head includes a pair of legs separated by an arcuate contact surface. The arcuate contact surface is configured to receive and engage the outer circumference of the valve being removed. 
     A handle is movably mounted on the elongated shaft near the second end of the elongated shaft. Specifically, the elongated shaft includes a threaded portion having external threads that are received within an internally threaded mating section formed on the handle. Rotation of the handle about the elongated shaft causes the handle to move along the length of the shaft. 
     A fixed length cable extends through the combined length of the handle and elongated shaft and an adjustable length portion of the cable forms a securing loop extending from the grasping head. A first end of the cable extends through one of the legs of the grasping head and includes a stop member that prevents the first end of the cable from passing back through the leg of the grasping head. The second end of the cable passes through the opposite leg of the grasping head and is movable relative to the grasping head such that the length of the securing loop extending from the grasping head is adjustable. In the preferred embodiment of the invention, the second end of the cable extends through the combined length of the elongated shaft and handle and extends out past the outer end of the handle. A locking member is attachable to the cable near the outer end of the handle to create a fixed length for the cable between the locking member and the stop member on the first end of the cable. 
     The grasping tool of the invention can be used to securely grasp the valve stem of a valve that is to be removed from the valve guide to be cleaned. Initially, the length of the securing loop is increased by rotating the handle relative to the elongated shaft. Once the length of the securing loop has been sufficiently increased, the securing loop is passed over the head of the valve such that the valve stem is positioned between the securing loop and the grasping head. The retainer attached to the end of the valve stem can then be removed and the piston contained within the cylinder is moved into contact with the valve head. Once the valve head is supported by the piston, the valve is then pushed from the valve guide until only the end portion of the valve remains within the valve guide. The length of the securing loop is then reduced by rotating the handle relative to the elongated shaft until the valve stem is securely entrapped between the securing loop and the grasping head. Once the securing loop has been sufficiently tightened, the valve can be fully removed from the valve guide. 
     After the valve guide has been cleaned, the grasping tool can be used to lift the valve back into the valve guide. Once the valve has been reinserted back into the valve guide, the piston is moved back into contact with the valve head to support the valve. Once supported by the piston, the handle of the grasping tool is rotated such that the securing loop is lengthened and the grasping tool is removed from the valve. Once the grasping tool has been removed, the valve can be fully inserted back into the valve guide and the engine returned back to normal operating conditions. 
     Because of the ability for the grasping tool to tighten very securely around the valve, the grasping tool can be used to remove and reinsert the valve into the valve guide, even though the tolerances between the valve guide and the valve are very small. Additionally, since the valve is always in the control of the engine mechanic, there is little chance that the valve will fall into the cylinder chamber and become lost, thereby requiring complete disassembly of the engine. 
     Various other features, objects and advantages of the invention will be made apparent from the following description taken together with the drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The drawings illustrate the best mode presently contemplated of carrying out the invention. 
     In the drawings: 
     FIG. 1 is a perspective view of the grasping tool of the present invention for use in removing and reinstalling a valve from an internal combustion engine; 
     FIG. 2 is a perspective view similar to FIG. 1 illustrating the movement of the handle relative to the elongated shaft to increase the length of the securing loop used to grasp a valve; 
     FIG. 3 is a partial section view illustrating the operating position of a valve of an internal combustion engine within its valve guide; 
     FIG. 4 is a partial section view illustrating the operation of the grasping tool of the present invention to securely hold the valve being removed from an internal combustion engine; 
     FIG. 5 is a section view taken along line  5 — 5  of FIG. 4; 
     FIG. 6 is an enlarged view illustrating the complete removal of the valve from the valve guide; 
     FIG. 7 is a partial perspective view illustrating an alternate embodiment of the invention having a specifically designed grasping head for a particular type of valve; and 
     FIG. 8 is a section view taken along line  8 — 8  of FIG.  7 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring first to FIG. 1, thereshown is the grasping tool  10  of the present invention. The grasping tool  10  generally includes an elongated shaft  12  having a handle  14  and a grasping head  16  attached to opposite ends of the shaft  12 . The grasping tool  10  further includes a securing loop  18  formed from a portion of a length of cable that extends from the grasping head  16 . As can be seen in FIG. 2, the length of the securing loop  18  can be adjusted such that the grasping tool  10  can be used to securely hold objects having varying sizes. 
     As can be seen in FIGS. 1 and 4, the elongated shaft  12  extends between a first end  20  and a second end  22 . The second end  22  of the elongated shaft includes a threaded portion  24  that has a series of external threads formed thereon. The external threads formed on the threaded portion  24  are received within an internally threaded mating section  26  formed on the handle  14 . The mating section  26  includes internal threads that correspond with the external threads formed on the threaded portion  24  such that the mating threads allow the handle  14  to be connected to and movable along the length of the elongated shaft  12 . 
     In addition to the threaded portion  24 , the elongated shaft  12  includes an angled section  28  that allows the grasping tool  10  to be inserted into the exhaust port  30  of the internal combustion engine, as shown in FIG.  4 . 
     Referring back to FIG. 4, the handle  14  generally includes a body  32  that receives the mating section  26 . In the embodiment of the invention illustrated, the body  32  is formed from wood or plastic while the mating section  26  is formed from a metallic material. The body  32  includes an open passageway  34  that extends through the entire length of the body  32  from the inner end  35  to the outer end  37 . 
     Referring now to FIGS. 2 and 5, the grasping head  16  is securely attached to the first end  20  of the elongated shaft  12  and includes a pair of legs  36  and  38 . The legs  36  and  38  are separated by an arcuate contact surface  40 . The arcuate contact surface  40  has an internal radius generally configured to correspond to the outer diameter of the object to be grasped, as illustrated in FIG.  5 . In the preferred embodiment of the invention, the grasping tool  10  is used to grasp the valve of an internal combustion engine. However, it should be understood that the grasping head  16  can be configured to grasp other types of articles. 
     Referring now to FIG. 5, the leg  38  includes a first cable passageway  42 , while the second leg  36  includes a second cable passageway  44 . Each of the cable passageways are sized to allow the cable to pass through the grasping head  16  to form the securing loop  18 . 
     As can be seen in FIGS. 1 and 2, the securing loop  18  is formed from a portion of a continuous length of cable  45  extending between a first end  46  and a second end  48 . The continuous length of cable  45  includes a stop member  49  attached to its first end  46  such that the first end of the cable is prevented from passing back through the first cable passageway  42 , as can be seen in FIG.  5 . Specifically, the stop member  49  is sized larger than the first cable passageway  42  and thus contacts the outer edge  51  of the grasping head  16 , as shown in FIG.  5 . 
     The length of the cable  45  passes through the first cable passageway  42  and forms the securing loop  18 . The cable  45  then passes through the second cable passageway  44  formed in the grasping head  16 . From the grasping head, the cable  45  passes through an open passageway  50  extending along the entire length of the elongated shaft  12  from the first end  20  to the second end  22 , as seen in FIG.  4 . The open passageway  50  formed in the elongated shaft  12  is aligned with the open passageway  34  formed in the handle  14  such that the second end  48  of the cable  45  extends past the outer end  37  of the handle  14 . 
     As can be seen in FIG. 4, the second end  48  of the cable  45  includes a locking member  52 . The locking member  52  has an outer diameter greater than the diameter of the open passageway  34  formed in the handle  14 , such that the locking member  52  contacts the outer end  37  of the handle  14  to prevent the second end of the cable  45  from passing through the handle  14 . In this manner, the locking member  52  fixes the length of the cable between the stop member  49  and the locking member  52 . 
     Although the cable  45  is described in the present invention as being formed from stranded wire, it is contemplated by the inventor that the cable  45  could be replaced by plastic, nylon, rope, or other equivalent material while operating within the scope of the present invention. 
     As can be understood in FIGS. 1 and 2, when the handle  14  is rotated in the direction indicated by arrow  54 , the threaded connection between the handle  14  and the elongated shaft  12  causes the handle  14  to move along the elongated shaft  12  toward the grasping head  16 . Movement of the handle  14  toward the grasping head  16  decreases the overall length of the grasping tool  10 . As the overall length of the grasping tool  10  decreases, the fixed length of the cable resulting from the interaction between the stop member  49  and the grasping head  16  and the interaction between the locking member  48  and the handle  14  causes the length of the securing loop  18  to increase, as illustrated by arrow  56 . If the handle  14  is rotated in the opposite direction, the handle  14  moves along the elongated shaft  12  away from the grasping head  16 . Movement of the handle  14  away from the grasping head  16  increases the overall length of the grasping tool, thereby causing the length of the securing loop  18  to decrease. By rotating the handle in this direction, the securing loop  18  can be tightened around any object to be grasped, as will be discussed in greater detail below. 
     Referring now to FIG. 3, thereshown are representative portions of an internal combustion engine including a valve  57  as shown positioned within a valve guide  58 . The valve  57  positioned within the valve guide  58  generally includes a valve head  60  and an elongated valve stem  62 . The outer end of the valve stem  62  opposite the valve head  60  includes a reduced diameter neck portion  64  and an end cap  66 . As shown in FIG. 3, a pair of valve springs  68  and  70  surround the valve stem  62  and are held in place by a retainer  72 . The retainer  72  interacts with the end cap  66  to compress each of the valve springs  68  and  70 . The valve springs  68  and  70  exert a bias force on the valve  57  such that the valve head  68  is biased against the exhaust outlet  74 . The valve  57  is opened by movement of a rocker arm  76  which depresses the valve  57  against the bias force of the valve springs  68  and  70  and moves the valve head  60  away from the exhaust outlet  74 . When the valve  57  is open, exhaust from within the cylinder is evacuated through the exhaust outlet  74  and out of the engine through the exhaust port  30 . 
     As discussed previously, during continued operation of the internal combustion engine, carbon particles create a carbon build up along the inner circumference of the valve guide  58 . Since the difference between the inner circumference of the valve guide  58  and the outer diameter of the valve stem  62  is relatively small, build up of carbon along the inner circumference of the valve guide  58  can cause the valve to seize up inside the valve guide  58  and thus cause malfunction of the internal combustion engine. In accordance with the present invention, the grasping tool  10  can be used to remove the valve  57  from within the valve guide  58  such that a cleaning mechanism can be used to clean out the valve guide  58 . The method of carrying out this function will now be described. 
     Referring first to FIG. 2, the handle  14  is rotated in the direction illustrated by arrow  54  to increase the length of the securing loop  18 , as illustrated by arrow  56  in FIG.  2 . Once the length of the securing loop  18  has been sufficiently increased, the grasping tool  10  is inserted into the exhaust port  30  and the securing loop  18  is placed over the head  60  of the valve. 
     Once the securing loop  18  has been placed over the head  60  of the valve  57 , the retainer  72  is removed from the valve stem  62  and the valve springs  68  and  70  are pulled away from the valve stem  62 . With the valve springs  68  and  70 , as well as the retaining cap  72 , removed, the piston  80  is moved into contact with the valve head  60  to help support the valve  57 , as shown in FIG.  4 . The piston  80  is moved within the cylinder by manual rotation of the crankshaft, now shown. Once the valve  57  is in contact with the piston  80 , the valve  57  is pushed into the interior of the cylinder until only the end cap  66  remains within the valve guide  58 , as illustrated in FIG.  4 . As can be seen in FIG. 4, the valve head  60  contacts the underside of the piston  80  to aid in supporting the valve  57  as the valve  57  is removed from the valve guide  58 . 
     Once the reduced diameter neck portion  68  has cleared the lower end of the valve guide  58 , the securing loop  18  and grasping head  16  are positioned to surround the neck portion  68 . 
     After the grasping head  16  and securing loop  18  are in position, the handle  14  is rotated, as illustrated by arrows  82  in FIG. 4, to move the handle  14  away from the grasping head  16 , thus decreasing the length of the securing loop  18 . The length of the securing loop  18  is decreased until the neck portion  68  of the valve stem  62  is securely held between the grasping head  16  and the securing loop  18 . Specifically, the handle  14  is rotated until the neck portion  68  is pressed into contact with the arcuate contact surface  40 . The tightening of the securing loop  18  around the valve stem  62  allows the mechanic utilizing the grasping tool  10  to have a secure hold on the valve  57 . 
     Once the securing loop  18  has been tightened, the piston  80  can be backed further away until the end cap  66  of the valve leaves the valve guide  58 , as illustrated in FIG.  6 . Once the valve has been removed from the valve guide  58 , the valve can be moved away from the valve guide  58  to allow the valve guide to be cleaned and re-bored as discussed above. 
     After the valve guide  58  has been thoroughly cleaned, the grasping tool  10  is used to guide the end cap  66  back into the valve guide  58 . Since the valve  57  is securely held by the grasping tool  10 , the end cap  66  can be repositioned in the opening for the valve guide  58 . Once the end cap  66  is back within the bottom portion of the valve guide  58 , the piston  80  is brought back into contact with the valve head  60 , as shown in FIG.  4 . After the valve  57  is supported as shown, the handle  14  is rotated in the direction opposite to arrow  82  such that the length of the securing loop  18  increases and the neck portion  68  of the valve is released. The length of the securing loop  18  is further increased until the securing loop  18  can freely pass over both the valve stem  62  and the head  60 . The valve  57  is then pushed back into the valve guide  58  and the securing loop  18  passes over the valve head  60  to release the valve. After the valve  57  has been released, the valve springs  68  and  70  are reinstalled and the retainer  68  attached, as illustrated in FIG.  3 . 
     Referring now to FIG. 7, thereshown is an alternate embodiment of the grasping head  16  of the present invention. In the embodiment of the invention illustrated in FIG. 7, the grasping head  16  includes a rib  84  protruding from the arcuate contact surface  40 . The protruding rib  84  is designed to be received within a notch  86  formed in the valve stem  62  of a specific type of valve assembly utilized by a different aircraft engine manufacturer. As shown in FIG. 8, the rib  84  is seated within the notch  86  and the securing loop  18  used to secure the valve stem  62  to the grasping tool  10 . It is contemplated by the inventor that various configurations for the grasping head  16  can be developed depending upon the particular configuration of the valve to be removed. In addition, the angled section  88  of the second embodiment of the invention is configured somewhat differently than the angled section  28  shown in FIG.  1 . The second embodiment of the angled section  88  is configured based upon the exhaust outlet for the engine being maintained. Again, it is contemplated by the inventor that various shapes of the angled section  88  are possible, depending upon the particular configuration of the engine being serviced. 
     Various alternatives and embodiments are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter regarded as the invention.