Abstract:
A bias element which urges the valves in an internal combustion engine into their closed positions and includes a pair of arms and a bight portion connecting the two arms. Each arm has an aperture therein with at least one arm having an aperture that is keyhole-shaped, or having a first portion and second portion that is larger than the first portion. The arm which has the keyhole-shaped aperture is in operative biasing engagement with the end portion of a valve stem and the keyhole-shaped aperture engages the valve stem in that the first portion of the aperture lockingly engages the neck portion of the valve stem. The other arm is engages the shank portion of the valve stem.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     The present invention relates to internal combustion engines, specifically springs for urging the intake and exhaust valves toward the closed position during operation of the engine. 
     2. Description of the Related Art 
     Use of springs to maintain internal combustion engine exhaust and intake valves in a closed position is known in the art. Springs which are used in existing engine combinations include coil springs, torsion bars, “hairpin” springs, and other such springs. However, such springs require an additional mechanism or retainer to keep the spring engaged with the exhaust and intake valves. 
     Previous methods of maintaining the spring engaged with the valve have included the use of additional flanges (U.S. Pat. No. 3,097,633) or the use of separate retainers (U.S. Pat. No. 972,434), as discussed above. These approaches require additional parts to be used with the valve spring, thereby increasing the cost and complexity of installation. When utilizing additional retainers for the spring, both the spring and retainer must be installed and connected rather than a single piece being installed. 
     What is needed is a valve spring which does not require additional elements or mechanisms such as retainers to maintain engagement with the exhaust and/or intake valves but which does provide ease of installation. 
     SUMMARY OF THE INVENTION 
     The present invention provides a bias element which urges the valves in an internal combustion engine toward their closed positions and includes a pair of arms and a bight portion connecting the two arms. Each arm has an aperture therein with at least one arm having an aperture that is keyhole-shaped, or having a first portion and second portion that is larger than the first portion. The arm which has the keyhole-shaped aperture is in operative biasing engagement with the head portion of a valve stem and the keyhole-shaped aperture engages the valve stem such that the first portion of the aperture is in locking engagement with the neck portion of the valve stem. The other arm engages the shank portion of the valve stem when the bias element is positioned on the head or block. 
     The bias element is a one-piece valve spring and retainer thereby overcoming the above described problems by reducing the number of parts machined or required and by eliminating the need for a separate spring retainer. Furthermore, by being only one piece, the spring and retainer may be installed easily in the engine without requiring that a spring be installed and then a separate retainer installed and attached to the spring. 
     In one form, the present invention provides a bias element for an internal combustion engine, which engine has an intake valve and an exhaust valve with each valve including a valve stem and having an open position and a closed position. Each valve stem has an end portion and a shank portion. The bias element urges the respective valve toward its closed position and includes a first arm, a second arm, and a bight portion therebetween. The first arm includes an aperture therein having a keyhole shape with a first portion and a second portion, in which the second portion is larger than the first portion. The first arm is in operative biasing engagement with the end portion of the valve stem with the first portion of the aperture being in locking engagement with the neck portion. The second arm has an aperture therein through which the shank portion of the valve stem extends. 
     The present invention further provides a method of assembling a valve spring and retainer to a valve or block wherein the spring and retainer have upper arm and a lower arm with each arm having an aperture therein, aligning the spring and retainer with a valve stem, sliding the valve stem through the apertures in both arms of the valve spring and retainer, and sliding the upper arm laterally to thereby lockingly engage the valve stem. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention itself will be better understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein: 
     FIG. 1 is a sectional view of a portion of an internal combustion engine including a valve spring and retainer in accordance with one form of the present invention; 
     FIG. 2A is a top view of the valve spring and retainer of FIG. 1; 
     FIG. 2B is a side view of the valve spring and retainer of FIG. 1 mounted on the valve stem; 
     FIG. 2C is a side view of a first configuration of the valve spring and retainer of FIG. 2A in an unmounted position; 
     FIG. 2D is a side view of a second configuration of the valve spring and retainer of FIG. 2A in an unmounted position; 
     FIG. 2E is a side view of a third configuration of the valve spring and retainer of FIG. 2A in an unmounted position; 
     FIG. 2F is a side view of a fourth configuration of the valve spring and retainer of FIG. 2A in an unmounted position; 
     FIG. 2G is a fragmentary enlarged side view of the upper arm of the valve and spring and retainer; and 
     FIG. 3 is a plan view of the valve spring and retainer prior to forming. 
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates an embodiment of the invention and such exemplification is not to be construed as limiting the scope of the invention in any manner. 
     DETAILED DESCRIPTION 
     Referring first to FIG. 1, a portion of a vertical shaft or horizontal shaft internal combustion engine  10  is shown as including cylinder head  12  and cylinder  14 , between which sealing gasket  16  is disposed. Internal combustion engine  10  is an air cooled overhead valve engine, such as that disclosed in U.S. Pat. No. 5,105,777, assigned to the assignee of the present invention, the disclosure of which is expressly incorporated herein by reference. Although the invention is shown mounted in an overhead valve engine, for purposes of illustration, the invention is not so limited and the valve and retainer could be utilized in side valve and overhead cam engines as well. Cylinder  14  includes cylinder bore  18  and push rod chamber  20 . Within cylinder head  12  is combustion chamber  22  aligned with and in communication with cylinder bore  18  and intake chamber  23  through which valve stem  28  extends. Valve  24  is seated on seat  26  to provide selective communication between combustion chamber  22  and intake chamber  23 . It is to be noted that the valve assembly of FIG. 1 is shown as an intake valve; however an exhaust valve assembly would be similar to this intake valve assembly. 
     Valve  24  includes valve stem  28  which is slidingly received in guide  30  fitted within boss  32  of cylinder head  12  and which includes end portion  34  and shank  38  including a reduced neck portion  36 . Valve spring and retainer  40  is seated on boss  32  at one end and engages underside surface  64  of end portion  34  at the other end thereof. In such a position, spring  40  is disposed in compression between boss  32  and end portion  34  such that valve  24  is urged against valve seat  26 . 
     Rocker arm  42  is pivotally mounted on rocker arm stud  44  located within rocker arm boss  46  of cylinder head  12 . Rocker arm  42  includes first end  48  abutting the top of end portion  34  of valve stem  28 . Second end  50  of rocker arm  42  is in engagement with push rod  54  at ball end  52  thereof. Further included within cylinder head  12  is rocker arm chamber  56  which is in alignment with push rod chamber  20  of cylinder  14  and through which push rod  54  extends. At the end of push rod  54  opposite ball end  52 , push rod  54  engages a cam (not shown) on a cam shaft (not shown) for operation of rocker arm  42  to actuate valve  24 . Covering rocker arm  42  and valve stem  28  is rocker arm cover  58  which is secured to cylinder head  12  by screws or bolts and is sealed by cover gasket  60 . 
     With reference to FIGS. 2A,  2 B,  2 C,  2 D,  2 E,  2 F, and  3 , valve spring and retainer  40  is shown as having upper arm  66 , lower arm  68  and bight portion  70  therebetween, and within each arm  66  and  68  is an aperture  72 . It should be noted that the terms “upper” and “lower” with reference to arms  66  and  68  merely indicates the arrangement of the arms with respect to cylinder head  12  and boss  32 . Valve spring and retainer  40  is made of stamped spring steel such as stainless steel  316  having a thickness of 0.040 inches. However, it should be noted that the invention is not limited to this particular type of material or thickness. Upper arm  66  forms an obtuse angle relative to bight portion  70  in the disclosed first bent configuration in FIGS. 2B and 2C and in the disclosed fourth configuration in FIG. 2F, with the angle between upper arm  66  and bight portion  70  of the fourth configuration being less than the angle of the first configuration. Alternatively, angle Φ, or the angle of upper arm  66  relative to a horizontal plane, is less in the fourth configuration than in the first. Each aperture is shown as having a keyhole shape with second portion  76  of the aperture being larger than first portion  74  to facilitate easy insertion of valve stem  28  through valve spring and retainer  40  when placing valve spring and retainer  40  in position, as described hereinbelow. In the second and third configurations of FIGS. 2D and 2E, upper arm  66  forms a substantially right angle with bight portion  70  rather than an obtuse angle. 
     When spring  40  slides into its position atop head  12 , valve stem  28  is guided into lower aperture  72 , located in flattened arm  68  abutting surface  78  of boss  32 , and then into upper aperture  72 , located in angled arm  66 . Once valve stem  28  has been inserted through both apertures  72 , specifically both portions  76 , then spring  40  slides laterally such that smaller portion  74  of upper aperture  72  engages neck portion  36  of valve stem  28 . This lateral sliding causes portion  66  of spring  40  to engage a portion of underside surface  64  of end portion  34 . It should be noted that offset portion  62  is included to facilitate placement; however, bent portion  62  is not required. Bent portion  62  may also used to lock spring  40  onto valve stem  28 ; spring  40  may be made without bent portion  62 , but such a bent portion facilitates locking spring  40 . Alternatively, bent portion  62  may be replaced with coined area  62 ′ (FIG. 2G) on upper arm  66  such that end portion  34  is locked within coined area  62 ′. Also, as shown in the second configuration of spring  40  is a C-shaped portion in which upper aperture  72  is located, such a portion may be used in a manner similar to coined area  62 ′ in that end portion  34  may seated therein when spring  40  and valve stem  28  are engaged. If offset portion  62  is not included, then spring  40  may be completely reversible end-for-end since an identical aperture  72  is included in each arm  66  and  68 . Since the diameter of the shank  38  of valve stem  28  is larger than the diameter of neck portion  36 , portion  74  of lower aperture  72  does not engage shank  38 , rather only portion  76  engages shank  38 . Once spring  40  slides laterally, placing portion  74  of upper aperture  72  in engagement with valve stem  28 , valve spring and retainer  40  is “locked” into position on valve stem  28 , and is thereby prevented from sliding laterally to unlock it. 
     Referring now specifically to FIG. 3, spring  40  is shown in its unbent position, or its state immediately after stamping has occurred. As such, apertures  72  are shown in an orientation such that when spring  40  is bent to its proper shape, apertures  72 , specifically portions  74  and  76 , are aligned in the same orientation. Additionally, optional circular aperture  80  is shown in FIG. 3 in approximately the center of the stamped piece; such an aperture facilitates stamping of the piece or insertion of a tool for easier placement in engine  10 , but is not required for operation. Circular aperture  80  may be used to facilitate sliding of spring  40  onto valve stem  28  and then laterally to lock spring  40  in its proper position. Although apertures  72  are shown as being symmetrical, apertures  72  need not be symmetrical, i.e., one aperture may be structured in the keyhole shape, as shown, while the other aperture may be a circular opening, or some other structure which facilitates sliding valve stem  28  therethrough. 
     In operation, valve spring and retainer  40  is used to maintain valve  24 , in this example, intake valve  24 , in the closed position during the appropriate times in the engine cycle. The upward force of spring  40 , particularly upper arm  66 , against underside surface  64  of end portion  34  maintains valve  24  in the closed position. 
     It is to be noted that although element  40  has sometimes been referred to as valve spring  40 , it is both a spring and a retainer. As such, a separate retainer is not needed to maintain the valve spring in its proper position; rather, by merely sliding the stamped valve spring and retainer  40  on to valve stem  28  and then laterally, spring and retainer  40  is located in its proper position. Further, valve spring and retainer  40  is maintained in that position through the locking engagement of aperture  72 , specifically portion  74 , with neck portion  36  of valve stem  28  and will not move upward and away from valve stem  28 . 
     While this invention has been described as having an exemplary structure, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.