Abstract:
A cylinder head assembly having a cylinder head and an adapter. The intake cavity of the cylinder head is relatively large, and the adapter fills a portion of the space in the cavity. The cylinder head has an intake runner that decreases in cross-sectional area as it progresses inward from the entrance to the intake port. The adapter has a runner filler that decreases in cross-sectional area as it extends away from a spacer, and is inserted into the intake runner. The volume of the runner filler is smaller than the volume of the intake runner, so a cavity is left within the intake runner. This cavity forms a portion of the intake passageway that leads from the carburetor to the cylinder. The position of the intake position may be altered to accommodate clearance problems with devices in which an engine is incorporated.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates, generally, to internal combustion engines, and more particularly, to internal combustion engines used in snow blowers, generators, vegetation cutting devices such as lawn mowers, or other outdoor power equipment.  
         BACKGROUND OF THE INVENTION  
         [0002]    Internal combustion engines are a common power source for various types of outdoor power equipment, such as lawn mowers or lawn tractors. In the engine industry, the engine manufacturer is usually different than the original equipment manufacturer (“OEM”). The engine manufacturer typically supplies engines to several different OEMs, all of which have different requirements for the location and placement of the engine. Redesigning engines to fit into confined spaces of existing OEM devices, such as lawn mowers or lawn tractors, significantly increases costs for the engine manufacturer. Thus, it is desirable for an engine manufacturer to have a flexible engine design and manufacturing method which can be easily modified to make engines that accommodate a variety of existing devices.  
           [0003]    Cylinder heads for engines are commonly made using a die casting method. When die casting, it is cost effective to maximize the number of parts fabricated with each die tool, and to use simple, compact die tools. Therefore, the layout of the die tool is an important factor in designing a part. Die casting prior art cylinder heads often requires an intake runner core or insert that must be inserted diagonally (“diagonal slide”) relative to the die opening direction. A diagonal slide can create a variety of parts, but it makes the tooling more complex and requires extra space and limits the number of parts each tool can make at the same time. Using straight slides, which move transverse to the die opening direction, restricts some prior art design options, but maximizes the efficiency of each die tool.  
         SUMMARY OF THE INVENTION  
         [0004]    The present invention solves some of the problems of redesigning engines to fit existing OEM devices by forming an intake runner cavity that is relatively large, and then filling at least some of the cavity space with a runner filler to form and position the intake passageway as desired. The present invention allows the same die tool to make cylinder heads with different intake positions. The cylinder heads are also die cast using straight slides to maximize the number of parts made with each simple, compact die tool.  
           [0005]    An important factor when an OEM selects an engine to use on a specific device is the location of certain engine parts, such as the intake position, mounting brackets, and drive shaft. An engine may not be compatible with an OEM device (e.g. a lawnmower deck) because existing features of the device interfere with parts of the engine. For example, there may not be enough room near the engine&#39;s intake position for a carburetor and fuel tank. This invention provides the flexibility to alter the intake position of an engine without redesigning the engine. This invention also enables a cylinder head incorporating the invention to be readily connected to a carburetor which would otherwise be at a different elevation than the intake passageway. Therefore, the engine can be used on a wider range of OEM devices.  
           [0006]    The cylinder head assembly of the present invention includes a cylinder head and an adapter. The cylinder head has an entrance, an intake runner, and an intake port. The entrance is an opening on a side of the cylinder head. The intake runner, which connects the entrance to the intake port, decreases in cross-sectional area from the entrance to the intake port. The intake port is disposed between the intake runner and the combustion chamber.  
           [0007]    The adapter is interconnected with the cylinder head and includes an inlet, a spacer, and a runner filler which is disposed within the intake runner. The inlet receives the air/fuel mixture from the carburetor. The spacer lies against the face of the cylinder head and acts as a thermal insulator for the carburetor. The runner filler is disposed within the cylinder head and at least partially forms the intake passageway that leads from the inlet to the intake port, and has a substantially uniform cross-sectional area.  
           [0008]    In a preferred embodiment, the entrance is elliptical in cross-sectional shape. The intake runner cross-sectional area decreases between the elliptical entrance and the circular intake port. The adapter inlet is preferably a cylindrical opening that opens into the intake passageway. The runner filler is disposed within the intake runner, and at least part of the intake passageway surface is defined by the intake runner and runner filler. The cross-sectional area of the intake passageway is substantially circular and substantially uniform.  
           [0009]    In another embodiment, the entrance and intake runner can be of any shape. At the entrance, the height dimension is larger than the width dimension. As the intake runner progresses from the entrance towards the intake port, the height dimension decreases until it is substantially the same as the width dimension.  
           [0010]    In another embodiment, the entrance could be circular in cross-section, and the intake runner could be circular in cross-section at least near the entrance. The entrance could possibly be any shape, although an important factor is how the shape of the intake passageway affects the flow of the air/fuel mixture. The intake runner cross-sectional area could decrease in any manner, but again, an important factor is how the shape affects the air/fuel flow in the intake passageway.  
           [0011]    In another embodiment of the present invention, at least a portion of the intake passageway is entirely enclosed within the runner filler. The runner filler completely defines at least a segment of the intake passageway between the inlet and the intake port. The intake runner may be any shape as long as the intake passageway maintains a substantially uniform cross-sectional area in the runner filler, and leading from the inlet to the intake port.  
           [0012]    Another alternate embodiment of the present invention changes the orientation of the intake runner and adapter. In a preferred embodiment discussed above, a line containing the height dimension of the entrance is substantially transverse to a longitudinal axis of a piston cylinder. In this alternate embodiment, a line containing the height dimension of the entrance is substantially parallel to a longitudinal axis of a piston cylinder. The intake runner and adapter may also be oriented at any angle between those two locations.  
           [0013]    In a carburetor engine, the air/fuel mixture is regulated by the carburetor, and anything that disrupts the air/fuel flow in the intake passageway of a carburetor engine may reduce engine efficiency by creating flow losses or by altering the air/fuel mixture. The present invention provides a substantially straight and uniform passageway from the carburetor to the cylinder. This objective is achieved by altering the intake position while maintaining a relatively short and straight intake passageway.  
           [0014]    The ability to alter the cylinder head&#39;s intake position allows the engine manufacturer to use existing engine designs for different OEM devices. This feature of the invention reduces costs for the engine manufacturer and OEMs and increases flexibility to adapt an engine to an OEM device.  
           [0015]    Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims and drawings.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    In the drawings, wherein like reference numerals indicate like parts:  
         [0017]    [0017]FIG. 1 is an end view of the cylinder head assembly and carburetor according to a preferred embodiment of the present invention;  
         [0018]    [0018]FIG. 2 is an exploded view of the cylinder head assembly shown in FIG. 1, illustrating the adapter and the cylinder head;  
         [0019]    [0019]FIG. 3 is a cross-sectional view of the cylinder head shown in FIG. 2, illustrating the intake runner;  
         [0020]    [0020]FIG. 4 is a cross-sectional view of the cylinder head assembly shown in FIG. 2, illustrating the runner filler within the intake runner;  
         [0021]    [0021]FIG. 5 is a cross-sectional view of the adapter;  
         [0022]    [0022]FIG. 6 is a perspective view of the adapter shown in FIG. 2, illustrating the spacer and runner filler;  
         [0023]    [0023]FIG. 7 is a perspective view of the adapter shown in FIG. 2, illustrating the spacer and inlet;  
         [0024]    [0024]FIG. 8 is a side view of an alternate embodiment of the cylinder head with the position of the intake runner and adapter changed;  
         [0025]    [0025]FIG. 9 is a cross-sectional view of the cylinder head assembly with the intake passageway at least partially enclosed within the runner filler.  
         [0026]    [0026]FIG. 10 is a cross-sectional view of the adapter shown in FIG. 9;  
         [0027]    [0027]FIG. 11 is a perspective view of the adapter in the alternate embodiment shown in FIG. 9, illustrating the spacer and runner filler;  
         [0028]    [0028]FIG. 12 is a perspective view of an alternate embodiment of the cylinder head assembly;  
         [0029]    [0029]FIG. 13 is a schematic representation of four cylinder heads which are capable of being produced using one compact die tool and one die casting machine. 
     
    
       [0030]    Before the embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.  
       DETAILED DESCRIPTION  
       [0031]    A preferred embodiment of the cylinder head assembly  2  of the present invention is illustrated in FIG. 1 as it would appear in an engine. The present invention may be used with any conventional engine and cylinder head. One such cylinder head  4  is shown by way of example only in the figures. The cylinder head assembly  2  is typically connected to a conventional carburetor  8  and a cylinder  44 , and forms an end of a combustion chamber  46 . The carburetor  8  creates the proper air/fuel mixture and is connected to the adapter  6  at the inlet  22 . As shown in FIG. 4, the air/fuel mixture proceeds into the inlet  22  and through the intake passageway  42 . In FIG. 1, the air/fuel mixture then passes through the intake port  10  and into the combustion chamber  46  of the cylinder  44 . The cylinder head  4  also includes an exhaust port  48 , an exhaust passageway  50  and a spark plug hole  52 .  
         [0032]    As illustrated in FIGS. 2 and 4, the cylinder head assembly  2  includes a cylinder head  4  and an adapter  6 . The cylinder head  4 , as can best be seen in FIGS. 2 and 3, includes an entrance  12 , an intake runner  14 , and an intake port  10 . Preferably, the entrance  12  has an elliptical shape and is on a side face of the cylinder head  4  (FIG. 2). The entrance  12  has a height dimension (h) and a width dimension (w). In this preferred embodiment, a line containing the height dimension (h) is substantially transverse to a longitudinal axis of a piston cylinder. The intake runner  14  starts at the entrance  12 , and the cross-sectional area of the intake runner  14  preferably decreases as the intake runner  14  approaches the intake port  10 . As the intake runner  14  progresses from the entrance  12  to the intake port  10 , the height dimension (h) preferably decreases until it is approximately equal to the width dimension (w).  
         [0033]    The intake runner  14  preferably has a straight side  16  and an inclined side  18 . The straight side  16  preferably has a surface of a segmented cylinder. The inclined side  18  preferably has a semi-circular cross section and begins at the end of the entrance opposite the straight side  16 . The distance between the inclined side  18  and the straight side  16  preferably decreases as they approach the intake port  10 . The intake port  10  is disposed between intake runner  14  and the cylinder  44  (FIG. 1), and permits the intake runner  14  to be in fluid flow communication with the cylinder  44  (FIG. 1).  
         [0034]    As shown in detail in FIGS. 5, 6 and  7 , the adapter  6  includes an inlet  22 , spacer  24 , and runner filler  26 . One with ordinary skill in the art will recognize that the adapter  6  can be made out of several materials using various methods of manufacture. In the preferred embodiment, the adapter  6  is made of plastic using injection molding.  
         [0035]    As illustrated in FIG. 7, the inlet  22  is preferably an open cylindrical extension with a substantially circular cross-sectional area. The inlet  22  is preferably long enough to interconnect to the carburetor  8 .  
         [0036]    In FIG. 6, the cylindrical opening of the inlet  22  continues through the spacer  24  to form the spacer opening  20 . The surface of the spacer  24  with the runner filler  26  preferably lies against a face of the cylinder head  4 . The spacer  24  may be solid or hollow and the thickness may vary, as long as the spacer provides adequate thermal insulation for the carburetor  8 . The thickness of the spacer  24  in the preferred embodiment is approximately 0.35 inches.  
         [0037]    The runner filler  26  preferably has two side surfaces  32 , a contact surface  28 , and a passage surface  30 . Preferably, the contact surface  28  has the shape of a segmented cylinder and extends substantially normal from the spacer  24 . The passage surface  30  preferably has a semi-circular cross-section and intersects the contact surface  28  at the end of the runner filler  26 . When viewed from the side, as in FIG. 5, the runner filler  26  in the preferred embodiment has a substantially triangular profile. Preferably, the edges of the passage surface  30  have a slight radius near the spacer  24  and near the end of the runner filler  26 . These slight curves smooth the change in direction of the intake passageway  42  (FIG. 4). In an alternate embodiment, the side profile of the runner filler  26 , as viewed similar to FIG. 5, could be a quarter circle shape, or any other similar shape, as long as the cross-sectional area of the intake passageway  42  (FIG. 4) remains substantially uniform.  
         [0038]    As illustrated in FIG. 2, the adapter  6  is preferably fastened to the cylinder head  4  with bolts  34  that pass through the bolt apertures  36  and into the threaded apertures  38 . One skilled in the art will recognize that any suitable fasteners may be used to attach the adapter  6  to the cylinder head  4 .  
         [0039]    As shown in FIG. 4, the runner filler  26  is at least partially disposed within the intake runner  14  and decreases in cross-sectional area as it extends away from the spacer  24 . Together the inclined surface  18  and the passage surface  30  preferably define at least a portion of the intake passageway  42 . The intake passageway  42  is preferably a substantially tubular shaped conduit that extends from the inlet  22  to the intake port  10 . Preferably, the intake passageway  42  has a substantially uniform cross-sectional area that is substantially the same size as the cross-sectional area of the inlet  22 .  
         [0040]    [0040]FIG. 8 shows an alternate embodiment where the intake runner and adapter  106  are oriented approximately 90 degrees from the position depicted in FIG. 2. In the embodiment in FIG. 8, a line containing the height dimension h 1  of the entrance is substantially parallel to a longitudinal axis of a piston cylinder. The actual orientation of the intake runner and adapter  106  to the cylinder head  104  is not critical to the invention. This alternate embodiment allows more options when fitting engines to existing OEM devices, and generates different and improved intake flow characteristics. The angle at which the intake runner can be oriented is only limited by the constraints of the other features of the engine or OEM device which may interfere with the intake runner, such as valves guides, mounting holes, or carburetor or fuel tank location, as well as die construction.  
         [0041]    Another alternate embodiment is shown in FIG. 9 where a section of the intake passageway  242  is completely enclosed within the runner filler  226 . In this embodiment the runner filler  226  completely surrounds the spacer opening  220  and entirely defines at least a segment of the intake passageway  242 . Only the adapter  206  must be changed to accommodate a slightly different intake position for the engine. Adapters with different intake positions can be used with cylinder heads  4  made with the same intake runner  14 . The intake passageway  242  of a conventional cylinder head is usually completely defined by the cylinder head and positioned approximately where the straight side  16  is located in the present invention. In the preferred embodiment of this invention, the inlet  222  is positioned near the inclined side  18  of the intake runner  14 . This alternate embodiment allows the inlet  222  to be positioned anywhere along the entrance  12 . Changing the location of the inlet  222  and enclosing a portion of the intake passageway  242  within the runner filler  226  permits adapters with an inlet position along this entire range to be used with the same cylinder head  4 .  
         [0042]    [0042]FIGS. 10 and 11 illustrate the adapter  206  of this alternate embodiment in more detail. In FIG. 11, a section of the intake passageway  242  is completely enclosed within the runner filler  226 . The entire length of the runner filler  226  encloses a portion of the intake passageway  242 , however any length of an enclosed segment of the runner filler  226  would be possible. The inlet  22  could also be at any point along the adapter  206  such that the intake passageway  242  still passes through the entrance of the intake runner.  
         [0043]    [0043]FIG. 12 illustrates another alternate embodiment of the cylinder head assembly  302 . In this embodiment, the intake runner  314  and the runner filler  326  have a substantially circular cross-section. The cross-sectional area of the intake runner  314  preferably decreases as the intake runner  314  progresses inward from the entrance  312 . The intake runner  314  and runner filler  326  may have a substantially conical shape. The intake passageway  342  may be enclosed by the runner filler  326 . This embodiment allows the inlet  322  to be located at almost any point on the face of the spacer  324 , as long as fluid losses are minimized and as long as the inlet  322  passes through the spacer  324  to intersect with the intake passageway  342  within the runner filler  326 . Therefore, a greater range of intake positions are possible by only changing the adapter  306  and using the same cylinder head  304 . Other variations are also possible with the cross-section of the intake runner  314  and runner  326  being any shape between an ellipse and circle.  
         [0044]    [0044]FIG. 13 depicts a layout for the die used to manufacture cylinder heads  4  according to the present invention. The cylinder head  4  is preferably designed to permit four cylinder heads  4  to be produced using one compact die tool and one die casting machine. The cylinder head is designed to include walls which allow for the needed draft angles given different orientations for each cylinder head within the die tool. The draft angles enable the cylinder head  4  to readily separate from the die. The cylinder head  4  is preferably designed to permit slide tooling access (i.e., the intake runner and exhaust passageway) when four cylinder heads are fabricated from one tool.  
         [0045]    In FIG. 13, the die is formed so that the spark plug holes  52  of corresponding cylinder heads  4  are adjacent to each other. The die is arranged so that the inserts which form the cavity of the intake runner  14  move in direction A, and the inserts which form the exhaust passageway  36  move in direction B. In a preferred embodiment, the die is positioned so that the directions A and B alternate in adjacent cylinder heads.  
         [0046]    By positioning the cylinder heads  4  in the manner described, the inserts used to form the cylinder heads are moved only along two directions, i.e., in directions A and B. This die configuration reduces the overall space required to make the cylinder heads  4 , while still enabling four cylinder heads  4  to be made at the same time.  
         [0047]    The embodiments described above and illustrated in the drawings are presented by way of example only and are not intended as a limitation upon the concepts and principles of the present invention. As such, it will be appreciated by one having ordinary skill in the art that various changes in the elements and their configuration and arrangement are possible without departing from the spirit and scope of the present invention as set forth in the appended claims.