Abstract:
A head gasket ( 48 ) which acts, when clamped between a cylinder head ( 28 ) and a block ( 22 ) in a liquid cooled internal combustion engine ( 20 ), to form a seal around the combustion chambers ( 24 ). A coolant flow path ( 32 ) routes through the engine ( 20 ) and its directed, in part, through the cylinder head ( 28 ) and the block ( 22 ), with a corresponding flow opening ( 54 ) formed in the head gasket ( 48 ) to accommodate flow of liquid coolant in a normal direction. The head gasket ( 48 ) includes a one-way valve ( 58 ) positioned in the flow opening ( 54 ) to allow the flow of coolant in a normal direction but to prevent the flow of liquid coolant through the flow opening ( 54 ) in an abnormal, reverse direction. The one-way valve ( 58 ) includes movable gate ( 66 ) which may be biased against a valve seat ( 64 ) in a normally closed condition. The one-way valve ( 58 ) can be made as a loose piece article of manufacture which is held in flow opening ( 54 ) by self-locking retention clips.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS  
       [0001]     This patent application claims priority to U.S. Provisional Patent Application Ser. No. 60/581898, filed Jun. 22, 2004. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The invention relates to a method and assembly for preventing abnormal coolant flow in an internal combustion engine, and more particularly toward an improved head gasket having an integrated one-way flow control valve.  
       DESCRIPTION OF THE RELATED ART  
       [0003]     Head gaskets act, when clamped between the cylinder head and the block of an internal combustion engine, to form seals around the cylinder bores. Head gaskets also provide openings for coolant flow paths and lubrication passages between the cylinder head and the block. The prior art includes various configurations of head gaskets which incorporate either mechanically or thermostatically operated valves mounted on the gasket body to control the flow of liquid between the cylinder head and the block. Such prior art gaskets are also know to include a check valve mounted on the gasket body to allow lubricant flow toward the cylinder head but to prevent lubricant flow toward the block for the purpose of retaining oil in the head to help with cold-starting lubrication.  
         [0004]     The prior art also includes examples of cylinder head gaskets including reed-type breather valves for the purpose of venting a crank case. These breather valves usually connect a crank case to a rocker arm chamber and assist with crank case ventilation to the intake valve.  
         [0005]     Most internal combustion engines for vehicular applications include a liquid cooling system characterized by a circuitous flow path throughout the engine, with certain passages strategically routing between the cylinder head and block. Such cooling systems also include external heat exchanging devices to properly manage the operating temperature of the engine and provide passenger compartment heat. In modern engines, it is common to incorporate multiple flow control valves in various locations in the cooling system. For example, a temperature sensitive valve, or thermostat, can be positioned in the flow path so that during cold-weather start-up, coolant will not circulate through the radiator but may circulate through the engine block. In other situations, it may be desirable to close certain valves so that coolant circulates through the heater core but does not circulate through the engine block until a specified temperature has been achieved. Other advance flow control situations are also possible with the incorporation of multiple flow control valves in the cooling system. Depending upon the combination of flow control vales actuated, it is possible to inadvertently establish an abnormal direction of coolant flow through the cooling system. This abnormal direction of flow is sometimes referred to as reverse coolant flow, and depending on the engine design can arise in the region between the cylinder head and the block. Reverse coolant flow is undesirable, and in some situations can result in damage to the engine components.  
       SUMMARY OF THE INVENTION AND ADVANTAGES  
       [0006]     The subject invention comprises a head gasket for clamped retention between a cylinder head and a cylinder block in an internal combustion engine. The head gasket comprises a gasket body having at least one cylinder bore opening formed in the gasket body. At least one coolant flow opening is disposed in the gasket body for passing liquid coolant between the cylinder head and the block when the liquid coolant is flowing in a circuitous normal direction. The improvement comprises a one-way valve carried on the gasket body and automatically closing the coolant flow opening to prevent flow of the liquid coolant in an abnormal direction.  
         [0007]     The subject invention overcomes the undesirable occurrence of reverse coolant flow by providing a one-way valve directly on the gasket body which functions to allow coolant flow in the normal direction but to prevent coolant flow in an abnormal direction.  
         [0008]     According to another aspect of the invention, a liquid cooled internal combustion engine comprises a block having at least one combustion chamber formed therein. A cylinder head is fixed to the block and covers the combustion chamber. A coolant system is integrated into the block and the cylinder head. The coolant system includes a circuitous flow path passing through the cylinder head and the block. A pump, in communication with the flow path, influences the movement of cooling liquid in the coolant system to circulate in a normal direction. At least one flow control valve is disposed in the flow path for selectively preventing the circulation of liquid in portions of the coolant system. A gasket body is compressed between the cylinder head and the cylinder block. The gasket body includes at least one cylinder bore opening aligned with the combustion chamber and at least one coolant flow opening aligned with the flow path. The improvement comprises a one-way valve carried on the gasket body and automatically closing the coolant flow opening to prevent flow of the liquid coolant in an abnormal direction while allowing the flow of the liquid coolant therethrough in the normal direction.  
         [0009]     According to yet another aspect of the invention, a method for preventing abnormal coolant flow in an internal combustion engine is provided. The method comprises the steps of providing an engine having a circuitous coolant flow path passing through a cylinder head and a block, circulating liquid coolant through the flow path in a normal direction, compressing a head gasket between the cylinder head and the block to contain combustion gases, forming a coolant flow opening in the head gasket aligned with the flow path to permit the movement of liquid coolant therethrough in the normal direction, and automatically blocking the flow opening with a one-way valve carried on the head gasket to prevent coolant flow through the engine in an abnormal direction. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]     These and other features and advantages of the present invention will become more readily appreciated when considered in connection with the following detailed description and appended drawings, wherein:  
         [0011]      FIG. 1  is a simplified schematic view of an internal combustion engine having a cooling system;  
         [0012]      FIG. 2  is a perspective view of a cylinder head gasket according to the subject invention;  
         [0013]      FIG. 3  is a fragmentary perspective view showing a portion of the head gasket including a one-way valve in the closed condition;  
         [0014]      FIG. 4  is a fragmentary perspective view of the one-way valve in an open condition;  
         [0015]      FIG. 5  is a perspective view of the subject one-way valve in cross-section showing the gate in a phantom open condition;  
         [0016]      FIG. 6  is a perspective view of the underside of the one-way valve;  
         [0017]      FIG. 7  is an enlarged perspective view showing the hinge and torsion spring configuration of the one-way valve;  
         [0018]      FIGS. 8A and 8B  are simplified cross-sectional views of an alternative embodiment of the one-way valve shown in closed and open positions, respectively;  
         [0019]      FIGS. 9A and 9B  are simplified cross-sectional views of a second alternative embodiment of the one-way valve shown in closed and open positions, respectively; and  
         [0020]      FIGS. 10A and 10B  are simplified cross-sectional views of a third embodiment of the subject one-way valve shown in closed and open positions, respectively. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0021]     Referring to the figures, wherein like numerals indicated like or corresponding parts throughout the several views, a simplified schematic of a liquid cooled internal combustion engine is generally shown a  20  in  FIG. 1 . The engine  20  includes a block  22  having a plurality of combustions chambers  24  formed therein. A piston  26  reciprocates in each combustion chamber  24  through two or four strokes to produce power through a combustion process which generates considerable heat as a byproduct. A cylinder head  28  is fixed to the block  22  and covers each of the combustion chambers  24  to seal in combustion gases.  
         [0022]     To manage the considerable heat generated through the combustion process, a cooling system, generally indicated at  30 , is provided with portions integrated into the block  22  and the cylinder head  28 . The cooling system  30  includes a circuitous flow path  32  through which liquid coolant is routed from the cylinder head  28  to the cylinder block  22  under the influence of a pump  34 . Excess heat in the cooling liquid can be removed through a heat exchanging radiator  36 . When the engine  20  temperature is low, such as during start-up or extreme cold weather conditions, a flow controlling valve in the form of a thermostat  38 , selectively prevents the circulation of liquid coolant into the radiator  36 . By this method, the thermostat  38  helps manage the operating temperature of liquid coolant in the cooling system  30 .  
         [0023]     The cooling system  30  can also include a heater core circuit in which a take-off line  40  directs liquid coolant to a heater core  42 . A heater fan  44  uses convection to transfer heat from the heater core  42  into the passenger compartment of the vehicle. A heater valve  46  can be incorporated into the take-off line  40  or in another advantageous location, for the purpose of controlling the flow of liquid coolant to the heater core  42 . For example, during hot weather operation, it may be desirable to prevent any liquid coolant flow to the heater core  42 .  
         [0024]     Although not shown, other flow control valves may be incorporated into the flow path  32  at different locations to better manage engine temperature and the heat energy contained in the coolant system. For example, the flow path  32  can be designed to provide a flow control valve or valves which allow liquid coolant to circulate through the heater core  42  without circulating through the cylinder head  28  or around the combustion chambers  24  in the block  22 . Such a condition may be motivated by the desire to direct all available heat energy to the heater core  42  where it can warm the passenger compartment as a first priority. Other, more sophisticated flow control strategies may be implemented as well.  
         [0025]     However, during such sophisticated control of the movement of liquid coolant though the flow path  32 , a possible undesirable reversal of coolant flow is possible. This reverse, or abnormal coolant flow direction can undermine proper management of engine temperatures and in extreme circumstances cause damage to components of the engine.  
         [0026]     A head gasket, generally indicated at  48 , is compressed between the cylinder head  28  and the block  22  for containing combustion gases within the combustion chamber  24 . The head gasket  48  includes a gasket body  50 , best shown in  FIGS. 2 through 4 . The gasket body  50  is of generally flat construction and fabricated from any of the known materials, for example, multi-layer steel (MLS), graphite, fiber, steel-elastomer, etc. The shape of the gasket body  50  is designed to correspond with the shape of the block  22  and cylinder head  28  as is generally known in the art. The gasket body  50  includes a cylinder bore opening  52  associated with each combustion chamber  24  to contain air/fuel and combustion gases during the engine cycles. At least one, coolant flow opening  54  is formed in the gasket body  50  and aligned with that portion of the flow path  32  which passes between the cylinder head  28  and the block  22 . Thus, as liquid coolant moves through the flow path  32 , the flow opening  54  in the gasket body  50  accommodates the free circulation. The gasket body  50  may further include additional openings  56  for various purposes, such as lubricating oil flow between the cylinder head  28  and the block  22 , push rods, fastening bolts, and the like.  
         [0027]     In most modem engines, liquid coolant in circulated in a normal direction through the flow opening  54  from the cylinder head  28  into the block  22 . This normal direction takes advantage of gravity and also places the lowest temperature liquid coolant proximate the highest temperature components in the engine. However, it is equally possible to design the engine  20  so that the normal flow direction through the flow opening  54  is from the block  22  toward the cylinder head  28 . In order to prevent coolant flow through the flow path  32  in an abnormal direction, i.e., from the block  22  into the cylinder head  28  in this example, a one-way valve, generally indicated at  58 , is carried on the gasket body  50 . The one-way valve  58  automatically closes the coolant flow opening  54  to prevent the flow of liquid coolant in an abnormal direction while allowing the flow of liquid coolant there through in the normal direction. Thus, if the various flow control valves in the coolant system  30  are set in a configuration which might allow or inadvertently encourage circulation of the coolant in a reverse circuit  28 , the one-way valve  58  will automatically close the flow opening  54  through the gasket body  50  and thereby arrest this undesirable abnormal flow direction.  
         [0028]     The one-way valve  58  is shown in one exemplary form in  FIGS. 2 through 7  including a loose-piece fabricated frame  60  having a shape generally conforming to the coolant flow opening  54  formed in the gasket body  50 . The frame  60  is fixedly joined to the gasket body  50  through an array of self-locking retention clips  62 . The retention clips  62  have barbed ends which respond to insertion of the frame  60  into the flow opening  54  and resiliently snap into a secure gripping condition when the frame  60  has reached a working position. The frame  60  can be made from an injection molded plastic material, in which it is generally rigid or alternatively can be made from an elastomeric material in which its features are compressible and resilient. Alternatively, the frame  60  can be integrated onto the gasket body  50 , without the need for a separate sub-assembly component operation.  
         [0029]     A valve seat  64  is formed in the frame  60  to establish an engagement surface for a movable gate  66  which is hingedly joined to the frame  60 . Pivoting upon the hinge  68 , the gate  66  swings toward and away from the valve seat  64 . The gate hinge  68  supports a biasing member  70  in the form of a torsion spring which reacts against the frame  60  to urge the gate  66  normally toward the valve seat  64 . In this condition, static and velocity pressure in the liquid coolant, when flowing the normal direction, will overcome the biasing force of the torsion spring and thereby open the one-way valve  58  to coolant flow through the flow opening  54 . However, when the static and/or velocity pressure in the liquid coolant is insufficient in the normal direction to overcome the torsion spring, the one-way valve  58  will be urged toward a closed condition and thus prevent any abnormal flow of liquid coolant.  
         [0030]     An alternative variation of the one-way valve  158  is shown in  FIGS. 8A and 8B , wherein for convenience the prefix “1” is applied to reference numbers used in preceding examples to represent corresponding features. In this first alternative embodiment, the biasing member is eliminated, and the hinged gate  166  is responsive entirely to pressure in the liquid coolant to move between its open and closed positions. Flow in the normal direction is represented by the arrow in  FIG. 8B .  
         [0031]     A second alternative embodiment of the subject one-way valve is illustrated in  FIGS. 9A and 9B . Here, the prefix “2” is used with previously established reference numbers to distinguish the components of this second alternative design. Here, the gate  266  takes the form of a spherical ball while the biasing member  270  comprises a simple compression spring. In this check-valve style arrangement, pressure in the liquid coolant flowing in the normal direction ( FIG. 9B ) urges the gate  266  against the biasing member  270  and away from the valve seat  264 . However, when the liquid coolant is not flowing, or flowing in an abnormal direction, the biasing member  270  moves the gate  266  toward a closed position ( FIG. 9A ) and thereby prevents an undesirable flow condition within the engine block.  
         [0032]     A third alternative embodiment of the subject one-way valve is shown in  FIGS. 10A and 10B . Here, the prefix “3” is used in connection with previously introduced reference numerals to indicate like or corresponding parts. Here, the gate  366  comprises a plate supported against a biasing member  370  in the form of compression springs. In response to coolant flow in the normal direction ( FIG. 10B ), the gate  366  translates away from the valve seat  364  to provide an open flow condition. However, during periods of no flow or reverse flow, the biasing member  370  closes the one-way valve  358  to thereby automatically close the coolant flow opening  354  and thus prevent the flow of liquid coolant in abnormal direction.  
         [0033]     The subject method prevents abnormal coolant flow in the internal combustion engine  20  through the steps of: providing an engine  20  having a circuitous coolant flow path  32  passing through the cylinder head  28  and the block  22 . Liquid coolant is circulated through the flow path  32  in a normal direction under the influence of a pump  34 . A head gasket  48  is compressed between the cylinder  28  and the block  22  to contain combustion gases. A coolant flow opening  54  is formed in the head gasket  48  and aligned with the flow path  32  to permit the movement of liquid coolant therethrough in the normal direction. The method advantageously includes the step of automatically blocking the flow opening  54  with a one-way valve  58  carried on the head gasket  48  to prevent coolant flow through the engine  20  in an abnormal direction. Because the liquid coolant is typically circulated through the flow path  32  in a direction which includes moving the liquid coolant from the cylinder head  28  toward the block  22 , the one-way valve  58  automatically prevents the flow of liquid coolant in a reverse direction. Optionally, the step of automatically blocking the flow opening with the one way valve  58  may include biasing the one-way valve  58  toward a closed condition, and overcoming this biasing in response to movement of liquid coolant through the flow path  32  in the normal direction.  
         [0034]     Other modifications and variations of the present invention will be readily appreciated by these skilled in the art. For example, the one-way valve can take any number of different forms and still provide the novel flow control functions here described. It is, therefore to be understood that invention has been described with words of description rather that of limitation. Accordingly, the invention is defined by the appended claims.