Abstract:
Two embodiments of water cooled internal combustion engines employing an EGR system. The embodiments also utilize direct cylinder injection. The EGR system is formed integrally within a housing assembly that also forms a portion of the cooling system for the engine and particularly a return coolant manifold. In this way, the exhaust gas recirculation valve can be cooled and its life and performance improved. In addition, this reduces the amount of heat added to the intake system and thus improves the volumetric efficiency of the engine.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to an internal combustion engine and more particularly to an engine cooling arrangement and a cooling arrangement that assist in cooling the EGR system of the engine. 
     As is well known, engines frequently embody an exhaust gas recirculation system (EGR) that is utilized to control the amount of nitrous oxides in the exhaust. By circulating a portion of the exhaust gases back into the combustion chambers, the combustion temperature can be lowered and nitrous oxide emissions reduced and/or controlled. 
     Normally the amount of exhaust gas recirculation is controlled by means of a valve in a conduit that extends from the exhaust system of the engine to the induction system. These valves are frequently reciprocating type valves having sealing surfaces that are brought into and out of engagement by a control element so as to control the amount of exhaust gases recirculated for a given engine running condition. 
     Obviously, the valve and its mounting body experiences a substantial amount of heat due to the fact that the exhaust gases are quite highly heated. This heat can deteriorate the operation of the EGR valve and also can generate excess heat in the engine. Furthermore, the introduction of hot exhaust gases into the intake system can raise the temperature of the air inducted and thus reduce the volumetric efficiency of the engine. 
     It is, therefore, a principal object of this invention to provide an improved and simplified arrangement for cooling an engine and more particularly cooling the EGR valve of engine. 
     It is a further object of this invention to provide a simple low cost and highly effective arrangement for cooling the exhaust gas recirculation valve of an engine without requiring extra components at the same time simplifying the overall engine construction. 
     SUMMARY OF THE INVENTION 
     This invention is adapted to be embodied in an internal combustion engine having a water cooled engine body, an exhaust manifold for collecting exhaust gases from the engine body and discharging them to the atmosphere through an exhaust system and an induction system for inducting air into the engine body for mixture with fuel and combustion therein. The engine body cooling jacket includes an external conduit which is formed in a unit with an exhaust gas recirculation valve so that the engine coolant will cool the exhaust gas recirculation valve. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an end elevational view of an internal combustion engine constructed in accordance with a first embodiment of the invention. 
     FIG. 2 is a side elevational view of the engine showing the induction side thereof. 
     FIG. 3 is a top plan view of the engine. 
     FIG. 4 is a partially exploded view of the engine looking from the front as shown in FIG.  1  and from the side shown in FIG. 2 (intake side). 
     FIG. 5 is a view looking in the same direction as FIG. 1 but is enlarged and shows only the upper portion of this end of the engine. 
     FIG. 6 is an enlarged cross-sectional view taken along the line  6 — 6  of FIG.  5  and shows the EGR valve body and associated cooling arrangement. 
     FIG. 7 is a cross-sectional view taken along the line  7 — 7  of FIG.  6 . 
     FIG. 8 is a side view of the valve assembly looking in the direction of the arrow  8  in FIG.  7 . 
     FIG. 9 is a cross-sectional view taken along the line  9 — 9  of FIG.  7 . 
     FIG. 10 is an end elevational view, in part similar to FIG. 5, showing another embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now in detail to the drawings and initially primarily to FIGS. 1-4, an internal combustion engine constructed and operated in accordance with a first embodiment of the invention is indicated by the reference numeral  11 . In the illustrated embodiment, the engine  11  is of the four cylinder inline type and is of a type frequently used for automotive applications. It will be apparent, however, to those skilled in the art how the invention can be utilized with a wide variety of engines of other types and other cylinder numbers and configurations and utilized in other than automotive applications. 
     The engine  11  is comprised of a cylinder block crankcase assembly, indicated generally by the reference numeral  12 , in which four inline cylinder bores are formed. Since the internal structure of the engine  11  forms no part of the invention, the interior of the engine is not illustrated as it is believed those skilled in the art will readily understand how the invention is practiced with engines of varying types. 
     A cylinder head assembly  13  is affixed to the cylinder block crankcase assembly  12  and contains at its upper end a pair of overhead cam shafts, which appear in phantom lines in FIG.  3  and are identified by the reference numerals  14  and  15 . These cam shafts  14  and  15  comprise intake and exhaust cam shafts, respectively, and are contained within a cam chamber formed in the upper part of the cylinder head assembly  13 . This cam chamber is closed by a cam cover  16 . 
     The cam cover  16  also covers, in part, a timing case  17  formed at one end of the engine in which a timing drive  18  is provided for driving the cam shafts  14  and  15  at one-half crankshaft speed, as is well known in this art. 
     As best seen in FIG. 4, the intake side of the cylinder head  13  is formed with a plurality of intake ports comprised of two ports for each cylinder. These are comprised of a primary port  19  and a secondary port  21  for each cylinder. 
     A control valve assembly, which is not shown in FIG. 4 but which does appear in the other figures and which is indicated by the reference numeral  22 , is fixed to this side of the cylinder head  13 . The control valve assembly  22  includes control valves for controlling the flow through the secondary ports  21  so that these ports will serve the combustion chambers of the engine primarily under high speed high load conditions. Any suitable control strategy, however, may be employed. 
     An induction system, indicated generally by the reference numeral  23  is provided for supplying a source of atmospheric air to these intake ports  19  and  21  through the control valve assembly  22 . The induction system  23  includes an air inlet conduit  24  which extends to the end of the engine opposite of that timing drive  18 . This conduit  24  has a flanged end  25  for connection to a throttle body assembly and air intake silencing and filtering system none of which are shown. 
     The air which flows into the intake pipe  24  passes through a plenum section  26  from which servers individual runners  27  extend to the individual cylinders and specifically the primary and secondary ports  19  and  21  thereof. 
     In the illustrated embodiment, the engine  11  is of the direct injected type. To this end, fuel injectors  28  are mounted in the cylinder head assembly  13  in a position juxtaposed to and below the intake ports  19  and  21  of each cylinder. These fuel injectors  28  may be of any known type and are supplied with high pressure fuel from an exhaust cam shaft driven high pressure mechanical fuel pump  29 . The fuel pump  29  has pumping cylinders  31  and delivers the high pressure fuel to a supply line  32  which extends across this end of the engine. There, the supply line  32  meets a fuel rail  33  which is associated with the injectors  28  in a known manner for the supply of high pressure fuel thereto. 
     Spark plugs  34  which are shown only in phantom in FIGS. 1 and 2 are mounted in the cylinder head assembly  13  for firing the fuel air charge formed therein. These spark plugs  34  are fired by combined coil and spark controllers  35  mounted on the terminal tips thereof. These coil assemblies  35  are triggered by a suitable ignition circuit mounted at an appropriate location on the engine. 
     An exhaust manifold, indicated generally by the reference numeral  36  (FIGS. 1,  3  and  5 ) is affixed to the side of the cylinder head assembly  13  opposite to the intake manifold  23 . This exhaust manifold  36  includes a plurality of runner sections  37 , each of which communicates with a respective exhaust port on this side of the cylinder head  13 . These exhaust manifold runners  37  communicate with a collector section  38  that is formed at a lower portion of the exhaust side of the engine  11 . This collector section  38  communicates with a suitable exhaust system (not shown) for discharge of the exhaust gases to the atmosphere. 
     Although the internal construction of the engine is not necessary to understand the construction or operation of the invention, it will be seen in FIG. 1 that the crankshaft  39  driven by the pistons and the cylinders of the cylinder block  12  extends through this end of the engine for coupling to a suitable transmission. 
     The invention deals primarily with a combined EGR valve and coolant return arrangement, indicated generally by the reference numeral  41 , which is preferably located at this end of the engine. The internal structure of this unit  41  will be described in more detail shortly by reference primarily to FIGS. 6-9. However, its connections to the engine will be described primarily by reference to FIGS. 1-5. 
     The assembly  41  includes a solenoid operator  42  that operates the EGR valve, to be described shortly, in accordance with a desired control strategy. The EGR valve collects exhaust gases from the manifold collector section  38  through an exhaust gas recirculation inlet line  43  which has a flange  44  at its inlet end that is affixed to the exhaust manifold collector section  38 . A delivery flange  45  at the other end of this conduit  43  is affixed to a body  46  control valve body  41  in a manner which will be described shortly so that the exhaust gases are delivered thereto. 
     Under the control of the EGR valve solenoid  42 , these exhaust gases are delivered to an EGR delivery tube  47  which has a flange  48  at its inlet end that is affixed to the body  46  of the assembly  41 . A flange  49  at the other end thereof is affixed to the induction system inlet pipe  24  as best seen in FIG.  2 . 
     The connecting flange  49  is juxtaposed to a mounting bracket assembly  51  which serves the purpose of fixing the induction system  23  to the intake side of the cylinder block assembly  12 . In addition, a further mounting bracket  52  connects the upper end of the inlet pipe  24  to the cylinder head  13 . 
     By delivering the exhaust gases to the inlet pipe  24 , they will be well mixed with the intake air with this mixing continuing the plenum chamber  26  and runner sections  27  so as to provide the desired degree of exhaust gas recirculation in well mixed quantities. 
     Obviously since the exhaust gases are quite hot, this presents a significant heat problem which is solved by the construction of the assembly  41  which will now be described by reference to the remaining and aforenoted mentioned figures. 
     The engine  11  is, as has been noted, of the liquid cool type. Basically the liquid system may be of any known construction but, in accordance with a feature of the invention, the cylinder head assembly  13  is provided with a coolant outlet  53  that is formed in the end thereof adjacent where the high pressure fuel pump  29  is located and driven. 
     Coolant from this coolant outlet opening  53  is delivered to the housing  46  which is fixed in mating relationship thereto by a plurality of threaded fasteners  54 . A sealing gasket  55  is interposed between the housing assembly  41  and the cylinder head  13  for water sealing purposes. 
     Referring now to primarily to FIGS. 6-9, the housing assembly  46  has formed therein a coolant inlet passage  56  which opens through the face  57  aforementioned that is held in abutting relationship with the gasket  55  and in communication with the cylinder head coolant outlet opening  53 . This coolant inlet passage  56  is positioned rather high in the body  46 . 
     This passage  56  merges into a circular coolant chamber portion  58  which is defined by an inner wall  59  of the housing  48  in which a cylindrical EGR chamber  61  containing an EGR valve body  65  is formed. A valve seat  62  extends in this valve body  65  across this chamber and has an opening that is valved by a poppet type valve  63  which is actuated by the aforenoted solenoid motor  42 . 
     As may be best seen in FIG. 7, the exhaust gas recirculation pipe  43  is connected to mate with an exhaust gas inlet passage  64  which is formed in the lower portion of the housing  48  beneath the water inlet  56 . This passageway  64  extends to communicate with an inlet opening formed in the valve body  65  that contains the valve seat  62  and the valve  63 . This valve body  65  has an outlet opening  66  which communicates with a exhaust gas delivery passage  67  in the housing  48 . This passage  67  receives the flange  47  of the exhaust gas delivery pipe  46 . 
     At the lower end of the cooling chamber  58 , which, as should be apparent from the foregoing description, encircles the valve body  65  and hence, will cool it and the valve element  62  and  63  contained therein. The chamber  58  then discharges through a coolant discharge passageway  68  formed in an extending nipple portion  69  of this housing  48 . 
     The nipple portion  69  receives a coolant return tube (not shown) for returning the coolant to a heat exchanger such as a radiator. Thus, the exhaust heat is not delivered to the coolant before it has an opportunity to cool the main engine body. However, even the heated coolant from the engine cooling jacket will be considerably cooler than the exhaust gases and hence, significant cooling of the EGR valve body  65  and its components can be obtained because of the proximity of the coolant passages to it. The large contact area provided by the described flow path also aids in this cooling. 
     A heater hose nipple  71  may also be formed in the nipple  69  for connection to the air conditioning system of the associated vehicle if desired. 
     In the figures the phantom arrows show the flow of liquid coolant while the open white arrows show the flow of exhaust gases. Thus, it should be readily apparent that this construction provides a very effective yet simple way of cooling the exhaust gas recirculation valve and also provides some cooling for the exhaust gases before they are mixed with the inducted air so as to reduce the heating thereof and the resulting loss of volumetric efficiency. 
     The housing  46  of the unit  41  also is provided with a pair of sensor receiving openings  72  and  73 . These openings receive sensors for sensing the engine coolant temperature and the exhaust gas temperature, respectively. It also should be noted that other coolant may be introduced into the device  41  via a further coolant receiving opening  74  having a nipple  75  for receiving a hose. This may be return hose from the heater or from some other system in the engine. 
     The housing assembly  48  may also be provided with an air bleed, shown in phantom at  76  so as to permit bleeding of air from the coolant system if desired. 
     In the embodiment as thus far described, the high pressure fuel pump  29  has been positioned and driven by the exhaust cam shaft  15  and the EGR valve  41  has been disposed on the side where the intake cam shaft  14  is located. Of course, the components could be reversed and such a reversed arrangement is shown in FIG.  10 . 
     This arrangement permits the high pressure fuel pump  29  to be located closer to the fuel injectors  28  and thus permits a somewhat shorter routing arrangement. In all other regards, this embodiment is the same as that previously described and therefore further description of the construction and operation of this embodiment is not believed to be necessary to permit those skilled in the art to practice the invention. 
     Of course, it should be readily apparent to those skilled in the art that the foregoing description is that of preferred embodiments of the invention. Various chambers and modifications may be made without departing from the spirit and scope of the invention, as defined by the appended claims.