A turbocharged internal combustion engine

Abstract: A turbocharger (12) for an internal combustion engine (10) is provided having a turbine section responsive to the engine exhaust gas flow and a compressor section communicating with the engine intake manifold (14). A pressure responsive adjustable fuel pump (15) is in communication with the engine combustion chambers. A wastegate unit (11) with an adjustable valve disposed within a bypass passageway formed in the turbine section is provided for regulating the diversion of a predetermined amount of exhaust gas flow away from a turbine wheel within the section. The unit valve is biased to assume a closed position with respect to the bypass passageway. A multiport connection (33) having an interior cavity is provided with a first port in pressure communication with the fuel pump (15); a second port in pressure communication with the intake manifold (14); and a third port in pressure communication with the wastegate unit (11). When pressure within the connection cavity is below a predetermined amount, the bias on the unit adjustable valve will close the secondary passageway and the fuel pump (15) responsive to the reduced cavity pressure reduces the fuel flow to the engine (10) and the speed of the turbocharger turbine wheel.

Description: This invention relates to an exhaust gas turbocharger for an internal combustion engine having an exhaust port and an intake port, in combination with pressure responsive fuel feed means for supplying fuel to combustion chambers of the engine, the turbocharger, which is known as a wastegate type turbocharger, comprising a turbine section provided with a housing having a primary passageway therethrough for connection to the exhaust port of the engine; a turbine wheel within the housing and responsive to exhaust flow through the primary passageway; a compressor section having a compressor wheel operatively connected to the turbine wheel and adapted for connection with the intake port of the engine; a bypass conduit communicating with the primary passageway upstream of the turbine wheel and capable of bypassing a predetermined amount of exhaust gas away from the turbine wheel when the engine is in a selected operating mode; a pressure responsive wastegate means having a valve for regulating the exhaust gas flow through the bypass conduit, the valve being biased to a closed position with respect to the bypass conduit; and a multiport connection with a first port in pressure communication with the wastegate means, a second port for connection to the outlet of the compressor section, and a third port in pressure communication with the fuel feed means; wherein the valve is designed to open to allow exhaust gas to bypass the turbine wheel when the pressure within the first port exceeds a predetermined pressure. Overspeeding of a wastegate type turbocharger is to be avoided so as to prevent severe engine damage. Failure of the wastegate unit is frequently due to a leakage in either the boost sensing line or the diaghragm of the unit causing in either instance the unit to normally assume a closed position without regulating the fuel flow and thus, the rapid buildup of excessive cylinder pressure due to overspeeding of the turbocharger rotors. Various preventive systems against turbocharger overspeeding have heretofore been proposed whereby the fuel feed means are caused to reduce the supply of fuel to the engine in the event of there being a build-up of excessive cylinder pressure due to overspeeding of the turbocharger wheels consequent on closure of the valve due to a fault. However, such systems are beset with one or more of the following shortcomings; a) costly and complex components are utilised; b) the system is prone to frequent malfunction; c) it is difficult to service and/or install; and d) it requires substantial modifications to be made to certain of the engine components. GB-A-2079364 discloses a distribution fuel injection pump for use with a diesel engine fitted with a wastegate type turbocharger, the pump being arranged so that fuel supply is dependent upon the pressure of the compressed air. According to one aspect of this invention there is provided a combination of an exhaust gas turbocharger for an internal combustion engine and an engine fuel pump for supplying fuel to the combustion chambers of the engine as claimed-by claim 1. The response of the pump to failure of the wastegate unit due to leakage in the wastegate boost sensing line or diaphragm may be slower than it should be due to sudden surges from the intake manifold. Accordingly, the combination is preferably as claimed by claim 2. Other preferred features are claimed by claims 3 and 4. This invention also relates in another aspect to an internal combustion engine including such a combination of an exhaust gas turbocharger and pressure responsive fuel feed means as claimed by claim 5. Thus, an improved wastegate type of turbocharged internal combustion engine has been provided which avoids all of the aforesaid shortcomings. With the improved engine, any failure due to leakage in either the wastegate boost sensing line or diaphragm, causes a reduction in the fuel flow to the engine cylinders. Such reduced fuel flow adversely affects the power output of the engine thereby providing incentive to operating personnel to remedy the wastegate problem before any progressive serious engine damage occurs. In accordance with one embodiment of the invention a turbocharged internal combustion engine is provided which utilizes a pressure responsive wastegate unit having an adjustable valve for regulating the exhaust gas flow to the turbine section of the turbocharger. The unit is in pressure communication with a port leading to an interior cavity formed in a multiport connection. A second port to the connection cavity is in pressure communication with the engine intake manifold. A third port to the cavity is in pressure communication with a fuel feed means for the engine. The wastegate unit adjustable valve is biased to assume a close position blocking bypass flow of the exhaust gas around the turbine section of the turbocharger. The bias pressure on the unit adjustable valve is in opposition to the pressure maintained within the connection cavity. Thus, when the pressure within the cavity is below the bias pressure, the adjustable valve will assume the close position causing the pressure imposed on the fuel feed means through the third port to be reduced resulting in the fuel fed to the engine cylinders to be reduced preventing overspeeding of the turbocharger rotors (e.g., turbine and compressor wheels). Description Of The Drawings For a more complete understanding of the invention reference is made to the drawings wherein: Fig. 1 is a schematic representation of one embodiment of the improved turbocharged internal combustion engine. Fig. 2 is an enlarged schematic representation of the wastegate unit per se incorporated in the engine of Fig. 1. Fig. 3 is an elevational view of the multiport connection per se incorporated in the engine of Fig. 1 with a portion of the connection removed so as to expose the interior cavity formed therein. Fig. 4 is an enlarged fragmentary perspective view of the turbocharger of Fig. 1 shown with the wastegate unit mounted thereon; segments of the unit and turbocharger being removed so as to expose interior portions thereof. Description Referring now to the drawings and more particularly to Fig. 1, one embodiment of a turbocharged internal combustion engine 10 is shown which utilizes a wastegate unit 11 in combination with a turbocharger 12, sometimes referred to as a wastegate type. The engine 10 includes a cylinder block and head combination 13 of conventional design; an air intake manifold 14 in communication with engine combustion chambers, not shown, formed in the cylinder head; and a fuel feed means (pump) 15 also in communication with the combustion chambers. The pump 15 is provided with a pressure sensitive control 15a which regulates the fuel flow from the pump to the combustion chambers. Each combustion chamber may be of conventional design and includes intake and exhaust valves which open and close in a timed sequence with the stroke of a corresponding piston. The exhaust gases generated in each combustion chamber and corresponding cylinder flow into an exhaust manifold, not shown. From the exhaust manifold the exhaust gases are directed to an intake side 17a of a housing 17 forming a component of the turbocharger turbine section 18, see Fig. 4. From the intake side 17a, the exhaust gases flow through an interior primary passageway 17e to a turbine wheel (rotor) not shown, which is rotatably mounted within the housing 17. From the turbine wheel the exhaust gases exit through a discharge side 17b of the housing. As seen in Fig. 4, the interior of housing 17 is provided with a bypass, or secondary, passageway 17c which is upstream of the turbine wheel and communicates at one end through port 17d with the primary passageway 17e and at the opposite end through a port 17f with the discharge side 17b, see Fig. 2. When the port 17d is fully open a predetermined amount of the exhaust gases is diverted around the turbine wheel through the secondary passageway 17c to the discharge side 17b. The flow of the exhaust gases through passageway 17c is regulated by an adjustable valve V forming a component of the wastegate unit 11, the latter to be described more fully hereinafter. As seen in Fig. 4, turbocharger 12 includes a compressor section 20 having a housing 21 in which is disposed a compressor wheel (rotor), not shown. The turbine section housing 17 and the compressor section housing 21 are interconnected by a sleeve 22 through which extends a shaft, not shown, keyed to the turbine and compressor wheels. Housing 21 is provided with an air intake side 21a and a discharge side 21b, the latter being connected via passageway 23 to the engine intake manifold 14, see Fig. 1. If desired, an air/air aftercooler, not shown, may be disposed within passageway 23 between the turbocharger 12 and the intake manifold 14. As seen in Fig. 2, the wastegate unit 11 includes a casing 24 in which is mounted a diaphragm D effecting separation of the casing interior into a pair of contiguous chambers 24a, 24b. Secured to the face of diaphragm D, which is adjacent chamber 24b, is one end 25a of a rod 25. The rod 25 slidably extends through an opening 26 formed in the exterior wall of casing 24. Disposed within housing chamber 24b between the diaphragm D and opening 26 is a bias spring 27. The opposite end 25b of the rod is pivotably connected to a linkage assembly 28 which is connected to valve V, see Fig. 2. The rod 25 is formed of two sections I and II which are interconnected in endwise relation by an internally threaded sleeve 30. Thus, by manually rotating the sleeve 30 the overall length of rod 25 can be adjusted so that valve V will open when the rated speed of the turbocharger has been exceeded. Casing 24 is provided with a port 31 which communicates with interior chamber 24a. Port 31 is connected by tubing 32, sometimes referred to as the boost sensing line, to a multiport connection 33. As seen in Fig. 3, connection 33 has a first port 34 connected to tubing 32; a second port 35 connected by tubing 36 to the engine intake manifold 14; and a third port 37 connected to the pressure sensitive control unit 15a forming a component of the fuel pump 15. The control unit 15a is a conventional design. All of the ports 34, 35 and 37 communicate with an interior cavity 38 formed in the connection 33, see Fig. 3. By reason of the connection 33, the pressure within the air intake manifold 14 is reflected in cavity 38 which, in turn, determines the pressure within chamber 24a and the setting of the wastegate unit valve V. The pressure within connection cavity 38 is also transmitted to the pump control unit 15a which regulates the rate of flow of the fuel from the fuel pump. Thus, if there should be a leak in the tubing 32 or diaphragm D, the pressure within chamber 24a and within the cavity 38 will be diminished with the result that the reduced pressure imposed on the pump control unit 15a will cause the rate of fuel flow to be automatically reduced causing the turbocharger to operate at a slower speed notwithstanding that the bypass passageway 17c is closed. With the reduced speed of the turbocharger, the power output of the engine is noticeably affected, thus signalling to the engine operator that there is a problem needing attention. In order to prevent sudden pressure surges from the air intake manifold 14 through tubing 36 to the connection cavity 38, an orifice 40 of a predetermined size is mounted on port 35 of the connection 33, see Fig. 3. The orifice enables the control unit 15a of the fuel pump to be more responsive to the pressure drop within unit chamber 24a. Thus, a turbocharger internal combustion engine has been described having a wastegate unit of simple construction which is mounted in such a way as to directly affect the output of the engine fuel pump and prevent overspeeding of the turbocharger when there is a leak in certain components of the unit.

Claims: The combination of an exhaust gas turbocharger (12) and an engine fuel pump (15) for an internal combustion engine (10) which has an exhaust port and an air intake port, the fuel pump (15) being provided with pressure responsive control means (15a) for regulating the fuel flow from the fuel pump (15) to the engine (10) and thereby controlling the operating speed of the engine (10), the exhaust gas turbocharger (12) comprising a turbine section (18) provided with a housing (17) having a primary passageway (17e) in which a turbine wheel is mounted, a bypass secondary passageway (17c) communicating with said primary passageway (17e) upstream of said turbine wheel, and a compressor section (20) provided with a compressor wheel operatively connected to said turbine wheel and having a discharge side (21b) for connecting to an air intake manifold (14) of the engine (10) via said air intake port; wastegate means (11) including a pressure responsive valve (V) for regulating exhaust gas flow through the secondary passageway (17c), said valve (V) being biased to assume a closed position with respect to said secondary passageway (17c); and a connection means (33) with a first port (34) in pressure communication with said wastegate means (11), whereby the pressure within the connection means (33) is in opposition to the valve bias, a second port (35) adapted to be in pressure communication with the engine air intake manifold (14) and a third port (37) which is in pressure communication with said pressure responsive control means (15a), wherein said valve (V) is designed to open to allow exhaust gas to bypass said turbine wheel when the pressure within said connection means (33) exceeds a predetermined pressure and a reduction in the fuel flow to the engine (10) is caused in the event of there being a build up of excessive cylinder pressure due to overspeeding of the turbocharger rotors consequent on closure of said valve (V) due to a fault, whereby said valve (V) is closed due to leakage in the pressure communication of said second port (35) with said wastegate means (11) which causes a reduction in the pressure within said connection means (33), that reduction in pressure is applied to said fuel feed means via said pressure communication whereby to cause the reduction in the fuel flow to the engine (10), characterised in that said connection means has an interior cavity (38) having an enlarged volume whereby the pressure within the air intake manifold (14) is reflected in said cavity (38) of enlarged volume which, in turn, determines the setting of the wastegate valve (v). The combination of an exhaust gas turbocharger and an engine fuel pump for an internal combustion engine as claimed in claim 1, wherein said second port (35) of said multiport connection (33) is provided with a pressure limiting orifice (40) whereby said fuel feed means (15) is more responsive to a drop in pressure within said first port (34). The combination of an exhaust gas turbocharger (12) and an engine fuel pump (15) for an internal combustion engine according to claim 1 or claim 2, wherein said wastegate means (11) includes a housing (24) with an interior having a diaphragm (D) mounted therein segregating said interior into a pair of continuous chambers (24a and 24b), one side of said diaphragm (D) being in pressure communication with said second port (37) and the other side of said diaphragm (D) being operatively connected to said valve (V). The combination of an exhaust gas turbocharger (12) and an engine fuel pump (15) for an internal combustion engine according to claim 3, wherein said wastegate means (11) is operably connected to said valve (V) by a pushrod (25) having a length; there being means (I, II and 30) for adjusting the bias on said valve (V) so as to change said predetermined pressure including means (30) for changing said length of said pushrod (25). An internal combustion engine (10) having a combination according to any one of claims 1 to 4.

Inventors: SCHLAMADINGER HANS J, SCHLAMADINGER, HANS J.
Applicants: CUMMINS ENGINE CO INC, CUMMINS ENGINE COMPANY, INC.
Application year: 1992
Main classification: F02B37
IPC codes: F02B37, F02D23, F02D43