Device built into a cylinder head for controlling amount of air fed into the intake of a turbocharged internal combustion engine and method using such a device

Abstract

The present invention relates to a device for controlling the amount of air fed into the intake of a charged internal combustion engine comprising two exhaust gas outlets (32, 36) which are each connected to an exhaust manifold (30, 34) of a group of at least one cylinder (12.sub.1, 12.sub.2, 12.sub.3, 12.sub.4). The device comprises a charging device (38) comprising a turbocompressor having a dual-inlet (46, 48) turbine (40) connected to the exhaust gas outlets and an external air compressor (44), and at least one duct for partially transferring compressed air from the compressor to the turbine inlets. According to the invention, the partial transfer duct (100, 102; 110, 112) is integrated into the cylinder head and comprises throttles (74, 76) controlling the circulation of compressed air in said duct.

Claims

1. A system for controlling a turbocharged internal combustion engine, the engine having a cylinder head, an intake, an exhaust manifold including two exhaust gas outlets respectively coupled to a different group of cylinders with each group containing at least one cylinder, comprising: a turbocharger including a turbine with two turbine inlets with each inlet being connected respectively to a different one of the two gas outlets, the turbine driving an air compressor for producing compressed air which is fed to the intake of the engine; at least one partial transfer duct built into the cylinder head of the internal combustion engine for partially transferring the compressed air from the air compressor to the turbine intakes; and at least one throttle located in the at least one partial transfer duct in the cylinder head for controlling the circulation of the compressed air flowing from the compressor through the at least one partial transfer duct into the turbine intakes; and wherein each cylinder comprises at least one intake valve and at least one exhaust valve.

2. The system of claim 1 wherein the at least one partial transfer duct comprises a non-return flap.

3. The system of claim 1 wherein at least two partial transfer ducts are integrated into the cylinder head and are connected to the two exhaust outlets of the cylinder head in communication with the two turbine inlets.

4. The system of claim 1 wherein the at least one partial transfer duct connects the intake of the cylinders and an exhaust duct of a single cylinder.

5. The system of claim 1 wherein the at least one partial transfer duct connects and air intake of one cylinder of another cylinder.

6. The system of claim 1 wherein each throttle comprise a proportional valve.

7. The system of claim 6 comprising a control for controlling each proportional valve.

8. A method for controlling a turbocharged internal combustion engine, the engine having a cylinder head, an intake, an exhaust manifold including two exhaust gas outlets respectively coupled to a different group of cylinders with each group containing at least one cylinder with each cylinder including at least one intake valve and at least one exhaust valve, a turbocharger including a turbine with two turbine inlets with each inlet being connected respectively to a different one of the two gas outlets, the turbine driving an air compressor for producing compressed air which is fed to the intake of the engine comprising: building the at least one partial transfer duct into the cylinder head between an intake duct in the cylinder head of the engine and the exhaust outlets in the cylinder head; and introducing part of the compressed air leaving the compressor via the at least on partial transfer duct in the cylinder head into the turbine inlets by controlling the compressed air leaving the compressor flowing through the at least one partial transfer duct with a throttle located in each partial transfer duct in the cylinder head.

9. The method as claimed in claim 8 comprising positioning at least two partial transfer ducts in the cylinder head and controlling the circulation of compressed air in each of the at least two partial transfer ducts with the throttle located therein.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Other characteristics and advantages of the invention will appear from reading the description below, which is given purely for illustrative purposes and is not limitative, and to which the following drawings are attached:

(2) FIG. 1 which illustrates an internal combustion engine with a diagrammatic representation of the principle of the charging device according to the invention;

(3) FIG. 2 which shows more precisely an embodiment of the internal combustion engine with its charging device comprising a transfer duct incorporated in the cylinder head.

(4) In FIG. 1, the internal combustion engine 10 comprises at least two cylinders with four cylinders being referenced 12.sub.1 to 12.sub.4 from the left of the figure.

(5) Preferably, the engine is a direct-injection internal combustion engine, in particular of the diesel type, but this in no way excludes any other type of internal combustion engine.

(6) In FIG. 1, each cylinder 12 comprises an intake 14 having at least one intake valve 16 with two intake valves being illustrated. The individual valves 16 respectively control an individual tube 18. The intake tubes 18 are connected to an intake manifold 20 which is supplied with compressed intake air from intake duct 22.

(7) This cylinder also comprises exhaust 24 for the combusted gases with at least one exhaust valve 26. Two valves each control one exhaust tube 28.

(8) In the example illustrated in FIG. 1, the engine functions with a firing sequence of 1-3-4-2. In view of this firing sequence, the exhaust tubes of the first cylinder 12.sub.1 and the second cylinder 12.sub.4, which form a first group of at least one cylinder, are connected to a first exhaust manifold 30 with a first exhaust gas outlet 32. The exhaust tubes of the third and fourth cylinders 12.sub.2 and 12.sub.3, which form a second group of at least one cylinder, are connected to a second exhaust manifold 34 which comprises a second exhaust gas outlet 36.

(9) The two exhaust gas outlets 32 and 36 lead to a turbocompressor 38 for compressing the air, and more particularly to the expansion turbine 40 of this turbocompressor.

(10) As illustrated in FIG. 1, the turbocompressor 40 is a dual-inlet turbocompressor, better known as a twin scroll turbocompressor.

(11) This type of turbocompressor comprises the expansion turbine 40 swept by the exhaust gases, which is connected to rotate a shaft 42 to drive compressor 44.

(12) At the turbine, the inlet of the exhaust gases is divided into two sections. A first inlet section 46 is connected to the first exhaust gas outlet 32 of the first manifold 30 and a second inlet section 48 is connected to the second exhaust gas outlet 36 of the second exhaust manifold 34.

(13) The evacuation of the gases 50 from the turbine 40 is conventionally connected to the exhaust pipe 52 of the engine.

(14) The compressor 44 of the turbocompressor 38 comprises an external air intake 54 supplied by an intake pipe 56. The compressed air outlet 58 of this compressor is connected to the intake duct 22 of the intake manifold 20 by a pipe 60.

(15) Advantageously, a cooling radiator 62 for the compressed air may be placed on the pipe 60 between the compressor and the duct 22.

(16) As best shown on FIG. 1, a transfer duct 64 allows circulation of part of the compressed air leaving the compressor 44 towards the intakes 46 and 48 of the turbine.

(17) This configuration shown in FIG. 1 better illustrates the principle of the invention by clearly describing the different compressed air circuits. However, when the present invention is produced according to FIG. 2, the scavenging ducts are arranged in the engine cylinder head.

(18) According to FIG. 1, the partial transfer duct starts on the pipe 60 at an intersection point 66 between the compressor and the cooling radiator 62, and then separates from a branch point 68 into two branches 70 and 72. The branch 70 leads to the inlet 46 of the turbine via its junction with the first exhaust gas outlet 32 and the branch 72 leads to the other inlet 48 of the turbine via its junction with the exhaust gas outlet 36.

(19) Each branch comprises throttles 74 and 76, such as a proportional valve, controlled by a control 78 which may be common to both throttles. This valve controls the circulation of compressed air circulating in the branch.

(20) Advantageously, each branch also comprises non-return flaps 80 and 82 which prevents the circulation of compressed air from the branch to the compressor by preventing the communication of the two branches.

(21) This configuration therefore allows, during operation of the engine, the benefit of exhaust zones of low pressure prevailing locally in the exhaust manifold, in order to introduce compressed air into the turbine and thus increase the flow of this turbine and consequently of the compressor. This also allows a more effective charging at low rotation speeds.

(22) During operation, if large quantities of air are required in the cylinders, valves 74 and 76 are commanded to open in order to introduce compressed air from the compressor 44 into the turbine 40.

(23) The compressed air leaving the compressor 44 circulates in the duct 64 and then in the branches 70 and 72 opening into the exhaust gas inlets 46 and 48 of the turbine 40, bringing a surplus of fluid to this turbine.

(24) Thus, not only do the exhaust gases from outlets 30 and 36 pass through the turbine, but also compressed air which is added to this gas. Therefore, the rotation of the turbine is increased, which leads to an increase in rotation of the compressor and consequently an increase in pressure of the compressed air leaving this compressor.

(25) Naturally, valves 74 and 76 are controlled by the control 78 to deliver the quantity of compressed air to the turbine which meets the charging needs of the engine.

(26) FIG. 2 describes an exemplary embodiment of the invention. Here, the compressed air loop at the engine intake is not modified between the outlet of the compressor 38 and the intake tubes 18 of the manifold 20. Also, the exhaust loop is not modified, in particular with respect to the part supplying the turbine 14.

(27) The present invention entails incorporation of partial transfer ducts for compressed air integrated into the body of the engine cylinder head.

(28) Thus at piston 124, a partial transfer duct 100 connects the duct of the cylinder head into which the intake tube opens, to the exhaust duct at the cylinder head. This partial transfer duct contains a valve 74 for controlling the flow of air, and a non-return flap 80 to prevent the back flow of exhaust gases to the intake. This flap may be arranged upstream or downstream of the valve or even integrated in the valve 76.

(29) This arrangement allows the introduction of compressed air from the compressor 44 to the inlet 46 of the turbine 40 through the cylinder 12.sub.4.

(30) Advantageously, another partial transfer duct 102 may be provided at the piston 12.sub.2, which connects the duct of the cylinder head into which the intake tube opens, to the exhaust duct. A valve 76 is provided on this partial transfer duct for controlling the flow of air, and a non-return flap 82 to prevent the back flow of exhaust gas to the intake.

(31) This arrangement allows the introduction of compressed air from the compressor 44 to the inlet 46 of the turbine 40 through the cylinder 12.sub.1.

(32) In a variant, from piston 123, another partial transfer duct 102 connects an intake to the exhaust duct of piston 122. Thus, the partial transfer of compressed air opens into the exhaust tube 34 which feeds the inlet 48 of the turbine 40. Like the transfer duct 100, the duct 102 is equipped with a flow control valve 76 and a non-return flap 82.

(33) Also, another partial transfer duct 110 may be provided at piston 12.sub.4, which connects an intake to the exhaust duct of piston 12.sub.1. This other duct is equipped with a valve 76 and a non-return flap 82. In this case, the partial transfer of compressed air opens into the exhaust tube 30 which feeds the inlet 46 of the turbine 40.

(34) As has been described with reference to FIG. 1, a control is connected to all control valves, so that the compressed air flows injected via the partial transfer ducts can be synchronized.

(35) The embodiments are not limited to those exemplified in FIG. 2. Other equivalent configurations of transfer ducts in the cylinder head may be considered, in particular depending on the type of cylinder head or engine.

(36) It is thus possible to provide the system either on all ducts (then requiring one system per duct) and on all cylinders (then requiring one system per duct and per cylinder), or on a limited number of ducts and/or cylinders.

(37) It is also possible to group the ducts of the same cylinder or several cylinders if the size of the cylinder head allows, or to cross the ducts between cylinders so as to maximize the short-circuited flows.

(38) In all cases, the flaps may be arranged upstream or downstream of the valve or integrated in the valve.

(39) The partial transfer ducts may be created at the same time as casting of the cylinder head with space reserved for the throttling equipment, or by machining of the ducts after production of the cylinder head.

(40) Naturally, a mixed embodiment is also possible.

(41) It remains within the scope of the present invention if the partial transfer ducts integrated in the cylinder head are produced by tubes arranged on the cylinder head and connected to the intake duct and the exhaust duct as described above, insofar as the device is integrated between the intake and exhaust manifolds, that is without affecting the conventional intake loop and exhaust loop.