JP3176208U - Turbocharged diesel engine - Google Patents

Abstract

Disclosed is a turbocharged diesel engine in which engine pipe contamination is reduced and NOx is reduced by changing the connection position of an exhaust gas recirculation pipe.
A “long path” exhaust gas recirculation pipe 118 that branches from a main exhaust pipe 114 downstream of a turbine 115 and joins the main intake pipe 106 of the engine upstream of a compressor 109 is provided. A short path recirculation system is provided directly inside the engine using an electronically controlled hydraulic system for variable valve operation in combination with the “long path” recirculation pipe 118. The system provides simultaneous opening of intake valves 7A, 7B and exhaust valves for each cylinder of the engine. In addition, the variable valve actuation system is configured to control the two intake valves of each cylinder in a differential manner so that the two intake valves create different movements of the air flow introduced into the cylinder. Are associated with the respective intake ducts 103 and 104 having different three-dimensional structures.
[Selection] Figure 2

Description

The present invention is a type comprising:
At least one cylinder having at least one intake valve and at least one exhaust valve for controlling the intake pipe and the exhaust pipe, respectively;
A compressor disposed in a main intake pipe connected to the intake pipe of the cylinder;
A turbine for driving the compressor disposed in a main exhaust pipe connected to the exhaust pipe of the cylinder;
Catalyst conversion means and particulate filter means disposed in the main exhaust pipe downstream of the turbine (the catalyst conversion means and particulate filter means may be integrated in a single component that performs both functions. An exhaust gas treatment procedure having two or more different components without excluding the possibility of other existing components such as NOx traps, etc.)
An exhaust gas recirculation pipe controlled by a respective exhaust gas recirculation valve for supplying at least a part of the exhaust gas flowing in the main exhaust pipe back to the main intake pipe, and a turbocharged diesel Related to the engine.

  A conventional engine of the type shown above typically comprises a plurality of cylinders and one or more turbochargers, optionally integrated with an electric compressor. In the engine generally used in automobiles, an exhaust gas recirculation (EGR) pipe branches from a main exhaust pipe upstream of the turbine and joins a main intake pipe downstream of the compressor. The known system is shown schematically in FIG. 1 of the accompanying drawings. In the figure, reference numeral 101 is attached to the entire diesel engine block having four cylinders 102 each having two intake pipes 103, 104. The two intake pipes 103 and 104 are controlled by respective intake valves (not shown), form part of the intake manifold 105, and receive air through the main intake pipe 106. In the main intake pipe 106, an air filter 107; a flow meter 108; a compressor 109; a cooling device, that is, an intercooler 110; and a throttle valve 111 are sequentially arranged. Further, an exhaust pipe 112 controlled by a respective exhaust valve (not shown) is associated with each cylinder 102 of the engine 101. The exhaust pipe 112 forms a part of the exhaust manifold 113 connected to the main exhaust pipe 114. In the main exhaust pipe 114, an exhaust gas processing device 117 having a turbine 115 that drives the compressor 109 via a transmission shaft 116, and a catalytic converter 117a and a particulate filter 117b that are arranged close to each other are sequentially arranged. Yes. In the case of the known arrangement shown in FIG. 1, an exhaust gas recirculation pipe 118 branched from the exhaust pipe 114 upstream of the turbine 115 and joined to the main intake pipe 106 downstream of the compressor 109 and the intercooler 110 is further provided. Is provided. A valve 119 that restricts the flow of gas through the recirculation pipe 118 is provided at a position that coincides with the junction. Further, in the illustrated example, the EGR pipe has an intermediate portion that branches into two pipes 118a and 118b parallel to each other. The pipe 118b crosses the intercooler 120. At the point where the EGR pipe branches into two parallel pipes 118a and 118b, a valve 121 for regulating the gas flow through each of the two parallel pipes 118a and 118b is provided so that the degree of cooling of the exhaust gas can be changed. Is provided.

  The exhaust gas recirculation system made in the known manner described above has several drawbacks. First, the exhaust gas being recirculated causes a phenomenon of fouling the engine pipe and the valve of the intercooler of the EGR system. Secondly, the mixing of recirculated gas and entrained air is not always optimal. This results in a lack of combustion uniformity in the engine cylinders. Another disadvantage is that the recirculated exhaust gas has a much higher temperature, resulting in harmful emissions and particulates, and a hot gas / air mixture when input to the engine. Finally, if all exhaust gas flow does not pass through the turbine, the turbine is not utilized in the most efficient manner.

In order to overcome the above-mentioned drawbacks, the subject of the present invention is a turbocharged diesel engine having all the features indicated at the beginning of the present specification and further characterized by a combination of the following features: It is.
a) The exhaust gas recirculation pipe branches off from the main exhaust pipe at a point downstream of the turbine and the exhaust gas treatment device and provides a main intake pipe at a point upstream of the compressor so as to provide a long path exhaust gas recirculation. To join.
b) The engine has two intake valves for each cylinder, and the two intake valves of each cylinder have different three-dimensional structures to create different movements of the air flow introduced into the cylinder. Associated with each intake duct.
c) The intake valve is controlled by an electronically controlled hydraulic system or variable valve actuation.
The electronically controlled hydraulic system or variable valve actuation is
Each tappet operates the intake valve,
Each intake valve is controlled by the respective tappet against the action of the return spring by the intervention of a hydraulic means including a compressed fluid chamber facing a pumping plunger connected to the tappet of the valve. A camshaft designed to communicate with a chamber of a hydraulic actuator associated with the valve;
1 associated with the intake valve of each cylinder and adapted to communicate the compressed fluid chamber with the exhaust channel in order to disconnect each intake valve from each tappet and, as a result of each return spring, quickly close the intake valve Two or more solenoid valves;
And an electronic control unit that controls the solenoid valve to change the opening and / or closing moment and lift of each intake valve in response to one or more operating parameters of the engine.
d) In addition to the long path exhaust gas recirculation, the electronic control unit provides a stage in which the intake valve and the exhaust valve are simultaneously opened to provide a short path exhaust gas recirculation directly inside the engine. It is configured as follows.
e) The variable valve actuation system controls the two intake valves of each cylinder in a differential manner so as to obtain different movements of the air flow introduced into the cylinders in multiple operating states of the engine. It is configured as follows.

  Due to the aforementioned features, the engine according to the present invention has several advantages. First, the gas recirculated through the long path recirculation line is not contaminated only if it has already passed through a treatment device having a catalytic converter and a particulate filter. Therefore, the phenomenon of fouling the valve and engine pipe is eliminated or in any case greatly reduced. A further advantage resulting from the present invention is that it ensures excellent mixing of the recirculated gas with clean air, with the resulting uniform combustion between the cylinders. Furthermore, since the recirculated gases are taken downstream of the turbine and the exhaust gas treatment device, their temperatures are relatively low. As a result, at the input to the engine, the mixture of recirculated gas and air is also at a relatively low temperature and emissions (particulates and NOx) can be reduced. Finally, the features of the present invention allow the entire exhaust gas flow through the turbine to control the compressor with maximum efficiency.

  In addition, the present invention provides a direct “internal” interior to the engine by maintaining the intake and exhaust valves open simultaneously at several stages of the engine operating cycle through an electronically controlled hydraulic system for variable valve actuation. "Including the additional provision of EGR. During the normal exhaust stroke of the engine cylinder, a portion of the exhaust gas returns to the intake pipe instead of flowing to the exhaust pipe, and is then reintroduced into the combustion chamber in the next introduction stroke. Furthermore, in the exhaust stroke, a portion of the exhaust gas that normally enters the exhaust pipe of the cylinder also returns to the combustion chamber again during the introduction stroke by opening the intake valve and the exhaust valve simultaneously. As a result, the two quantities of exhaust gas described above return to the combustion chamber to perform another combustion in subsequent cycles.

  By providing an additional “internal” EGR, the disadvantages of long path EGR are avoided. This disadvantage is due to the slow reaction during engine transients and the cold engine conditions due to the relatively low temperature of the recirculated gas / air mixture at the input to the engine. The increase in carbon monoxide and hydrocarbon emissions during start-up.

  In a preferred embodiment, a gas cooling device is arranged in the exhaust gas recirculation pipe.

  Furthermore, a throttle actuator (or a device having an equivalent function) can be provided to increase the pressure jump in the exhaust gas recirculation pipe for the purpose of forcing a large amount of gas through the recirculation pipe. The throttle device may be provided without distinction in the main intake pipe upstream of the junction with the exhaust gas recirculation pipe or in the main exhaust pipe downstream of the point where the exhaust gas recirculation pipe branches.

  In the system according to the invention, the mixture of recirculated exhaust gas and drawn-in air is then compressed by a compressor and an intercooler (air-air or air-water exchanger provided in an intake pipe downstream of the compressor). ).

  The valve for regulating the flow of the recirculation gas may be any known type of valve, for example, may be provided at the junction of the recirculation pipe to the intake pipe.

  The present invention will now be described with reference to the accompanying drawings, which are provided solely by way of non-limiting examples.

The figure regarding the conventional engine by a well-known technique. The figure which shows desirable embodiment of the engine concerning this invention. The figure which shows the example of the electronically controlled hydraulic system for the variable action | operation of the intake valve incorporated in the engine of this invention. The figure which shows the different shape of the two intake conduits associated with each cylinder of the engine of the present invention.

  In FIG. 2, the same parts as those in FIG.

  The main difference from the conventional system shown in FIG. 1 is that, in the case of the present invention, an exhaust gas recirculation pipe denoted by reference numeral 118 starts from a point A located downstream of the gas processing device 117. The point diverges from the exhaust pipe 114 and joins the intake pipe 106 at a point located upstream of the compressor 109. Located at a point upstream of the compressor 109 is a valve 121, which may be of any known type that controls the flow of exhaust gas recirculated through the pipe 118.

  Of course, consistent with the prior art, the actuator of valve 121 is preferably controlled by electronic control means in accordance with pre-programmed logic. Also in the case of the present invention, preferably, an intercooler 120 disposed inside the exhaust gas recirculation pipe 118 is provided. In addition, for the purpose of forcing the passage of a large amount of exhaust gas, a throttle valve 122 is preferably provided that can increase the pressure jump through the recirculation pipe 118 along with a corresponding actuator device 123. As shown in FIG. 2, the apparatus does not distinguish between the intake pipe upstream of the recirculation gas intake point 121 or the exhaust pipe 114 downstream of the region A into which the recirculated gas is drawn. Can be installed.

  With the arrangement described above, the advantages broadly shown in the preceding description are achieved.

  In combination with the long path EGR system shown in FIG. 2, the engine also comprises an internal EGR system in accordance with the teachings of European Patent Application EP1273770A2 in the name of the applicant. This internal EGR is obtained through the use of an electronically controlled hydraulic system for variable actuation of the engine intake valve described below with reference to FIG.

  Referring to FIG. 3, the cylinder head 1 is shown in cross section. The cylinder head 1 has, for each cylinder, a cavity 2 formed by the base surface 3 of the cylinder head 1 and defining a combustion chamber. Two intake ducts 4, 5 and two exhaust ducts 6 exit from the combustion chamber. The communication between the two intake ducts 4 and 5 and the combustion chamber 2 is controlled by two conventional poppet type intake valves 7 each having a stem 8 slidably mounted on the body of the cylinder head 1.

  Each valve 7 is returned to a closed position by a spring 9 disposed between the inner surface of the cylinder head 1 and the valve retainer end 10. The communication of the two exhaust ducts 6 with the combustion chamber is controlled by two conventional valves 70 associated with springs 9 returning towards the closed position.

  The opening of each intake valve 7 is controlled by a method described below by a camshaft 11 rotatably mounted around a shaft 12 inside a support portion of the cylinder head 1, and the operations of the plurality of intake valves 7 are performed. The cam 14 is provided.

  Each cam 14 that controls the intake valve 7 is slidably mounted along a shaft 17 arranged at approximately 90 degrees with respect to the shaft of the valve 7 in the case of the example shown in the cited prior art. Cooperates with the plate 15 of the tappet 16. The plate 15 is returned to the cam 14 by a spring associated with the plate 15. The tappet 16 constitutes a pumping plunger slidably mounted inside a bushing 18 supported by the body 19 of the unit 20 assembled in advance. The unit 20 incorporates all the electronic and hydraulic devices associated with the operation of the intake valve according to what is described in detail below.

  The pumping plunger 16 is a compressed fluid (preferably oil coming out of the engine lubrication circuit) present in the pressure chamber C facing the pumping plunger 16 so that the valve 7 opens against the action of the elastic means 9. The thrust can be transmitted to the stem 8 of the valve 7 by the plunger 21 slidably mounted on the cylindrical body constituted by the bushing 22 which is also supported by the body 19 of the subassembly 20.

  In the known solution shown in FIG. 1, the compressed fluid chamber C associated with each intake valve 7 can be arranged to communicate with the exhaust channel 23 via a solenoid valve 24. The solenoid valve 24, which may be of any known type suitable for the function shown here, is controlled by an electronic control means labeled 25 in the figure, such as the position of the accelerator and the engine speed. Control is performed in accordance with a signal S indicating the operation parameter.

  When the solenoid valve 24 is opened, the compressed fluid existing in the chamber C flows into the channel, and the chamber C communicates with the channel 23 so that the cam 14 and each tappet 16 are disconnected from the intake valve 7. Therefore, the intake valve 7 quickly returns to the closed position by the action of the return spring 9. By controlling the communication between the chamber C and the exhaust channel 23, the time and stroke of opening each intake valve 7 can be changed as desired.

  All of the exhaust channels 23 of the plurality of solenoid valves 24 protrude outward, and the same longitudinal channel 26 communicates with the pressure accumulator 27. In FIG. 1, only one of them can be seen.

  The tappet 16 with associated bushing 18, plunger 21 with associated bushing 22, solenoid valve 24, and corresponding channels 23, 26 are all pre-loaded for the advantages of engine assembly speed and ease. It is supported and configured by the body 19 of the assembled unit 20.

  In principle, in the case of the prior art cited, the exhaust valve 70 associated with each cylinder is shown in FIG. In this embodiment, it is controlled in a conventional manner by a respective camshaft 28 via a respective tappet 29.

  Referring again to FIG. 1, the plunger 21 defined within the bushing 22 (shown in FIG. 1 with the chamber at its minimum volume, assuming the plunger 21 is at the upper end of the plunger 21 travel position). The volume-variable chamber facing each other communicates with the compressed fluid chamber C through an opening 30 formed in the end wall of the bushing 22. The opening 30 forces oil present in the variable volume chamber to flow into the compressed fluid chamber C through a clearance existing between the end nose 31 and the wall of the opening 30 engaged by the end nose 31. As far as possible, when the valve is close to the closed position, it is engaged by the end nose 31 of the plunger 21 to provide a hydraulic brake for the movement of the valve 7 in the closed phase. In addition to the communication formed by the opening 30, the compressed fluid chamber C and the variable volume chamber of the plunger 21 are formed in the body of the plunger 21 and communicate with each other via an internal passage controlled by a non-return valve 32. . In the internal passage, fluid can be passed only from the compressed fluid chamber C to the variable volume chamber of the plunger 21.

  During normal operation of the known engine shown in FIG. 1, oil present in the chamber is transmitted by the cam 14 when the solenoid valve 24 eliminates communication with the exhaust channel 23 of the compressed fluid chamber C. The movement of the pumping plunger 16 is transmitted to the plunger 21 that governs the opening of the valve 7. In the initial stage of opening the valve, the fluid coming from the chamber C passes through the non-return valve 32 and a passage arranged in the internal cavity of the plunger 21 to reach the variable volume chamber of the plunger 21. It has a tubular steric structure and communicates with a variable volume chamber. After the first movement of the plunger 21, the nose 31 exits from the opening 30. Therefore, the fluid coming from the chamber C can flow directly into the variable volume chamber through the vacant opening 30.

  In the opposite movement of closing the valve, as already said, during the final phase, the nose 31 avoids impact of the valve body against its seat, for example following opening of the solenoid valve 24. Apply the hydraulic brake to the valve and enter the opening 30. In this way, the valve 7 returns immediately to the closed position.

  In the system described, when the solenoid valve 24 is activated, the engine valve follows the cam motion (full lift). A quick closing is obtained by deactivating (opening) the solenoid valve 24 so that the action of the respective return spring empties the hydraulic chamber and the engine valve is closed. Similarly, delaying valve opening can be obtained by delaying actuation of the solenoid valve. On the other hand, a combination of delaying valve opening and expediting valve closing is obtained by actuating and deactivating the solenoid valve during the corresponding cam thrust. According to an alternative strategy, in accordance with the teachings of the patent application EP 1726790 A1 filed in the name of the applicant, each intake valve is operated in “multilift” mode, ie opening and closing more than once. It can be controlled by “sub-cycle”. In each subcycle, the intake valve opens and then closes completely. As a result, the electronic control unit can change the opening and / or closing moment and / or lift of the intake valve in response to one or more operating parameters of the engine. This maximizes engine efficiency and minimizes fuel consumption in all operating conditions.

  In the case of the present invention, the control unit 25 is programmed so that the intake and exhaust valves are kept open simultaneously at some stage of the engine's operating cycle. Therefore, during the exhaust stroke of the engine cylinder, part of the exhaust gas returns to the intake pipe, and in the subsequent introduction stroke, the exhaust gas previously supplied to the intake pipe remains temporarily open during the introduction stroke. It returns to the combustion chamber with another exhaust gas coming from the exhaust pipe made into the exhaust and returning to the combustion chamber. As a result, the total amount of the two aforementioned exhaust gases returning to the combustion chamber is again used for the combustion stroke. Therefore, EGR is provided inside the engine. The arrangement of the internal EGR in combination with the long path recirculation system according to the present invention can also maximize the advantages of the solution without having the disadvantages of the internal EGR described above.

  According to another important feature of the invention, the engine has two intake valves 7A, 7B (see FIG. 2) for each cylinder. The two intake valves of each cylinder are associated with respective intake ducts 103, 104 having different three-dimensional structures in order to create different movements of the air flow introduced into the cylinder. Further, the variable valve actuation system controls the two intake valves of each cylinder in a differential manner so as to obtain different movements of the air flow introduced into the cylinders in multiple operating states of the engine. It is configured.

  As shown in FIG. 4, the two suction ducts of each cylinder are shaped to optimize the “tumble” type and “swirl” type flow inside the cylinder, respectively. The shape of the movement is essential for optimal distribution of the air charge inside the cylinder. Said shape substantially influences the possibility of reducing the emission of pollutants in the exhaust. More particularly, the conduit 103 terminates in a spiral portion that generates a vortex around the axis of the conduit. On the other hand, the conduit 104 terminates at a portion oriented in a tangential direction with respect to the cylinder axis.

  As explained, in accordance with the present invention, the variable valve actuation system differentiates the two intake valves in each cylinder so as to obtain different movements of the air flow introduced into the cylinders in multiple operating states of the engine. It is comprised so that it may control by the method of attaching. This can be done by providing a separate solenoid valve for each of the two intake valves of each cylinder and / or differentiating the return springs of the two intake valves of each cylinder to obtain different valve lifts. By attaching and / or by providing one solenoid valve for the two intake valves of each cylinder. The one solenoid valve has two or more operation positions corresponding to a state where both intake valves are operated, a state where both intake valves are not operated, or a state where only one intake valve is operated.

  In this way, the operation of the two intake valves 7A, 7B can be controlled independently for each valve because of the advantage of reducing diesel engine pollutant emissions.

  Of course, without prejudice to the principles of the present invention, structural details and embodiments may be widely varied from what has just been described and illustrated by way of example without departing from the scope of protection of the present invention.

DESCRIPTION OF SYMBOLS 1 Cylinder head 2 Combustion chamber 3 Base surface 4 Intake duct 5 Intake duct 6 Exhaust duct 7 Intake valve 7A, 7B Intake valve 8 Stem 9 Return spring 10 Valve retainer end part 11 Cam shaft 12 Shaft 14 Acting cam 15 Plate 16 Tappet 17 Shaft 18 Bushing 19 Body 20 Unit 21 Plunger 22 Bushing 23 Exhaust channel 24 Solenoid valve 25 Electronic control means 26 Channel 27 Pressure accumulator 28 Camshaft 29 Tappet 30 Opening 31 End nose 32 Non-return valve 70 Exhaust valve 101 Diesel engine 102 Cylinder 103 Intake Pipe 104 Intake pipe 105 Intake manifold 106 Main intake pipe 107 Air filter 108 Flow meter 109 Compressor 110 Cooling device or intercooler 1 DESCRIPTION OF SYMBOLS 1 Throttle valve 112 Exhaust pipe 113 Exhaust manifold 114 Main exhaust pipe 115 Turbine 116 Transmission shaft 117 Exhaust gas processing apparatus 117a Catalytic converter 117b Filter for fine particles 118 Exhaust gas recirculation pipes 118a and 118b Pipe 119 Valve 120 Intercooler 121 Valve 122 Throttle valve 123 Actuator device

Claims (5)

A turbocharged diesel engine,
At least one cylinder (102) having at least one intake valve (7) and at least one exhaust valve respectively controlling the intake pipe (103, 104) and the exhaust pipe (112);
A compressor (109) disposed inside a main intake pipe (106) connected to the intake pipe (103, 104) of the cylinder (102);
A control turbine (115) for driving the compressor (109) disposed inside a main exhaust pipe (114) connected to the exhaust pipe (112) of the cylinder (2);
An exhaust gas treatment procedure (117) disposed inside the main exhaust pipe (114) downstream of the turbine (115) and having catalyst conversion means (117a) and particulate filter means (117b);
An exhaust gas recirculation pipe (118) controlled by each exhaust gas recirculation valve (119) to deliver at least a portion of the exhaust gas flowing through the main exhaust pipe (114) back to the main pipe (106). Is characterized by a combination of the following characteristics in a turbocharged diesel engine with:
a) The exhaust gas recirculation pipe (118) is arranged at the main point at a point (A) downstream of the turbine (115) and the exhaust gas treatment procedure (117) to provide long path exhaust gas recirculation. Branching from the exhaust pipe (114) and joining the main intake pipe (106) at a point (121) upstream of the compressor (109);
b) The engine has two intake valves (7A, 7B) for each cylinder, the two intake valves of each cylinder creating different movements of the air flow introduced into the cylinder , Associated with each intake duct (103, 104) having a different three-dimensional structure,
c) The intake valves (7A, 7B) are controlled by an electronically controlled hydraulic system or variable valve actuation;
The electronically controlled hydraulic system or variable valve actuation operates the intake valves (7A, 7B) with respective tappets (15),
Each return valve (7A, 7B) acts on the return spring (9) by the intervention of hydraulic means including a compressed fluid chamber (C) facing a pumping plunger (16) connected to the valve tappet (15). And a camshaft controlled by the respective tappet (11) and designed to communicate with the chamber of the hydraulic actuator (21) associated with each intake valve.
Each intake valve is disconnected from its respective tappet (15), and as a result of each return spring (9), the compressed valve chamber (C) is discharged in association with the intake valve of each cylinder to quickly close the intake valve. One or more solenoid valves (24) adapted to communicate with the channel (23);
An electronic control unit (25) for controlling the solenoid valve (24) to change the opening moment and / or closing moment and lift of each intake valve in response to one or more operating parameters of the engine. ,
d) In addition to the long-path exhaust gas recirculation, the electronic control unit (25) includes the intake valves (7A, 7B) and the short-path exhaust gas recirculation directly in the engine. The exhaust valve (125) is configured to provide a stage of opening simultaneously;
e) The variable valve actuation system is configured such that, in a plurality of operating states of the engine, the two intake valves of each cylinder in a differential manner so as to obtain different movements of the air flow introduced into the cylinder. A turbocharged diesel engine characterized by being configured to control the engine.   The turbocharged diesel engine according to claim 1, wherein an intercooler (120) is disposed in the exhaust gas recirculation pipe (118).   The turbocharged diesel engine according to claim 1, wherein the exhaust gas recirculation valve (121) is arranged at a confluence of the exhaust gas recirculation pipe (118) of the main intake pipe (106). engine.   The throttle valve (122) is arranged inside the main intake pipe (106) upstream of the junction (121) of the exhaust gas recirculation pipe (118). The listed turbocharged diesel engine.   The turbo valve according to claim 1, wherein a throttle valve (121) is arranged inside the main exhaust pipe (114) downstream of the branch (A) of the exhaust gas recirculation pipe (118). A diesel engine with a charger.

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