JP2010281271A - Internal combustion engine with two-stage supercharger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal combustion engine with a two-stage supercharger for actualizing smooth changeover from the high-pressure stage supercharger to the low-pressure stage supercharger. <P>SOLUTION: A diesel engine 1 includes the high-pressure stage supercharger 8 and the low-pressure stage supercharger 9 connected in a two-stage series. A high-pressure-stage turbine 8a of the high-pressure stage supercharger 8 has an inlet and an outlet connected to each other through first an second bypass exhaust pipes 12a, 12b arranged in parallel to each other and in which first and second valves 14a1, 14b1 are arranged, respectively. Each of the first and second valves 14a1, 14b1 and a rod 25a of an actuator 25 for opening and closing it are connected to each other via a link mechanism 26. When the first valve 14a1 is opened at a preset valve opening or greater, the second valve 14b1 is linked therewith to be opened by the link mechanism 26. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an internal combustion engine with a two-stage supercharger, and more specifically, an internal combustion engine with a two-stage supercharger capable of smoothly switching from a high-pressure supercharger to a low-pressure supercharger. About.

  In an internal combustion engine with a two-stage supercharger, two superchargers having a capacity difference between a high pressure stage and a low pressure stage are provided in series, and an appropriate supercharger can be selected according to the operating state of the internal combustion engine. Thus, a bypass is provided to expand the operating area of the supercharging system. In other words, the high-pressure stage turbocharger is used during low-speed rotation / low-load operation, and the low-pressure stage turbocharger is used during high-speed rotation / high-load operation. And a low-pressure supercharger.

  By the way, in an internal combustion engine with a two-stage supercharger, when switching from a high-pressure supercharger to a low-pressure supercharger, the outlet pressure of the compressor of the high-pressure supercharger is used as a stage before using the exhaust switching valve. The opening and closing of the waste gate valve on the turbine side of the high-pressure supercharger is controlled by a positive pressure drive system using the. For this reason, at the time of transient operation, work smoothly transfers from the high-pressure stage supercharger to the low-pressure stage supercharger.

  When controlling the waste gate valve by this positive pressure drive system, the waste gate valve opens when the outlet pressure of the compressor of the high pressure turbocharger reaches a preset pressure, and the high pressure turbocharger opens the low pressure stage. The usage area switches to the turbocharger.

  Since the outlet pressure of the compressor of the high-pressure supercharger increases in proportion to an increase in engine speed or load (fuel injection amount), it is necessary to further open the waste gate valve. However, if the inlet pressure of the high-pressure turbocharger turbine becomes higher than the effective opening area of the wastegate valve (that is, the exhaust gas flow rate increases), the pressure before and after the wastegate valve reaches the critical pressure ratio. The flow rate of exhaust gas passing through the waste gate valve is constant regardless of the opening degree of the waste gate valve (hereinafter, this state is referred to as a choke state). When the engine speed or load further increases from this choke state, exhaust gas that cannot be released to the turbine of the low-pressure supercharger flows to the turbine of the high-pressure supercharger through the bypass where the wastegate valve is arranged. For this reason, the internal pressure of the exhaust manifold increases. In addition, since the switching from the high-pressure stage supercharger to the low-pressure stage supercharger cannot be performed smoothly, a necessary amount of air cannot be ensured. For this reason, since an EGR (Exhaust Gas Recirculation) gas flow rate cannot be increased, exhaust performance relating to nitrogen oxide (NOx) in the exhaust gas is deteriorated. Moreover, since the inlet pressure of the turbine of the high-pressure turbocharger also increases, the exhaust manifold internal pressure rises, which adversely affects fuel consumption and the like.

  In addition, under conditions where the engine speed or load is high, the exhaust switching valve is opened to switch to a mode in which the low-pressure supercharger alone is supercharged. If so, the flow rate of the exhaust gas flowing to the exhaust gas flow path and the low-pressure supercharger greatly changes, and therefore, during transient operation, NOx exhaust performance in exhaust gas, fuel consumption, etc. are adversely affected.

  On the other hand, there is also a method of controlling a waste gate valve using an electromagnetic variable regulation valve (EVRV) like an exhaust switching valve, but in this method, the response does not follow during transient operation. There are problems such as difficulty in controlling the turbo lag.

  From these facts, it is considered best to control the waste gate valve by a positive pressure drive system that uses the outlet pressure of the compressor of the high-pressure supercharger. In this system, as described above, the waste gate valve is controlled. The choke may occur in the valve, so that improvement is necessary.

  As a countermeasure against this choke, it is sufficient to increase the effective opening area. Therefore, a method of enlarging the waste gate valve diameter and enlarging the gas flow path is conceivable, but in this method, the force applied to the waste gate valve ( Since the exhaust gas pushing force of the waste gate valve increases in proportion to the valve diameter, there is a problem that the valve opening force needs to be increased and the size of the actuator needs to be increased.

  For example, in Patent Document 1, the inlet side of the high-pressure stage turbocharger and the inlet side of the low-pressure stage turbocharger are connected by two bypass exhaust pipes having different large and small diameters, and are arranged in the respective bypass exhaust pipes. By controlling the opening / closing of the main / sub bypass valve (corresponding to the above-mentioned waste gate valve), the flow rate of the exhaust gas flowing to the turbine of the high-pressure turbocharger is controlled with high accuracy, and according to the operating state of the internal combustion engine. A technique for switching between a high-pressure stage supercharger and a low-pressure stage supercharger is disclosed. However, this technique does not consider the problem related to the choke state described above, and does not consider operating the two waste gate valves in conjunction with each other as a countermeasure.

JP 2007-138845 A

  An object of the present invention is to provide an internal combustion engine with a two-stage supercharger that can smoothly switch from a high-pressure supercharger to a low-pressure supercharger.

  Another object of the present invention is to provide an internal combustion engine with a two-stage supercharger that can improve fuel efficiency.

  In order to achieve the above object, an internal combustion engine with a two-stage supercharger according to the present invention has a configuration in which a high-pressure supercharger and a low-pressure supercharger are connected in series in two stages in order from the internal combustion engine body side. An internal combustion engine with a stage-type supercharger, comprising: a bypass exhaust pipe that connects an inlet and an outlet of a high-pressure turbine of the high-pressure stage turbocharger; and a waste gate valve device that opens and closes the bypass exhaust pipe, The bypass exhaust pipe has a first bypass exhaust pipe and a second bypass exhaust pipe connected in parallel, and the waste gate valve device includes a first valve disposed in the first bypass exhaust pipe, A second valve disposed in the second bypass exhaust pipe, an actuator for opening and closing the first and second valves, and a driving force transmission body of the actuator for both the first valve and the second valve. And a link mechanism for connecting, when the valve opening degree of the first valve is equal to or higher than a preset valve opening, the second valve performs control to open in conjunction with the link mechanism.

  In the internal combustion engine with a two-stage supercharger, the link mechanism has a mechanism for converting the movement in the first direction of the driving force transmission body of the actuator into the movement in the second direction intersecting therewith. Is.

  Thereby, the freedom degree of arrangement | positioning of a waste gate valve apparatus can be improved, and since a waste gate valve apparatus can be accommodated compactly as a whole, a waste gate valve apparatus is arrange | positioned also in the limited space. Therefore, the versatility of the waste gate valve device can be enhanced.

  In the internal combustion engine with a two-stage supercharger, the link mechanism includes an urging unit having an elastic member that urges the first and second valves in a closing direction, and the first valve. A first connecting body for connecting to the first member of the biasing means, a second connecting body for connecting the first member to a driving force transmitting body of the actuator, and a second valve for the second valve of the biasing means. A third connecting body connected to a member, and the biasing means includes a main shaft on which the elastic member is disposed, the first member disposed in a state of being movable along the main shaft, and the main shaft. The second member disposed between the first member and the elastic member in a movable state along the first member, and the driving force of the actuator is transmitted to the first member through the second connection body, The first member moves in a direction against the urging force of the elastic member Then, the first connecting body connected to the first member is interlocked to open the first valve, and when the valve opening of the first valve is equal to or greater than a preset valve opening, the first valve The second member moves in a direction against the urging force of the elastic member due to the movement of the member, and the third connector connected to the second member performs interlocking control to open the second valve. It is.

  In the internal combustion engine with a two-stage supercharger, the actuator is driven according to the pressure on the outlet side of the high-pressure compressor of the high-pressure supercharger.

  Thereby, since the valve opening states of the first and second valves can be controlled according to the pressure on the outlet side of the compressor of the high-pressure supercharger, the controllability during transient operation can be improved.

  According to the internal combustion engine with a two-stage supercharger of the present invention, when the choke state is established at the opening of the first bypass exhaust pipe, the second valve of the second bypass exhaust pipe opens in conjunction with the bypass exhaust pipe. Therefore, the choke state can be avoided. For this reason, since it is possible to secure a flow path for the exhaust gas flowing from the high-pressure stage turbocharger side to the low-pressure stage turbocharger through the bypass exhaust pipe, the switching from the high-pressure stage turbocharger to the low-pressure stage turbocharger is smooth. Can be done.

  Further, since it is not necessary to increase the opening force of the first and second valves, the size of the actuator that drives the first and second valves is not increased. Further, since the second valve is linked to the operation of the first valve, it is not necessary to increase the number of actuators that drive the first and second valves. Therefore, an increase in weight is not caused.

  Further, according to the internal combustion engine with a two-stage supercharger of the present invention, it is possible to smoothly switch from the high-pressure supercharger to the low-pressure supercharger, so that a necessary amount of air can be secured. it can. As a result, the EGR rate can be increased.

  In addition, since the switching from the high pressure supercharger to the low pressure supercharger can be performed smoothly, an increase in the pressure of the exhaust gas can be suppressed or prevented. As a result, fuel consumption can be improved.

1 is a configuration diagram of an internal combustion engine with a two-stage supercharger according to an embodiment of the present invention. It is a block diagram of the waste gate valve apparatus of the two-stage supercharging system in the internal combustion engine with a two-stage supercharger of FIG. It is the block diagram which showed the state at the time of opening and closing of the waste gate valve apparatus of FIG. It is sectional drawing which showed typically the relationship between the valve | bulb of the wastegate valve apparatus of FIG. 2, and an exhaust pipe. It is a block diagram at the time of valve closing of the waste gate valve apparatus of FIG. It is a block diagram at the time of the valve opening operation | movement process of the wastegate valve apparatus following FIG. It is a block diagram at the time of the valve opening operation | movement process of the wastegate valve apparatus following FIG. It is sectional drawing which showed typically the relationship between the valve | bulb of the wastegate valve apparatus of FIG. 7, and an exhaust pipe. It is a block diagram at the time of the valve opening operation | movement process of the wastegate valve apparatus following FIG. FIG. 10 is a cross-sectional view schematically showing the relationship between the valve and the exhaust pipe of the waste gate valve device of FIG. 9. FIG. 10 is a configuration diagram at the time of a valve opening operation process of the waste gate valve device following FIG. 9. It is sectional drawing which showed typically the relationship between the valve | bulb of the wastegate valve apparatus of FIG. 11, and an exhaust pipe. FIG. 2 is a graph showing a measurement result of an intake air amount with respect to a fuel injection amount of a low-pressure supercharger in the internal combustion engine with a two-stage supercharger in FIG. FIG. 2 is a graph showing measurement results of compressor work with respect to fuel injection amounts of a low-pressure supercharger and a high-pressure supercharger in the internal combustion engine with a two-stage supercharger in FIG. 1. FIG. 2 is a graph showing a measurement result of a pressure ratio with respect to a fuel injection amount of a low-pressure supercharger and a high-pressure supercharger in the internal combustion engine with a two-stage supercharger in FIG. 1. FIG. 2 is a graph showing the measurement results of the expansion ratio with respect to the fuel injection amount of the low pressure supercharger and the high pressure supercharger in the internal combustion engine with a two-stage supercharger in FIG. 1. It is a block diagram at the time of valve closing of the conventional waste gate valve apparatus. It is a block diagram at the time of valve opening of the conventional waste gate valve apparatus. It is the block diagram which showed the opening-and-closing operation state of the conventional wastegate valve apparatus. FIG. 18 is a graph showing a measurement result of an intake air amount with respect to a fuel injection amount of a low-pressure supercharger in a conventional internal combustion engine with a two-stage supercharger using the waste gate valve device of FIG. 17. FIG. 18 is a graph showing measurement results of compressor work with respect to fuel injection amounts of a low-pressure supercharger and a high-pressure supercharger in a conventional internal combustion engine with a two-stage supercharger using the waste gate valve device of FIG. 17. . FIG. 18 is a graph showing measurement results of pressure ratios with respect to fuel injection amounts of a low-pressure supercharger and a high-pressure supercharger in a conventional internal combustion engine with a two-stage supercharger using the waste gate valve device of FIG. 17. . FIG. 18 is a graph showing the measurement result of the expansion ratio with respect to the fuel injection amount of the low-pressure supercharger and the high-pressure supercharger in the conventional internal combustion engine with a two-stage supercharger using the waste gate valve device of FIG. 17. .

  Hereinafter, an internal combustion engine with a two-stage supercharger according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 shows a configuration diagram of an internal combustion engine with a two-stage supercharger according to the present embodiment. In addition, the arrow in a figure has shown the flow of air.

  The internal combustion engine with a two-stage supercharger according to the present embodiment is expanded in the cylinder by, for example, expansion based on self-ignition that occurs when fuel is supplied to air that has been compressed and heated to high temperature in the cylinder (combustion chamber). This is a diesel engine (hereinafter simply referred to as an engine) 1 having a configuration for pushing out the piston. In addition, this invention is not limited to a diesel engine, It can also apply to a gasoline engine etc.

  The engine 1 includes an engine body 2, an exhaust manifold 3, an intake manifold 4, a two-stage supercharging system 5, an EGR (Exhaust Gas Recirculation) system 6, and an air cleaner 7. Yes.

  The two-stage supercharging system 5 includes a high-pressure stage supercharger 8 and a low-pressure stage supercharger 9 that are arranged in two stages in series, and an appropriate supercharger according to the operating state of the engine 1. A bypass described later is provided so that the operating range of the supercharging system can be expanded. That is, the high-pressure stage turbocharger 8 is used during low-speed rotation / low-load operation, while the low-pressure stage supercharger 9 is used during high-speed rotation / high-load operation, depending on the operating state of the engine 1. The supercharger 8 and the low-pressure stage supercharger 9 are switched and used.

  The high-pressure supercharger 8 includes a high-pressure turbine 8a and a high-pressure compressor (compressor) 8b. The high-pressure turbine 8a and the high-pressure compressor 8b are formed by providing a plurality of blades at both ends of a single shaft, and the high-pressure turbine 8a receives the force of exhaust gas exhausted from the engine body 2. Then, the high pressure compressor 8b is interlocked by the driving force to send the compressed air to the engine body 2.

  The low pressure supercharger 9 includes a low pressure turbine 9a and a low pressure compressor (compressor) 9b. The low-pressure stage turbine 9a and the low-pressure stage compressor 9b are formed by providing a plurality of blades at both ends of one shaft, similarly to the high-pressure stage supercharger 8, and the low-pressure stage turbine 9a is formed of the engine body 2. When it is rotationally driven by receiving the force of the exhaust gas exhausted from the engine, the low pressure compressor 9b is interlocked with the driving force to send the compressed air to the engine body 2. The capacity of the low pressure stage turbine 9a is larger than the capacity of the high pressure stage turbine 8a, and the capacity of the low pressure stage compressor 9b is larger than the capacity of the high pressure stage compressor 8b.

  The exhaust system of the two-stage turbocharging system 5 includes a first exhaust pipe 10a, a second exhaust pipe 10b, a third exhaust pipe 10c, a main bypass exhaust pipe 11, a sub bypass exhaust pipe (bypass exhaust pipe) 12, The exhaust gas switching valve device 13 and the waste gate valve device 14 are provided.

  The first exhaust pipe 10a is a pipe that connects the exhaust manifold 3 and the inlet of the high-pressure turbine 8a, and sends exhaust gas from the engine body 2 to the high-pressure turbine 8a. The second exhaust pipe 10b is a pipe that connects the outlet of the high-pressure turbine 8a and the inlet of the low-pressure turbine 9a, and sends exhaust gas from the high-pressure turbine 8a to the low-pressure turbine 9a. An exhaust gas switching valve device 13 is provided in the middle of the second exhaust pipe 10b. The third exhaust pipe 10c is a pipe through which exhaust gas from the outlet of the low-pressure turbine 9a flows to the outside.

  The main bypass exhaust pipe 11 is a pipe that connects the exhaust manifold 3 and the second exhaust pipe 10b (inlet of the low-pressure stage turbine 9a) without passing through the high-pressure stage turbine 8a. 13 is provided.

  The exhaust gas switching valve device 13 is opened when the exhaust gas discharged from the engine body 2 flows through the main bypass exhaust pipe 11 to the low-pressure turbine 9a, and is closed when the flow path of the main bypass exhaust pipe 11 is shut off. It has become. The valve main body of the exhaust gas switching valve device 13 is opened and closed by an actuator using air pressure (or vacuum pressure).

  The sub bypass exhaust pipe 12 is a pipe connecting the first exhaust pipe 10a and the second exhaust pipe 10b. That is, it is a pipe that connects the upstream (inlet) side and the downstream (outlet) side of the high-pressure turbine 8a without passing through the high-pressure turbine 8a. A waste gate valve device 14 is provided in the middle of the sub bypass exhaust pipe 12. The waste gate valve device 14 opens the valve body of the waste gate valve device 14 when the pressure on the upstream (inlet) side of the high-pressure stage turbine 8 a becomes high, and causes the exhaust gas to be high-pressure through the sub-bypass exhaust pipe 12. It has a function of directly escaping from the upstream (inlet) side to the downstream (outlet) side of the stage turbine to prevent excessive rotation of the high-pressure turbine 8a and the high-pressure compressor 8b.

  The opening and closing of the valve body of the waste gate valve device 14 is controlled by a positive pressure drive system using the outlet pressure of the high-pressure compressor 8b. That is, the input of the actuator that drives the valve body of the wastegate valve device 14 is connected to the outlet of the high-pressure compressor 8b through the pipe 15, and the actuator controls the opening / closing drive of the valve body according to the outlet pressure. . Thereby, excessive rotation of the high pressure turbine 8a and the high pressure compressor 8b can be prevented. A sub bypass exhaust pipe that connects the inlet and the outlet of the low-pressure turbine 9a may be provided, and a waste gate valve device may be provided in the middle thereof.

  Switching between the operation of the high-pressure turbine 8a and the low-pressure turbine 9a is performed by the exhaust gas switching valve device 13, the waste gate valve device 14, and the like. For example, when the exhaust gas switching valve 13 is opened, the high-pressure stage supercharger 8 does not operate because there is no pressure difference between the inlet and outlet of the high-pressure stage turbine 8a, and only the low-pressure stage turbocharger 9 operates. Further, when the exhaust gas switching valve device 13 and the waste gate valve device 14 are fully closed, all the exhaust gas discharged from the exhaust manifold 3 flows to the high pressure turbine 8a, and the high pressure turbocharger 8 operates. At this time, if there is a waste gate valve device on the low pressure stage supercharger 9 side, the exhaust gas bypasses the low pressure stage turbine 9a by fully opening it, so the low pressure stage supercharger 9 does not operate. Further, when the exhaust gas switching valve device 13 is slightly opened and the waste gate valve device on the low pressure stage supercharger 9 side is fully closed, the high pressure stage supercharger 8 and the low pressure stage supercharger 9 operate simultaneously.

  On the other hand, the intake system of the two-stage turbocharging system 5 includes a first intake pipe 20a, a second intake pipe 20b, a third intake pipe 20c, a bypass intake pipe 21, and an intake air switching valve device 22. Yes.

  The first intake pipe 20a is a pipe that connects the air cleaner 7 and the inlet of the low-pressure stage compressor 9b and flows the air purified by the air cleaner 7 to the low-pressure stage compressor 9b. The second intake pipe 20b is a pipe that connects the outlet of the low-pressure compressor 9b and the inlet of the high-pressure compressor 8b and allows air to flow from the low-pressure compressor 9b to the high-pressure compressor 8b. The third intake pipe 20c is a pipe that connects the outlet of the high-pressure compressor 8b and the intake manifold 4 and allows air to flow from the high-pressure compressor 8b to the engine body 2 through the intake manifold 4.

  The bypass intake pipe 21 is a pipe that connects the second intake pipe 20b (the outlet of the low-pressure compressor 9b) and the third intake pipe 20c (the intake manifold 4) without passing through the high-pressure compressor 8b.

  The intake air switching valve device 22 is disposed at the intersection of the second intake pipe 20b and the third intake pipe 20c, and the flow path on the low pressure stage supercharger 9 side when the high pressure stage supercharger 8 operates. When the low-pressure supercharger 9 is closed, the flow path on the high-pressure supercharger 8 side is closed.

  The EGR system 6 described above is a system in which a part of the exhaust gas after combustion is taken out and guided to the intake side to be re-intaked, and the exhaust manifold 3 side is located in the middle of the pipe 6a connecting the exhaust manifold 3 and the intake manifold 4. The EGR cooler 6b and the EGR valve 6c are connected in order.

  2 is a configuration diagram of the waste gate valve device 14 described above, FIG. 3 is a configuration diagram showing a state when the waste gate valve device 14 of FIG. 2 is opened and closed, and FIG. 4 is a configuration diagram of the waste gate valve device 14 of FIG. It is sectional drawing which showed typically the relationship between this valve | bulb and an exhaust pipe. 2 and 4 indicate the flow of exhaust gas, and arrows B1 to B4 in FIG. 3 indicate the operation directions of the respective parts of the waste gate valve device 14 when the valve is opened and closed.

  In the two-stage turbocharging system 5 of the engine 1 of the present embodiment, as shown in FIGS. 2 and 4, the sub-bypass exhaust pipe 12 on the high-pressure supercharger 8 side is connected to the first sub-bypass exhaust pipe ( There are two exhaust pipes, a first bypass exhaust pipe) 12a and a second sub bypass exhaust pipe (second bypass exhaust pipe) 12b. The first and second sub-bypass exhaust pipes 12a and 12b are connected in parallel between the first exhaust pipe 10a and the second exhaust pipe 10b.

  The opening areas of the first and second sub-bypass exhaust pipes 12a and 12b are the same. By making the opening areas the same, it is possible to share parts and reduce costs. However, the opening areas of the first and second sub-bypass exhaust pipes 12a and 12b may be changed. If the opening area of the first sub-bypass exhaust pipe 12a is larger than the opening area of the second sub-bypass exhaust pipe 12b, the exhaust gas flow rate may increase depending on operating conditions and the pressure may increase. In this case, the force applied to the opening increases, and there is a possibility that the waste gate valve cannot be opened and closed smoothly. For this reason, when changing the opening area of the first and second sub-bypass exhaust pipes 12a and 12b, the opening area of the second sub-bypass exhaust pipe 12b should be larger than the opening area of the first sub-bypass exhaust pipe 12a. Is preferred.

  As shown in FIGS. 2 and 3, the waste gate valve device 14 includes a first waste gate valve portion 14 a, a second waste gate valve portion 14 b, an actuator 25, and a link mechanism 26. .

  The first waste gate valve portion 14a includes a first valve 14a1 and a first support portion 14a2 that supports the first valve 14a1, and the second waste gate valve portion 14b includes a second valve 14b1 and a second valve that supports the second valve 14b1. And a support portion 14b2. The first valve 14a1 is disposed at the opening of the first sub bypass exhaust pipe 12a, and the second valve 14b1 is disposed at the opening of the second sub bypass exhaust pipe 12b, and opens and closes each opening. . The configuration (size, shape, material, etc.) of the first and second waste gate valve portions 14a, 14b is exactly the same.

  The actuator 25 is a drive source for opening and closing the first valve 14a1 and the second valve 14b1. 2 and 3 exemplify a case where the actuator 25 is arranged vertically so as to be along the direction in which the first and second waste gate valve portions 14a and 14b are arranged (the vertical direction in FIGS. 2 and 3). ing.

  The actuator 25 is controlled by a positive pressure drive system. That is, the outlet of the high-pressure compressor 15 is connected to the input of the actuator 25 through the pipe 15, and the actuator 25 is driven according to the air pressure at the outlet of the high-pressure compressor 8b. As a result, the open states of the first valve 14a1 and the second valve 14b1 can be controlled according to the air pressure at the outlet of the high-pressure compressor 8b, so that the controllability during transient operation can be improved.

  In addition, a diaphragm is installed inside the actuator 25 so as to be movable in the vertical direction in FIGS. 2 and 3. This diaphragm is biased upward by FIGS. 2 and 3 by a spring. On the other hand, when the air pressure input to the actuator 25 through the pipe 15 from the outlet of the high-pressure compressor 8b exceeds the setting force of the spring of the actuator 25, the diaphragm moves downward in FIGS. 2 and 3, and the rod connected to the diaphragm 25a drives downward in FIGS.

  The rod 25a of the actuator 25 is connected to both the first and second waste gate valve portions 14a and 14b via the link mechanism 26, and the driving force of the actuator 25 causes the link mechanism 26 to move from the rod 25a. Via the first valve 14a1 and the second valve 14b1.

  The link mechanism 26 is disposed between the actuator 25 and the first and second waste gate valve portions 14a and 14b, and moves the rod 25a of the actuator 25 in the first direction (vertical direction in FIGS. 2 and 3). It has a mechanism for converting into motion in a second direction (the left-right direction in FIGS. 2 and 3) intersecting this. When the actuator 25 and the first and second waste gate valve portions 14a and 14b are directly connected without interposing the link mechanism 26 between the actuator 25 and the first and second waste gate valve portions 14a and 14b, the actuator 25 is arranged horizontally long so as to intersect with the arrangement direction of the first and second waste gate valve portions 14a, 14b. However, in this case, there is a case where the waste gate valve device 14 cannot be arranged due to the space of the vehicle. On the other hand, in the waste gate valve device 14, the link mechanism 26 is provided, so that the degree of freedom of arrangement of the waste gate valve device 14 in the vehicle can be improved. Further, since the rod 25a of the actuator 25 and the first to third links 26a to 26c of the link mechanism 26 can be arranged so as to intersect with each other, the waste gate valve device 14 can be accommodated compactly as a whole. Therefore, the waste gate valve device 14 can be arranged in a limited space in the vehicle, and the versatility of the waste gate valve device 14 can be enhanced.

  The link mechanism 26 includes the first link (first connection body) 26a, the second link (second connection body) 26b, and the third link (third connection body) 26c, as well as the spring portion (attachment). Force means) 26d.

  The spring portion 26d is installed between the actuator 25 and the first and second waste gate valve portions 14a and 14b, and at a position corresponding to the center between adjacent first and second waste gate valve portions 14a and 14b. ing. The first and second waste gate valve portions 14a and 14b are arranged so as to be symmetric with respect to the spring portion 26d. Thereby, the opening and closing control of the first and second valves 14a1 and 14b1 can be facilitated.

  The spring portion 26d includes an urging shaft (main shaft) 26d1, a spring (elastic member) 26d2, a first member 26d3, and a second member 26d4.

  The spring 26d2 is made of, for example, a coil spring, and is installed on the biasing shaft 26d1 in a state where the biasing shaft 26d1 is inserted into the inner diameter thereof.

  The first and second members 26d3 and 26d4 are each formed in a hollow shape, and are attached in a state where the urging shaft 26d1 is inserted into the hollow and movable along the urging shaft 26d1. It is installed on the force shaft 26d1.

  One end of each of the first link 26a and the second link 26b is connected to the first member 26d3 in a rotatable state. The other end of the first link 26a is pivotally connected to the opposite end of the second support portion 14b2 in the first support portion 14a2 of the first waste gate valve portion 14a. On the other hand, the other end of the second link 26b is connected to the tip of the rod 25a of the actuator 25 in a rotatable state.

  The second member 26d4 is installed between the first member 26d3 and the spring 26d2. One end of the third link 26c is connected to the second member 26d4 in a rotatable state. The third link 26c is disposed so as to intersect the first and second links 26a and 26b. The other end of the third link 26c is pivotally connected to the opposite end of the first support portion 14a2 in the second support portion 14b2 of the second waste gate valve portion 14b.

  The first and second valves 14a1 and 14b1 of the waste gate valve device 14 are pressed by the urging force of the spring 26d2 and closed as shown in FIG. From this state, as shown in FIG. 3, when the rod 25a of the actuator 25 moves downward in FIG. 3 as shown by the arrow B1, one end of the second link 26b connected thereto is pulled downward. The first member 26d3 connected to the other end of the two links 26b moves in the left direction indicated by the arrow B2. As a result, the first link 26a connected to the first member 26d3 is pulled in the left direction indicated by the arrow B2, so that the end of the first valve 14a1 connected thereto moves in the rotational direction indicated by the arrow B3. The first valve 14a1 is opened. When the valve opening of the first valve 14a1 is equal to or greater than a preset valve opening, the second valve 14b1 is interlocked and opened by the link mechanism 26. That is, since the second member 26d4 is pushed in the direction of the arrow B2 by the first member 26d3 and moves, the third link 26c connected to the second member 26d4 is pulled in the left direction indicated by the arrow B2. As a result, the end of the second valve 14b1 connected to the second valve 14b1 moves in the rotational direction indicated by the arrow B4, so that the second valve 14b1 opens. Here, it is set so that the second sub-bypass exhaust pipe 12b starts to open when the choke state described above occurs in the first sub-bypass exhaust pipe 12a, or immediately before or immediately thereafter. Thereby, since the effective opening area of the sub bypass exhaust pipe 12 can be increased, a choke state can be avoided. For this reason, a flow path of exhaust gas flowing from the high-pressure turbine 8 a of the high-pressure turbocharger 8 to the low-pressure turbine 9 a of the low-pressure turbocharger 9 through the sub-bypass exhaust pipe 12 can be secured. Switching from the feeder 8 to the low-pressure supercharger 9 can be performed smoothly.

  Next, the opening / closing operation of the waste gate valve device 14 will be described with reference to FIGS.

  First, in FIG. 5, the outlet pressure of the high-pressure compressor 8b is lower than the preset valve opening pressure of the waste gate valve device 14, and the first and second sub valves 14a1 and 14a2 are closed. The state where the bypass exhaust pipes 12a and 12b are completely blocked is shown. The sub-bypass path is closed using the pressure of the exhaust gas, and has a structure with no leakage.

  Subsequently, as shown in FIG. 6, the outlet pressure of the high-pressure compressor 8b starts to become higher than the preset valve opening pressure of the waste gate valve device 14, and the rod 25a moves downward as indicated by an arrow B1 in FIG. Begin to. As a result, one end of the second link 26b connected to the rod 25a is also pulled downward, so that the first member 26d3 connected to the other end of the second link 26b moves along the biasing shaft 26d1 to the arrow B2 in FIG. Start moving to the left shown. For this reason, one end of the first link 26a connected to the first member 26d3 is pulled in the left direction in FIG. 6, so that the first valve 14a1 starts to move as indicated by the arrow B3, and the first valve 14a1 starts to open gradually. . At this time, the second valve 14b1 is stationary and closed.

  Subsequently, as shown in FIGS. 7 and 8, the outlet pressure of the high-pressure compressor 8b is further increased, and the rod 25a further moves downward as indicated by the arrow B1 in FIG. Further, the first member 26d3 is further pulled in the left direction indicated by the arrow B2 in FIG. 6, and the opening degree of the first valve 14a1 is increased. Also at this time, the second valve 14b1 is stationary and closed.

  Subsequently, as shown in FIGS. 9 and 10, when the rotational speed and load of the engine 1 are increased and the high-pressure compressor 8b performs work, the outlet pressure of the high-pressure compressor 8b is further increased, and the first valve 14a1 is opened. The degree becomes larger than a certain value. Then, a choke state starts to occur in the first sub-bypass exhaust pipe 12a. Then, the movement of the first valve 14a1 is transmitted to the first member 26d3 via the first link 26a, and the first member 26d3 moves to the left as shown by the arrow B2 in FIG. 9 to move the second member 26d4 to the arrow B2. Press to the left as shown. As a result, the third link 26c connected to the second member 26d4 is pulled to the left, so that the second valve 14b1 held by the spring 26d1 begins to move gradually as shown by the arrow B4 in FIG. Start to open as shown.

  Subsequently, as shown in FIGS. 11 and 12, when the engine rotation and load are further increased from the choke state, and the outlet pressure of the high-pressure compressor 8b is further increased, the opening degree of the first valve 14a1 is further increased, The first member 26d3 and the second member 26d4 operate integrally. That is, when the first and second members 26d3 and 26d4 are integrally moved in the left direction indicated by the arrow B2 in FIG. 11, the first and second valves 14a1 and 14b1 are moved to the arrows B3 and B4 in FIG. It operates simultaneously in the direction of rotation shown and opens as shown in FIG.

  As described above, in the engine 1 of the present embodiment, even when the choke state is established at the opening of the first sub-bypass exhaust pipe 12a, the second sub-bypass exhaust pipe 12b is opened, so that the exhaust gas is supplied to the low-pressure stage turbine 9a. Flows smoothly.

  Next, a conventional waste gate valve device on the high pressure stage supercharger side will be described with reference to FIGS. 17 to 19 for comparison.

  FIGS. 17 to 19 are configuration diagrams of a conventional positive pressure drive type wastegate valve device 70. 17 shows a state when the valve is closed, FIG. 18 shows a state when the valve is opened, and FIG. 19 shows a state when the valve is opened and closed. Arrow A7 indicates the flow of exhaust gas, and arrow B7 indicates the operating direction of the valve.

  Conventionally, since there is one sub-bypass exhaust pipe on the high-pressure supercharger side, there is also one valve 70a of the waste gate valve device 70. The valve 70a is a part that opens and closes the sub-bypass exhaust pipe, and is supported by the valve support 70b. The valve support portion 70b is directly connected to the rod 70c and is connected to the actuator 70d through this. The outlet of the high-pressure compressor 71 is connected to the input side of the actuator 70d through a pipe 70e. The actuator 70d opens and closes the valve 70a by reciprocatingly driving the rod 70c according to the outlet pressure of the high-pressure compressor 71.

  Next, changes in pressure, work, etc. due to the opening / closing operation of the conventional waste gate valve device 70 shown in FIG. 17 are shown in FIGS. Arrow D indicates the start of valve opening of the waste gate valve device 70, and arrow E indicates the occurrence of a choke state in the sub-bypass exhaust pipe on the high-pressure turbine side. Symbol L0 indicates the measurement result on the low-pressure stage supercharger side, and symbol H0 indicates the measurement result on the high-pressure stage supercharger side.

  In the conventional method, a choke state occurs in the sub-bypass exhaust pipe on the high-pressure turbine side, and work is not switched from the high-pressure compressor to the low-pressure compressor. In addition, the use of the high-pressure stage supercharger under a high load or high rotation condition indicates that the high-pressure stage supercharger is used under inefficient conditions. For this reason, it becomes impossible to introduce air required for the engine body 2, and exhaust performance of NOx or the like in the exhaust gas is deteriorated. In addition, since the inlet pressure of the high-pressure turbine increases, the internal pressure of the exhaust manifold increases, which adversely affects fuel consumption.

  In contrast, FIGS. 13 to 16 show changes in pressure, work, and the like due to the opening / closing operation of the waste gate valve device 14 in the engine 1 of the present embodiment. An arrow F indicates the occurrence of a choke state in the first sub-bypass exhaust pipe 12a on the high-pressure turbine side and the start of opening of the second waste gate valve portion 14b. Reference sign L1 indicates the measurement result on the low pressure stage supercharger 9 side of the engine 1 of the present embodiment, and reference sign H1 indicates the measurement result on the high pressure stage turbocharger 8 side of the engine 1 of the present embodiment. Yes.

  Since the waste gate valve device 14 can avoid the choke state, as shown by reference numerals L1 and H1, the work can be smoothly switched from the high-pressure compressor 8b to the low-pressure compressor 9b. Moreover, use of the high-pressure stage supercharger 8 under high load or high rotation conditions can be avoided, and the low-pressure stage supercharger 9 can be supercharged under efficient conditions.

  As described above, according to the engine 1 of the present embodiment, when the choke state is established at the opening of the first bypass exhaust pipe 12a, the second bypass exhaust pipe 12b is opened in conjunction with the second valve 14b1, thereby opening the sub bypass. Since the effective opening area of the exhaust pipe 12 can be increased, a choked state can be avoided. For this reason, a sufficient flow path for the exhaust gas flowing from the high-pressure supercharger 8 side to the low-pressure supercharger 8 through the sub-bypass exhaust pipe 12 can be secured. Switching to the feeder 9 can be performed smoothly. Further, by opening the valve of the exhaust gas switching valve device 13, switching to the low-pressure supercharger 9 can be performed smoothly.

  Further, since the opening area of one sub-bypass exhaust pipe is not increased, it is not necessary to increase the valve opening force of the waste gate valve device 14. For this reason, it is not necessary to increase the size of the actuator 25 that drives the waste gate valve device 14. Further, since the second valve portion 14b1 is interlocked with the operation of the first valve 14a1, it is not necessary to increase the number of actuators 25 just because the number of sub-bypass exhaust pipes is increased and the number of valves is increased. Accordingly, the weight of the vehicle is not increased. Further, it is not difficult to control the actuator 25.

  Therefore, according to such an engine 1, since switching from the high pressure stage supercharger 8 to the low pressure stage supercharger 9 can be performed smoothly, air can be efficiently introduced into the engine body 2. More air can be introduced into the engine body 2 (that is, a necessary amount of air can be secured). Here, when the same amount of fuel is injected, the ratio between the fuel and air changes, and more air than necessary is introduced into the engine body 2, so EGR gas is introduced instead of the increased amount of air. As a result, the EGR rate can be increased. As a result, the amount of EGR gas can be increased (the EGR rate can be increased) without reducing the amount of oxygen in the fresh air in the engine body 2, and as a result, NOx can be reduced.

  In addition, since the switching from the high-pressure stage supercharger 8 to the low-pressure stage supercharger 9 can be performed smoothly, an increase in exhaust gas pressure can be suppressed or prevented. As a result, the fuel consumption of the vehicle can be improved.

  In the internal combustion engine with a two-stage supercharger according to the present invention, when the valve opening degree of the first valve of the waste gate valve device is greater than or equal to a preset valve opening degree, the second valve of the waste gate valve device is interlocked. By opening, it is possible to smoothly switch from the high-pressure stage supercharger to the low-pressure stage supercharger, and therefore, it can be used for an internal combustion engine with a two-stage supercharger for use in automobiles.

1 Diesel engine (internal combustion engine with two-stage turbocharger)
2 Engine body 5 Two-stage supercharging system 8 High-pressure turbocharger 8a High-pressure turbine 8b High-pressure compressor (high-pressure compressor)
9 Low pressure stage turbocharger 9a Low pressure stage turbine 9b Low pressure stage compressor (low pressure stage compressor)
10a 1st exhaust pipe 10b 2nd exhaust pipe 10c 3rd exhaust pipe 12 Sub bypass exhaust pipe (bypass exhaust pipe)
12a First sub bypass exhaust pipe (first bypass exhaust pipe)
12b Second sub bypass exhaust pipe (second bypass exhaust pipe)
13 Exhaust gas switching valve device 14 Waste gate valve device 14a First waste gate valve portion 14a1 First valve 14b Second waste gate valve portion 14b1 Second valve 15 Pipe 20a First intake pipe 20b Second intake pipe 20c Third intake pipe 25 Actuator 25a Rod (driving force transmission body)
26 Link mechanism 26a First link (first connecting body)
26b Second link (second connecting body)
26c 3rd link (3rd connection body)
26d Spring part (biasing means)
26d1 Energizing shaft (main shaft)
26d2 spring (elastic member)
26d3 first member 26d4 second member

Claims (4)

In the internal combustion engine with a two-stage supercharger having a configuration in which a high-pressure stage supercharger and a low-pressure stage supercharger are connected in series from the internal combustion engine main body side,
A bypass exhaust pipe connecting an inlet and an outlet of a high-pressure turbine of the high-pressure turbocharger;
A wastegate valve device for opening and closing the bypass exhaust pipe,
The bypass exhaust pipe has a first bypass exhaust pipe and a second bypass exhaust pipe connected in parallel;
The waste gate valve device is:
A first valve disposed in the first bypass exhaust pipe;
A second valve disposed in the second bypass exhaust pipe;
An actuator for opening and closing the first and second valves;
A link mechanism for connecting a driving force transmission body of the actuator to both the first valve and the second valve;
An internal combustion engine with a two-stage supercharger that performs control to open the second valve in conjunction with the link mechanism when the valve opening of the first valve is greater than or equal to a preset valve opening.   2. The internal combustion engine with a two-stage supercharger according to claim 1, wherein the link mechanism has a mechanism for converting a movement in a first direction of a driving force transmission body of the actuator into a movement in a second direction intersecting therewith. The link mechanism is
An urging means having an elastic member for urging the first and second valves in a closing direction;
A first connector for connecting the first valve to the first member of the biasing means;
A second connection body for connecting the first member to the driving force transmission body of the actuator;
A third connecting body for connecting the second valve to the second member of the biasing means,
The biasing means is
A main shaft on which the elastic member is disposed;
The first member arranged to be movable along the main axis;
The second member disposed between the first member and the elastic member in a movable state along the main axis;
When the driving force of the actuator is transmitted to the first member through the second connection body and the first member moves in a direction against the urging force of the elastic member, the first member connected to the first member. When the first valve is opened in conjunction with the connecting body and the valve opening of the first valve is greater than or equal to a preset valve opening, the second member is attached to the elastic member by the movement of the first member. The internal combustion engine with a two-stage supercharger according to claim 1 or 2, wherein the second valve is controlled to move in a direction against the force and the second connector connected to the second member is interlocked to open the second valve. organ.   The internal combustion engine with a two-stage supercharger according to any one of claims 1 to 3, wherein the actuator is driven according to a pressure on an outlet side of a high-pressure compressor of the high-pressure supercharger.

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