JP2018184902A - Multistage turbo supercharger system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multistage turbo supercharger system capable of avoiding generation of a high pressure stage side surge in the case of sudden speed reduction and/or sudden load decrease (cutoff) of an engine.SOLUTION: The present invention relates to a multistage turbo supercharger system in which a small-sized side high pressure stage turbo supercharger 50 and a large-sized side low pressure stage turbo supercharger 60 are connected in series from the side of an engine body 10. The multistage turbo supercharger system comprises: a low pressure stage exhaust bypass path 33 bypassing a low pressure stage turbine 61 of the low pressure stage turbo supercharger 60; a low pressure stage waste gate valve WG2 opening/closing the low pressure stage exhaust bypass path 33; and high pressure stage side surge avoiding means 90 by which, in a case where an actuation condition that a suction pressure P1 at an upstream side of a high pressure stage compressor 52 of the high pressure stage turbo supercharger 50 is higher than a suction pressure P2 at a downstream side of the high pressure stage compressor 52 is satisfied, the low pressure stage waste gate valve WG2 is opened.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a multi-stage turbocharger system in which a small-sized high-pressure turbocharger and a large-sized low-pressure turbocharger are connected in series from the engine body side.

  In this type of multi-stage turbocharger system, for example, as shown in Patent Document 1, air is compressed by a low-pressure stage compressor of a low-pressure stage turbocharger, and a high-pressure stage compressor of a high-pressure stage turbocharger. In addition, the air is compressed and supercharged to the engine body. In normal engine operation, the intake pressure relationship is such that the intake pressure upstream of the high-pressure compressor is lower than the intake pressure downstream of the high-pressure compressor. It has become.

JP 2009-270470 A

By the way, the large-sized low-pressure turbocharger has a larger inertia than the small-sized high-pressure turbocharger.
Therefore, in such a multi-stage turbocharging system, the engine suddenly decelerates from a normal operation state in which the intake pressure upstream of the high-pressure compressor is smaller than the intake pressure downstream of the high-pressure compressor, and / or When sudden load decreases (shuts off), the large-pressure low-pressure turbocharger with large inertia rotates inertially more slowly than the low-pressure turbocharger with small inertia, and the upstream side of the high-pressure compressor In some cases, the intake pressure rises and the relationship between the upstream intake pressure and the downstream intake pressure is reversed.
In this way, when the relationship between the upstream intake pressure and the downstream intake pressure of the high-pressure compressor is reversed and the upstream intake pressure becomes larger than the downstream intake pressure, a high-pressure compressor is required. There is a risk that a surge (hereinafter referred to as a high-voltage stage side surge) may occur due to the rotation as described above.

  In Patent Document 1, when the occurrence of a high-pressure stage side surge is predicted due to a decrease in the intake air amount or the like, the air compression ratio of the high-pressure stage compressor (the outlet / inlet pressure ratio of the high-pressure stage compressor) is reduced. Although described, this technique is a technique for avoiding a high-pressure stage side surge that occurs when the air compression ratio of the high-pressure stage compressor is too high, and the engine is suddenly decelerated and / or the load is reduced ( When the intake pressure (inlet pressure) on the upstream side of the high-pressure stage compressor becomes larger than the intake pressure (outlet pressure) on the downstream side due to the difference in inertia described above, A high-pressure stage surge that occurs when the compressor is rotated in an idling state without a compression load is not expected.

  In view of this situation, the main problem of the present invention is that when the engine is suddenly decelerated and / or sudden load is reduced (cut off), the large-sized low-pressure turbocharger is replaced with the small-sized high-pressure turbocharger. The purpose of the present invention is to provide a multistage turbocharging system capable of avoiding the occurrence of a high-pressure stage side surge due to the fact that the inertia is larger than that of the machine.

A first characteristic configuration of the present invention is a multi-stage turbocharging system in which a small-sized high-pressure turbocharger and a large-sized low-pressure turbocharger are connected in series from the engine body side,
A low-pressure stage exhaust bypass that bypasses the low-pressure stage turbine of the low-pressure stage turbocharger;
A low pressure stage waste gate valve that opens and closes the low pressure stage exhaust bypass path;
The low pressure stage waste gate valve is opened when an operating condition is established in which the intake pressure upstream of the high pressure stage compressor of the high pressure turbocharger is greater than the intake pressure downstream of the high pressure stage compressor. And a high-voltage stage side surge avoiding means.

  According to this configuration, when the engine suddenly decelerates and / or sudden load decreases (cuts off), the large-sized low-pressure turbocharger has a larger inertia than the small-sized high-pressure turbocharger. As a result, the relationship between the intake pressure on the upstream side of the high-pressure stage compressor and the intake pressure on the downstream side reverses, and the intake pressure on the upstream side of the high-pressure stage compressor becomes larger than the intake pressure on the downstream side. When the intake pressure relationship is likely to cause a side surge, the operating condition of the high pressure stage surge avoidance means is established, and the high pressure stage surge avoidance means opens the low pressure stage waste gate valve. By opening the low-pressure stage waste gate valve, the amount of exhaust gas flowing into the low-pressure stage turbine can be reduced by bypassing the exhaust gas through the exhaust bypass passage, and the inertia is larger than that of the high-pressure stage turbocharger. The inertial rotation of the low pressure stage on the shape side can be decelerated.

Therefore, when the engine suddenly decelerates and / or sudden load decreases (cuts off), the relationship between the intake pressure on the upstream side of the high-pressure compressor and the intake pressure on the downstream side reverses, causing the occurrence of a high-pressure-side surge. Even if there is a risk of an intake pressure relationship (a relationship where the intake pressure on the upstream side of the high-pressure compressor is greater than the intake pressure on the downstream side) It is possible to quickly return to the atmospheric pressure relationship (a relationship in which the upstream intake pressure is equal to or lower than the downstream intake pressure).
Therefore, when the engine suddenly decelerates and / or sudden load decreases (cuts off), the large-sized low-pressure turbocharger has a larger inertia than the small-sized high-pressure turbocharger. Thus, it is possible to avoid occurrence of a high-voltage stage side surge.

The second characteristic configuration of the present invention is provided with a pressure type valve operating mechanism that applies a valve opening operating force according to the upstream intake pressure to the low pressure stage waste gate valve using the upstream intake pressure as a driving force. ,
The high-pressure stage side surge avoiding means includes an electric valve operating mechanism that applies a valve-opening operation force to the low-pressure stage waste gate valve using electric power as a driving force, and the pressure-type valve operation is performed when the operating condition is satisfied. The valve opening operating force of the electric valve operating mechanism is added to the valve opening operating force of the mechanism to open the low pressure stage waste gate valve.

  According to this configuration, the high-pressure stage side surge avoiding means can open the low-pressure stage waste gate valve using the valve-opening operating force of the pressure-type valve operating mechanism when the operating condition is satisfied. Therefore, the drive power for applying the valve opening operating force to the low pressure stage waste gate valve by the electric valve operating mechanism can be kept low, and the power supply for supplying power to the electric valve operating mechanism can be downsized. be able to.

The third characteristic configuration of the present invention is provided with a swing lever that transmits an operating force to the low-pressure stage wastegate valve to open and close the low-pressure stage wastegate valve,
The pressure type valve operating mechanism includes a pressure type actuator capable of swinging the swing lever in a valve opening direction via a pressure side link,
The electric valve operating mechanism includes an electric actuator capable of swinging the swing lever in a valve opening direction via an electric side link.

According to this configuration, the valve-operating force of the pressure-type valve operating mechanism is applied to the low-pressure stage wastegate valve by swinging the swing lever in the valve opening direction via the pressure-type side link with the pressure-type actuator. It can work properly. In addition, by operating the same swing lever in the valve opening direction via the motorized side link with the electric actuator, the valve opening operating force of the electric valve operating mechanism is appropriately applied to the low-pressure stage wastegate valve. Can act.
Therefore, when the operating condition is satisfied, the low pressure stage waste gate valve is efficiently opened by the cooperation of the valve opening operating force of the pressure type valve operating mechanism on the low pressure stage side and the valve opening operating force of the electric valve operating mechanism. Can be said.

Engine block diagram showing normal operation Block diagram of the engine showing a sudden deceleration and / or a sudden load decrease (cut off) from the normal operation state State transition diagram showing the transition of the engine state when sudden deceleration and / or sudden load decrease (cut off) from normal operation state The figure which shows the pressure type valve operating mechanism and electric valve operating mechanism of the low pressure stage side Diagram showing the operating characteristics of the low-pressure stage wastegate valve

An embodiment of a multistage turbocharging system according to the present invention will be described with reference to the drawings.
FIG. 1 and FIG. 2 are block diagrams of an engine having a multistage turbocharging system according to the present invention, and the block-shaped arrows in the drawings indicate the flow of intake and exhaust. Further, FIG. 1 shows a normal operation state, and FIG. 2 shows a state where sudden deceleration and / or sudden load decrease (cut off) are performed from the normal operation state.

(Entire engine configuration)
As shown in FIG. 1, the engine 1 can be configured as a diesel engine, for example, and has an engine body 10 having a combustion chamber (not shown), an intake passage 20 for introducing fresh air into the combustion chamber, and exhaust from the combustion chamber. An exhaust passage 30 for discharging gas, an ECU (engine control unit) 40 for controlling the operating state of the engine 1, and the like are provided.
Further, the engine 1 is configured by connecting a small-sized high-pressure turbocharger 50 and a large-sized low-pressure turbocharger 60 in series from the engine body 10 side. The air can be compressed by the large-sized low-pressure turbocharger 60 and further compressed by the small-sized high-pressure turbocharger 50 to be supercharged to the engine body 10.

The low-pressure stage turbocharger 60 includes a low-pressure stage turbine 61, a low-pressure stage compressor 62, and a shaft 63 that connects these in a freely rotating manner.
The low-pressure turbine 61 is arranged on the downstream side of the exhaust passage 30 and is configured to rotate using the energy of the exhaust gas. The low-pressure stage compressor 62 is arranged on the upstream side inside the intake passage 20 and is configured to rotate with the rotation of the low-pressure stage turbine 61 and to suck in air from the outside and compress it.

The high-pressure turbocharger 50 includes a high-pressure turbine 51, a high-pressure compressor 52, and a shaft 53 that connects these in a freely rotating manner.
The high-pressure stage turbine 51 is disposed on the upstream side of the low-pressure stage turbine 61 in the exhaust passage 30 and is configured to rotate using the energy of the exhaust gas on the upstream side of the low-pressure stage turbine 61. The high-pressure stage compressor 52 is disposed on the downstream side of the low-pressure stage compressor 62 in the intake passage 20, and is configured to rotate with the rotation of the high-pressure stage turbine 51 and further compress the air compressed by the low-pressure stage compressor 62. ing.

The intake passage 20 is configured as an air passage that sequentially passes through the low pressure stage compressor 62, the high pressure stage compressor 52, and the air supply manifold 20A from the outside.
The exhaust passage 30 includes a main exhaust passage 31 that sequentially passes through the exhaust manifold 30A, the high-pressure turbine 51, and the low-pressure turbine 61 from the engine body 10 side, a high-pressure exhaust passage 32 that bypasses the high-pressure compressor 52, and a low pressure. A low-pressure stage exhaust bypass passage 33 that bypasses the stage compressor 62 is provided.

The high-pressure stage exhaust bypass path 32 communicates a part between the exhaust manifold 30 </ b> A and the high-pressure stage turbine 51 in the main exhaust path 31 and a part between the high-pressure stage turbine 51 and the low-pressure stage turbine 61 in the main exhaust path 31.
The low-pressure stage exhaust bypass path 33 communicates a part between the high-pressure stage turbine 51 and the low-pressure stage turbine 61 in the main exhaust path 31 and a part on the downstream side of the low-pressure stage turbine 61 in the main exhaust path 31.

  The high-pressure stage exhaust bypass path 32 is provided with a high-pressure stage waste gate valve WG1 that opens and closes the high-pressure stage exhaust bypass path 32. In addition, a high-pressure stage side pressure type valve operating mechanism 70 is provided that applies a valve opening operating force to the high-pressure stage waste gate valve WG1.

  The high pressure stage pressure type valve operating mechanism 70 is configured as a mechanical type that does not use electric power, and the high pressure stage is driven by the intake pressure P2 (the discharge pressure of the high pressure stage compressor 52) downstream of the high pressure stage compressor 52 as a driving force. The waste gate valve WG1 is configured to apply a valve opening operation force corresponding to the intake pressure P2 on the downstream side of the high-pressure compressor 52. The pressure type valve operating mechanism 70 on the high pressure stage side automatically opens the high pressure stage waste gate valve WG1 when the intake pressure P2 on the downstream side of the high pressure stage compressor 52 exceeds the set intake pressure.

  For example, the pressure type valve operating mechanism 70 on the high pressure stage side automatically activates the high pressure stage waste gate valve WG1 when the intake pressure P2 on the downstream side of the high pressure stage compressor 52 exceeds the set intake pressure in the normal operation state of the engine 1. Thus, the rotation of the high-pressure turbine 51 is suppressed in such a manner that a part of the exhaust gas is allowed to flow through the high-pressure stage exhaust bypass passage 32, and the intake pressure P2 on the downstream side of the high-pressure stage compressor 52 is returned to the set range.

  Although not shown in the figure, the high pressure stage pressure type valve operating mechanism 70 opens, for example, a swing lever that opens and closes the high pressure stage waste gate valve WG1 by transmitting an operating force to the high pressure stage waste gate valve WG1. A pressure actuator such as a diaphragm actuator capable of swinging in the direction can be provided.

  The low-pressure stage exhaust bypass path 33 is provided with a low-pressure stage waste gate valve WG2 that opens and closes the low-pressure stage exhaust bypass path 33. In addition, a low pressure stage side pressure type valve operating mechanism 80 is provided which applies a valve opening operating force to the low pressure stage waste gate valve WG2.

  The pressure-type valve operating mechanism 80 on the low-pressure stage side is configured as a mechanical type that does not use electric power, and the intake pressure P1 (on the low-pressure stage compressor 62) on the downstream side of the low-pressure stage compressor 62 (upstream side of the high-pressure stage compressor 52). The valve opening operation force according to the intake pressure P1 downstream of the low-pressure stage compressor 62 is applied to the low-pressure stage waste gate valve WG2 using the discharge pressure as a driving force. The pressure type valve operating mechanism 80 on the low pressure stage side automatically opens the low pressure stage waste gate valve WG2 when the intake pressure P1 on the downstream side of the low pressure stage compressor 62 exceeds the set intake pressure.

  For example, the pressure type valve operating mechanism 80 on the low pressure stage side automatically activates the low pressure stage waste gate valve WG2 when the intake pressure P1 on the downstream side of the low pressure stage compressor 62 exceeds the set intake pressure in the normal operation state of the engine 1. Thus, the rotation of the low-pressure turbine 61 is suppressed in a form in which a part of the exhaust gas is allowed to flow through the low-pressure stage exhaust bypass passage 33, and the downstream side intake pressure of the low-pressure stage compressor 62 is returned to the set range. The specific configuration of the pressure type valve operating mechanism 80 on the low pressure stage side will be described later.

  In the engine 1 configured as described above, sudden deceleration and / or sudden load decrease from a normal operation state in which the intake pressure P1 upstream of the high-pressure compressor 52 is equal to or lower than the intake pressure P2 downstream of the high-pressure compressor 52. (Shut off), the large-pressure low-pressure turbocharger 60 having a large inertia rotates more inertially than the high-pressure turbocharger 50 having a small inertia, and the intake pressure P1 upstream of the high-pressure compressor 52 is increased. In some cases, the relationship between the intake pressure P1 on the upstream side and the intake pressure P2 on the downstream side of the high-pressure compressor 52 is reversed. When the relationship between the upstream intake pressure P1 and the downstream intake pressure P2 of the high-pressure compressor 52 is reversed in this way, and the upstream intake pressure P1 becomes larger than the downstream intake pressure P2, the high pressure There is a possibility that the stage compressor 52 is rotated more than necessary and a high-pressure stage surge occurs.

  In view of this, in the engine 1, the suction on the downstream side of the high-pressure stage compressor 52, which is a condition that may cause a high-pressure stage side surge when suddenly decelerating and / or suddenly reducing (cutting off) the load from the normal operation state. When an operating condition is established in which the pressure P2 is greater than the upstream intake pressure P1, the low pressure stage waste gate valve WG2 is opened to generate a high pressure stage surge as shown in FIG. A high-pressure-stage surge avoiding means 90 for avoiding is provided. Hereinafter, the high-pressure stage side surge avoiding means 90 will be described.

(Operation timing of high-pressure stage surge avoidance means)
FIG. 3 is a diagram showing the transition of the state when the engine 1 suddenly decelerates and / or sudden load decreases (cuts off) from the normal operating state, and the upper part of the figure shows the engine speed, The middle stage in the figure shows the relationship (P2-P1) between the intake pressure P2 on the downstream side of the high pressure compressor 52 and the intake pressure P1 on the upstream side, and the lower stage in the figure shows the open / closed state of the low pressure stage waste gate valve WG2. Show.

  As shown in FIG. 3, the high-pressure stage surge avoiding means 90 is configured such that the upstream side intake pressure P1 of the high-pressure stage compressor 52 is equal to or lower than the downstream side intake pressure P2 (the position on the positive (+) side in FIG. 3). The engine 1 suddenly decelerates and / or sudden load decreases (cuts off) from the normal operating state, and the intake pressure P1 on the upstream side of the high-pressure compressor 52 is greater than the intake pressure P2 on the downstream side (negative in FIG. 3). When a reverse operation of the intake air pressure relation (position on the (−) side) occurs and the operating condition is satisfied, the low pressure stage waste gate valve WG2 is automatically opened.

  By opening the low-pressure stage waste gate valve WG2, the amount of exhaust gas flowing into the low-pressure stage turbine 61 is reduced in such a manner that a part of the exhaust gas is bypassed in the low-pressure stage exhaust bypass passage 33, and a high-pressure stage side surge is generated. To the original appropriate intake pressure relationship (a relationship in which the upstream intake pressure P1 is equal to or lower than the downstream intake pressure P2). The high pressure stage side surge avoiding means 90 automatically closes the low pressure stage waste gate valve WG2 when returning to the original intake pressure relationship where there is no possibility of occurrence of the high pressure stage side surge.

(Configuration of high pressure stage surge avoidance means)
As shown in FIG. 2, the high-pressure stage side surge avoiding means 90 is an electric valve operating mechanism 91 that applies a valve opening operating force to the low-pressure stage waste gate valve WG2 using electric power as a driving force, and the operation of the electric valve operating mechanism. It is comprised from ECU40 etc. which control this. The high pressure stage side surge avoiding means 90 outputs an operation command from the ECU 40 to the electric valve operating mechanism 91 to operate the electric valve operating mechanism 91 when the operating condition is satisfied, thereby operating the low pressure stage waste gate valve WG2. Open the valve.

  In the intake passage 20, a first intake pressure sensor S 1 that detects an intake pressure P 1 upstream of the high pressure compressor 52 and a second intake pressure sensor S 2 that detects an intake pressure P 2 downstream of the high pressure compressor 52 are provided. It has been. The intake pressures P1, P2 detected by the first intake pressure sensor S1 and the second intake pressure sensor S2 are input to the ECU 40.

  The first intake pressure sensor S <b> 1 is provided in the portion of the intake passage 20 between the low pressure compressor 62 and the high pressure compressor 52, specifically, in the vicinity of the low pressure compressor 62 on the downstream side of the low pressure compressor 62. Then, the pressure of the part is detected as the intake pressure P1 on the upstream side of the high-pressure compressor 52.

  The second intake pressure sensor S2 is provided on the downstream side of the high-pressure compressor 52 in the intake passage 20, specifically, in the supply manifold 20A, and the pressure of the supply manifold 20A is adjusted downstream of the high-pressure compressor 52. Detected as intake pressure P2.

Then, the ECU 40 compares the upstream intake pressure P1 input from the first intake pressure sensor S1 and the second intake pressure sensor S2 with the downstream intake pressure P2, and the upstream intake pressure P1 is compared with the downstream intake pressure P2. When the operating condition that is greater than the atmospheric pressure P2 is satisfied, an operating command for applying a valve opening operating force to the low pressure stage waste gate valve WG2 is output to the electric valve operating mechanism 91. The electric valve operating mechanism 91 is operated by the operation command from the ECU 40, and the low-pressure stage waste gate valve WG2 is opened.
When the upstream intake pressure P1 becomes lower than the downstream intake pressure P2 and the operation condition is not satisfied, the operation command is not output from the ECU 40, the electric valve operating mechanism 91 is stopped, and the low pressure stage waste gate valve WG2 is closed. To be spoken.

Further, the high pressure stage side surge avoiding means 90 adds the valve opening operating force of the electric valve operating mechanism 91 to the valve opening operating force of the pressure type valve operating mechanism 80 on the low pressure stage side when the operating condition is satisfied. Thus, the low-pressure stage waste gate valve WG2 can be opened.
With this configuration, the driving power for applying the valve opening operating force to the low-pressure stage waste gate valve WG2 by the electric valve operating mechanism 91 can be kept low, and the electric power is supplied to the electric valve operating mechanism 91. It is possible to reduce the size of the power supply that supplies the power.

FIG. 4 is a view showing a pressure type valve operating mechanism 80 and an electric valve operating mechanism 91 on the low pressure stage side.
When the low pressure stage waste gate valve WG2 (see FIG. 1) is closed, the pressure type valve operating mechanism 80 and the electric valve operating mechanism 91 on the low pressure stage side are operated as indicated by the dotted arrows in the figure, and the low pressure stage waste gate is operated. A state in which the valve WG2 is opened (fully opened) is shown.

As shown in FIG. 4, there is provided a swing lever 81 that transmits an operating force to the low pressure stage waste gate valve WG2 to open and close the low pressure stage waste gate valve WG2. The swing lever 81 is connected to the operating shaft A of the low-pressure stage waste gate valve WG2 on the center side thereof.
The pressure-type valve operating mechanism 80 on the low-pressure stage side opens the swing lever 81 via a pressure-type side link 82 disposed on one end side (the lower end side in FIG. 4) of the swing lever 81, for example. A pressure actuator 83 such as a diaphragm actuator that can be swung in a direction is provided.

  The pressure type valve operating mechanism 80 on the low pressure stage side configured as described above uses the intake pressure P1 on the upstream side of the high pressure stage compressor 52 from the state where the low pressure stage waste gate valve WG2 is closed, to the pressure type actuator 83. The swing lever 81 is swung in the valve opening direction indicated by R in the figure by pushing one end side of the swing lever 81 into the opposite side of the pressure actuator 83 (the right side indicated by the dotted arrow in the figure). Then, the operating shaft A connected to the swing lever is rotated in the valve opening direction indicated by R in the figure.

  On the other hand, the electric valve operating mechanism 91 is disposed, for example, on the other end side (upper end side in FIG. 4) of the swing lever 81 on the opposite side of the pressure-type side link 82 with respect to the operating axis A. An electric actuator 93 that can swing the swing lever 81 in the valve opening direction via the electrically driven side link 92 is provided.

The electric valve operating mechanism 91 configured as described above is swung by the rod of the electric actuator 93 from the state where the low-pressure stage waste gate valve WG2 is closed according to the operation command from the ECU 40 when the operation condition is satisfied. By pulling the other end side of the moving lever 81 toward the electric actuator 93 side (the left side indicated by the dotted line arrow in the figure), the swing lever 81 is indicated by R in the figure as in the pressure type valve operating mechanism 80 on the low pressure stage side. A swing operation is performed in the valve opening direction, and the operating shaft A connected to the swing lever is rotated in the valve opening direction indicated by R in the figure.
In the state shown in FIG. 4 in which the low-pressure stage waste gate valve WG2 is fully opened, the valve opening operating force of the electric valve operating mechanism 91 (the pulling force of the electric link 92) is applied to the operating shaft A and the electric link 92. The relative positions of the electric actuator 93, the operating shaft A, and the electric link 92 are set so as to act at a right angle with respect to the line segment connecting the two.

That is, when the operating condition is satisfied, the pressure actuator 83 of the pressure type valve operating mechanism 80 on the low pressure stage side is used to press the one end side of the swing lever 81 from the state where the low pressure stage waste gate valve WG2 is closed. In addition to pushing to the side opposite to the actuator 83, the electric actuator 93 of the electric valve operating mechanism 91 pulls the other end of the swing lever 81 toward the electric actuator 93, so that the pressure type on the low pressure stage side. By the cooperation of the valve opening operating force of the valve operating mechanism 80 and the valve opening operating force of the electric valve operating mechanism 91, the operating shaft A connected to the swing lever 81 is rotated in the valve opening direction indicated by R in the figure. The state shown in FIG. 4 can be achieved, and the low-pressure stage waste gate valve WG2 can be opened efficiently.
At the time of this cooperation, a pushing force acts on one end side of the swing lever 81 and a pulling force acts on the other end side of the swing lever 81, so that the operating shaft connected to the center side of the swing lever 81 The bending moment in the falling direction applied to A is reduced, and the operation of the operating shaft A can be made smooth.
The swing lever 81, the pressure-type side link 82, and the electric-side link 92 constitute a linkage mechanism that links the low-pressure stage pressure-type valve operation mechanism 80 and the electric valve operation mechanism 91.

Next, the opening operation of the low-pressure stage waste gate valve WG2 by the pressure type valve operating mechanism 80 and the electric valve operating mechanism 91 will be described with reference to FIG.
FIG. 5 is a diagram showing the operating characteristics of the low-pressure stage waste gate valve WG2. The valve operating force of the pressure-type valve operating mechanism 80 acting on the low-pressure stage waste gate valve WG2 on the vertical axis (the valve opening operation by the intake pressure P1). Pressure), and the abscissa indicates the lift amount (valve opening operation amount) of the low-pressure stage waste gate valve WG2.
In FIG. 5, Pa indicates the valve opening operating force of the pressure type valve operating mechanism 80 that acts on the low pressure stage waste gate valve WG2 by the intake pressure P1 during rated operation, and Pb indicates when the low pressure stage waste gate valve WG2 starts to open. The valve opening operating force of the pressure type valve operating mechanism 80 is shown, and Pc shows the valve opening operating force of the pressure type valve operating mechanism 80 when the low pressure stage waste gate valve WG2 is fully opened.

As shown by the thick solid line portion in FIG. 5, when the intake pressure P1 downstream of the low-pressure compressor 62 exceeds the set intake pressure in the normal operation state of the engine 1, the intake pressure P1 depends on the intake pressure P1. The valve opening operating force of the pressure type valve operating mechanism 80 is larger than the valve opening operating force Pb at the start of opening of the low pressure stage waste gate valve WG2, and only the valve opening operating force of the pressure type valve operating mechanism 80 is low pressure stage waste. The gate valve WG2 is opened.
On the other hand, when the operating condition is satisfied, the electric valve operating mechanism 91 is operated, so that the valve opening operating force of the pressure type valve operating mechanism 80 has any value as shown by the thick broken line arrow in FIG. Even so, the low-pressure stage waste gate valve WG2 can be fully opened.

[Another embodiment]
(1) In the above-described embodiment, the case where the two-stage turbochargers 50 and 60 are connected in series from the engine body 10 side is shown as an example. These turbochargers may be connected in series.

  (2) In the above-described embodiment, the valve opening operating force of the pressure type valve operating mechanism 80 on the low pressure stage side and the valve opening operating force of the electric valve operating mechanism 91 via the common swing lever 81 are reduced to the low pressure stage waste. Although the case of acting on the operating shaft A of the gate valve WG2 has been shown as an example, the valve opening operating force of the low pressure stage side pressure type valve operating mechanism 80 and the electric valve operating mechanism 91 are provided via separate swing levers or the like. May be configured to act on the operating shaft A of the low-pressure stage wastegate valve WG2, and a linkage mechanism that links the pressure-type valve operating mechanism 80 and the electric valve-operating mechanism 91 on the low-pressure stage side. The specific configuration can be changed as appropriate.

  (3) In the above-described embodiment, the high pressure stage side surge avoiding means is configured to include the electric valve operating mechanism 91, and when the operating condition is satisfied, the valve opening of the low pressure stage pressure type valve operating mechanism 80 is opened. The case where the valve opening operating force of the electric valve operating mechanism 91 is added to the operating force to open the low pressure stage waste gate valve WG2 is shown as an example. The low-pressure stage waste gate valve WG2 may be configured to be openable by operating force alone. Further, the high-pressure stage side surge avoiding means may be configured to include another type of valve operation mechanism instead of the electric valve operation mechanism 91.

DESCRIPTION OF SYMBOLS 10 Engine body 33 Low pressure stage exhaust bypass 50 High pressure stage turbocharger 51 High pressure stage turbine 52 High pressure stage compressor 60 Low pressure stage turbocharger 61 Low pressure stage turbine 62 Low pressure stage compressor 80 Pressure type valve operating mechanism 81 on the low pressure stage side Swing lever 82 Pressure-type side link 83 Pressure-type actuator 90 High-pressure stage side surge avoiding means 91 Electric valve operating mechanism 92 Electric-side link 93 Electric actuator P1 Intake pressure (intake pressure on the upstream side of the high-pressure stage compressor)
P2 Intake pressure (Intake pressure downstream of high-pressure stage compressor)
WG2 Low pressure stage waste gate valve

Claims (3)

A multi-stage turbocharger system in which a high-pressure turbocharger on the small side from the engine body side and a low-pressure turbocharger on the large side are connected in series,
A low-pressure stage exhaust bypass that bypasses the low-pressure stage turbine of the low-pressure stage turbocharger;
A low pressure stage waste gate valve that opens and closes the low pressure stage exhaust bypass path;
The low pressure stage waste gate valve is opened when an operating condition is established in which the intake pressure upstream of the high pressure stage compressor of the high pressure turbocharger is greater than the intake pressure downstream of the high pressure stage compressor. And a high-pressure stage surge avoiding means. A pressure-type valve operating mechanism that applies a valve opening operating force according to the upstream intake pressure to the low pressure stage waste gate valve using the upstream intake pressure as a driving force;
The high-pressure stage side surge avoiding means includes an electric valve operating mechanism that applies a valve-opening operation force to the low-pressure stage waste gate valve using electric power as a driving force, and the pressure-type valve operation is performed when the operating condition is satisfied. The multistage turbocharging system according to claim 1, wherein the low pressure stage waste gate valve is configured to be opened by adding a valve opening operation force of the electric valve operation mechanism to a valve opening operation force of the mechanism. A swing lever that transmits operating force to the low-pressure stage wastegate valve to open and close the low-pressure stage wastegate valve is provided,
The pressure type valve operating mechanism includes a pressure type actuator capable of swinging the swing lever in a valve opening direction via a pressure side link,
The multistage turbocharging system according to claim 2, wherein the electric valve operating mechanism includes an electric actuator capable of swinging the swing lever in a valve opening direction via an electric side link. .

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