JP2907534B2 - Exhaust control system for turbocharged engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention has two turbochargers, operates one turbocharger in a low speed range, and two turbochargers in a high speed range. The present invention relates to an exhaust control device used in a so-called sequential twin-turbo engine, which is operated at the same time.

[Prior Art] Conventionally, in Japanese Patent Application Laid-Open No. 60-252120, two turbochargers having different output characteristics are mounted on one engine,
There is disclosed a turbocharged engine in which one turbocharger is operated in a low speed range, and both turbochargers are continuously operated in a high speed range.

This engine has two exhaust passages connected to a plurality of cylinders. A low-speed primary turbocharger turbine is connected to one exhaust passage,
A high-speed secondary turbocharger turbine is connected to the other exhaust passage. An exhaust pipe is connected to an exhaust outlet of each turbine, and an exhaust control valve for closing the exhaust pipe when the engine speed is low is provided in an exhaust pipe of the secondary turbocharger.

By the way, the exhaust control valve is opened / closed between an open position in which exhaust gas flows into the exhaust pipe by an actuator and a closed position in which the exhaust gas is shut off. The conventional actuator includes a cylindrical pressure vessel. The interior of the pressure vessel is divided into two chambers, a supercharging chamber in which a supercharging pressure is introduced by a diaphragm, and an atmospheric pressure chamber, and an operation rod linked to an exhaust control valve is connected to the diaphragm. I have. The atmospheric pressure chamber accommodates a coil spring that urges the diaphragm in a direction in which the exhaust control valve closes.

Therefore, the exhaust control valve is held at the closed position by the biasing force of the coil spring, and when the supercharging pressure introduced into the supercharging pressure chamber exceeds the biasing force of the coil spring, the exhaust control valve moves in the opening direction. Activated.

[Problems to be Solved by the Invention] However, when the exhaust control valve is operated to the closed position, the exhaust control valve always receives the pressure of the exhaust gas in the exhaust pipe. Since the exhaust control valve is held in the closed position only by the urging force, in order to reliably hold the exhaust control valve in the closed position,
The biasing force of the coil spring had to be set large.

For this reason, the wire diameter of the coil spring tends to be large or the number of turns tends to be large, and accordingly, there is a problem that the actuator is enlarged.

The present invention has been made in view of such circumstances, and it is possible to hold an exhaust control valve in a closed position using exhaust pressure, to reduce the urging force required by a spring member, and to reduce the size of an actuator. It is an object of the present invention to provide an exhaust control device for a turbocharged engine that can be converted into an engine.

[Means for Solving the Problems] Therefore, in the present invention, the turbocharger is operated over an open position through which exhaust gas flows to a turbine and a closed position at which the flow of exhaust gas in the turbine is blocked, In a turbocharged engine comprising: an exhaust control valve for controlling the flow of exhaust gas to a turbine; and an actuator for driving the exhaust control valve to open and close, the actuator includes a pressure vessel; Is divided into two chambers, a supercharging chamber and an exhaust pressure chamber, by a movable member interlocking with the exhaust control valve, and a supercharging pressure is introduced into the supercharging chamber to open the exhaust control valve. The movable member is urged in a direction in which the exhaust control valve is closed by introducing exhaust pressure into the exhaust pressure chamber, and the exhaust control chamber is urged in the exhaust pressure chamber. The direction in which the valve closes It is characterized by containing a spring member for urging the movable member.

[Operation] According to this configuration, the movable member of the actuator is pressed by the exhaust pressure and the biasing force of the spring member in a direction to hold the exhaust control valve in the closed position, so that the exhaust control valve is attached to the spring member. The urging force of the spring member can be set smaller than in the related art where the urging force alone is used to hold the closed position.

Therefore, this spring member can be downsized,
The actuator can be formed compact.

[Example] The present invention will be described below based on an example shown in the drawings.

FIG. 3 shows an in-line six-cylinder engine for an automobile. In a cylinder block 1, six cylinders 2a to 2f from the first to the sixth are provided in a line. Each cylinder 2a
2f accommodate pistons 3, and a combustion chamber 5 is formed between the pistons 3 and the cylinder head 4. The cylinder head 4 has an intake port 6 and an exhaust port 7 connected to the combustion chamber 5. Six intake pipes 8 are connected to the intake ports 6 of the cylinders 2a to 2f. Each of the intake pipes 8 is provided with a fuel injection valve 9, and the upstream end of the intake pipe 8 is connected to a surge tank 10. At the upstream end of the intake of the surge tank 10, a throttle valve 11 and a throttle opening sensor 12 for detecting the opening of the throttle valve 11 are provided.

In the case of the present embodiment, the ignition order of each of the cylinders 2a to 2f is as follows.
The order is the first cylinder 2a → the fifth cylinder 2e → the third cylinder 2c → the sixth cylinder 2f → the second cylinder 2b → the fourth cylinder 2d.

As shown in FIG. 3, the exhaust ports 7 of the cylinders 2a to 2f are connected to exhaust outlet paths 13a to 13f. These exhaust outlet routes
13a to 13f are integrally formed inside the cylinder head 4, and the exhaust outlet paths 13a to 1c of the first to third cylinders 2a to 2c.
3c and the exhaust outlet 13d of the fourth to sixth cylinders 2d to 2f
13f are gathered inside the cylinder head 4 respectively.

Therefore, the exhaust outlet paths 13a to 13f of the six cylinders 2a to 2f
Is divided into two groups for each of the three cylinders 2a to 2f, and is grouped together for each group.
These two exhaust collecting portions 14a and 14b are connected to the cylinder head 4
It is open on the side.

An exhaust manifold 15 is connected to the exhaust collecting portions 14a and 14b of the cylinder head 4. Exhaust manifold 15
Are two exhaust passages 16a, 16b connected to the exhaust collecting portions 14a, 14b.
It has. The exhaust passages 16a and 16b are
And extend linearly from the side surface in parallel with each other. The exhaust passages 16a and 16b are communicated with each other through a communication passage 17 in the middle. The communication passage 17 includes an exhaust passage 16a,
It extends in a direction perpendicular to 16b. As shown in FIG. 3, the diameter d of the communication passage 17 is formed smaller than the diameter D of the exhaust passages 16a and 16b in order to prevent exhaust interference between the exhaust passages 16a and 16b.

The exhaust manifold 15 is provided with a twin turbo assembly 20. As shown in FIG. 4, the twin turbo assembly 20 includes a primary turbocharger 21 that operates over the entire rotation range from a low rotation range including idling to a high rotation range, Is provided with a secondary turbocharger 22 which is activated continuously when the pressure is reached. These turbochargers 21 and 22 have turbines 23 and 24, respectively, and compressors 25 and 26 rotationally driven by the turbines 23 and 24, and the cylinders 2a to 2f
Are arranged side by side in the parallel direction. Exhaust inlets 27 and 28 extending in the tangential direction are formed in the turbines 23 and 24, and the exhaust inlets 27 and 28 are connected to the exhaust passages 16a and 16b of the exhaust manifold 15. Exhaust outlets 29, 30 are formed in the center of the turbines 23, 24. Exhaust outlet 2
9 and 30 are opposed to each other on the side of the cylinder head 4, and the exhaust outlets 29 and 30 are connected by a single conduit 31. The communication pipe 31 has a substantially linear shape, and one exhaust pipe connection port 32 extending downward is integrally formed at the center of the lower surface.

For this reason, the exhaust outlets 29, 30 of both turbines 23, 24 are
The exhaust outlet 29,
An exhaust pipe 33 is connected to the exhaust pipe connection port 32, which is an aggregation of the 30.

On the other hand, the compressors 25 and 26 have intake inlets 36 and 37 opening at their central portions and an intake outlet opening tangentially.
38 and 39 are formed. The intake ports 36a and 37 are connected to intake pipes 40a and 40b, respectively. Intake inlet pipes 40a, 40b
After being guided above the twin turbo assembly 20,
It is assembled just above the communication pipe 31. This air intake pipe
The collecting portion 41 of 40a and 40b is connected to an air cleaner 43 via an air flow meter 42.

Supercharge pipes 45a and 45b are connected to intake outlets 38 and 39 of the compressors 25 and 26, respectively. Secondary turbocharger 2
As shown in FIG. 3, the supercharging pipe 45b from the pipe 2 passes between the cylinder head 4 and the intake pipes 40a, 40b and is led to one end side along the longitudinal direction of the cylinder head 4. One end of the head 4 is joined to a supercharging pipe 45a from the primary turbocharger 21. This supercharging pipe 45a, 4
The junction 46 of 5b is connected to the surge tank 10 via an intercooler 47.

Incidentally, the communication pipe 31 is provided with a swing-type exhaust control valve 50 for interrupting communication between the turbine 24 of the secondary turbocharger 22 and the exhaust pipe 33. Exhaust control valve 50
Has a valve box 51 interposed between the communication pipe 31 and the exhaust outlet 30, as shown in FIG. At the center of the valve box 51, a housing recess 52 that opens toward the communication pipe 31 is formed. The accommodation recess 52 has a larger diameter than the exhaust outlet 30 and is eccentric upward with respect to the exhaust outlet 30.A valve hole 53 for communicating the communication pipe 31 and the exhaust outlet 30 is formed on an end surface of the accommodation recess 52. Is formed.

For this reason, in the upper part of the accommodation concave portion 52, a space portion 54 is formed which is out of the streamline of the exhaust gas flowing from the exhaust outlet 30. I have. A disc-shaped valve body is provided on the outer circumference of the valve shaft 55 via an arm 56.
57 are supported. The valve body 57 is rotated around a valve shaft 55 as a fulcrum between a closed position for closing the valve hole 53 and an open position for opening the valve hole 53, and the valve body 57 is rotated to the closed position. In this state, the valve body 57 has two turbochargers 2
It is located between 1,22 exhaust outlets 29,30. In addition, when the valve body 57 rotates from the closed position to the open position, the valve body 57 rotates toward the exhaust outlet 29 side of the primary turbocharger 21, and when the valve body 57 is rotated to the open position, the exhaust It is held at a position substantially parallel to the streamline.

In the case of the present embodiment, at the center of the upper surface of the communication pipe 31,
A guide portion 58 protruding toward the exhaust pipe connection port 32 is formed. The guide portion 58 projects between the exhaust outlets 29, 30 of the two turbines 23, 24. The surface of the guide portion 58 facing the exhaust outlet 29 of the primary turbocharger 21 is curved downward in an arc shape, and the exhaust from the exhaust outlet 29 is smoothly directed toward the exhaust pipe connection port 32. It is leading.

In addition, as shown in FIG. 2, an exhaust pipe connection port from the exhaust outlet 29 of the primary turbocharger 21 to an assembly portion thereof
The distance A to the center of 32 is shorter than the distance B from the exhaust outlet 30 of the secondary turbocharger 22 to the center of the exhaust pipe connection port 32. Because of this, the primary turbocharger
Exhaust resistance in the low speed range where only 21 is operated is kept small, and the engine output in this low speed range is increased.

An end of a valve shaft 55 of the exhaust control valve 50 is led out of the valve box 51, and the valve shaft 55 is rotated by an actuator 60. The actuator 60 is arranged at a position adjacent to the compressor 26 of the secondary turbocharger 22. The actuator 60 includes a cylindrical pressure vessel 61 as shown in FIG. The pressure vessel 61 is
And a second container 62b. A diaphragm 6 as a movable member is provided between the containers 62a and 62b.
3 are supported. The diaphragm 63 divides the inside of the pressure vessel 61 into two chambers, a boost pressure chamber 64 and an exhaust pressure chamber 65.
An operation rod 66 is connected to the center of the diaphragm 63. The operating rod 66 extends through the exhaust pressure chamber 65 to the outside of the pressure vessel 61, and the leading end of the operating rod 66 is connected to the valve shaft 55 via a lever 67.

The operating rod 66 is supported by the pressure vessel 61 via a bearing 68 so as to be slidable in the axial direction.A part of the operating rod 66 that penetrates the pressure vessel 61 has a seal for keeping the exhaust pressure chamber 65 airtight. A member 69 is provided.

A coil spring 70 as a spring member is interposed between the diaphragm 63 and the bottom surface of the exhaust pressure chamber 65 in a compressed state. The coil spring 70 constantly presses the diaphragm 63 toward the boost pressure chamber 64 side. Due to the pressing of the coil spring 70, the operating rod 66 urges the valve shaft 55 to rotate in a direction to keep the valve body 57 in the always closed position.

The pressure vessel 61 is supported by the compressor 26 of the secondary turbocharger 22 via a bracket 71.

As shown in FIG. 5, the exhaust pressure chamber 65 of the pressure vessel 61 is connected to the exhaust pipe connection port 32 via an exhaust pressure introduction path 73. Therefore, during the operation of the engine, the exhaust pressure downstream of the two turbochargers 21 and 22 is constantly introduced into the exhaust pressure chamber 65, and the first container 62a constituting the exhaust pressure chamber 65 A relief valve 72 is provided to release the exhaust pressure when the pressure in the exhaust pressure chamber 65 exceeds the upper limit.

The supercharging pressure chamber 64 of the pressure vessel 61 is connected to a supercharging pipe 45a of the primary turbocharger 21 via a supercharging pressure introduction path 74. The supercharging pressure introduction path 74 is connected to an intake introduction pipe 40b of the secondary turbocharger 22 via a communication path 75, and the intake introduction pipe 40b is provided with a normally open type on-off valve 76. I have.

A normally-closed intake control valve 80 that opens and closes the supercharging pipe 45b is provided in the supercharging pipe 45b of the secondary turbocharger 22.
Is provided. The drive section 80a of the intake control valve 80 is connected upstream of the intake control valve 80 of the supercharging pipe 45b via a supercharging pressure introduction path 81, and the supercharging pressure introduction path 81 has a normally closed type. An on-off valve 82 is provided. For this reason, when the on-off valve 82 is opened and a boost pressure is applied to the drive section 80a of the intake control valve 80, the intake control valve 80 is opened.

The intake pipe 40b of the supercharging pipe 45b of the secondary turbocharger 22 is in communication with the intake pipe 40b. The intake bypass passage 83 bypasses the compressor 26 of the secondary turbocharger 22. The intake bypass passage 83 is provided with a normally open bypass valve 84. The driving portion 84a of the bypass valve 84 is connected to the supercharging pressure introduction passage 81.
It is connected to the.

The exhaust passage 16 connected to the primary turbocharger 21
a, and the exhaust connection port 32, an exhaust bypass passage 86
Connected by The exhaust bypass passage 86 bypasses the turbine 23 of the primary turbocharger 21, and in the middle of the exhaust bypass passage 86, the exhaust bypass passage 86
A normally-closed supercharging pressure control valve 87 is provided for opening and closing the valve.
The drive section 87a of the supercharging pressure control valve 87 is connected to the junction 46 of the supercharging pipes 45a and 45b via a supercharging pressure introducing section 88.
The supercharging pressure introduction passage 88 is connected to the intake introduction pipe 40 through a communication passage 89.
The communication passage 89 is provided with a normally open on-off valve 90.

The opening and closing timing of each of the on-off valves 76, 82, and 90 is controlled by a signal output from the microcomputer 91 during operation of the engine.

That is, during operation of the engine, the microcomputer 91
Various signals indicating the engine operation status, for example, a signal indicating the throttle opening from the throttle opening sensor 12, a signal indicating the intake air amount from the air flow meter 42, and the like are input thereto. And the microcomputer 91
Sends a drive signal optimal for the current operating condition to the open / close valves 76, 82, 90 and the fuel injection valve 9 based on these signals.

Here, the control by the microcomputer 91 will be specifically described. At the time of low-speed operation with a low engine speed, the microcomputer 91 sends a signal for maintaining the open state to the on-off valve 76. In a state where the on-off valve 76 is open, the supercharging pressure of the primary turbocharger 21 introduced into the supercharging pressure introducing path 74 is higher than the supercharging pressure chamber 64 of the actuator 60 and flows through the communication passage 75. The air is discharged to the intake pipe 40b of the secondary turbocharger 22 via the air inlet.

On the other hand, since the exhaust pressure is always introduced into the exhaust pressure chamber 65 of the actuator 60 via the exhaust pressure introduction path 73, the pressure of the exhaust pressure chamber 65 is higher than the pressure of the supercharging chamber 64. Become. The biasing force of the coil spring 70 also acts synergistically on the diaphragm 63, so that the diaphragm 63 is deformed in the direction of projecting into the boost pressure chamber 64, and the operation rod 66 is moved to the pressure vessel 61. Be drawn in. Then, the valve shaft 55 rotates clockwise in FIG. 5, and by the rotation of the valve shaft 55, the valve body 57 of the exhaust control valve 50 is rotated to the closed position, and the valve hole 55 is rotated.
Close 53.

Therefore, the exhaust outlet 30 of the secondary turbocharger 22 is closed, and the exhaust from the fourth to sixth cylinders 2d to 2f flows into one exhaust passage 16a via the communication passage 17.

For this reason, the exhaust gas from all the cylinders 2a to 2f is introduced into the turbine 23 of the primary turbocharger 21, and the rise of the supercharging is accelerated even in the low-speed operation in which the flow rate of the exhaust gas is small.

At the time of low-speed operation, the microcomputer 91 sends a signal to the on-off valve 82 to maintain the closed state. At this time, exhaust from each cylinder 2a to 2f is all
Since the turbine 24 is guided to the turbine 23, the turbine 24 and the compressor 26 of the secondary turbocharger 22 are not operating, and the supercharging pressure is not generated in the supercharging pipe 45b. . As a result, no supercharging pressure is applied to the drive unit 80a of the intake control valve 80 and the drive unit 84a of the bypass valve 84, so that the intake control valve 80 is kept closed and the bypass valve 84 is opened. Will be maintained.

At the same time, during low-speed operation, the microcomputer 91
Sends a signal to the on-off valve 90 to maintain the open state,
The supercharging pressure introduced into the supercharging pressure introduction passage 88 is returned to the collecting part 41 of the intake introduction pipes 40a and 40b via the communication passage 89. For this reason, the supply of the supercharging pressure to the driving portion 87a of the supercharging pressure control valve 87 is stopped, so that the supercharging pressure control valve 87 maintains the closed state,
The exhaust bypass passage 86 is closed.

When the engine speed increases and the boost pressure rises to some extent, a signal from the microcomputer 91 sends a signal
76 begins to move in the closing direction and the primary turbocharger 21
Is introduced into the supercharging pressure chamber 64 of the actuator 60. The pressure in the boost pressure chamber 64 increases, and this pressure
When the pressure and the urging force of the coil spring 70 are overcome, the operating rod 66 is pushed out of the pressure vessel 61, and the valve body 57 of the exhaust control valve 50 starts to open. For this reason, the fourth or sixth cylinder
Part of the exhaust from 2d to 2f is supplied to the secondary turbocharger 22
And the preliminary rotation of the turbine 24 starts. The preliminary rotation of the turbine 24 allows the compressor
At 26, supercharging starts. At this point, the intake control valve 80
Remains closed, but since the bypass valve 84 is open as described above, the upstream side and the downstream side of the compressor 26 are short-circuited by the intake bypass passage 83, and the supercharged air flows from the downstream side of the compressor 26. It circulates upstream to prevent the occurrence of surging.

As the engine speed further increases, the engine speed
When shifting to the high load operation range, the microcomputer 91
Sends a signal to the on-off valve 76 to close it. Then
Since all of the supercharging pressure of the primary turbocharger 21 acts on the supercharging pressure chamber 64 of the actuator 60, the diaphragm 63 is maximally deformed toward the exhaust pressure chamber 65 as shown in FIG. 66 is pushed further. Therefore, the valve body 57 of the exhaust control valve 50 is rotated to the open position, and the exhaust outlet 30 of the secondary turbocharger 22 is fully opened.

As a result, all of the exhaust from the fourth to sixth cylinders 2d to 2f is introduced into the turbine 24 of the secondary turbocharger 22, and this secondary turbocharger 22 is connected to the primary turbocharger 21. Actuated.

In addition, the microcomputer 91 continues to operate the on-off valve.
A signal is sent to 82 to open this. As a result, the supercharging pressure acts on both the drive unit 80a of the intake control valve 80 and the drive unit 84a of the bypass valve 84, so that the intake control valve 80 is fully opened and the reverse bypass valve 84 is fully closed. , And the intake bypass passage 83 is closed. Therefore, in addition to the supercharged air from the primary turbocharger 21, the supercharged air from the secondary turbocharger 22 passes through the supercharging pipes 45a and 45b, the intercooler 47, the surge tank 10, and the intake pipe 8. Each cylinder
It is supplied to the combustion chambers 5 of 2a to 2f.

When the supercharging pressure becomes excessive, the on-off valve 90 is closed by a signal from the microcomputer 91, and the supercharging pressure acts on the driving portion 87a of the supercharging pressure control valve 87. For this reason,
The supercharging pressure control valve 87 is fully opened, and the exhaust gas introduced into the turbine 23 of the primary turbocharger 21 via the exhaust bypass passage 86 bypasses the turbine 23 and escapes to the exhaust pipe 33.

According to such an embodiment of the present invention, the pressure vessel 61 of the actuator 60 includes a supercharging pressure chamber 64 in which a supercharging pressure is introduced by a diaphragm 63, and an exhaust pressure chamber 65 in which an exhaust pressure is constantly introduced. And the exhaust control valve is provided in the exhaust pressure chamber 65.
A coil spring that presses the diaphragm 63 in the direction in which 50 closes
When the valve body 57 of the exhaust control valve 50 closes the valve hole 53, the diaphragm 63 of the actuator 60 applies the pressure of the exhaust gas introduced into the exhaust pressure chamber 65 and the urging force of the coil spring 70. The pressure is pressed in a direction to hold the exhaust control valve 50 in the closed position.

Therefore, the urging force of the coil spring 70 can be set smaller than in the conventional case where the exhaust control valve 50 is held at the closed position only by the urging force of the coil spring, and the coil spring
By reducing the size of 70, the actuator 60 can be formed compact.

In the above embodiment, the diaphragm is used as the movable member that partitions the inside of the pressure vessel into two chambers. However, the present invention is not limited to this, and a free piston may be used instead of the diaphragm.

Further, the exhaust control valve is not limited to the one provided on the downstream side of the secondary turbocharger, and may be provided on the upstream side of the secondary turbocharger.

Further, the type of the exhaust control valve is not limited to the swing type, but may be, for example, a butterfly type.

According to the present invention described in detail above, the movable member of the actuator holds the exhaust control valve in the closed position by the pressure of the exhaust gas introduced into the exhaust pressure chamber and the urging force of the spring member. Therefore, the urging force of the spring member can be set smaller than in the conventional case where the exhaust control valve is held at the closed position only by the urging force of the spring member, and the spring member is reduced in size accordingly. Thus, the actuator can be made compact.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS The drawings show one embodiment of the present invention. FIG. 1 is a sectional view of an actuator for opening and closing an exhaust control valve, FIG. 2 is a sectional view of a mounting portion of the exhaust control valve, and FIG. FIG. 4 is a front view of the twin turbo assembly as viewed from the direction of the IV line in FIG. 3, and FIG. 5 is a schematic diagram showing an exhaust path and a supercharging path of the engine. FIG. 22… Turbocharger (secondary turbocharger), 24…
... Turbine, 50 ... Exhaust control valve, 60 ... Actuator, 61 ... Pressure vessel, 63 ... Diaphragm, 64 ... Supercharging pressure chamber, 65 ... Exhaust pressure chamber, 70 ... Spring member (coil spring) .

Claims (1)

(57) [Claims] An exhaust control that is operated between an open position where exhaust gas flows to a turbine of a turbocharger and a closed position where exhaust gas flows through the turbine is controlled to control the flow of exhaust gas to the turbine. A turbocharged engine comprising: a valve; and an actuator for opening and closing the exhaust control valve. The actuator includes a pressure vessel, and the inside of the pressure vessel is interlocked with the exhaust control valve. The movable member is divided into two chambers of a supercharging pressure chamber and an exhaust pressure chamber, and a supercharging pressure is introduced into the supercharging chamber to urge the movable member in a direction in which the exhaust control valve opens. Exhaust pressure is introduced into the exhaust pressure chamber to urge the movable member in a direction in which the exhaust control valve closes, and further, the movable member is urged in the exhaust pressure chamber in a direction in which the exhaust control valve closes. Housed spring members An exhaust control device for a turbocharged engine.