JP2006144715A - Exhaust device for engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust device for an engine preventing wear of a connecting part and stably operating a variable nozzle mechanism by preventing vibration of a nozzle vane from being transmitted to the connecting part of a link assembly driving a nozzle vane of a variable displacement supercharger with a vary simple means. <P>SOLUTION: In the exhaust device for the engine provided with a variable displacement type exhaust turbocharger varying displacement of a turbine by a variable nozzle mechanism transmitting drive force of an actuator to a nozzle vane rotatbly supported by a turbine casing via a link assembly to vary angle of the nozzle vane, a pressure difference generating means generating pressure difference between a nozzle chamber provided in the nozzle vane in the turbine casing and a link chamber formed in the turbine casing and having the link assembly stored therein at a time of exhaust brake operation, and pressing the nozzle vane against one side side wall of the nozzle chamber by the pressure difference is provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an engine exhaust system that is mainly applied to an engine equipped with an exhaust turbocharger for a vehicle and has a turbine capacity variable by a variable nozzle mechanism that changes a blade angle of a nozzle vane.

  In an engine equipped with an exhaust turbocharger, the driving force of the actuator is rotatably supported on the turbine casing via a link assembly including a drive ring, a lever plate, and a pin connecting the drive ring and the lever plate. 2. Description of the Related Art A variable displacement exhaust turbocharger equipped with a variable nozzle mechanism that transmits to a nozzle vane and changes the blade angle of the nozzle vane according to engine output (engine load) is widely used.

Such a variable nozzle mechanism requires that the blade angle of the nozzle vane be accurately changed by the driving force of the actuator controlled by the engine output (engine load). Means to avoid the occurrence have been proposed.
One of the means is a technique disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 2001-27124).
In such a technique, a spring (between a pin fixed to the drive ring connecting the drive ring and the lever plate, which constitutes the link mechanism that transmits the driving force of the actuator to the nozzle vane, and the connecting groove of the lever plate ( An elastic member) is interposed, and the side surface of the pin is always pressed against the connecting groove side by the spring, thereby avoiding the occurrence of “back” at the pin connecting portion.

JP 2001-27124 A

  In an engine with a variable displacement exhaust turbocharger having the variable nozzle mechanism as described above, an exhaust brake provided on the outlet side of the exhaust turbocharger is operated to close the exhaust passage downstream of the turbine. As a result, the pulsation of the exhaust gas acting on the nozzle vanes of the variable nozzle mechanism changes (a phenomenon occurs in which the pressure upstream and downstream of the turbine is reversed), and this pulsation changes causes the nozzle vane to vibrate around its rotational axis. To do. Due to this vibration, the connecting portion of the link assembly including the drive ring that drives the nozzle vane, the lever plate, and the pin that connects the drive ring and the lever plate is likely to be worn.

In the technique disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 2001-27124), the vibration generated as described above is a connecting portion between the pin fixed to the drive ring side and the lever plate. When this is transmitted to the pin, the side surface of the pin is always pressed against the connecting groove side by the spring to avoid the occurrence of “rattle” of the pin connecting portion. Therefore, it is difficult to reliably reduce the wear of the pin connecting portion only by pressing the side surface of the pin against the connecting groove side by a spring.
Therefore, in this prior art, it is difficult to maintain the stable operation of the variable nozzle mechanism by preventing wear of the pin connecting portion.

  In view of the problems of the prior art, the present invention prevents wear of the connecting portion by preventing transmission of the vibration of the nozzle vane to the connecting portion of the link assembly that drives the nozzle vane by an extremely simple means. Another object of the present invention is to provide an exhaust system for an engine equipped with a variable displacement exhaust turbocharger capable of maintaining a stable operation of a variable nozzle mechanism.

The present invention achieves such an object, and transmits a driving force of an actuator to a nozzle vane rotatably supported by a turbine casing via a link assembly, and a turbine is provided by a variable nozzle mechanism that changes a blade angle of the nozzle vane. In an exhaust system for an engine having a variable capacity exhaust turbocharger with a variable capacity and an exhaust brake device in an exhaust passage,
A pressure difference is generated between a nozzle chamber provided with the nozzle vane in the turbine casing and a link chamber formed in the turbine casing and housing the link assembly when the exhaust brake device is operated; A differential pressure generating means for pressing the nozzle vane against a side wall on one side of the nozzle chamber by a pressure difference is provided.

  As described above, in a variable displacement exhaust turbocharger equipped with a variable nozzle mechanism, when the exhaust brake is operated to close the exhaust passage downstream of the turbine, the exhaust pulsation acting on the nozzle vanes changes, and the exhaust pulsation As a result, vibration around the rotation axis of the nozzle vane is generated, and this vibration causes wear on the connecting portion of the link assembly including the drive ring that drives the nozzle vane, the lever plate, and the pin that connects the drive ring and the lever plate. appear.

  Therefore, according to the invention, even when the exhaust brake device is operated to reduce the exhaust gas flow rate, the turbine casing in which the nozzle chamber provided with the nozzle vane in the turbine casing and the link assembly are accommodated. Since a constant pressure difference is always generated between the link chambers by the differential pressure generating means, the nozzle vane is pressed against the side wall on one side of the nozzle chamber by this pressure difference, and the pressing force The vibration of the nozzle vane is suppressed by the frictional resistance caused by the contact between the nozzle vane and the side wall accompanying the action.

This prevents vibration from propagating from the nozzle vane to the connecting portion of the link assembly including the drive ring that drives the nozzle vane, the lever plate, and the pin that connects the drive ring and the lever plate. Since vibration is suppressed, wear of the connecting portion due to the vibration can be prevented.
In this case, since the variable nozzle mechanism does not operate during the operation of the exhaust brake device, even if the nozzle vane is pressed against the side wall on one side of the nozzle chamber due to the pressure difference, there is no problem in the operation of the engine.

In this invention, preferably, the differential pressure generating means includes an air extraction passage connecting the link chamber and the intake passage of the engine, and releases the pressure in the link chamber into the intake passage through the air extraction passage. Consists of intake side pressure release means.
With this configuration, the exhaust turbocharger hardly operates during the operation of the exhaust brake device, and therefore the pressure in the link chamber is released into the intake passage where the intake pressure is low. The pressure in the chamber is always lower than the pressure in the nozzle chamber, so that a differential pressure can be reliably generated between the nozzle chamber and the link chamber, and the nozzle vane is pressed against the side wall of the nozzle chamber by the differential pressure. And the wear of the connecting part of the link assembly can be prevented.

In the invention, preferably, the differential pressure generating means includes an air extraction passage connecting the link chamber and a downstream exhaust passage of the exhaust brake device, and the pressure in the link chamber is exhausted through the air extraction passage. The exhaust side pressure release means opens into the passage.
With this configuration, during the operation of the exhaust brake device, the pressure in the link chamber is released through the air extraction passage to the exhaust passage in the downstream portion of the exhaust brake device that is always lower than the pressure in the nozzle chamber. The pressure in the link chamber is always lower than the pressure in the nozzle chamber, so that a differential pressure can be reliably generated between the nozzle chamber and the link chamber, and the nozzle vane is pressed against the side wall of the nozzle chamber by the differential pressure, The vibration of the nozzle vane can be suppressed, and the wear of the connecting portion of the link assembly can be prevented.

Further, in the above configuration, an exhaust gas purification device is provided in the exhaust passage downstream of the exhaust brake device, and an outlet side of the air extraction passage of the exhaust side pressure release means is disposed between the exhaust brake device and the exhaust gas purification device. It is preferable to connect to the site.
With this configuration, the gas in the link chamber mixed with the exhaust gas can be introduced into the exhaust gas purification device and purified together with the main exhaust gas.

  According to the present invention, preferably, the differential pressure generating means having an air extraction passage for extracting the gas in the link chamber to a low-pressure portion is provided between the nozzle chamber in which the nozzle vane is provided and the link chamber in which the link assembly is accommodated. A differential pressure is generated and the nozzle vane is pressed against the side wall on one side of the nozzle chamber by the differential pressure and pressed, and the vibration of the nozzle vane is suppressed by the frictional resistance caused by the contact between the nozzle vane and the side wall due to the action of the pressing force. The wear of the connecting portion in the link assembly can be prevented by a very simple and low-cost means of preventing the transmission of vibration from the nozzle vane side to the link assembly side, and the variable nozzle mechanism is stable. The operation can be maintained.

  Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in this example are not intended to limit the scope of the present invention only to specific examples unless otherwise specified. Only.

FIG. 4 is a cross-sectional view taken along the axial center line of the variable displacement exhaust turbocharger to which the present invention is applied.
In FIG. 4, 30 is a turbine casing, 30a is a scroll chamber formed in a spiral shape on the outer periphery of the turbine casing 30, and 34a is an exhaust gas outlet for sending exhaust gas that has been expanded by the turbine rotor to the outside of the system. It is. Reference numeral 31 denotes a compressor housing, and 36 denotes a bearing housing for connecting the compressor housing 31 and the turbine casing 30.
Reference numeral 34 denotes a turbine wheel, 35 denotes a compressor wheel, 33 denotes a turbine shaft that connects the turbine wheel 34 and the compressor wheel 35, and 37 denotes a bearing that is attached to the bearing housing 36 and supports the turbine shaft 33. 01 is the rotational axis of the turbine shaft 33.

Reference numeral 40 denotes a nozzle vane. A plurality of nozzle vanes 41 are arranged on the inner peripheral side of the scroll chamber 30a at equal intervals in the circumferential direction of the turbine, and a nozzle shaft 40a integrally formed with the nozzle mount 41 is attached to the turbine casing 30. The blade angle of the nozzle vane 40 is changed by the rotation of the nozzle shaft 40a.
70 is a variable nozzle mechanism for controlling the blade angle of the nozzle vane 40 (details will be described later), 50 is an actuator, and the driving force of the actuator 50 rotates the nozzle vane 40 via the variable nozzle mechanism 70, and the blade The angle is changed.

The present invention relates to prevention of wear of components of the variable nozzle mechanism 70 in such a variable capacity exhaust turbocharger.
FIG. 1A is a cross-sectional view of the main part near the variable nozzle mechanism installation portion in the variable displacement exhaust turbocharger according to the first and second embodiments of the present invention, and FIG. It is an arrow view.
In the figure, reference numeral 70 denotes a variable nozzle mechanism configured as follows.
Reference numeral 73 denotes a drive ring formed in an annular shape and rotatably supported on the outer periphery of the turbine casing 30 (or the nozzle mount 41 as shown in FIG. 4). Reference numeral 71 denotes a lever plate for connecting the drive ring 73 to the nozzle shaft 40a and the nozzle vane 40, and the base portion is fixed to the nozzle shaft 40a.
Further, as shown in FIG. 1B, the drive ring 73 and the lever plate 71 are fitted with a pin 72 having one end fixed to the drive ring 73 in a long groove 71a formed in the lever plate 71. Are connected.

Reference numeral 30b denotes a link chamber formed in the turbine casing 30, in which a link assembly 700 such as the drive ring 73, lever plate 71, and pin 72 is accommodated.
2 is an air vent hole drilled in the turbine casing 30 in communication with the link chamber 30b, 1 is an air vent passage connected to the air vent hole 2 via a flange 1a, and the pressure in the link chamber 30b Is opened to the air extraction passage 1 through the air extraction hole 2.
30a is a scroll chamber, and 30h is a nozzle chamber in which the nozzle vanes 40 are installed.

FIG. 2 is a plan view showing the configuration of the intake side pressure releasing means of the differential pressure generating means in the first embodiment of the present invention.
In the figure, 100 is an engine, 101 is a cylinder of the engine 100, 102 is an intake manifold, 103 is an exhaust manifold, and 106 is a radiator. The exhaust turbocharger 110 is configured in detail as shown in FIG. 4, and exhaust gas is introduced into the turbine 110a of the exhaust turbocharger 110 through the exhaust pipe 107 from the engine 100, and the turbine 110a. Is supposed to drive.
110 b is a compressor of the exhaust turbocharger 110 and is coaxially driven by the turbine 110 a and supplies air (intake air) to the intake manifold 102 of the engine 100 through the intake pipe 104. 105 is an air cooler provided in the intake pipe 104, 108 is an exhaust pipe connected to the exhaust outlet of the turbine 110a, and an exhaust brake 109 and an exhaust gas purification device 111 are installed in the exhaust pipe 108. .

1 is an air extraction passage, as shown in FIG. 1, the inlet side is connected to the air extraction hole 2 of the turbine casing 30 via a flange 1a, and is communicated with the link chamber 30b via the air extraction hole 2. The outlet side is connected to the intake manifold 102 via a flange 1b. Accordingly, the pressure in the link chamber 30b is released into the intake manifold 102 through the air extraction hole 2 and the air extraction passage 1.
In FIG. 2, a solid line arrow indicates the flow of exhaust gas, and a broken line arrow indicates the flow of air (intake).

Next, the operation of the first embodiment will be described with reference to FIGS.
The exhaust pipe from the variable displacement exhaust turbocharger 110 having the variable nozzle mechanism 70 during operation of the engine with the variable displacement exhaust turbocharger having the variable nozzle mechanism 70 configured as described above. When the exhaust brake 109 provided in 108 is operated to close the exhaust passage downstream of the turbine, a change occurs in the exhaust pulsation, and the change in the exhaust pulsation causes the nozzle vane 40 to rotate, that is, the nozzle shaft 40a. It is vibrated around the center 40s.

However, according to the embodiment, even when the exhaust brake 109 is operated to reduce the exhaust gas flow rate, the inside of the link chamber 30 b is in the intake air via the air extraction hole 2 and the air extraction passage 1. While connected to the manifold 102 and the exhaust brake 109 is in operation, the output of the exhaust turbocharger 110 decreases and communicates with the intake pressure in the intake manifold 102 and the intake manifold 102. the pressure P ₂ of the link chamber 30b is opened to the intake manifold 102 becomes lower than the pressure P ₁ in the nozzle chamber 30h of the nozzle vanes 40 is provided.

Due to the force F generated by the differential pressure P ₁ -P ₂ , the nozzle vane 40 is pressed against the side wall 30f on one side of the nozzle chamber 30h, and the nozzle vane 40 and the side wall 30f come into contact with the pressing force F. The vibration of the nozzle vane 40 is suppressed by the frictional resistance.
By the differential pressure between the pressure P ₂ of such nozzle chambers 30h pressure P ₁ and the link chamber 30b of the gas within the nozzle chamber 30h is as shown by the arrow in FIG. 1, the nozzle shaft and the hole 30c of the turbine casing even become possible outflow link chamber 30b through the leak gap 30e between the 40a, the pressure P ₂ in the link chamber 30b as described above is open to the intake manifold 102, the differential pressure P ₁ -P ₂ is securely held.

As described above, the vibration of the nozzle vane 40 is suppressed, so that the drive ring 73, the lever plate 71, and the pin 72 that connects the drive ring 73 and the lever plate 71 are driven from the nozzle vane 40. Propagation of the vibration to the connecting portion of the link assembly 700 including this is prevented, and the vibration of the connecting portion is suppressed. In particular, as shown in FIG. Wear due to the vibration at the contact portion between the pin 72 and the pin 72 can be prevented.
Note that the since during operation of the exhaust brake 109 variable nozzle mechanism 70 is not actuated, one side engine also be pushed by biased to the side wall 30f of the differential pressure P ₁ -P ₂ nozzle vane 40 by a nozzle chamber 30h There is no hindrance to driving.
Further, when the exhaust brake 109 is released, the rotation of the turbine rises, so that the intake pressure also rises. As the intake pressure rises, the pressure in the link chamber 30b is increased, and the nozzle vane 40, the side wall 30f, Therefore, during the normal operation when the exhaust brake 109 is not operated, the opening degree control of the nozzle vane 40 can be performed without any trouble.

FIG. 3 is a sectional view of an essential part in the vicinity of the exhaust brake showing the configuration of the exhaust-side pressure release means of the differential pressure generating means in the second embodiment of the present invention.
In the second embodiment, the outlet end of the air extraction passage 1 is connected to the downstream part of the exhaust brake 109 of the exhaust pipe 108.
That is, in FIG. 3, 109a is a valve body of the exhaust brake 109, and is provided to be rotatable around the valve shaft 109b. Reference numeral 109c denotes a pneumatic cylinder, which rotates the valve shaft 109b and the valve body 109a from the pneumatic cylinder 109c through a link 109d to change the passage area of the exhaust passage in the exhaust pipe 108. Reference numeral 111 denotes an exhaust gas purification device, which is installed on the downstream side of the exhaust brake 109.
The configurations of the exhaust brake 109 and the exhaust gas purification device 111 are known.
Reference numeral 1 denotes the air extraction passage, which is connected between the exhaust brake 109 of the exhaust pipe 108 and the exhaust gas purification device 111 via a flange 1f.

According to the second embodiment, during operation of the valve body 109a to close the exhaust brake 109, the exhaust pipe downstream portion of the exhaust brake 109 than at all times the nozzle chamber 30h in the pressure P ₁ becomes the low pressure 108 through the air extraction passage 1 within, so releasing the pressure in the link chamber 30b, the pressure P ₂ of the link chamber 30b is lower than the pressure P ₁ always nozzle chamber 30h, the nozzle chamber 30h and the link chamber 30b reliably to generate a pressure differential _P 1 -P ₂ during, pressing the nozzle vane 40 on the side wall 30f of the nozzle chamber 30h by differential pressure _P 1 -P _2, to suppress the vibration of the nozzle vanes 40, the Wear of the connecting portion of the link assembly 700 can be prevented.

  Furthermore, since the outlet side of the air extraction passage 1 is connected to a portion of the exhaust pipe 108 between the exhaust brake 109 and the exhaust gas purification device 111, the gas in the link chamber 30b mixed with the exhaust gas is exhausted. It can be introduced into the device 111 and purified along with the main exhaust gas.

  According to the present invention, it is possible to prevent the transmission of the vibration of the nozzle vane to the connecting portion of the link assembly that drives the nozzle vane by extremely simple means, thereby preventing the wear of the connecting portion and the variable nozzle mechanism. It is possible to provide an engine exhaust device having a variable displacement exhaust turbocharger capable of maintaining stable operation.

(A) is principal part sectional drawing of the variable nozzle mechanism installation part vicinity in the variable displacement type | mold exhaust turbocharger which concerns on 1st, 2nd Example of this invention, (B) is an AA arrow view in (A). FIG. It is a top view which shows the structure of the intake side pressure release means of the differential pressure | voltage production | generation means in 1st Example of this invention. It is principal part sectional drawing of the exhaust-brake vicinity which shows the structure of the exhaust side pressure release means of the differential pressure | voltage production | generation means in 2nd Example of this invention. It is sectional drawing which follows the axial center line of the variable displacement type | mold exhaust turbocharger to which this invention is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Air extraction passage 2 Air extraction hole 30b Link chamber 30f Side wall 30h Nozzle chamber 40 Nozzle vane 70 Variable nozzle mechanism 71 Lever plate 72 Pin 73 Drive ring 100 Engine 109 Exhaust brake 110 Exhaust turbo supercharger 111 Exhaust gas purification device 700 Link assembly

Claims (4)

A variable displacement exhaust turbo engine in which the displacement of the turbine is variable by a variable nozzle mechanism that transmits the driving force of the actuator to a nozzle vane rotatably supported by a turbine casing via a link assembly, and changes the blade angle of the nozzle vane. In an exhaust system for an engine having a supercharger and an exhaust brake device in an exhaust passage,
A pressure difference is generated between a nozzle chamber provided with the nozzle vane in the turbine casing and a link chamber formed in the turbine casing and housing the link assembly when the exhaust brake device is operated; An exhaust system for an engine, comprising: differential pressure generating means for pressing the nozzle vane against a side wall on one side of the nozzle chamber by a pressure difference.   The differential pressure generating means includes an air extraction passage connecting the link chamber and the intake passage of the engine, and an intake side pressure release means for releasing the pressure in the link chamber into the intake passage through the air extraction passage. The engine exhaust system according to claim 1, wherein   The differential pressure generating means includes an air extraction passage that connects the link chamber and a downstream exhaust passage of the exhaust brake device, and exhausts the pressure in the link chamber into the exhaust passage through the air extraction passage. 2. The engine exhaust system according to claim 1, comprising pressure release means.   An exhaust gas purification device is provided in the exhaust passage downstream of the exhaust brake device, and an outlet side of the air extraction passage of the exhaust side pressure release means is connected to a portion between the exhaust brake device and the exhaust gas purification device. The engine exhaust system according to claim 3, wherein

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