JP2000130175A - Variable capacity turbo charger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize a turbo charger and prevent the drop of turbine efficiency by improving the open/close action of a flow rate control valve. SOLUTION: The drive shaft of a flow rate control valve 40 for controlling the communication of an exhaust inlet 12a with an outer periphery scroll part 32 is rotatably provided in a turbine housing 12 so as to extend in nearly right angle direction for the axial direction of the shaft, and the flow rate control valve 40 is swingably provided on the end of the drive shaft positioning in the outer periphery scroll part 32 in response to the rotation of the drive shaft.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a variable capacity turbocharger for supercharging an internal combustion engine.

[0002]

2. Description of the Related Art As a conventional variable capacity turbocharger, for example, there is one disclosed in Japanese Patent Application Laid-Open No. 10-8977. The variable-capacity turbocharger includes a shaft, a turbine rotor fixed to one end of the shaft, and an exhaust inlet, an exhaust outlet, and an exhaust inlet and an exhaust inlet and an exhaust outlet communicating with the turbine rotor through the turbine rotor. A turbine housing having a scroll portion whose cross-sectional area gradually decreases, a compressor rotor fixed to the other end of the shaft and housed in the compressor housing, and a scroll portion radially extending into an inner circumferential scroll portion and an outer circumferential scroll portion. A partition wall which is divided and has a communication passage communicating between both scroll portions, and is swingably pivotally supported on a turbine housing via a drive shaft, and controls opening and closing of communication between an exhaust inlet and an outer scroll portion to form an outer periphery. A flow control valve capable of controlling the flow rate of exhaust gas to the scroll section.

In this variable capacity turbocharger, in a low speed region of an internal combustion engine having a small amount of exhaust gas, communication between an exhaust inlet and an outer scroll portion is cut off by a flow control valve, and exhaust gas flows only into an inner scroll portion. By obtaining a small exhaust inflow angle to the blades of the turbine rotor and a high exhaust flow velocity, the turbine rotor is accelerated to increase the supercharging pressure. Further, after the middle speed range where the amount of exhaust gas increases, the exhaust gas also flows into the outer scroll portion via the flow control valve, flows into the inner scroll portion via the communication passage, and the exhaust gas hits the turbine rotor. By decreasing the flow velocity and increasing the exhaust inflow angle, the acceleration of the turbine rotor is limited, and the supercharging pressure is kept constant.

[0004]

However, in the above-described conventional variable capacity turbocharger, the drive shaft is rotatably provided on the turbine housing so as to extend into the outer peripheral scroll portion in the axial direction of the shaft. The flow control valve is attached to the drive shaft so that the inside of the outer scroll part can be swung according to the rotation of the shaft, and the communication port between the exhaust inlet and the outer scroll part formed at the end of the partition wall on the exhaust inlet side can be opened and closed. Have been. For this reason, in order to secure the swing space of the flow control valve, the portion of the outer peripheral scroll portion that accommodates the flow control valve has to be formed in a radially outwardly projecting shape, and as a result, the turbine housing becomes large, There has been a problem that there is a great restriction when mounting on an internal combustion engine.

Further, when the flow control valve opens the communication port and the exhaust gas flows into the outer peripheral scroll portion, the projecting shape restricts the exhaust gas at the communication port and immediately reduces the volume of the accommodation portion of the flow control valve. After expanding in a large part, it is throttled in the outer scroll part, so the loss of exhaust gas flow is large,
There is also a problem that the efficiency of the turbocharger is reduced.

Therefore, the present invention provides an improved variable capacity turbocharger in which the opening / closing operation of the flow control valve is improved,
It is an object of the present invention to reduce the size of a turbocharger and to prevent a decrease in turbine efficiency.

[0007]

Technical means taken to solve the above problems include a shaft, a turbine rotor fixed to one end of the shaft, a housing for accommodating the turbine rotor, an exhaust inlet, and an exhaust gas. An outlet, the exhaust inlet and the exhaust outlet communicate with each other through the turbine rotor, a turbine housing having a scroll portion whose sectional area gradually decreases, and fixed to the other end of the shaft;
A compressor rotor housed in a compressor housing, a partition wall dividing the scroll portion radially into an inner peripheral scroll portion and an outer peripheral scroll portion, and a plurality of communicating portions communicating the inner peripheral scroll portion and the outer peripheral scroll portion. A communication passage, and a flow rate pivotally supported by the turbine housing via a drive shaft so as to be able to control opening and closing of communication between the exhaust inlet and the outer scroll portion to control an exhaust flow rate to the outer scroll portion. And a control valve, wherein the drive shaft is rotatably provided in the turbine housing so as to extend in a direction substantially perpendicular to the axial direction of the shaft, and is located in the outer peripheral scroll portion. The flow control valve is provided at an end of the drive shaft so as to swing in accordance with the rotation of the drive shaft.

According to the above-described means, the flow control valve swings around the drive shaft in the outer scroll portion in response to the rotation of the drive shaft provided to extend substantially perpendicular to the axial direction of the shaft. Since it moves, there is no need to make the portion of the outer peripheral scroll portion that accommodates the flow control valve a radially outwardly protruding shape in order to secure a swing space for the flow control valve.
Accordingly, the size of the turbine housing can be reduced, and the exhaust gas can smoothly flow along the wall surface of the outer scroll portion, thereby preventing a decrease in turbine efficiency.

In the above means, the partition wall is formed so that an inner peripheral surface thereof is continuous from an inner peripheral surface of the exhaust inlet, and the outer peripheral scroll portion is provided at an end of the partition wall on the exhaust inlet side. It is preferable that a communication port capable of communicating with the exhaust port is provided.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a variable capacity turbocharger according to the present invention will be described below with reference to the drawings.

In FIG. 1, the variable displacement turbocharger has a cylindrical bearing housing 10 having a shaft hole 10a formed therein, and a radial bearing 21 in the shaft hole 10a. A shaft 20 is rotatably supported via 22. The radial bearings 21 and 22 are rotatably fitted in the shaft hole 10a, and the movement in the axial direction to the sides facing each other is restricted by the snap ring. The radial bearing 22 is restricted from moving rightward in the figure by a step formed on the shaft 20. A small-diameter portion is formed on the left side of the shaft 20 fitted in the radial bearing 21, and a flange portion is formed on the right-hand end portion of the small-diameter portion to contact one end surface of the radial bearing 22. A cylindrical bush 23 is fitted. The bush 2
A bush 29 having a flange formed at the right end in the figure is fitted on the left side of the figure 3. Bush 2
An oil seal is fitted in an annular groove formed on the outer periphery of the bearing housing 9.
The inner peripheral cylindrical portion of the plate seal 25 fitted in the large-diameter hole formed on the left side of the 0 shaft hole 10a in the drawing slides in a liquid-tight manner. The compressor rotor 19 is fitted to a small diameter portion of the shaft 20 on the left side of the bush 29 in the drawing, and is fixed by a nut 27 screwed to an end of the small diameter portion. Thus, the bushes 23 and 29 are sandwiched between the illustrated right end surface of the compressor rotor 19 and the step portion of the small diameter portion of the shaft 20, and rotate integrally with the shaft 20 together with the compressor rotor 19. A thrust bearing 24 fixed to the right side of the large-diameter hole in the bearing housing 10 in the drawing is interposed between the flange portions of the bushes 23 and 29. The thrust bearing 24 includes the bearing housing 1
0, and communicates with oil passages for supplying oil to the radial bearings 21 and 22, and the bushes 23 and 29
An oil supply hole for supplying oil between the sliding portion and the flange portion is formed. In addition, the plate seal 25 includes
An oil shielding plate 26 having a hole through which the cylindrical portion of the bush 29 passes is fixed. A compressor housing 18 having an intake port 18a and an intake port 18b is hermetically fixed to the bearing housing 10, and a compressor rotor 19 is accommodated in the compressor housing 18.

A turbine rotor 13 is fixed to the right end of the shaft 20 in the figure. The turbine rotor 13 is housed in a second turbine housing 12 which is airtightly fixed via a gasket to a first turbine housing 11 fixed to the right end of the bearing housing 10 in the figure. The second turbine housing 12 has an exhaust inlet 12a
(See FIG. 2) and an exhaust outlet 12b are formed. An exhaust manifold of an internal combustion engine (not shown) is connected to the exhaust inlet 12a, and an exhaust outlet pipe (not shown) is airtightly connected to the exhaust outlet 12b. I have. Incidentally, in FIG.
Is a shielding plate whose outer peripheral end is sandwiched and fixed between the first turbine housing 11 and the bearing housing 10 and whose inner peripheral end extends to the back of the turbine rotor 13.

As shown in FIGS. 1 and 2, the second turbine housing 12 is provided with a scroll portion for guiding the exhaust gas introduced into the exhaust inlet 12 a to the outer periphery of the turbine rotor 13. The scroll portion includes an involute partition wall 30 provided in the second turbine housing 12.
An inner peripheral scroll groove 12d and an outer peripheral scroll groove 12c radially partitioned by are formed.
By closing the opening of 12c by the first turbine housing 11, the inner peripheral scroll part 31 and the outer peripheral scroll part 32 having a larger volume than the inner peripheral scroll part 31 are provided.
Are formed in a compartment. The inner and outer scroll portions 31 and 32 have a sectional area of the turbine rotor 1.
3 is provided so as to gradually decrease in the rotation direction (clockwise direction in FIG. 2), and communicates with the downstream end portion of the involute partition wall 30.

Further, a different inclined surface (first outer peripheral portion of the inner peripheral scroll portion 31 whose inner periphery is open to the outer peripheral portion of the blade of the turbine rotor 13) on the downstream side of the involute partition wall 30 is used. And a second surface), and a plurality of communication holes 30a communicating with the inner and outer scroll portions 31, 32 are formed. The first surface, which is the inclined surface on the upstream side of each communication hole 30a,
The second surface, which is a sloping surface on the downstream side of each communication hole 30a, extends tangentially to the inner circumferential scroll portion 31 at an angle nearly perpendicular to the rotation center of the turbine rotor 13. It extends to the peripheral scroll part 31 side. In the present embodiment, as shown in FIG. 2, the involute partition wall 30 is formed such that its inner peripheral surface is continuous from the inner peripheral surface of the exhaust inlet 12a.

The exhaust inlet 12 of the involute partition wall 30
As shown in FIG. 2, an opening 33 communicating between the outer peripheral scroll portion 32 and the exhaust inlet 12a is provided at the a-side end (upstream end).
Are formed. A flow control valve 40 that opens and closes the opening 33 by being seated on and separated from a valve seat formed on the outer edge of the opening 33 on the outer scroll portion 32 side is provided in the outer scroll portion 32. As shown in FIGS. 2 and 3, the flow control valve 40 extends in a direction perpendicular to the axial direction of the shaft 20, and is rotatably supported by the second turbine housing 12 via a bush 43. The end of the shaft 42 located inside the outer peripheral scroll portion 32 is connected via a lever 42. A well-known negative pressure actuator 45 is connected via a link 44 to the other end of the drive shaft 42 protruding outside the second turbine housing 12. Thus, when the drive shaft 42 is rotated via the negative pressure actuator 45 and the link 44, the flow control valve 40 swings around the drive shaft 42 together with the drive shaft 42 integrally with the lever 41, and the opening 33 Open / close control.

The operation of this embodiment having the above configuration will be described.

When an internal combustion engine (not shown) is started, supercharging by a variable capacity turbocharger is started. That is,
The exhaust gas flowing from the exhaust manifold into the exhaust inlet 12a drives the turbine rotor 13 to rotate, and the compressor rotor 19 rotates together with the shaft 20, thereby supercharging an internal combustion engine (not shown).

In a low speed range of the internal combustion engine having a small amount of exhaust gas, a negative pressure type actuator 4 is controlled by a control device (not shown).
5, no negative pressure is supplied from a negative pressure source (not shown), and the flow control valve 40 is in a closed state shown in FIG.
Therefore, the exhaust gas flowing from the exhaust manifold into the exhaust inlet 11a is supplied to the turbine rotor 13 only through the inner peripheral scroll portion 31, and the turbine rotor 13 is driven to rotate. This functions as a turbocharger having a small A / R (small scroll capacity) to obtain a high exhaust flow velocity, and exhaust gas flows in the tangential direction of the turbine rotor 13 via the inner peripheral scroll portion 31 (turbine rotor). 13) at a small inflow angle), the turbine rotor 13 is efficiently rotated, the turbine rotor 13 is accelerated, and the supercharging pressure is increased. At this time,
In the present embodiment, as described above, the involute partition wall 30 is formed so that its inner peripheral surface is continuous from the inner peripheral surface of the exhaust inlet 12a (see FIG. 2).
Since the flow of the exhaust gas is not greatly disturbed by the opening 33, the turbine efficiency is not reduced, and a desired turbine efficiency in a low speed range can be obtained.

After the middle speed range of the internal combustion engine where the amount of exhaust gas increases, a negative pressure is supplied from a negative pressure source (not shown) to the negative pressure type actuator 45, and the flow control valve 40 swings around the drive shaft 42. The opening 33 is opened. Therefore, the exhaust gas flowing from the exhaust manifold to the exhaust inlet 12 a flows into the inner peripheral scroll part 31 and also flows into the outer peripheral scroll part 32 through the opening 33. Outer scroll part 31
The exhaust gas that has flowed into the inner scroll portion 31 through the communication hole 30 a of the involute partition wall 30 toward the rotation center of the turbine rotor 13 and re-joins with the exhaust gas flowing into the inner circumferential scroll portion 31. In addition, the flow of the exhaust gas in the inner peripheral scroll portion 31 in the tangential direction of the turbine rotor 13 is changed to the flow toward the rotation center of the turbine rotor 13, and the flow velocity of the exhaust gas impinging on the turbine rotor 13 is reduced. As a result, the exhaust gas hits the blades of the turbine rotor 13 at a small inflow angle,
The efficiency of rotating the turbine rotor 13 is reduced, the rotation of the turbine rotor 13 is suppressed from rising, and the supercharging pressure is kept constant.

In this embodiment, the drive shaft 42 for swinging the flow control valve 40 is provided so as to extend in a direction perpendicular to the axial direction of the shaft 20. Therefore, unlike the conventional apparatus, the portion of the outer peripheral scroll portion 32 in which the flow control valve 40 is accommodated does not need to be formed in a radially outwardly protruding shape in order to secure the swing space of the flow control valve 40. As shown in the figure, the radially inner wall of the outer peripheral scroll portion 32 is kept in an involute curve. As a result, the size of the second turbine housing 12 can be reduced, the size of the variable capacity turbocharger can be reduced, and the mountability to the internal combustion engine can be improved. In order to secure a swing space for the flow control valve 40, a portion of the outer peripheral scroll portion 32 in which the flow control valve 40 is accommodated has a protruding shape in the axial direction of the shaft 20. There is no problem for the turbocharger because it is a dead space part or a part that is hardly restricted by mounting.

Further, when the flow control valve 40 is opened, the exhaust gas flows smoothly along the inner wall surface of the outer scroll portion 32 having an involute curve. Turbine efficiency can be obtained.

[0022]

As described above, according to the first aspect of the present invention, as in the conventional apparatus, the portion of the outer peripheral scroll portion in which the flow control valve is accommodated for securing the swing space of the flow control valve is provided. There is no need to form a radially outwardly projecting shape, and the radially outwardly inner wall of the outer peripheral scroll portion 32 is maintained in a desired curved shape. As a result, the size of the turbine housing can be reduced, and the size of the variable capacity turbocharger can be reduced.
The mountability on an internal combustion engine can be improved.

Further, when the flow control valve is opened, the exhaust gas flows smoothly along the inner wall surface of the outer peripheral scroll portion having a desired curved shape, so that the loss of the exhaust gas flow is small, and the turbine efficiency after the middle speed range is reached. Can be improved.

According to the second aspect of the present invention, the exhaust gas can smoothly flow into the inner peripheral scroll portion along the partition wall without disturbing the flow of the exhaust gas. The size can be reduced, and the efficiency of the turbocharger can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of a variable capacity turbocharger according to the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a view as seen in the direction of arrow B in FIG. 2;

DESCRIPTION OF SYMBOLS 10 Bearing housing 11 First turbine housing 12 Second turbine housing 12a Exhaust inlet 12b Exhaust outlet 13 Turbine rotor 18 Compressor housing 19 Compressor rotor 20 Shaft 30 Involute partition wall 30a Communication hole 31 Inner peripheral scroll part 32 Outer peripheral scroll Part 33 Opening (communication port) 40 Flow control valve 42 Drive shaft

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3G005 EA04 EA15 EA16 FA05 FA52 GA03 GB02 GB09 GB24 GB72 GC05 GD17 GD18 JA39

Claims (2)

[Claims] 1. A shaft, a turbine rotor fixed to one end of the shaft, a housing for accommodating the turbine rotor, and an exhaust inlet, an exhaust outlet, and the exhaust inlet and the exhaust outlet connected through the turbine rotor. A turbine housing having a scroll portion that is communicated with and having a cross-sectional area gradually reduced, a compressor rotor fixed to the other end of the shaft, and housed in a compressor housing, and a radially inner scroll portion including the scroll portion in a radial direction. A partition wall divided into an outer peripheral scroll portion, and a plurality of communication paths communicating the inner peripheral scroll portion and the outer peripheral scroll portion,
A flow control valve pivotably supported by the turbine housing via a drive shaft to control opening and closing of communication between the exhaust inlet and the outer scroll portion to control an exhaust flow rate to the outer scroll portion; In the variable capacity turbocharger provided, the drive shaft is rotatably provided on the turbine housing so as to extend in a direction substantially perpendicular to the axial direction of the shaft, and the drive shaft located in the outer peripheral scroll portion. A variable displacement turbocharger, wherein the flow control valve is provided at an end of the valve so as to be swingable in accordance with the rotation of the drive shaft. 2. The partition wall has an inner peripheral surface formed so as to be continuous from an inner peripheral surface of the exhaust inlet, and the outer peripheral scroll portion and the exhaust inlet are provided at an end of the partition wall on the exhaust inlet side. The valve opening / closing timing control device according to claim 1, further comprising a communication port that can communicate with the valve.