JP4281723B2 - Variable capacity turbocharger - Google Patents

Description

  The present invention relates to a variable capacity turbocharger.

  As a conventional technique related to a variable capacity turbocharger, for example, there is one disclosed in Patent Document 1.

In this conventional variable displacement turbocharger, a ring nozzle in which a large number of movable nozzle vanes are arranged in a scroll portion between a turbine rotor and a turbine housing having an involute inner wall surface is arranged. And by changing the angle of each nozzle vane, the angle which the exhaust gas which flows through a scroll part is adjusted, and the force which the turbine blade of a turbine rotor receives is adjusted as follows. In the low speed range where the exhaust gas flow rate is small, the turbine rotor is efficiently rotated by increasing the torque received by the turbine blades so that the exhaust gas flows in the tangential direction of the turbine rotor. The torque received by the turbine blades is reduced by allowing the exhaust gas to flow toward the rotating shaft of the turbine rotor, so that the turbine rotor is not rotated more than necessary.
Japanese Utility Model Publication 8-7061

  However, in the variable displacement turbocharger described above, a link mechanism that simultaneously changes the angles of a large number of nozzle vanes is required. Also, the scroll part has a high ambient temperature of nearly 1000 ° C., and molding a large number of nozzle vanes and link mechanisms with a heat-resistant material is problematic in terms of cost. Further, the exhaust gas contains many carbides and carbonized scales, which may cause problems in terms of reliability, for example, affecting the movement of the link mechanism.

  The present invention provides a variable capacity turbocharger that solves the above-mentioned problems of the prior art.

The means taken in the inventions of claim 1 and claim 2 are: a variable capacity turbocharger having a shaft, a turbine rotor having turbine blades attached to one end of the shaft, and the turbine rotor; A turbine housing that forms a scroll portion on the outer periphery of the shaft, a compressor rotor attached to the other end of the shaft, a compressor housing that houses the compressor rotor, and a turbine housing that is attached to the turbine housing and that cuts the scroll portion in the circumferential direction. A single partition wall that radially divides into an inner scroll and an outer scroll, each of which gradually decreases in area, and extends so as to continuously surround the turbine rotor in the circumferential direction, and is formed on the partition wall. A plurality of scrolls always communicating with the outer scroll; And a switching means for switching between a state in which exhaust gas flows only to the inner scroll and a state in which exhaust gas flows to both the inner scroll and the outer scroll, and the communication portion is connected to the turbine rotor. It has an inclined surface cut in the rotation direction. Therefore, the exhaust gas introduced into the scroll part flows into both the inner scroll and the outer scroll. However, when supercharging is required, the exhaust gas is caused to flow to the inner scroll located near the turbine rotor by the switching means. When torque is applied to the turbine rotor by the gas, and the supercharging is not required, the switching means causes the exhaust gas to flow to the outer scroll, and the exhaust gas flows into the inner scroll through the communication portion to reduce the torque applied to the turbine rotor. Can do that.

The means taken in the invention of claim 3 is that the partition wall is radially divided into the inner scroll and the outer scroll over the entire circumference of the turbine rotor.

The means taken in the invention of claim 4 is that the communication portion is formed in the partition wall in the circumferential direction so as to be separated over the entire circumference of the turbine rotor.

  According to the first aspect of the present invention, a plurality of communicating portions are formed in a single partition wall that extends so as to continuously surround the turbine rotor in the circumferential direction and is divided into an inner scroll portion and an outer scroll portion, The communicating part has an inclined surface cut in the rotating direction of the turbine rotor, and the switching means switches between a state in which exhaust gas flows only to the inner scroll and a state in which exhaust gas flows to both the inner scroll and the outer scroll. Since it is configured, rotational torque is given to the turbine rotor by the exhaust gas flowing through the inner scroll located near the turbine rotor in the low speed region where the exhaust gas is low, and the exhaust gas flowing through the outer scroll is communicated in the high speed region where there is a lot of exhaust gas. The torque that flows into the inner scroll through the section and is applied to the turbine rotor can be reduced.Since the scroll portion does not require a large number of nozzle vanes and a link mechanism for adjusting these angles, it is advantageous in terms of cost and can be a variable capacity turbocharger that does not cause problems in terms of reliability. .

  An embodiment of a variable capacity turbocharger according to the present invention will be described with reference to the drawings.

  FIG. 1 shows a cross section of a variable capacity turbocharger according to a first embodiment using the present invention.

  The compressor housing 10 is provided with a compressor introduction port 12, a compressor discharge port 14, and ring-shaped scrolls 16 and 18. The scrolls 16 and 18 extend from a position adjacent to the compressor discharge port 14 by the outer periphery of the compressor housing 10 and communicate with the compressor discharge port 14. And it is comprised so that a cross-sectional area may be expanded gradually as the compressor discharge port 14 is approached. A diffuser 20 that partitions the scrolls 16 and 18 is attached to the compressor housing 10 with bolts 22.

  A lubricating oil inlet 32 is formed on the outer periphery of the bearing housing 30 adjacent to the compressor housing 10. The lubricating oil introduction port 32 communicates with branch oil passages 36, 38, and 40 through an oil passage 34 formed in the axial direction, and supports the shaft 50 and the shaft 50 with lubricating oil supplied from an oil pump (not shown). The bearings 42, 43, 44, 45, and 46 are supplied to the sliding surfaces. The lubricating oil supplied to the sliding surface is discharged from the lubricating oil discharge port 54 through a space 52 formed in the bearing housing 30. 56 is a cooling water passage for cooling the variable capacity turbocharger, and 58 is a plate seal. In addition, 59 is a piece of the bearing housing 30 divided in order to mold each part provided in the bearing housing 30.

  An exhaust gas introduction port 62 and an exhaust gas discharge port 64 are formed in the turbine housing 60 adjacent to the bearing housing 30. In addition, as shown in FIG. 2, an involute inner wall surface is provided on the inner peripheral side of the turbine housing 60 to form a scroll portion. An inner scroll 66 and an outer scroll 68 having a larger volume than the inner scroll 66 are formed in the scroll portion by an involute partition wall 67 attached to the turbine housing 60. The involute partition wall 67 has communication holes (communication portions) of different inclined surfaces (first surfaces) 67 a and (second surfaces) 67 b, and communicates the inner scroll 66 and the outer scroll 68. . The extending direction of the inclined surface 67a toward the inner scroll 66 is a gentle inclined surface that approximates the tangent to the turbine rotor 80 that rotates in the direction opposite to the clockwise rotation, while the inclined surface 67b moves toward the inner scroll 66. The extending direction is an inclined surface that approaches the rotation center of the turbine rotor 80 and is nearly vertical. A switching valve (switching means) 90 is provided on the exhaust gas inlet 62 side of the involute partition wall 67. The switching valve 90 has a distal end extending to the inner peripheral side and the outer peripheral side of the turbine housing 60, and a rotary shaft 94 positioned at the distal end of the exhaust gas inlet 62 of the involute partition wall 67 by a rotating means (not shown). 2 is switched between an inlet closing position 92 of the outer scroll 68 indicated by a solid line in FIG. 2 and an inlet closing position 96 of the inner scroll 66 indicated by a broken line in FIG.

  As shown in FIG. 1, the shaft 50 supported by bearings 42, 43, 44, 45, 46 of the bearing housing 30 has a compressor rotor 70 fixed by bolts 74 and nuts 76 at the end on the compressor housing 10 side. The turbine rotor 80 is attached so as not to be relatively rotatable, and the turbine rotor 80 is attached so as not to be relatively rotatable at the end on the turbine housing 60 side. A compressor blade 72 and a turbine blade 82 extending in the radial direction are attached to the compressor rotor 70 and the turbine rotor 80, respectively. By rotating the turbine rotor 80, the compressor rotor 70 rotates integrally. Yes.

  Next, the operation of the variable capacity turbocharger of the first embodiment will be described.

  The exhaust gas introduced from the exhaust gas introduction port 62 is guided to the scroll portion inside the turbine housing 60 and is discharged from the exhaust gas discharge port 64 by rotating the turbine rotor 80. The rotation of the turbine rotor 80 is transmitted to the compressor rotor 70 via the shaft 50, and the compressor rotor 70 compresses the intake gas (atmosphere) supplied to the engine led to the compressor introduction port 12 and the engine via the compressor discharge port 14. High-density intake gas is introduced to the intake port.

  In the low-speed region where the exhaust gas flow rate is small, the exhaust gas introduction port 62 is configured with the switching valve 90 as a closed position 92 for closing the introduction port of the outer scroll 68 in order for the exhaust gas to efficiently rotate the turbine rotor 80. The exhaust gas taken in from is led only to the inner scroll 66 having a small volume. Since the exhaust gas guided to the inner scroll 66 and whose flow velocity is increased flows in the tangential direction of the turbine rotor 80 (abuts against the turbine blades 82 of the turbine rotor 80 at a large inflow angle), the turbine rotor 80 can be efficiently rotated. it can. On the other hand, in the high speed region where the exhaust gas flow rate is large, the exhaust gas does not rotate the turbine rotor 80 more than necessary, so that the switching valve 90 is set to the closed position 96 where the inlet of the inner scroll 66 is closed. The exhaust gas taken in from the outside is led to the outer scroll 68. While the exhaust gas guided to the outer scroll 68 flows through the outer scroll 68, the turbine rotor 80 is not rotated. Further, when the exhaust gas passes through the communication portion formed by the inclined surfaces 67a and 67b and flows into the inner scroll 66, the exhaust gas hits the inclined surface 67b by the inclined surface 67a at a moderate angle, The exhaust gas flows along the slope toward the rotation center of the turbine rotor 80 (the flow velocity is low and the turbine blade 80 hits the turbine blades 82 with a small inflow angle), and the efficiency of rotating the turbine rotor 80 is remarkably high. It is possible to prevent the turbine rotor 80 from rotating more than necessary. In the middle speed range, it is possible to obtain a desired supercharging pressure by controlling the position of the switching valve to an appropriate position (for example, a position where both the inner scroll and the outer scroll are opened).

  FIG. 3 shows the inside of the turbine housing 60 of the variable capacity turbocharger of the second embodiment corresponding to FIG.

  In the switching valve 100 shown in FIG. 3, the hinge portion 102 and the valve portion 104 are fixed with bolts 106, and the opening / closing of the introduction port of the outer scroll 68 is switched. Further, the communication portion provided in the involute partition wall 67 is disposed only on the downstream side of the involute partition wall 67.

  The switching valve 100 of this embodiment closes the inlet of the outer scroll 68 and flows the exhaust gas into the inner scroll 66 in a low speed region where the exhaust gas flow rate is small. On the other hand, in a high speed region where the exhaust gas flow rate is large, the switching valve 100 is rotated to a position indicated by a broken line 108 by a rotating means (not shown), and the exhaust gas taken in from the exhaust gas inlet 62 flows to the outer scroll 68 and the inner scroll 66. By flowing the exhaust gas through the outer scroll 68 and the inner scroll 66, the exhaust gas flowing through the outer scroll flows into the inner scroll 66 through the communication portion, and the direction of this flow is directed toward the rotation center of the turbine rotor 80. Therefore, it acts like an air curtain on the flow of exhaust gas flowing through the inner scroll 66, and the angle of the flow of exhaust gas flowing through the inner scroll 66 can be directed to the turbine rotor 80 side. It can be prevented from rotating.

  4 and 5 show the inside of the turbine housing 60 of the variable capacity turbocharger of the third embodiment corresponding to FIG.

  The configuration shown in FIGS. 4 and 5 is the same as the second embodiment shown in FIG. 3 for the inner scroll 66, the involute partition wall 67, the outer scroll 68, the turbine rotor 80, the turbine blade 82, and the switching valve 100. is there.

  In the third embodiment, the vane 110 is disposed at the innermost part of the outer scroll 68. The vane 110 has a substantially crescent shape along the outer periphery of the turbine blade 82, and includes a thick end portion 110a and a tapered end portion 110b. Further, the vane 110 is held so as to be freely rotatable within a predetermined range by a vane shaft 112 disposed in parallel with a shaft 50 (see FIG. 1) that supports the turbine rotor 80. That is, in a low speed region where the exhaust gas flow rate is small, the exhaust gas flows only to the inner scroll 66 by closing the switching valve 100 as shown in FIG. 4, so that the exhaust gas flows to the vane shaft 112 and the vane 110. The region between the thick end portion 110a and the thick end portion 110a is urged, and the thick end portion 110a comes into contact with the flange portion 61 of the inner scroll 60 as shown in FIG. On the other hand, in the high speed region where the exhaust gas flow rate is large, the exhaust gas flows between the vane shaft 112 and the vane 110 by allowing the exhaust gas to flow to the outer scroll 68 by opening the switching valve 100 as shown in FIG. The region between the tapered end portion 110b and the tapered end portion 110b is urged, and the tapered end portion 110b comes into contact with the flange portion 61 of the inner scroll 60 as shown in FIG.

  As described above, by arranging the vane 110 that can freely rotate within a predetermined range in the innermost part of the outer scroll 68, the most exhaust gas out of the exhaust gas outlets flowing through the outer scroll 68 flows toward the turbine blades 82. The angle of the innermost part which is a part can be changed according to the flow of exhaust gas. Although the vane 110 can be driven by an actuator such as a motor, in this embodiment, the angle is adjusted by the flow of exhaust gas without using an actuator. There can be no reliable configuration.

  Further, when the supercharging pressure is not required, the conventional supercharging pressure is required because the switching valve 90 and the switching valve 100 can prevent the turbine rotor 80 from rotating more than necessary by flowing the exhaust gas to the outer scroll. If not, it is not necessary to provide a bypass passage through which exhaust gas flows.

  In the first and second embodiments, the switching of the switching valve 90 and the switching valve 100 is switched by detecting the speed. However, the switching may be performed by detecting the amount of exhaust gas or the state of the engine load. Is possible.

  As described above, in the above-described embodiment, a plurality of communication portions are formed on a single partition wall that extends so as to continuously surround the turbine rotor in the circumferential direction and is divided into an inner scroll portion and an outer scroll portion. The communication portion has an inclined surface cut in the rotating direction of the turbine rotor, and the switching means switches between a state in which exhaust gas flows only to the inner scroll and a state in which exhaust gas flows to both the inner scroll and the outer scroll. Therefore, in the low speed region where the exhaust gas is low, rotational torque is given to the turbine rotor by the exhaust gas flowing through the inner scroll located near the turbine rotor, and in the high speed region where the exhaust gas is large, the outer scroll flows. Exhaust gas flows into the inner scroll through the communication part and reduces the torque applied to the turbine rotor. It can be.

  Further, since the vane is formed at the innermost scroll and the outermost scroll, the flow direction of the exhaust gas at the junction of the inner scroll and the outer scroll can be changed by the vane to obtain a desired angle.

  Further, since the vane is supported by the vane shaft parallel to the shaft and freely rotated within a predetermined range, an actuator such as a motor for rotating the vane within the predetermined range is not required, and the exhaust gas flowing through the inner scroll or the outer scroll is not required. The vane angle can be set according to the gas flow rate.

  Further, the communication portion has a first surface gently cut in the rotational direction of the turbine rotor provided on the upstream side of the involute partition wall and a second surface cut sharply in the rotational direction of the turbine rotor provided on the downstream side of the involute partition wall. When the exhaust gas flowing through the outer scroll flows into the inner scroll through the communication portion, the flow is directed toward the rotating shaft of the turbine rotor, resulting in a small flow of rotational torque applied to the turbine rotor. The momentum of the inner scroll can be blocked.

  Further, since the switching valve for closing the outer scroll is provided as the switching means, it is possible to select whether or not the exhaust gas flows to the outer scroll, and it is located near the turbine rotor particularly in the low speed region where the exhaust gas is small. By controlling the exhaust gas to flow to the inner scroll, it is possible to efficiently apply torque to the turbine rotor. Further, by using the switching valve, the only member that needs to move in the scroll portion that becomes high temperature is the switching valve, and a highly reliable variable capacity turbocharger can be obtained.

  In addition, since the switching valve is attached to the end of the involute partition wall on the scroll inlet side and closes at least one of the inner scroll and the outer scroll, the switching valve causes the exhaust gas flowing through the scroll portion to flow between the inner scroll and the outer scroll. It can be selected between the scroll and the turbine rotor is efficiently torqued by controlling the exhaust gas to flow to the inner scroll located near the turbine rotor, especially in the low speed range where the exhaust gas is low. be able to.

  In addition, since the communication portion is provided on the downstream side of the scroll portion of the involute partition wall, the turbine rotor driving portion where the communication portion is not provided on the involute partition wall on the outer periphery of the turbine rotor, and the turbine rotor provided with the communication portion on the involute partition wall The non-driving part can be clarified, and the characteristic of the variable capacity turbine can be easily determined by determining the ratio of the turbine rotor driving part and the turbine rotor non-driving part at the design stage.

It is sectional drawing of the variable capacity | capacitance turbocharger of the 1st Embodiment of this invention. FIG. 2 is a cross-sectional view taken along line AA in FIG. 1. It is drawing corresponding to FIG. 2 of the variable capacity | capacitance turbocharger of the 2nd Embodiment of this invention. It is drawing corresponding to FIG. 2 of the variable capacity | capacitance turbocharger of the 3rd Embodiment of this invention (state which the switching valve closed). It is drawing corresponding to FIG. 2 of the variable capacity | capacitance turbocharger of the 3rd Embodiment of this invention (the state which open | released the switching valve).

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Compressor housing 50 ... Shaft 60 ... Turbine housing 66 ... Inner scroll 67 ... Involute partition wall 67a ... 1st surface 67b ... 2nd surface 68 ... Outer scroll 70 ... compressor rotor 80 ... turbine rotor 82 ... turbine blades 90, 100 ... switching valve (switching means)
110 ... Vane 112 ... Vane shaft

Claims (4)

A shaft,
A turbine rotor with turbine blades attached to one end of the shaft;
A turbine housing that houses the turbine rotor and forms a scroll portion on an outer periphery of the turbine rotor;
A compressor rotor attached to the other end of the shaft;
A compressor housing that houses the compressor rotor;
The scroll portion is attached to the turbine housing, and the scroll portion is radially divided into an inner scroll and an outer scroll whose cross-sectional area gradually decreases in the circumferential direction, and extends so as to continuously surround the turbine rotor in the circumferential direction. A single partition wall,
A plurality of communicating portions formed on the partition wall and always communicating with the inner scroll and the outer scroll;
Switching means for switching between a state in which exhaust gas flows only to the inner scroll and a state in which exhaust gas flows to both the inner scroll and the outer scroll;
The communication portion is a variable capacity turbocharger having an inclined surface cut in a rotating direction of the turbine rotor. A shaft,
  A turbine rotor with turbine blades attached to one end of the shaft;
  A turbine housing that houses the turbine rotor and forms a scroll portion on an outer periphery of the turbine rotor;
  A compressor rotor attached to the other end of the shaft;
  A compressor housing that houses the compressor rotor;
  The scroll portion is attached to the turbine housing, and the scroll portion is radially divided into an inner scroll and an outer scroll whose cross-sectional area gradually decreases in the circumferential direction, and extends so as to continuously surround the turbine rotor in the circumferential direction. A single partition wall,
  A plurality of communicating portions formed on the partition wall and always communicating with the inner scroll and the outer scroll;
  Switching means for switching between a state in which exhaust gas flows only to the inner scroll and a state in which exhaust gas flows to both the inner scroll and the outer scroll;
  The communication part has an inclined surface cut in the rotational direction of the turbine rotor,
  In the circumferential upstream side portion and the circumferential downstream side portion of the scroll portion that are adjacent to each other through the communication portion of the partition wall, the circumferential downstream side portion is more in the turbine rotor than the circumferential upstream portion. Variable capacity turbocharger that is not located outside in the radial direction. 3. The variable capacity turbocharger according to claim 1, wherein the partition wall is radially divided into the inner scroll and the outer scroll over the entire circumference of the turbine rotor. The variable capacity turbocharger according to claim 3, wherein the communication portion is formed in the partition wall so as to be separated in the circumferential direction over the entire circumference of the turbine rotor.

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