JPH0416607B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a radial inflow type variable displacement turbine, and particularly to a variable displacement turbine suitable as an exhaust turbine in a turbocharger.

<Prior art> In a radial inflow turbine used as an exhaust turbine for a turbocharger, it is sometimes desirable to maintain a supercharging effect even in a region where the engine rotational speed is low. , it is preferable to increase the inflow velocity of the fluid by narrowing the passage on the upstream side of the turbine wheel. However, when the passage is narrowed in this way, the inlet pressure of the turbine, that is, the back pressure against the exhaust gas of the engine increases, which causes a disadvantage that the efficiency of the engine is reduced.

Therefore, as described in Japanese Patent Publication No. 38-7653, a plurality of movable vanes are arranged in an annular manner in the nozzle part where exhaust gas flows from the turbine scroll to the turbine wheel, and these movable vanes are tilted. By configuring the turbine so that the actual opening area of the nozzle formed between these vanes changes, it is possible to secure the supercharging effect even in the low speed range of the engine, and to maintain the supercharging effect in the mid to high speed range of the engine. In some cases, it is possible to keep the back pressure against the exhaust gas of the engine small. However, according to the above configuration, since these vanes are arranged in a region where the fluid velocity is relatively high,
Fluid resistance loss tends to be relatively large,
Therefore, there is a problem that the efficiency of the turbine decreases. In addition, since the nozzle is formed between adjacent movable vanes, especially in areas where the nozzle opening area is small, even a slight deviation in the tilting angle of the vane will cause the nozzle and opening area to be affected. tends to change significantly, and there are difficulties in controlling the accuracy. Particularly when such a turbine is utilized as an exhaust turbine in a turbocharger, it is difficult to reliably adjust these movable vanes due to their exposure to the high temperature exhaust gas stream.

As disclosed in Japanese Unexamined Patent Publication No. 53-136113, there is also a structure in which a flap forming a part of the wall of the scroll passage of the turbine casing can be tilted to vary the cross-sectional area of the scroll passage. It has become publicly known. Although this type of variable nozzle structure has a simple structure and can adjust the velocity of fluid flowing into the turbine wheel with relatively little resistance loss, the variable nozzle structure does not necessarily have a sufficiently wide variable range. In addition, especially when the flap opening degree is large, the flow of fluid toward the turbine wheel is disturbed, and the flow velocity distribution becomes uneven, which causes a problem in that the efficiency of the turbine decreases.

<Problems to be Solved by the Invention> In view of the problems of the prior art, the main object of the present invention is to achieve relatively low fluid flow resistance, high control accuracy, and a turbine wheel control system. It is an object of the present invention to provide a radial inflow type variable capacity turbine which is improved so as to improve turbine efficiency by uniformizing the flow velocity distribution of fluid flowing toward the turbine, and to achieve a wide range.

<Means for Solving the Problems> According to the present invention, this object includes a turbine wheel, an inlet nozzle formed at a position facing the outer periphery of the turbine wheel, and an inflow nozzle formed further on the outer periphery of the turbine wheel. In a radial inflow type variable capacity turbine having a turbine scroll, the inside of the turbine scroll is divided into an inflow passage and an outer circumferential passage on a certain circumference outside the inflow nozzle, each of which has a portion. A fixed vane and a movable vane each having an arc shape are arranged in an annular manner, and the movable vane is tilted inward from the circumference using one end thereof as a fulcrum, so that the fixed vane and the movable vane face each other. This is achieved by providing a radial inflow variable capacity turbine characterized in that a variable nozzle is formed between the edges of the radial inflow type variable capacity turbine. In particular, it is preferable to use a plurality of sets of fixed vanes and movable vanes, and to make the size of the variable nozzle along the axial direction of the turbine wheel larger than the size of the inflow nozzle.

<Function> In this way, the variable nozzle is provided in a portion with a relatively large cross-sectional area of the flow path, so that the resistance loss of the fluid can be kept low. Furthermore, since the variable nozzle is annularly provided on the outer periphery of the turbine wheel, even when the nozzle opening is large, the flow velocity distribution of the fluid flowing into the turbine wheel can be made uniform. Moreover, since one side of the nozzle component is fixed, the nozzle rigidity can be increased, and by making the variable nozzle dimension relatively large along the axial direction of the turbine wheel, the side leakage amount of the variable nozzle part can be reduced. Since it can be relatively reduced, it is possible to achieve improved stability in controlling the opening degree of the variable nozzle.

<Examples> Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 and 2 show an engine turbocharger to which a radial inflow type variable capacity turbine according to the present invention is applied. This turbocharger has a casing consisting of a compressor casing 1 that forms a scroll of the compressor part, a back plate 2 that closes the back side of the compressor casing, and a structure that pivotally supports the main shaft of the turbocharger and lubricates the bearing. It has a built-in lubricating part casing 3 and a turbine casing 4 forming a scroll of the turbine section.

A scroll passage 5 and an axial passage 6 are formed inside the compressor casing 1, and a compressor is provided in the center of the scroll passage 5 and in an area adjacent to the inner end side of the axial passage 6. A wheel 7 is provided. The compressor wheel 7 is attached to one end of a main shaft 8 of a turbocharger rotatably supported in the center of the lubricating part casing 3 in a manner described later. On the compressor side, the scroll passage 5 constitutes an intake outlet passage, and the axial passage 6 constitutes an intake inlet.

The compressor casing 1 and the back plate 2 are integrated by screwing bolts 10 onto the outer periphery of the compressor casing 1 via a ring member 9. Casing 3 is connected.

The main shaft 8 is pivotally supported in the bearing holes 11 and 12 formed inside the lubricating part casing 3 by the radial bearing metal 13 as described above. Further, a thrust bearing metal 14 is interposed between the back plate 2 and the end face of the lubricating part casing 3, and a collar 15, a thrust bearing metal 14, a bushing 16, and a compressor are attached to the stepped part of the main shaft 8. By fitting the wheels 7 in this order and screwing the nut 18 onto the threaded portion 17 cut into the compressor side end of the main shaft 8, the main shaft 8 is supported in the thrust direction and the compressor wheel 7 is mounted. .
Note that the collar 15 functions as a spacer for setting the clamping pressure of the thrust bearing metal 14.

When tightening the nut 18, by grasping the hexagonal section 19 provided at the free end of the threaded portion 17 with another tool, it is possible to prevent the main shaft 8 from rotating together, and also to prevent the main shaft 8 from rotating at the same time. The inconvenience of applying excessive torsional force is avoided.

The turbine casing 4 defines therein a scroll passage 21, an inlet opening 21a thereof opening in the tangential direction, an outlet passage 22 extending in the axial direction, and an opening 22a thereof.

A back plate 23 is interposed between the turbine casing 4 and the lubricating part casing 3, and has a flange 23a formed outwardly on its outer periphery. The connection between the turbine casing 4 and the lubricating part casing 3 is achieved by tightening a nut 26 through a ring member 25 to a stud bolt 24 screwed onto the side of the turbine casing 4. This is done by sandwiching the outer peripheral part of the lubricating part casing 3 and the outward flange 23a of the back plate 23 between the ring member 25 and the ring member 25.

A fixed vane member 27 is disposed at the center of the scroll passage 21 to partition the inside of the scroll passage into an outer peripheral portion 21b and an inflow passage 21c. This fixed vane member 27 includes a cylindrical portion 28a formed in the center, a disk portion 28b formed radially outward from an axially intermediate portion of the cylindrical portion 28a, and a lubricating member from the outer peripheral portion of the disk portion. A fixed vane 29 is provided to protrude along the axial direction toward the casing 3, and a turbine wheel 30 formed on the other end side of the main shaft 8 is received inside the cylindrical portion 28a. The cylindrical portion 28a protrudes away from the outlet opening 22a so as to surround the outer periphery of the turbine wheel 30 with a small gap between the cylindrical portion 28a and the inner peripheral side surface of the back plate 23. To,
A fixed nozzle N serving as an inflow nozzle facing the outer periphery of the turbine wheel 30 is separated. The cylindrical portion 28a is fitted into the inner end of the outlet passage 22 via a metal seal ring 31, and the axial end of the fixed vane 29 is coupled to the back plate 23 with bolts 32. .

As shown in FIG. 2, four fixed vanes 29 are formed on the outer periphery of the fixed vane member 27 so as to concentrically surround the turbine wheel 30. These fixed vanes 29 each have a partial arc shape, and are provided at equal widths and equal intervals along the circumferential direction. The space between these fixed vanes 29 is opened and closed by a movable vane 34 fixed to the free end of a pin 33 rotatably attached to the back plate 23. These movable vanes 3
4 has an arc shape with the same curvature as the fixed vane 29, and is located on approximately the same circumference. Further, these movable vanes 34 are pivoted at positions close to the circumferential end edges of the corresponding fixed vanes 29, and are configured to be able to tilt only toward the inside of the circumference. In the most outwardly tilted state, both vanes 29, 34 are formed in a continuous airfoil shape. Therefore, these fixed vanes 29 and the corresponding movable vanes 34 are connected to the outer peripheral path 21b of the scroll passage 21.
The four vanes each form a leading edge portion and a trailing edge portion for fluid flowing through the vanes. The pins 33 that support these movable vanes 34 are each connected to a drive actuator (not shown) via appropriate link mechanisms 35, and the inclination angle of these movable vanes 34 is adjusted by a separate control signal. be done.

Further, a shield plate 36 extending to the back of the turbine wheel 30 is interposed between the back plate 23 on the turbine side and the lubricating part casing 3, and the heat of the exhaust gas flowing through the exhaust turbine part is transferred to the lubricating part casing 3. This prevents the air from being transmitted to the inside of the casing 3. In addition, in order to prevent exhaust gas from the turbine side from leaking toward the inside of the lubricating part casing 3, the main shaft 8 is connected to the center hole 37 of the lubricating part casing 3.
An annular groove 38 functioning as a labyrinth groove is recessed in a portion penetrating the groove.

Next, the lubrication system for this turbocharger will be explained.

A lubricating oil introduction hole 40 is bored in the upper end of the lubricating part casing 3 in FIG. The lubricating oil is supplied to the radial bearing metal 13 and the thrust bearing metal 14 through a drilled lubricating oil passage 41. The lubricating oil discharged from each lubricating part is transferred to the lubricating part casing 3.
The lubricating oil is discharged from the lubricating oil outlet 42 defined within the
The oil is collected in an oil sump (not shown).

In particular, in order to prevent the lubricating oil supplied to the thrust bearing metal 14 from adhering to the outer circumferential surface of the bushing 16 and flowing into the compressor side, the outer circumferential surface of the bushing 16 is inserted into the center of the back plate 2 through the seal ring 43. It passes through the hole 44, and a guide plate 45 is interposed between the back plate 2 and the thrust bearing metal 14, with a bushing 16 inserted through the hole provided at the center thereof. Further, the lower end portion of this guide plate 45 is formed into a curved shape.

Therefore, the lubricating oil flowing out from the thrust bearing metal 14 is thrown away from the outer peripheral surface of the bushing 16 by centrifugal force, is caught by the guide plate 45, and is returned to the oil sump.

Next, the operation of this embodiment will be explained.

When the engine speed is low and the exhaust gas flow rate is relatively small, the movable vane 34 is tilted outward as shown by the solid line in FIG. The edge and
The gap between the nozzles formed at the lap portion with the rear edge of the movable vane 34 is set to have the smallest gmin. Therefore, the exhaust gas is throttled and accelerated to the maximum extent by this nozzle, becomes a swirling flow in the inflow path 21c between the fixed vane member 27 and the turbine wheel 31, and then reaches the turbine wheel 30 via the fixed nozzle N. Therefore, the exhaust flow is accelerated in stages to drive the turbine wheel 31, and the supercharging effect can be ensured even in the low speed range of the engine.

When the rotational speed of the engine increases and the supercharging effect becomes sufficient, the movable vane 34 is tilted inward as shown by the imaginary line (Fig. 2),
The size of the nozzle defined between the fixed vane 29 and the movable vane 34 is increased. As a result, the exhaust flow is not accelerated and reaches the turbine wheel 30 with relatively little resistance in the flow path, making it possible to reduce the exhaust back pressure to the engine.

On the other hand, the axial dimension of the inlet passage 21c, which constitutes the variable nozzle, is larger than the axial dimension of the fixed nozzle N. According to this, since the flow passage cross-sectional area of the variable nozzle portion becomes relatively large, the ratio of the amount of leakage from the side clearance of the movable vane 34 to the total flow rate is relatively reduced. Therefore, it is possible to improve control accuracy by reducing the influence of leak gas in a low flow rate region.

3 to 5 respectively show modified embodiments of the present invention, and parts corresponding to the above embodiments are given the same reference numerals and detailed explanation thereof will be omitted.

These vanes are equipped with six sets of fixed vanes 29 and movable vanes 34 shown in FIG. 3, three sets shown in FIG. 4, and two sets shown in FIG. It is controlled in the same manner as the first embodiment with a set of fixed vanes 29 and movable vanes 34.

In this way, by appropriately setting the number of variable nozzles, it is possible to set the change characteristics of the turbine capacity as desired.

In particular, when the number of nozzles is small, such as the three-set configuration shown in Figure 4 or the two-set configuration shown in Figure 5,
It is preferable to arrange a movable vane near the inlet opening 21a of the scroll passage 21 in order to further reduce the inflow resistance when the nozzle is fully open.

<Effects of the Invention> As described above, according to the present invention, the variable nozzle configured in the inflow passage having a relatively large flow passage cross-sectional area and the fixed nozzle provided just on the outer periphery of the turbine wheel are used to gradually reduce the Since the fluid is accelerated, the resistance loss of the fluid flowing into the turbine can be kept small, and the variable range of the variable nozzle can be made extremely large, which can be used to improve controllability of turbochargers, etc., or to improve wastegate valve control. This makes it possible to eliminate turbines, improve turbine efficiency,
Particularly when applied to turbochargers, it can have a great effect on improving engine performance. Further, since a fixed vane is provided in a portion of the nozzle vane located upstream of the fluid where a relatively large thermal stress acts, the influence of thermal deformation on control accuracy can be reduced.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a turbocharger to which a variable displacement turbine according to the present invention is applied. FIG. 2 is a view taken from the - line in FIG. 1 when looking at the turbine casing side. 3 to 5 are layout diagrams of variable nozzles similar to FIG. 2 showing modified embodiments of the present invention. 1... Compresssa casing, 2... Back plate,
3... Lubricating part casing, 4... Turbine casing, 5... Scroll passage, 6... Axial passage, 7... Compressor wheel, 8... Main shaft,
9...Ring member, 10...Bolt, 11, 12
... Bearing hole, 13 ... Radial bearing metal, 14
...Thrust bearing metal, 15...Color, 16
. . . Bushing, 17 . . . Threaded portion, 18 .
1c...Inflow passage, 22...Outlet passage, 22a...
Outlet opening, 23... back plate, 23a... flange,
24... Stud bolt, 25... Ring member,
26...Nut, 27...Fixed vane member, 28
a... Cylindrical part, 28b... Disc part, 29... Fixed vane, 30... Turbine wheel, 31... Seal ring, 32... Bolt, 33... Pin, 3
4...Movable vane, 35...Link mechanism, 36...
...shield plate, 37 ... center hole, 38 ... annular groove, 40 ... lubricant oil introduction hole, 41 ... lubricant oil passage, 42 ... lubricant oil discharge hole, 43 ... seal ring, 44 ... center hole , 45...Guide plate.

Claims (1)

[Scope of Claims] 1. A radial inflow type variable capacity turbine comprising a turbine wheel, an inflow nozzle formed at a position facing the outer periphery of the turbine wheel, and a turbine scroll formed further on the outer periphery. A fixed vane and a movable vane each having a partial arc shape are arranged in an annular manner on a certain circumference outside the inflow nozzle so as to divide the inside of the turbine scroll into an inflow path and an outer peripheral path. and by tilting the movable vane inwardly from the circumference using one end as a fulcrum, a variable nozzle is formed between the edges of the fixed vane and the movable vane that face each other. A radial inflow type variable capacity turbine characterized by: 2. Claim 1, characterized in that at least two sets of the fixed vane and the movable vane are provided.
The radial inflow type variable capacity turbine described in . 3. Claim 1, wherein a dimension of the variable nozzle along the axial direction of the turbine wheel is larger than a dimension of the inflow nozzle along the axial direction of the turbine wheel.
The radial inflow type variable capacity turbine according to item 1 or 2.