JPH0416608B2 - - Google Patents

Description

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

<Prior art> In a radial turbine used as an exhaust turbine of a turbocharger, it is sometimes desired to ensure a supercharging effect even in a region where the engine rotational speed is low. By narrowing the upstream passage of
It is preferable to increase the inflow velocity of the fluid. 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 at the throat facing the outer circumference of the turbine wheel, and by tilting these movable vanes, a structure is created between these vanes. If the opening area of the nozzle is changed, it is possible to ensure the supercharging effect even in the low speed range of the engine, and to keep the back pressure against the engine exhaust gas small in the medium to high speed range of the engine. I can do it.
However, according to the above configuration, since these vanes are arranged in a region where the fluid velocity is relatively high, the fluid resistance loss tends to be relatively large, which reduces the efficiency of the turbine. There's a problem. In addition, since the nozzle is formed between adjacent movable vanes, the nozzle opening area can change significantly due to a slight deviation in the tilting angle of the vane, especially in areas where the nozzle opening area is small. There is a problem with the control 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 order to solve these problems in the prior art, it is necessary to create a variable opening area on the outside of the fixed inlet nozzle part, which is provided at a position facing the outer circumference of the turbine wheel. Although it is preferable to arrange the nozzles in an annular shape, the gap between the movable vanes forming the variable nozzle, especially when the variable nozzle is at its minimum opening, has a large effect on the efficiency of the turbine, and its control can become a problem. In view of the problems of the prior art and the findings of the inventor, the main object of the present invention is to minimize the gap, especially on the sides, of the movable vane when the variable nozzle is at its minimum opening, thereby increasing the efficiency of the turbine. An object of the present invention is to provide a variable nozzle structure for a variable capacity turbine.

<Means for Solving the Problems> According to the present invention, the object is to provide a turbine wheel, a turbine scroll formed on the outer periphery of the turbine wheel, and a turbine wheel concentric with the turbine wheel on the outer periphery of the turbine wheel. A variable nozzle structure for a turbine having a variable nozzle consisting of a plurality of fixed vanes and a movable vane arranged annularly on a circumference of the turbine, the variable nozzle structure being separate from a turbine casing member forming the majority of the turbine scroll. In order to define a gas inflow path to the turbine wheel through the body, a back plate and a top plate, each having a substantially perfect circular shape, are integrally fastened to each other using fastening means near their outer peripheries, and then inserted into the turbine casing. a shoulder provided substantially parallel to the axial direction of the movable vane, the movable vane being rotatably supported between the back plate and the top plate, and having a shape complementary to each side edge of the movable vane; A portion is formed on the back plate and the top plate, and the minimum opening position of the variable nozzle is determined by abutting on each shoulder portion, and each side edge portion is characterized by the above. This is accomplished by providing a variable nozzle structure for the turbine.

<Function> In this way, the minimum opening degree of the variable nozzle is defined by the side end of the movable vane coming into contact with the shoulder having a complementary shape, and the gap between the movable vanes, especially on the sides, can be minimized. , it is possible to prevent fluid leakage at the minimum opening of the variable nozzle and increase the efficiency of the turbine. In addition, since the back plate and top plate each have a shoulder portion that the side edges of the multiple movable vanes come into contact with, each having a substantially perfect circular shape, the amount of thermal deformation in the radial direction of each plate is uniform. be converted into Moreover, since both plates are integrally fastened to each other near the support portion of the movable vane, the displacement difference between the two shoulder portions is minimized. This improves both the accuracy of interlocking between the plurality of variable nozzles and the stability of the minimum opening degree.

<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 variable displacement 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. Built-in lubrication 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.
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 serving as a back plate is interposed between the turbine casing 4 and the lubricating part casing 3 and has a flange 23a projecting outward from 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 circumferential passage 21b and an inflow passage 21c. This fixed vane member 27 includes a cylindrical portion 28a formed at the center, a disk portion 28b forming a top plate formed radially outward from an axially intermediate portion of the cylindrical portion 28a, and a disk portion 28b forming a top plate. It consists of a fixed vane 29 that protrudes along the axial direction from the outer periphery toward the lubricating part casing 3, and has a cylindrical part 28a.
A turbine wheel 30 formed on the other end side of the main shaft 8 is received inside. And the cylindrical part 28a
is fitted into the inner end of the outlet passage 22 via a metal seal ring 31, and the fixed vane 2
9 is attached to the back plate 23 by bolts 32.
is combined with

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 with the same curvature, and are provided with the same width and at equal intervals along the circumferential direction.
The gaps between these fixed vanes 29 are formed by the back plate 23.
It is opened and closed by a movable vane 34 fixed to the free end of a pin 33 which is rotatably pivotally connected to the movable vane 34. These movable vanes 34 have an arc shape with the same curvature as the fixed vanes 29, and are generally located on the same circumference centered on the main shaft 8. In addition, these movable vanes 34 are attached to a back plate 23 which has a substantially perfect circular shape at a position close to the circumferential end edge of the corresponding fixed vane 29.
and the disk portion 28b, and can be tilted only toward the inside of the circumference, and in the fully closed 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 21 of the scroll passage 21.
The four vanes form leading and trailing edge portions, respectively, for the fluid flowing through b. The pins 33 that support these movable vanes 34 are each connected to an actuator having an appropriate structure (not shown) via appropriate link mechanisms 35, and these movable vanes 3 are controlled by a separate control signal.
4 inclination angles are adjusted.

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 the exhaust gas from the turbine side from leaking toward the inside of the lubricating part casing 3, the center hole 37 of the lubricating part casing 3 of the main shaft 8 is provided.
An annular groove 38 functioning as a labyrinth groove is recessed in a portion penetrating the groove.

In particular, when the opening degree of the movable vane 34 is the smallest, that is, when the gap between the movable vane 34 and the fixed vane 29 reaches gmin, leakage of exhaust gas from the axial end face of the movable vane 34 becomes a problem. . In the case of this embodiment, the axial dimension of the part that receives the movable vane at the minimum opening is extremely high because the fixed vane member 27 is rigidly connected to the back plate 23 by the fixed vane 29 part. Therefore, the leakage of exhaust gas from the axial end face of the movable vane 34 can be kept relatively small. Moreover, as clearly shown in FIGS. 3 and 4, in order to define the minimum opening position of the movable vane 34, both ends of the movable vane 34 in the axial direction are connected to the back plate 23.
Shoulder portions 50 and 51 are provided on opposing surfaces of the disk portion 28b of the fixed vane member 27, respectively, and have complementary shapes to both ends of the movable vane 34 in the axial direction. Leakage of exhaust gas from the axial end is minimized, and the efficiency of the turbine can be suitably increased.

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 rotational speed of the engine is low and the flow rate of exhaust gas is relatively small, as shown by the solid line in FIG. 2, by closing the movable vane 34, the front edge of the fixed vane 29 The gap between the nozzle formed at the lap portion with the rear edge of the movable vane 34 is set to the minimum 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, so that the exhaust gas is The engine is accelerated 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.

<Effects of the Invention> As described above, according to the present invention, the resistance loss of the fluid flowing into the turbine can be suppressed to a small value, and the variable area of the variable nozzle can be made extremely large. This is highly effective because it minimizes the lateral gaps between the turbines and increases the efficiency of the turbine. Moreover, according to the above configuration, the back plate and the disc part have a substantially perfect circular shape, and each shoulder part corresponding to a plurality of movable vanes is provided on the same circumference centered on the main axis. The amount of thermal deformation in the radial direction in the plurality of movable vanes becomes equal, and the interlocking error between the movable vanes can be kept extremely small. Further, since the back plate and the disk portion are integrally fastened to each other at a position relatively close to the pivot portion of the movable vane, the difference in displacement between the two shoulder portions due to thermal expansion can be kept extremely small. Therefore, there is no unnecessary gap caused by thermal deformation when the variable nozzle is at its maximum position.
It becomes possible to suitably suppress deterioration of characteristics due to thermal stress.

[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. FIG. 3 is an enlarged view showing a part of FIG. 2 in detail. Figure 4 is - of Figure 3.
FIG. 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, 50,
51...Shoulder.

Claims (1)

[Scope of Claims] 1. A turbine wheel, a turbine scroll formed around the outer periphery of the turbine wheel, and a plurality of scrolls arranged annularly on a circumference concentric with the turbine wheel on the outer periphery side of the turbine wheel. A variable nozzle structure for a turbine having a variable nozzle consisting of a fixed vane and a movable vane, wherein a gas inflow path to a turbine wheel is formed separately from a turbine casing member forming a majority of the turbine scroll. In order to achieve this, a back plate and a top plate, each having a substantially perfect circular shape, are integrally fastened to each other by fastening means near their outer peripheries, and are provided substantially parallel to the axial direction within the turbine casing, and these back plates are The movable vane is rotatably supported between the plate and the top plate, and shoulder portions having complementary shapes to the end edges on each side of the movable vane are formed on the back plate and the top plate, A variable nozzle structure for a turbine, characterized in that a minimum opening position of the variable nozzle is determined by abutting an end edge against each of the shoulders.