JPH0372803B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a variable displacement turbine used in a turbocharger, etc., and more specifically, the edge of one side of a movable vane is tilted to prevent thermal distortion from occurring. The present invention relates to a variable capacity turbine that prevents movable vanes from biting against the wall surface of an exhaust passage.

(Prior art) A variable displacement turbine is used as an exhaust turbine for a variable displacement turbocharger.
The one described in Publication No. 7653 is known. This variable displacement turbocharger has multiple movable vanes arranged at the throat facing the outer periphery of the turbine wheel to form a variable exhaust throttle, and these movable vanes are driven by an actuator to control the variable throttle during low-speed engine operation. This throttle throttle increases the supercharging effect during low-speed engine operation.
However, in such a variable capacity turbine, the variable throttle is configured in the gap between the movable vanes, so the opening degree of the variable throttle is greatly affected by even a slight deviation in the tilt angle of the movable vane. It was difficult to accurately control the opening in the low opening range.

Therefore, in the specification of Japanese Patent Application No. 61-124996 (Japanese Unexamined Patent Publication No. 62-282122) filed on May 30, 1985, the present applicant accurately manages the low opening range of the variable aperture. We are proposing a variable capacity turbine that can This variable capacity turbine has a turbine housing provided with a base plate and a top plate to surround a turbine wheel, and a movable vane and a fixed vane on the outer periphery of the turbine wheel and on parallel opposing wall surfaces of the base plate and top plate, respectively. It is installed adjacently to form a variable exhaust throttle.

(Problems to be Solved by the Invention) However, in the variable displacement turbine according to the above-mentioned application by the present applicant, the movable vane is connected to the drive shaft whose base end passes through the base plate, and the movable vane is connected to the base plate and the top. Because it is tiltably arranged between parallel and opposing walls with the plate,
If the drive shaft of the movable vane tilts due to thermal strain, etc., if the parallelism of the wall surfaces between the base plate and top plate decreases, or if the wall surface becomes distorted, the movable vane may become stuck to the wall surface. There was a problem that it prevented smooth operation.

This invention was made in view of the above-mentioned problems, and aims to provide a variable capacity turbine that prevents movable vanes from seizing when thermal strain occurs, and to ensure smooth operation thereof. .

(Means for Solving the Problems) This invention forms an exhaust passage in the turbine housing that guides exhaust gas to the turbine wheel, and movable vanes are tiltably disposed between partition walls facing substantially parallel to the exhaust passage. in a variable displacement turbine in which a variable exhaust throttle is configured, and a drive shaft passing through the partition wall is coupled to the movable vane to drive the movable vane, wherein a stopper of the movable vane is set at a minimum opening of the variable throttle. A stepped portion that abuts against the movable vane is provided on the end faces of both opposing walls, and an edge of the movable vane on the side opposite to the end on the side connected to the drive shaft is provided in the width direction of the movable vane from the joint of the drive shaft. Formed into a tapered shape as if shrinking,
Moreover, the point is that the most tapered part thereof is located within the step.

(Function) According to the variable displacement turbine according to the present invention, the edge of the movable vane at the side end opposite to the end connected to the drive shaft is reduced in the width direction from the joint to the drive shaft toward the tip. The movable vane is formed into a tapered shape, and a gap is formed between the connecting end of the movable vane and the picture wall. Therefore, even if the drive shaft of the movable vane is tilted due to thermal effects, the parallelism of the painting wall is decreased, or distortion occurs, the movable vane will not bite into the painting wall. , ensuring smooth operation. In addition, a stepped part is formed on the picture wall to act as a stopper against the movable vane at the minimum opening of the variable diaphragm, and the movable vane's tip end is located at the step, so that the minimum opening of the variable diaphragm The position of the variable vane can be accurately defined, and leakage of exhaust gas from the sides of the movable vane can be suppressed.

The present invention is configured such that the exhaust passage is configured as a scroll passage, and a turbine wheel is disposed in the center of the scroll passage, and a variable throttle consisting of a fixed vane and a movable vane is arranged around the turbine wheel. However, the resistance to the flow of exhaust gas can be reduced.

Further, in this embodiment, both the partition walls are formed separately from the turbine housing, the fixed vane is integrally formed on the wall surface of one partition facing the other partition, and the fixed vane is connected to the other partition wall. A pair of picture walls are assembled in contact with the wall surface, and the assembled picture walls are assembled into the scroll passage, making it easier to manage the clearance around the variable aperture and improving ease of assembly. can.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

1 to 3 show a variable displacement turbine according to an embodiment of the present invention applied to a turbocharger, in which FIG. 1 is a longitudinal cross-sectional view of the turbocharger, and FIG. 3 are enlarged cross-sectional views of the main parts.

In the figure, reference numeral 11 denotes a compressor housing that rotatably accommodates a compressor impeller, which will be described later.
Reference numeral 2 indicates a turbine housing that rotatably accommodates a turbine wheel, which will be described later. Reference numeral 13 indicates a center housing that supports a shaft that connects the compressor impeller and the turbine wheel. are integrally joined in between. The compressor housing 11 has a back plate 14 with bolts 15 and a mounting plate 16 at the left open end in the figure.
An axial passage 1 and a scroll passage 18 are defined therein. Back plate 14
is connected to the center housing 13 by bolts 19. The left end of the axial passage 17 in the figure communicates with the center of the scroll passage 18, and a compressor impeller 21 attached to the right end of the shaft 20 in the figure communicates with the center of the scroll passage 18.
is rotatably housed. The axial passage 17 has an intake inlet 17a that introduces intake air at the right end in the figure, and the scroll passage 18 has an intake outlet (not shown) opened upward that communicates with the combustion chamber of the engine (not shown). are doing.

Two bearing parts 22 and 23 are formed inside the center housing 13, and these bearing parts 22 and 23
The shaft 2 is connected to the bearing holes 22a and 23a formed in the shaft 2 through float bearings 24 and 25, respectively.
0 is rotatably supported. Shaft 20
The right end in the figure rotatably penetrates the back plate 14 via the bush 26 and is connected to the compressor impeller 21, and the left end in the figure is connected to the turbine wheel. Note that 27 is a washer, 28 is a collar, and 29 is a thrust bearing, which are interposed between the stepped portion of the shaft 20 and the bush 26.

The center housing 13 also includes float bearings 24 and 2 above the bearings 22 and 23.
The oil supply passage 30 that supplies lubricating oil to the bearing portion 2
Oil drain passage 31 that discharges lubricating oil below 2, 23
A hole 31 (designated with the same reference numeral as the oil drain passage 31) is formed. The refueling passage 30 is
An introduction hole 30a whose upper end is open, and the introduction hole 30a
The right end in the figure is the thrust bearing 2.
A horizontal hole 30b opened on the sliding surface with the horizontal hole 3
0b, and are connected to the bearing holes 22a, 2, respectively.
Two distribution holes 30c, 30 opened on the circumferential surface of 3a
It is composed of d and. The upper end of the introduction hole 30a is connected to a lubricating oil supply source such as an oil pump (not shown), and the lower end of the hole 31 is connected to an oil pan or the like. These oil supply passage 30 and oil drain passage 31 guide lubricating oil supplied from a lubricating oil supply source to the bearings 24, 25, 29 to provide lubrication and cooling, and then return this lubricating oil to the oil pan. to recover. Note that 32 is a water jacket for cooling water formed on the turbine housing 12 side of the oil supply passage 30 and the oil drainage passage 31, and this water jacket 32 has a water inlet at the bottom and a drain opening at the top. . This water jacket 32 is attached to the turbine housing 1.
It also prevents heat transfer from the bearing part 2, and also evaporates the cooling water during heat soak back and uses the heat of vaporization to cool the bearing part 2.
2 and 23 are cooled.

The turbine housing 12 has stud bolts 3
3 is screwed and fixed to the center housing 13 by a mounting plate 35 fastened to the stud bolt 33 with a nut 34. The opening end of the turbine housing 12 on the right side in the figure is closed by a vane holding member (base plate) 36 whose outer peripheral edge is sandwiched between the turbine housing 12 and the center housing 13. A top plate 38 fixed by bolts 37 fits into the inner circumference. The turbine housing 12 has a scroll passage 39 and an outlet passage 40 defined therein, and an exhaust inlet 39a opening tangentially to the scroll passage 39 and an exhaust exhaust opening opening at the left end of the exit passage 40. An outlet 40a is formed. The center portion of the scroll passage 39 and the right end portion of the outlet passage 40 communicate with each other, and a turbine wheel 41 fixed to the left end portion of the shaft 20 is rotatably disposed in the portion where these passages 39 and 40 communicate.

The top plate 38 is connected to the turbine housing 1
A cylindrical portion 38a fitted into the inner end of the outlet passage 40 of No. 2 through a seal ring 42;
and a disk portion 38b integrally extending in the radial direction from the axial center portion of the outer periphery. Cylindrical part 3
The aforementioned turbine wheel 41 is rotatably arranged within 8a with a predetermined clearance, and the disc portion 38b divides the scroll passage 39 into an outer circumferential path 39b and an inner circumferential path 39c. As shown in FIG. 3, this top plate 38 has a step wall 38h formed on the end surface of a disc portion 38b, which serves as a stopper for the fully closed position of the movable vane, which will be described later. This step wall 38h partially extends along the blade shape of the outer peripheral edge of the movable vane. This top plate 38 is fixed to the vane holding member 36 by the aforementioned bolts 37 which pass through the disc portion 38b and the vane holding member 36 from the turbine housing 12 side and are screwed into the vane holding member 36.

The vane holding member 36 includes a disk portion 36a through which the shaft 20 rotatably passes, and four fixed vanes 43 that extend integrally from the outer peripheral portion of the disk portion 36a toward the top plate 38 in the axial direction. It consists of The disk portion 36a is located parallel to the disk portion 38b of the top plate 38 mentioned above. A heat shield plate 44 is fitted onto the end face of the vane holding member 36 on the center housing 13 side, and a heat insulating layer 44a is formed between the vane holding member 36 and the disk portion 36a.
A step wall 36g (see FIG. 2) which functions as a stopper for the movable vane (described later) is formed on the surface of the movable vane along the wing shape of the movable vane. The bolts 37 mentioned above protrude from the surface of the heat shield plate 44 on the center housing 13 side, and the protruding ends of the bolts 37 and the surface of the heat shield plate 44 on the center housing 13 side are welded to prevent the bolts 37 from loosening. Prevented.

As shown in FIG. 2, the fixed vanes 43 have a partially arcuate shape and are arranged concentrically with the turbine wheel 41 at equal intervals in the rotational direction. Four partially arcuate movable vanes 45 are arranged between these fixed vanes 43, and these fixed vanes 43 and movable vanes 45 connect the outer circumferential path 39b and the inner circumferential path 39c of the scroll passage 39. A variable aperture 46 is configured in between. The movable vane 45 is
A pin 47 (drive shaft) that rotatably penetrates the disc portion 36a of the vane holding member 36 is fixed to the base end. As shown in detail in FIG. 3, this movable vane 45 has a boss portion 45a protruding coaxially with the pin 47 on the vane holding member 36 side at the base end, and a boss portion 45a on the edge portion on the top plate 38 side. A tapered portion 45b is formed that tapers toward the vane holding member 36 from the end toward the tip. This movable vane 45
The height of the boss portion 45a is formed to be smaller than the above-mentioned step wall 36g so that the edge on the side of the vane holding member 36 can come into contact with the step wall 36g during hot and cold times, and similarly, the height of the boss portion 45a is formed to be smaller than the step wall 36g described above. The inclination of the tapered part 45b is set so that the end edge of the side can come into contact with the step wall 38h even when it is cold, and by forming the boss part 45a and the tapered part 45b as described above, the minimum of the variable aperture 46 can be This suppresses leakage of exhaust gas from between the step walls 36g and 38h when the opening degree is reached, and prevents binding (described later). The movable vane 45 tilts as the pin 47 rotates to change the flow path area (opening degree) of the variable throttle 46, and opens the variable throttle 46 to the minimum at the position where it abuts the step wall 36g of the vane holding member 36. degree, and tilts inward from this position to increase the opening degree of the variable diaphragm 46. Although not shown, the end of the pin 47 protruding toward the center housing 13 is connected to the actuator via a link mechanism disposed between the center housing 13 and the vane holding member 36.

In addition, 48 is a disk-shaped shield plate whose outer peripheral edge is sandwiched between the inner peripheral end of the heat shield plate 44 and the outer peripheral wall of the center housing 13, and 49 is a mounting stud screwed onto the turbine housing 12. is a bolt,
The shield plate 48, together with the heat shield plate 44 described above, prevents heat from the exhaust gas from being transferred to the center housing 13.

Next, the operation of this embodiment will be explained.

In this turbocharger, when the rotational speed of the engine is relatively low and the flow rate of exhaust gas is low, the movable vane 45 moves between the step walls 36g and 3 as shown in FIG.
8i, and the variable diaphragm 46 is set to the minimum opening degree. Therefore, the exhaust gas introduced from the exhaust introduction port 39a is transferred to the outer peripheral path 39b of the scroll passage 39.
is accelerated through the variable aperture 46 and passes through the inner circumferential path 39c.
The liquid flows into the inner peripheral path 39c and generates a swirling flow to drive the turbine wheel 41. Therefore, the compressor impeller 21 is rotated at high speed to pressurize the intake air, thereby ensuring a supercharging effect during low speed operation of the engine.

Further, when the rotational speed of the engine increases and the flow rate of exhaust gas also increases, the movable vane 45 is driven toward the center in accordance with the rotational speed of the engine, and the opening degree of the variable throttle 46 increases. Therefore, it is possible to ensure an appropriate supercharging effect depending on the operating condition, and the flow resistance of the exhaust gas is also reduced.Since the opening area can be made large, the exhaust back pressure of the engine can be reduced without the need for a special waste gate or control valve. can do. Then, as mentioned above, the turbine wheel 4
1 is driven by exhaust gas, and a compressor impeller 21 pressurizes intake air to perform supercharging.

On the other hand, in this variable displacement turbocharger, the temperatures of the bearing portions of the vane holding member 36 and the heat shield plate 44, which support both ends of the pin 47, are different, and the temperature of the top plate 38 is also different between the outer circumferential portion and the inner circumferential portion. In contrast, these bearings and the top plate 38 are susceptible to thermal distortion. In particular, since the vane holding member 36 is at a higher temperature than the heat shield plate 44, the pin 47
The movable vane 45 side end is deformed so as to expand outward, and the tip of the movable vane 45 is displaced toward the top plate 38 side. However, since a tapered portion 45b is formed at the edge of the movable vane 45 on the top plate 38 side and there is a gap between the movable vane 45 and the top plate 38, even if the top plate 38 or the pin 47 is distorted. The movable vane 45 does not bite the top plate 38 or the vane mounting member 36, ensuring smooth operation.

(Effects of the Invention) As explained above, according to the variable displacement turbine according to the present invention, a stepped portion is formed on the partition wall of the exhaust passage as a stopper for the movable vane at the minimum opening of the variable aperture, and The edge opposite to the edge that connects the vane to the drive shaft is tapered and both edges in the width direction are located within the step and come into contact with the step at the minimum opening of the variable aperture. Since the movable vanes are in contact with each other, even if the painting wall surrounding the movable vanes is thermally distorted, the movable vanes will not bite into the surrounding wall surface, ensuring smooth operation, and also preventing exhaust gas from flowing from the sides of the movable vanes. Leakage can be suppressed.

In addition, in this invention, a turbine wheel is arranged in the center with the exhaust passage being a scroll passage, and a plurality of fixed vanes are arranged circumferentially apart from each other around the turbine wheel, and a movable vane is arranged between these fixed vanes. Since the arrangement constitutes a variable throttle, the resistance to the flow of exhaust gas can be reduced.

In addition, in this aspect, by configuring the drawing wall to be assembled in advance with the fixed vane and the movable vane, and by incorporating this sub-assembly into the exhaust passage, clearance management can be performed accurately and easily. can be further improved.

[Brief explanation of drawings]

1 to 3 show a variable displacement turbine according to an embodiment of the present invention, in which FIG. 1 is a longitudinal sectional view of a turbocharger, FIG. is an enlarged sectional view of the main part. 12... Turbine housing, 36... Vane holding member, 38... Top plate, 38h...
Step wall, 39... Scroll passage (exhaust introduction passage), 41... Turbine wheel, 43... Fixed vane, 45... Movable vane, 45a... Boss portion, 45b... Taper portion, 46... Variable aperture, 4
7...Pin (drive shaft).

Claims (1)

[Claims] 1. An exhaust passage that guides exhaust gas to a turbine wheel is formed in the turbine housing, and a movable vane is tiltably arranged in a wall tube facing substantially parallel to the exhaust passage to create a variable exhaust throttle. In the variable capacity turbine configured to drive the movable vane by coupling a drive shaft passing through the drawing wall to the movable vane, the movable vane includes a step portion that comes into contact with the movable vane as a stopper when the variable aperture is at a minimum opening. Provided on the end faces of both opposing picture walls, and in the width direction of the movable vane, the edge of the side end opposite to the end on the side where the movable vane is connected to the drive shaft is directed from the joint with the drive shaft toward the tip of the movable vane. 1. A variable displacement turbine characterized in that the turbine is formed into a tapered shape so as to reduce in size, and the most tapered part thereof is located within the step. 2. The exhaust passage is constituted by a scroll passage, the turbine wheel is arranged in the center of the scroll passage, and a plurality of fixed vanes are arranged circumferentially apart from each other around the turbine wheel, and a space between the fixed vanes is arranged. 2. The variable capacity turbine according to claim 1, wherein the movable vane is arranged at the movable vane and the movable vane and the fixed vane adjacent to each other constitute the variable throttle. 3. The pair of partition walls are configured separately from the turbine housing, the fixed vane is integrally formed on the opposing wall surface of one partition wall, and the fixed vane is brought into contact with the wall surface of the other partition wall. 3. The variable displacement turbine according to claim 2, wherein a pair of partition walls are assembled, and the assembled partition walls are incorporated into the scroll passage.