JPH0758041B2 - Variable capacity nozzleless radial bottle - Google Patents

Description

The present invention relates to a variable capacity radial turbine applied to an exhaust gas turbocharger for an internal combustion engine or the like.

[Prior Art] An exhaust gas turbocharger for an internal combustion engine (hereinafter referred to as "supercharger") has a flow rate characteristic (constant constant) depending on engine operating conditions (combination of rotational speed and torque, or acceleration). It is considered that the flow rate of the working gas) is variable under the pressure conditions of the above. In a supercharger with a nozzleless radial turbine, a variable tongue-shaped variable capacity as shown in Figs. 3 and 4 is used. A radial turbine of the type disclosed in JP-A-60-25205 has been proposed.

An outline of such a conventional technique will be described with reference to FIGS. 3 and 4.

Movable tongue 14, trailing edge 141, rotating shaft 14A, turbine impeller 20, side plate 3
A passage 11 for guiding the working fluid is provided inside the volute casing 10 in which the 0, the bearing box 40, and the turbine impeller 20 are installed, and the fluid is supplied from an opening on the inner peripheral side of the volute casing 20.
Supply in the direction of the arrow in the figure.

The movable tongue 14 is provided along the inner peripheral side of the passage 11 slightly downstream of the inlet 10A of the volute casing 10, and the movable tongue 14 is configured such that the front edge of the movable tongue 14 is configured as a rotating shaft 14A. It is movable.

In the above structure, the rear edge 141 of the movable tongue 14 is rotated by rotating the movable tongue 14 (rotation from the solid line to the broken line in FIG. 3).
The volute throat At ₁ formed by the outer wall 12 of the volute casing changes to At ₂ , and the flow rate changes correspondingly.

Such a turbine having a function capable of changing the flow rate characteristic by some means is generally referred to as a variable displacement type turbine.

[Problems to be solved by the invention]

However, in the above-mentioned conventional one, when the movable tongue 14 is in the state of the broken line in the figure (that is, in the state where the flow rate is reduced), the fluid passage after the volute throat At ₂ expands rapidly, so that a large vortex 15 is generated in this portion. And a large fluid loss,
The effectiveness of the turbine is significantly reduced.

The present invention solves the above problems and prevents the generation of a large vortex and a large amount of fluid loss due to the large expansion of the passage after the volute throat while the movable tongue is in the small flow rate position. The purpose is to avoid a reduction in turbine efficiency.

[Means and actions for solving problems]

In order to solve the above problems, the present invention divides a part of the passage in the volute casing into an outer peripheral passage and an inner peripheral passage,
The feature is that the inner peripheral passage is opened and closed by a movable tongue to prevent the generation of large vortices, which is seen in the conventional ones.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. 10 is a volute casing, 11 is a passage in the volute casing 10, 10A is an inlet of the casing 10, 12 is an outer peripheral wall, 14 is a movable tongue, 14A is a rotating shaft of the movable tongue 14, 2
0 is a turbine wheel, 30 is a side plate, and 40 is a bearing box.

A passage 11 provided inside the volute casing 10
A part of is divided into an outer peripheral passage 11B and an inner peripheral passage 11C by a partition wall 13. Further, the movable tongue 14 has a rotating shaft.
14A After turning around 14A and coming to the outermost side, this trailing edge 141
And the front edge 131 of the partition wall 13 are in contact with each other.

This structure will be described in more detail. The inner peripheral passage 11C
The rear passage 11D and the rear passage 11D are formed so that the area change with respect to the circumferential flow of the passage decreases continuously in the counterclockwise direction in FIG. 1, while the outer passage 11B has the same circumferential direction. No area reduction for flow or previous 2
It is getting smaller for people.

Next, the operation of the variable capacity turbine having the above configuration will be described.

(1) Maximum flow rate state The movable tongue 14 is located at the solid line position in FIG. 1, that is, the trailing edge 141 is located on the innermost peripheral side.

In this state, the fluid flowing from the inlet 10A of the volute casing 10 is divided into the outer peripheral passage 11B and the inner peripheral passage 11C by the partition wall 13 at the rear end of the front passage 11A, and the flow rate to each passage is the second throat. It is limited by At ₂ and the first throat At ₁ , and the sum of them is the maximum value of the channel. The fluid introduced into the outer peripheral passage 11B flows in the passage having almost no area change at a substantially constant speed in the circumferential direction and is sent to the rear passage 11D. From the opening on the inner peripheral side of the rear passage 11D, the turbine impeller Inflow to 20. on the other hand,
The fluid introduced into the inner peripheral passage 11C immediately flows into the turbine impeller 20 from the opening on the inner peripheral side thereof.

(2) Minimum flow rate state The movable tongue 14 is at the broken line position 14a in FIG. 1, that is, the rear edge 141 is on the outermost peripheral side and is in contact with the front edge 131 of the partition wall 13, and the inlet portion of the inner peripheral passage 11C is the front passage 11A. It has been blocked from. In this state, the fluid flowing from the inlet 10A of the volute casing 10 is introduced into the rear passage 11D through the front passage 11A and the outer peripheral passage 11B, and then flows into the turbine impeller 20 from here.

Further, a part of the fluid flows around the rear passage 11D again and flows into the rear turbine impeller 20 which is also introduced into the inner passage 11C.

The total amount of flow through the turbine is limited by the cross-sectional area of the outer peripheral passage 11B (typically represented by the second throat At ₂ ),
It is sufficiently smaller than the total sum of throat areas At ₁ + At ₂ at the maximum flow rate described above, and the flow rate that can be flowed is also approximately corresponding to this ratio.

〔The invention's effect〕

The present invention is configured as described above, and according to the present invention, when the throat area of the volute casing is changed to make the flow rate variable, there is no danger of expanding the passage in the volute for each condition, Since the passage shape is always changed smoothly, large vortices are not generated unlike the conventional one, the fluid loss in the flow is much smaller than the conventional one, and it is possible to prevent the deterioration of turbine efficiency. it can.

[Brief description of drawings]

1 and 2 show an embodiment of the present invention. FIG. 1 is a sectional view of a volute casing in a radial turbine to which the present invention is applied, taken perpendicular to the axis, and FIG. 2 is a sectional view taken along the axis of the turbine. It is a figure. 3 and 4 are sectional views corresponding to FIGS. 1 and 2 showing a conventional example. 10 …… Volute casing, 11 …… Passage, 11A …… Front passage, 11B …… Outer passage, 11C …… Inner passage, 14 …… Movable tongue.

Claims (1)

[Claims] 1. In a nozzleless radial turbine for driving a fluid by introducing a fluid introduced from an outer peripheral side of a volute casing in a radial direction of a turbine impeller, a part of a flow passage in the volute casing is provided with an inner periphery. A partition wall that divides into a passage and an outer peripheral passage, and is provided at the inlet portion of the inner peripheral passage to open and close the inlet of the inner peripheral passage, and when the rear edge portion reaches the outermost peripheral position, the front edge portion of the partition wall A variable displacement nozzleless radial turbine, comprising: a movable tongue configured to abut.