JPS6065205A - Variable capacity radial turbine - Google Patents

Abstract

PURPOSE:To enhance the efficiency by putting the edge of a flap member of a variable capacity radial turbine, stretching along the flow line, in surface contact with the detent surface projecting from the side wall of a turbine scroll, and thereby preventing gas leakage at the time of minimum rate of flow. CONSTITUTION:In a radial turbine in which the rate of gas flow can be varied by giving a flap member 24, arranged along the flow line of a turbine scroll 3, possibility of swinging in the radial direction of the turbine rotor 1, the edge of said flap member 24 stretching along the flow line is put in surface contact with the detent surfaces 30A, 31A projecting from the side wall of the turbine scroll. This will eliminate gas leak at the gap between the side face of the flap member 24 and side wall of turbine scroll during minimum rate of flow to contribute enhancement of the efficiency.

Description

Detailed Description of the Invention The present invention relates to a variable displacement radial turbine, and in particular to a variable displacement radial turbine, in which the flow characteristics of a turbine such as a turbocharger are varied by operating a swingable tongue member provided on a scroll. In a typical internal combustion engine with a turbocharger, its output characteristics are determined by the diameter of the turbine rotor and the φ ratio in the turbocharger, that is, the flow passage cross-sectional area A of the scroll inlet, which will be described later, from the rotor center axis to the inlet cross-section. It is determined approximately by the value divided by the vertical distance R to the area center of gravity position. For example, the larger the A/R ratio is, the higher the speed is suitable, and the torque in the high rotation region is increased.

Therefore, the tongue-shaped member (variable nozzle) is operated as described above according to the engine operating conditions to change the flow passage cross-sectional area A of the scroll inlet, thereby controlling the flow rate of exhaust gas flowing into the sflow ★. Variable displacement radial turbines have been proposed that are capable of achieving an appropriate increase in torque by maintaining appropriate supercharging from a low-speed operating range to a high-speed operating range.

Figures 1 (2) and (B) show an example of a conventional variable geometry radial turbine. Ku 111
This is disclosed in Publication No. 123 and the like. Here, it is a turbine rotor, and 2 is a turbine housing provided in the outer peripheral part of the turbine rotor l. A cast product is generally used for the turbine housing 2.

Furthermore, 3 is a turbine scroll provided in this turbine housing and forming a spiral flow path.The inlet 3A to the scroll 3 is connected to an exhaust manifold (not shown), and the exhaust gas from the manifold is connected to the turbine scroll 3. is guided from this inlet 3A to the rotor along the flow path 3B of the scroll 3.

In this example, the tongue portion t is centered at the beginning of winding of the scroll 3, that is, the position where the outer peripheral side wall surface of the flow path 3B is closest to the rotor. (Hereinafter, the tongue part which can freely swing in this way will be referred to as a tongue member), and the width in the radial direction at the nozzle opening (scroll entrance part) B is changed, Therefore, the cross-sectional area A of the flow path in this portion is made variable.

Further, 7 shown in FIG. 1 (4) is an electromagnetic actuator disposed outside the housing λ, and this actuator 7 is operated according to the operating conditions of the engine, for example, the engine speed. By the operation 7, the tongue-like member can be swung in the radial direction of the rotor l via the link member.

Furthermore, in FIG. 1(B), wa is a center housing which pivotally supports the rotor shaft /A via a bearing 10, and // is a center housing provided between the center housing 9 and the rotor shaft /A. The ring seal /2 is a shroud plate forming the disk-shaped back surface of the turbine rotor /2. The shroud plate 2 is kept in such a state that its surrounding flange is fitted into the annular groove of the turbine housing 2, and is fixed in this state by a port 13 that fixes the center housing 9.

In the variable capacity radial turbine configured in this way, the scroll flow path 3 passes from the inlet 3A through the inlet portion 6.
When the exhaust gas is introduced to B, the actuator 7 is operated in accordance with the operating conditions to swing the tongue-shaped member ring and change the flow passage cross-sectional area A of the inlet portion l.

Therefore, the exhaust gas with a flow rate corresponding to the position of the tongue-shaped member is guided from the flow path 3B to the turbine rotor/ to rotate the rotor/, and the exhaust gas after doing work is sent to the outlet shown in Fig. 1 (B). It is discharged to the outside from part 3C.

However, in such a conventional variable displacement radial turbine, due to the difference in thermal expansion coefficient that exists between the tongue member l that performs an oscillating motion and the turbine housing 2,
The side surfaces llA and 44'B of the tongue-like member l are connected to the housing inner wall surfaces 2 and 2 on both sides at the scroll entrance part B.
There is a risk that it will come into contact with B and become unable to swing.
The structure was such that a gap C was maintained between IA and 4'B and the inner wall surfaces 2 and 2B.

For this reason, especially at low flow rates when the cross-sectional area A of the inlet flow path is narrowed, the gas flow rate that leaks directly to the rotor/side through this gap C increases. This leaked gas flow mixes with the main flow that flows into the rotor without being swirled along the throttle channel 3B by the tongue-shaped member lIK, resulting in a large fluid loss due to flow turbulence and reducing turbine efficiency.

The object of the present invention is to eliminate the above-mentioned drawbacks, to reduce the flow rate of the turbine by preventing leakage from the side surface of the tongue member at the minimum flow rate, and to improve the turbine efficiency. It is an object of the present invention to provide a variable displacement radial turbine that can obtain a significant increase in torque especially when the engine rotates at low speeds.

In order to achieve such an objective, the present invention provides a system in which the flow rate of gas flowing into the scroll is at a minimum flow rate.
Both end edges of the tongue-like member abut against engaging surfaces protruding from the scroll side wall to prevent leakage from the sides of the tongue-like member.

The present invention will be described in detail below based on the drawings.

FIGS. 2A and 2B show a first embodiment of the present invention. In this example, it is a shape. Here, the turbine housing has a housing cover I, and the housing and the housing cover both have flow passage wall surfaces A and 2/2 perpendicular to the rotor axis/A.
A is formed, and these wall surfaces 20A and 2/
A, a scroll outer peripheral wall ffB formed on the turbine housing side, and a scroll inner peripheral wall 2/B formed on the nousing cover U side form a scroll passage 3B.

Here, the housing cover l has a fitting groove 2/O formed in an annular shape around it, and the fitting part jf79 of the housing 〃 is fitted into this fitting groove 2/0 via the backing n. , and fixed with bolts 27.

Further, the housing cover 21 is formed with a shroud portion 2/D along the blade tip of the rotor I and an outlet portion 3C.

2Il is a tongue-like member having an airfoil-shaped cross section, and B is a rotation shaft integrated with the tongue-like member 24I. The rotation shaft B is rotatably supported by a bushing I press-fitted into the housing cover 2/, and a strip-shaped arm plate 1 as shown in Fig. 3 is fixed to the outside of the shaft B. , On the other hand, by forming the threaded section of the shaft B to match this shape, the hole 27 is formed.
Fit the threaded part into A, and fix the arm plate l to the shaft B with the nut 1.

Reference numeral 3 denotes a connecting pin attached to the arm plate 1. By connecting this connecting pin with an actuator (not shown), the actuator can cause the tongue-like member 2 to swing.

Here, the side surfaces J A and 2'l B of the tongue-like member 2Il
is precisely finished by machining so that it is parallel to the corresponding wall surfaces A and 2/A, and one wall surface 2DA
And 2/A can be finished with a smooth surface in the same way. Furthermore, 30 and 31 are these wall surfaces 27A and 2
/ This is a protruding part protruding from A, and the protruding parts 3θ and 3
A member 2I is provided on each side where the tongue-like member 2G of 1 is arranged.
Engagement surfaces 30A and 31A are formed which abut on the cylindrical surface 1.

Thus, when the tongue-like member 21 is swung to the minimum flow position as shown by the dotted line in FIG. so that they come into close contact with the protrusion engaging surfaces 3θA and 3/A. That is, the surface shapes of the engaging surfaces 3θA and 3/A in the flow path direction are made into an arched shape with an inverted curve to match the surface 2110 of the tongue-like member 24t, so that the surface 2410 of the tongue-like member 21
By making contact with both ends of the engagement surfaces 3θA and 3/A in a state that matches the shape of the engagement surfaces 3θA and 3/A, leakage from this portion is prevented.

In this way, by preventing leakage from the gap in this part by the tongue member 2g at the minimum flow rate, the turbine efficiency will be improved, and the engine speed to obtain a constant boost pressure, that is, the intercept engine speed. The number can be lowered and the torque can be increased. On the other hand, if the turbine efficiency is not maintained well, even if the intercept engine speed is lowered, it will not be possible to increase the shift torque due to an increase in the exhaust pressure.

That is, in the variable displacement radial turbine configured in this way, it is necessary to prevent leakage from the tongue-like member 2 for variable displacement at the minimum flow position. It is possible to improve efficiency and increase torque while reducing intercept engine speed. Note that FIG. 3 shows the state of the protrusion 31 provided on the housing cover 21 side of this example.

Next, a second embodiment of the present invention will be explained with reference to FIG. In this example, protruding stepped portions % and g/ are formed on the wall surface ffA on the turbine housing side and on the wall surface 2/A on the housing cover I side. Therefore, at the minimum flow rate, both ends of the surface 211C of the tongue member 21I come into contact with the stepped surfaces 4t0A and 4I/A of the stepped portions ψ and l/, as shown in FIGS. make contact with them.

In this example, in order to simplify machining, the wall surface ff
The step that limits A and the stepped portion p is the surface f17A.

The stepped surface 41/A that limits the wall surface 2/A and the stepped portion f'/ forms a surface 41/A over the entire circumference including the portion that contacts the tongue-shaped member surface 2FQ.

The other configurations and operations are the same as those in the first embodiment, and their explanations will be omitted. However, in this example, since the stepped section and F/ are formed in a continuous state with the wall surfaces 27A and 2/A, cracking due to thermal distortion can be prevented and durability can be achieved.

Figure 3 shows a third embodiment of the invention. In this example, the tongue-like member 2 is designed to prevent leakage from around the base portion 2IID, which is the center of rotation thereof. Therefore, in this example, the base 2'l of the tongue member 2g
l) Protrude the fixed tongue part from the housing side in the vicinity so that the step is along the surface % A, and the tongue part 2 part at the minimum flow rate is attached to the face part A formed by the tongue part part 2. The vicinity of the base 2 of the face 2 of the base 2 of the base 2 of the base 2 is brought into contact with the part D.

The rest of the structure is the same as the example shown in FIGS. 6 to 6 g, and this example can also prevent leakage from around the base 211D, as described above.

FIG. 1θ shows a first embodiment of the present invention. In this example, a stepped portion is also provided on the tongue-like member side, and the stepped portion has a surface formed on the housing side, and the stepped portion is brought into contact with the surface. Furthermore, in this example, a driving device for the tongue-shaped member is provided on the housing side.

Here, SII is a tongue-like member, n is a stepped portion projecting on both sides along the surface iD on the turbine axis IA side, tj and ! I have Party B. Therefore, on one side of the turbine housing, the stepped surface shown in Fig. 1 forms a surface mA, and the stepped surface shown in Fig. 1θ forms a surface QB. Stepped part SS and! The stepped surfaces sjA and j4A provided on the housing side are in contact with the surfaces IA and %B, respectively.

In addition, in this example, since part of the bushing n is related to the surface uA (see Figure 1θ), for machining, after press-fitting the pushbutton into the housing, the stepped surface 4t0A should be cut. do.

In this case, the steps formed on the housing side are easy to match in terms of machining, and the relative positions of the steps formed on the surfaces ψA and ψB and the steps formed on the tongue-like member Sa are aligned with jjA and j4A, making assembly easier. Not only is it easy to process and process, but it is also possible to reduce the external dimensions.

Fig. 72 shows the stepped surface of the push bar which pivotally supports the tongue member shaft with respect to the center housing shown in Fig. 1.
10A, and this part is formed so that it is flush with the wall surface.By forming it in this way, it is not only easy to fit the bushing, but also easy to install. There is no need to cut the bushing, and the tongue-shaped member jQ can be easily assembled.

As explained above, according to the present invention, when the gas flow rate flowing into the rotor is at the minimum flow rate, the end edge along the flow path of the tongue-like member for varying the flow rate provided at the winding start portion of the scroll However, since it maintains surface contact with the retaining surface formed on the scroll side wall, at the minimum gas flow rate, gas flows directly into the flow path on the rotor side from the gap between the side surface of the tongue member and the scroll side wall. It is possible to prevent leakage, reduce the flow rate of the turbine, improve turbine efficiency, and significantly increase the torque at low rotational speeds of the engine compared to before.

[Brief explanation of the drawing]

Figure 1 (4) is a schematic diagram showing an example of the configuration of a conventional variable displacement radial turbine; A sectional view showing an example of the configuration of the variable displacement radial turbine of the present invention, FIG. 3 is a plan view of the arm plate for operating the tongue member, FIG. 3 is a front view of the turbine housing, and FIG. 3 is a view of the housing cover. 6 is a sectional view showing the configuration of the second embodiment of the present invention, a close-up view is a front view of the turbine housing, FIG. g is a front view of the housing cover, and FIG. A front view of the turbine housing according to the third embodiment, FIG. 7θ is a sectional view showing the configuration of the third embodiment of the present invention, FIG. 1 is a front view of the turbine housing, and FIG. It is a front view of what changed the processing form of a part. l... Turbine rotor, /A... Rotor shaft, Co... Turbine/1 housing, Core A, 2B... Inner wall surface, 3... Turbine scroll, 3A... Inlet, 3B... ...Flow path, G...tongue (tongue-shaped member), HiroA, ψB...side, S...shaft, 6...inlet, 7...actuator, l...link Components, 9...Center housing, lθ...Bearing, //...Ring seal, 12...Shroud plate, /3...Bolt, 〃...Turbine/1 housing, 〃A...・Wall surface, 〃B...outer peripheral wall, 〃C...fitting part, 〃...housing cover, 2/A...wall surface, 2/B...inner peripheral wall, 2/O... Fitting groove, 2/D...shroud part, n...backing, B...bolt, 2g...tongue member, 2g A, 21IB...side, 2g C... Surface, 2g D...base, B...rotating shaft, I...button, l...arm plate, np,...connection hole, X...nut, 〃...connection Pin, 30, 3/...Protruding part, 30k, nA...Engaging surface, Mon, G/...Stepped part, Fll, 41/A...Stepped is surface, q2...・Fixed tongue part, slI...tongue-like member, iD...surface, sr, st...stepped part, ssh, sth...stepped part is surface. Patent applicant Nissan Motor Co., Ltd. Figure 1 (B) 4 Figure 2 3A ? 9 Figure 4 23 Figure 5 1 Figure 6 3A ? 9 Figure 7 Figure 8 Figure 9 Figure 10 Figure 0 Figure 11 Pot

Claims (1)

[Claims] In a variable displacement radial turbine in which a tongue-shaped member provided along a flow path of a turbine scroll is swingable in the radial direction of the turbine rotor to change the gas flow rate, the tongue-shaped member changes the gas flow rate. In a state where the tongue-like member is swung to the minimum position, the end edge portion of the tongue-like member along the flow path is brought into surface contact with a retaining surface protruding from the side wall of the turbine scroll, and the side surface of the tongue-like member A variable displacement radial turbine characterized in that no gap is formed between the turbine scroll and the side wall of the turbine scroll.