DE2831519A1 - EXHAUST TURBINE FOR CHARGER - Google Patents

Description

HITACHI, LTD., Tokyo, Japan

Exhaust gas turbine for superchargers

The invention relates to an exhaust gas turbine for superchargers that emerge from an internal combustion engine Exhaust gases is driven, in particular an improved turbine housing for an exhaust gas turbine.

So far, in existing exhaust gas turbines for superchargers, these have been ejected from several cylinders at different times Exhaust gases are collected and passed into the turbine housing. In US Pat. No. 3,292,364, e.g. B. proposed a turbine housing, which has two spiral chambers, which are separated from one another by a partition, so that for the spiral chambers Throttle portions are formed; this prevents the exhaust gas flow from one of the cylinders from stopping the operation the other cylinder interferes. In the case of such a turbine housing, the edge section of the partition wall is concentric to the axis

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of the turbine runner and close "to the ends of the turbine blades, so that the exhaust gas flow directed into one spiral chamber is effectively prevented from that with the other Disturbing spiral chamber connected cylinder.

In such turbine housings, however, the pressure distribution characteristics change in the spiral chambers and the flow velocity of the exhaust gas flow entering the impeller depending on different areas in the spiral chambers or on the spiral angle. In particular, increase the pressure of the exhaust gas flow in the spiral chambers and the flow velocity of the chambers from the spiral exhaust gases entering the impeller with increasing spiral angle of the turbine housing. Hence the exhaust fumes will not introduced evenly around the entire circumference of the impeller, reducing the efficiency of the turbine. In particular when the engine is operated at high load and high speed, the flow velocity of the exhaust gas flow increases at the throttle sections of the turbine housing at the spiral end (the section with the larger spiral angle) of the Turbine housing, and the risk of a reduction in turbine efficiency is very great.

The object of the invention is to create a turbine housing for an exhaust gas turbine for superchargers, whereby the energy the exhaust gases of an internal combustion engine can be used effectively without the scavenging efficiency of the engine being impaired.

The turbine housing according to the invention is constructed in such a way that the dimension of each throttle section opening towards the impeller of the spiral chambers increases with the size of the spiral angle, i.e. towards the end of the spiral. At such an

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Order the exhaust gases from the spiral chambers into the impeller with a constant flow velocity around the The entire circumference of the impeller is initiated, and the scavenging properties of the motor are not affected by the pulse pressure wave of the exhaust gas flow is impaired, since the dimensions of the throttle sections at the beginning of the spiral (the section with smaller spiral angle) of the turbine housing.

The invention thus specifies an exhaust gas turbine for superchargers, with a turbine housing which is provided with a plurality of exhaust gas lines is connected to lead the exhaust gases from the engine cylinders, with a spiral in the turbine housing around the center of the turbine housing rotatable impeller, wherein the turbine housing has two or more spiral chambers, which the exhaust gases from the exhaust pipes to the entire circumference of the impeller, while the exhaust gases are kept separate from each other, with a partition, which is arranged on an inner wall of the turbine housing and runs around the impeller and the interior of the Turbine housing divided into the spiral chambers, and with between a radially inner end portion of the partition wall and the side walls of the spiral chambers defined throttle sections for guiding the exhaust gases from the spiral chambers to Impeller circumference, the size of the throttle sections being dimensioned so that they are in the direction of the spiral end of the spiral chambers get bigger and bigger.

The invention is explained in more detail, for example, with the aid of the drawing. Show it:

Pig. 1 is a partially broken front view of a conventional exhaust gas turbine for charger;

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FIG. 2 shows a bottom view of the exhaust gas turbine according to FIG. 1;

3 A shows a spiral angle in the turbine housing;

Fig. 3B shows the relationship between the spiral angle and the dimensions of the throttle part in the conventional turbine housing (dashed line) and in the turbine housing according to the invention (solid line);

Fig. 3C shows the relationship between the flow rate of the exhaust gas stream to the Throttles and the spiral angle in the conventional turbine housing (dashed line) or in the turbine housing according to the invention (solid line);

4A shows the pressure wave of the exhaust gas flow in the spiral beginning of each spiral chamber of the conventional one Turbine housing;

Fig. 4B shows the pressure wave of the exhaust gas flow in the spiral end of each spiral chamber of the conventional one Turbine housing;

5 shows a sectional view of an exemplary embodiment of the exhaust gas turbine for superchargers according to the invention;

Fig. Sk shows the pressure wave of the exhaust gas flow in

Spiral beginning of each spiral chamber of the turbine housing according to the invention;

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] pig. 6B shows the pressure wave of the exhaust gas flow in

Spiral end of each spiral chamber of the turbine housing according to the invention;

Pig. 7 shows a front view of a further exemplary embodiment of the exhaust gas turbine according to FIG the invention; and

Pig. 8 shows a sectional view VIII-VIII according to Pig. 7c

The Pig. 1 and 2 show a conventional exhaust gas turbine 10 for superchargers. Exhaust gases from an engine with six cylinders 1 will be supplied to the turbine 10 through a pair of exhaust pipes 2, 3, each of which has three cylinders with the same exhaust stroke at one end and a spiral chamber 16 at the other end, 17 of the turbine is connected.

The turbine 10 includes a turbine housing 14 in which a Impeller 20 is arranged rotatably about an axis of rotation 23. The impeller 20 has multiple turbine blades (not shown) on, which are acted upon by the thrust of the introduced exhaust gas flow, so that the impeller rotates "

The turbine housing 14 comprises two spiral chambers 16, 17, the guide the introduced exhaust gases on a spiral path. The two spiral chambers 16, 17 are from each other separated by a partition wall 21 which extends from an inlet flange 15. The partition is in a radial direction Plane perpendicular to the axis of rotation 23 of the impeller and divides the interior of the turbine housing 14 into the two spiral chambers, the substantially same cross-sectional area

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to have. A radially inner end 22 of the partition wall 21 extends concentrically with the axis of rotation 23 of the impeller and lies in the circumference of a radius * t \

In such a conventional exhaust gas turbine for superchargers, the waveform of the exhaust pressure is that output from the engine Exhaust gases at the inlet area (spiral beginning) of the turbine housing 14 mainly from a pulsating waveform. Every disturbance pressure wave that can occur in the other exhaust gas line due to the pulse-shaped exhaust gas pressure is on Prevented occurrence by the partition wall 21 separating the spiral chambers 16, 17 from one another. The waveform of the exhaust pressure however, at the spiral end includes a pulsating waveform in a smaller part and a smooth one Waveform in a larger part.

During high-speed operation, however, the pressure of the exhaust gases in the turbine housing and the flow velocity change of the exhaust gases entering the impeller from the nozzle part considerably between the beginning of the spiral and the end of the spiral. In particular (cf. curve 43 in FIG. 3C), the flow velocity of the exhaust gases at the spiral end increases with it as the engine speed increases, and therefore there is no smooth entry of the exhaust gases into the impeller 20. This is a Problem that the efficiency of the impeller 20 is reduced.

The Pig. 4A and 4B illustrate an example of the pressure waveform at the spiral inlet A and at the spiral end B to Pig. 1, which as the aforementioned inlet area of the turbine housing and said spiral end were chosen. The ordinate represents the pressure in the turbine housing in kg / cm and the abscissa the time. The upper half of FIG. 4A shows the pressure waveform in the spiral chamber 16

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and the lower half that in the spiral chamber 17. The pressure of the engine cylinders 1 through the exhaust pipe 2 exhaust gases conducted to the spiral chamber 16 cyclically generate main pressure waves 51 and a main pressure wave 32 of the exhaust gases in the spiral chamber 17 is generated exactly between the main pressure waves 31 in terms of time. The between adjacent main pressure waves 31 and 33 occurring low waves 32 and 34 are disturbance pressure waves, which by the Leakage exhaust gas flow (main pressure waves 31, 33) caused from the other spiral chamber through the throttle section has left.

Fig. 4-B shows the waveform of the exhaust pressure in the scroll end B, the upper and lower halves showing the waveform of the exhaust gases in the spiral chambers 16 and 17, respectively. in the When compared with the waveform at the inlet area A, the waveform at the section B in both chambers is the basic component Constant pressure components with a higher level, the peaks of the main pressure waves 35, 37 and the disturbance pressure waves 36, 38 are close to each other and the pulse wave components are decreased.

As already explained, the waveform of the exhaust gas pressure at the inlet area A of the turbine housing is a major part the pulse wave component, and it is therefore necessary to consider the generation of the aforementioned shock waves to keep the scavenging effect for the engine small. The dividing wall separating the spiral chambers 16, 17 serves to prevent interference between the pressure waves, but the pulse components of the pressure wave are reduced when the exhaust gas flow increases moved to the scroll end portion B. However, the turbine housing of the conventional exhaust gas turbine for superchargers is constructed so that the end 22 of the partition wall 21 (cf.

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Pig. 1) with the same distance (^ = constant) from the The axis of rotation 23 of the impeller 20 is provided and that extends from the spiral chambers 16, 17 to the impeller 20 smallest throttle sections at every point around the total circumference of the impeller have constant dimensions, such as shows straight line 42 in Figure 3B. As a result, the pressure of the exhaust gases in the scroll chambers and the flow rate increase of the exhaust gas flow from the spiral chambers to the impeller towards the spiral end. Especially when it comes to operation with a high load and high speed, the flow velocity of the exhaust gases at the throttle section increases (see curve 43 in Fig. 3C) towards the scroll end, and a high pressure throttling condition is generated (a part of the exhaust gas flow is led back to the beginning of the spiral), which ensures the even entry of the exhaust gas flow into the impeller disturbs, whereby the efficiency of the turbine is reduced.

An exemplary embodiment of the exhaust gas turbine according to the invention will now be explained with reference to FIG. 5, wherein the same parts as in Fig. 1 have the same reference numerals. The turbine of Fig. 5 differs from that according to Fig. 1 in that the dimensions of the throttle sections, which are defined by the side walls of the spiral chambers 16, 17 and the end portion 22 of the partition wall 21 separating the chambers from one another are defined, with increasing Helix angles θ become larger (see. Fig. 3B).

According to FIG. 5, the end section 22 of the partition wall 21 separating the spiral ducts 16, 17 lies on the circumference at an equal distance A from the axis of rotation 23 of the impeller 20, but the throttle sections 19, 19 'are designed so

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that its size increases toward the scroll end (S " T ^ S ¹ ) · Therefore, the resistance to the exhaust gases admitted into the impeller 20 can be reduced, so that the aforementioned throttling phenomenon is prevented from occurring. As indicated by the solid line in Fig. 3C is indicated, the flow speed of the exhaust gases at the throttle portion can be maintained at a value compared with that of the conventional turbine housing substantially constant regardless of the spiral angle θ in the turbine housing, and thereby the rotational energy around the entire circumference of the impeller 20 is uniform.

6A and 6B show waveforms of the exhaust gas pressure at locations in the turbine housing of the first embodiment, these locations corresponding to locations A and B in the spiral chambers 16, 17 according to FIG. The waveform of the exhaust pressure at the inlet portion A in Fig. 6A has pulse components similar to those of FIG. 4A, as a result of which interference pressure waves 32, 34 are kept small. In the waveform of the exhaust pressure at the spiral end portion B in Fig. 6B, the pulse components 35, 37 have average values and have none strong influence on the scavenging effect of the engine.

In the above-explained turbine housing, the inlet part is formed with throttle portions which are essentially have the same dimensions as those of the conventional turbine housing, so that the scavenging effect for the engine cannot be reduced; the dimensions of the throttle sections at the volute end section are enlarged, so that the throttling phenomenon that usually occurs is eliminated. It is therefore possible to use an exhaust turbine for superchargers to create at which a uniform flow velocity around the entire circumference of the impeller can be achieved is.

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The distance is £. from the axis of rotation 23 to the edge 22 of the partition wall 21 essentially constant around the entire circumference of the impeller, and the dimension S of the throttle sections defined by the side walls of the spiral chambers and the edge section 22 of the partition wall is different.

In the second embodiment of the exhaust gas turbine for superchargers according to FIGS. 7 and 8, the same parts are again provided with the same reference numerals. The exhaust gas turbine differs from that of Fig. 1 in that the distance << £ from the axis of rotation 23 to the edge section 22 of the partition wall 21, which separates the spiral chambers 16, 17 from one another, increases in the direction of the spiral end (^ " y ^ in Fig 8) Therefore, the cross-sectional area of the throttle sections 19, 19 'for introducing the exhaust gases into the impeller 20 is larger due to the fact that the edge portion 22 of the partition wall in the direction of the spiral end B of the turbine housing is further away from the axis of rotation of the impeller is, whereby a smooth passage of the exhaust gases is achieved, which tend to be compressed against the scroll end B. This reduces the flow resistance in the vicinity of the scroll end B of the turbine casing 14, so that the occurrence of the throttling phenomenon is prevented and a uniform rotational energy around the entire circumference of the impeller 20 is obtained.

In the conventional turbine housing 14 according to FIG. 1, the distance between the edge portion 22 of the partition wall 21 and the outer circumference of the impeller 20 constant, and the cross-sectional area of the spiral chambers 16, 17 is against the Spiral end as well as the throttle section smaller. thats why

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the flow velocity of the exhaust gases entering the impeller from the spiral chambers is high at the spiral end B. (cf. curve 43 in FIG. 3C), so that the exhaust gases having such a high flow velocity cause the rotation of the impeller. At the turbine after the Pig. 7 and 8 take the dimensions of the throttle sections with the helix angle increases (see curve 41 in Fig. 3B), and therefore it becomes the same effect as that before illustrated embodiment.

In the turbine housing of the exhaust gas turbine for superchargers, the energy of the exhaust gas flow of an internal combustion engine is im The impeller of the turbine can be used with high efficiency without reducing the flushing effect.

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Claims (1)

Expectations \\ J exhaust gas turbine for superchargers, with a turbine housing, an impeller rotating therein around the center of the turbine housing spiral, the turbine housing having at least two spiral chambers for conducting exhaust gases from an internal combustion engine to the entire circumference of the impeller and the exhaust gases are kept separate from one another a partition wall attached to an inner wall of the turbine housing, which divides the interior of the housing into the spiral chambers, and with throttle sections formed by side walls of the spiral chambers and a radially inner end portion of the partition wall, which throttle sections open from the spiral chambers substantially to the entire circumference of the impeller, characterized, that the throttle sections (19 _f 19 ') gradually become larger in the direction of the spiral end (B) of the spiral chambers (16, 17). 2. exhaust gas turbine according to claim 1,
characterized, that the distance (j £) between the axis of rotation (23) of the impeller (20) and the inner end portion (22) of the partition wall (21) increases in the direction of the spiral end (B) of the spiral chambers (16, 17). 81- (A 296i-03) -schö 809885/0927 ORIGINAL INSPECTED 3. exhaust gas turbine according to claim 1,
characterized, that the distance (- /?) between the axis of rotation (23) of the Impeller (20) and the inner end portion (22) of the partition wall (21) substantially over the entire circumference of the impeller (20) and the distance between the inner end portion (22) of the partition wall (21) and the side walls is constant the spiral chambers (16, 17) in the direction of the spiral end (B) the spiral chambers (16, 17) increases. 4. exhaust gas turbine according to claim 2, characterized, that the distance between the inner end portion (22) of the partition wall (21) and the side walls of the spiral chambers (16, 17) in the direction of the spiral end (B) of the spiral chambers (16, 17) increases. 809885/0927