JPH0452402Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a variable displacement exhaust gas turbine, particularly to a variable displacement exhaust gas turbine in a turbocharger, which is driven using exhaust gas from a vehicle engine as a working medium and drives a compressor.

Engines for automobiles and other vehicles are operated over an extremely wide range of rotation speeds, from idle speed to maximum speed, and within a load range that fluctuates widely, so the amount of exhaust gas varies widely depending on the operating conditions. fluctuate. Therefore, with an exhaust gas turbine having a constant flow rate characteristic, it is not possible to sufficiently recover and utilize the exhaust gas energy discharged from the engine. Therefore, a partition wall is provided in the housing of the exhaust gas turbine to form a plurality of divided exhaust gas passages in the rotor axial direction, and valve devices are provided in these exhaust gas passages so that the valve device can be adjusted according to the operating state of the engine. A device has already been proposed in which the cross-sectional area of the passage is controlled by appropriately selecting an exhaust gas passage that opens and closes to allow exhaust gas to flow. However, in conventional exhaust gas turbines of this type, the structure of the exhaust gas passage within the turbine housing has not yet been sufficiently studied.

The present invention has been devised in view of the above circumstances, and includes a variable capacity exhaust gas turbine in which a partition wall is provided in the turbine housing to form first and second exhaust gas passages divided in the rotor axial direction. The first and second exhaust gas passages have flow path cross-sectional areas different from each other, and the cross-sectional area changes within a plane including the rotor axis at each angular position around the rotor axis from the scroll inlet portion to the winding end portion thereof. have almost the same proportions, furthermore, the scroll inlet cross-sectional area is F, the scroll outlet width in the rotor axis direction is l, and the distance from the rotor axis to the scroll inlet cross-sectional center is r.
By making the values obtained by the formula F/l·r equal for each of the first and second exhaust gas passages, the first and second exhaust gas passages have approximately equal exhaust gas outflow angles with respect to the rotor. The gist of this invention is a variable capacity exhaust gas turbine characterized by having:

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the drawing, reference numeral 10 generally indicates an exhaust gas turbine of a turbocharger, 12 is a turbine housing, 14 is a scroll inlet portion of the turbine housing that guides the exhaust gas of an engine (not shown) to a turbine rotor 16, and 18 is a housing 1
The axis O- of the turbine rotor 16 provided in 2
The housing 12 is partitioned by the partition wall 18 and has different cross-sectional areas, as shown in FIG. Two exhaust gas passages A and B are formed. Exhaust gas passages A and B
As shown in FIG.
4, the respective cross-sectional areas are F ₀ and F ₁ , and from the entrance portion 14 to the scroll end portion 20
(from the inlet portion 14 around the rotor axis O-O)
At each angular position around the axis O-O, the cross-sectional area of each section corresponds to the line A',
They are configured to change at the same rate, as shown by B′. By configuring the exhaust gas passages A and B in this way, the pressure loss in the exhaust gas passages A and B before flowing into the turbine rotor 16 is significantly reduced, and the energy retained in the exhaust gas is effectively transferred to the turbine rotor 16. It can be supplied to the rotor 16. (In addition, in Fig. 5, exhaust gas passage A,
A case is shown in which the cross-sectional areas A' and B' of B vary linearly in the angular direction, but these curves are also acceptable.) Next, Figures 1, 3, and 4 are shown. In reference to,
Consider exhaust gas passage A. Now, ρ ₁ , ρ ₂ :
Exhaust gas density at the scroll inlet cross section and the nozzle outlet 22 of the exhaust gas passage to the turbine rotor 16, C ₀ , C ₁ : Absolute velocity of the exhaust gas at the scroll inlet cross section and the nozzle outlet 22, d ₁ : Diameter of the nozzle outlet 22 ( 2r ₁ ), l ₁ : Width of the nozzle outlet 22 in the rotor axis direction, r ₀ : Distance from the rotor axis O to the center of the scroll inlet cross section 14, α ₁ : Exhaust gas outflow angle at the nozzle outlet 22, α ₀ : If the inflow angle of exhaust gas at the scroll inlet cross section 14 is the continuity equation between the scroll inlet cross section 14 and the nozzle outlet 22, ρ ₀ C ₀ F ₀ = ρ ₁ C ₁ πd ₁ l ₁ sinα ₁ ...(1) Also, from the free eddy condition, C ₀ r ₀ cosα ₀ = C ₁ d ₁ /2cosα ₁ ...(2) From equations (1) and (2) above, assuming α ₀ 0, tanα ₁ = 1/2π・ρ ₀ /ρ ₁・F ₀ /l ₁ r _0Furthermore , if we set ρ ₀ ρ ₁ , the outflow angle is α ₁ = tan ^-1 (1/2π・F ₀ /l ₁ r ₀ )...(3) This From equation (3), the exhaust gas outflow angle α ₁ is determined by the cross-sectional area F ₀ at the scroll inlet portion 14 and the distance r ₀ from the rotor axis O to the center of the cross-section of the inlet portion 14.
and the width l ₁ of the nozzle outlet 22. This relationship holds true for the adjacent exhaust gas passage B as well. And these two exhaust gas passages A,
In B, since r ₀ in the above equation (3) is common, the exhaust gas outflow angle of each passage is determined by the ratio of (scroll inlet cross-sectional area/nozzle outlet width). Therefore, in the present invention, the design of the turbine rotor 16 (mainly the design of its blades) is made to be the most efficient with respect to the outflow angle α ₁ of the exhaust gas passage A, and at the same time, the outflow angle of the exhaust gas passage B is The scroll inlet cross-sectional area F ₁ and nozzle exit width l ₂ are designed so that α ₁ is substantially the same. As a result, depending on the operating conditions such as engine speed and load, exhaust gas is supplied to either exhaust gas passage A or B, or when exhaust gas is supplied to both passages A and B. In either case, substantially the same exhaust gas outflow angle can be obtained, and the turbine efficiency can always be maintained at a good level. As mentioned above, the cross-sectional area of the two exhaust passages A and B in the turbine housing 12 is changed at approximately the same rate at each angular position around the rotor axis from the scroll inlet to the end of the winding. Therefore, the flow loss within the housing is reduced, and at the same time, each of the exhaust passages A and B is
By setting the exhaust gas outflow angles at the nozzle exits to approximately equal angles that can exhibit high efficiency for the turbine rotor, it is possible to provide an exhaust gas turbine that has excellent overall efficiency over the entire operating range. It is.

As described above, the variable displacement exhaust gas turbine according to the present invention is a variable displacement exhaust gas turbine in which a partition wall is provided in the turbine housing to form first and second exhaust gas passages divided in the rotor axial direction. In the above, the first and second exhaust gas passages have flow path cross-sectional areas different from each other, and have cross-sectional areas in a plane including the rotor axis at each angular position around the rotor axis from the scroll inlet portion to the winding end portion thereof. The first and the first and second By equating the values obtained by the formula F/l·r for each of the two exhaust gas passages, the first and second exhaust gas passages have approximately equal exhaust gas outflow angles with respect to the rotor. This feature makes it possible to provide an exhaust gas turbine of this type that can consistently exhibit high efficiency under a wide range of engine operating conditions, which is extremely beneficial.

Further, the variable capacity exhaust gas turbine has a first
Since the cross-sectional areas of the exhaust gas passage and the second exhaust gas passage are different, by switching and using each exhaust gas passage, it is possible to use only one exhaust gas passage or both exhaust gas passages. It can be used to vary the turbine capacity in three ways.

Furthermore, when switching between the first exhaust gas passage and the second exhaust gas passage as described above, the above 3.
In any normal usage condition, the outflow angles of the exhaust gas with respect to the rotor are approximately the same, and rotational fluctuations due to differences in outflow angles do not occur, so there is an advantage that reduction in efficiency can be prevented.

[Brief explanation of the drawing]

Figure 1 is a side view showing one embodiment of the present invention;
The figure is a sectional view taken along the - line in Fig. 1, Fig. 3 is a sectional view taken along the - line in Fig. 1, and Fig. 4 is a drawing showing the outflow angle α ₁ of the exhaust gas at the nozzle outlet in the turbine of the present invention. , FIG. 5 is a diagram showing how the cross-sectional areas of the exhaust gas passages A and B change in the turbine of the present invention. 12... Turbine housing, 14... Scroll inlet portion, 16... Rotor, 18... Partition wall,
20... Scroll end portion, 22... Exhaust gas passage nozzle inlet, A, B... Exhaust gas passage, α ₁
...Outflow angle.

Claims (1)

[Claims for Utility Model Registration] A variable displacement exhaust gas turbine in which a partition wall is provided in the turbine housing to form first and second exhaust gas passages divided in the rotor axial direction. The exhaust gas passages have flow path cross-sectional areas that are different from each other, and the cross-sectional area changes at approximately the same rate in a plane including the rotor axis at each angular position around the rotor axis from the scroll inlet to the end of the winding. Further, when the scroll inlet cross-sectional area is F, the scroll outlet width in the rotor axis direction is l, and the distance from the rotor axis to the scroll inlet cross-sectional center is r, the above first
By making the values obtained by the formula F/l·r equal for each of the first and second exhaust gas passages, the first and second exhaust gas passages have approximately equal exhaust gas outflow angles with respect to the rotor. A variable displacement exhaust gas turbine characterized by having: