JPS6112084B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exhaust turbine supercharger equipped with a swirl turbine casing in which no guide vanes are provided in the nozzle portion.

As shown in FIG. 1, a relatively large exhaust turbine supercharger for ships and industry uses a guide vane 12 provided at a nozzle portion of a turbine casing 11 to give a swirling component to the working fluid, thereby causing a turbine impeller 13. The structure is such that it rotates. Furthermore, as shown in FIGS. 2 and 3, an exhaust turbine supercharger used in an automobile engine has a structure in which a swirling component is imparted to the working fluid by a swirl turbine casing 3 to rotate a turbine impeller 1. JP-A-49-101722, the nozzle part of the volute turbine casing is not provided with guide vanes, and JP-A-51
A device in which a guide vane is provided in the nozzle part is known, as in No. -94010.

As shown in Fig. 7, the performance curve L of an exhaust turbine supercharger without guide vanes in the nozzle part
Compared to the performance curve L1 of the exhaust turbine supercharger equipped with guide vanes, curve 2 shows that the efficiency changes gradually over a wide range, and is advantageous when used at a point other than the maximum efficiency point. is considerably inferior. In addition,
In FIG. 7, the horizontal axis represents the flow rate of the turbine, and the vertical axis represents the efficiency.

By the way, when an exhaust turbine supercharger is attached to an engine, the energy of the exhaust gas is small when the engine speed is low, so the turbine does not rotate sufficiently and the supercharging effect becomes insufficient, deteriorating the torque characteristics of the engine. One effective way to improve this is to design the turbine so that the operating line passes through the turbine's highest efficiency point when the engine is at low speed. However, in the case where guide vanes are not provided in the nozzle, even if the turbine is designed so that the operating line passes through the maximum efficiency point at low engine speeds, as is clear from the performance curve L2 in Fig. 7, the efficiency decreases. The improvement is small and its effects cannot be expected. Further, if guide vanes are provided in the nozzle portion, the maximum efficiency point of the turbine will be significantly increased, but the structure will be complicated, the manufacturing cost will increase, and the efficiency will decrease at points other than the low speed design point.

An object of the present invention is to improve turbine efficiency at low engine speeds and to maintain high turbine efficiency over a wide range of turbine flow rates.

A feature of this invention is that the wall surface of the nozzle portion of the turbine casing has a large number of grooves formed at intervals from each other, and these grooves pass through the inner circumferential end of each groove and the rotation center of the turbine impeller. The reason is that the turbine impeller is tilted in the direction opposite to the direction of rotation of the turbine impeller relative to the straight line.

With this configuration, when the engine is at low speed, the turbine flow rate is low, so the guiding effect of the grooves on the wall of the nozzle on the gas flowing through the nozzle is stronger than when the engine is at low speed, so that the gas flows through the nozzle. The flow turbine efficiency is improved in the direction along the groove of the section. On the other hand, when the engine speed is not low, the turbine flow rate increases, so the guiding effect of the nozzle groove on the gas is
It is smaller than when the engine is running at low speed.

Therefore, according to the present invention, the turbine efficiency is improved at low engine speeds, and the turbine efficiency is higher at low engine speeds and at turbine flow rates other than low speeds, compared to a nozzle without a guide vane. The maximum efficiency is lower than with guide vanes, but the turbine flow rate range where the turbine efficiency is higher is wider than with guide vanes.

Hereinafter, one embodiment of the present invention will be explained with reference to FIGS. 4 to 6.

A turbine impeller 6 is housed inside a spiral turbine casing 1 equipped with an inlet 2 and a scroll 3, and a large number of grooves 5 are provided at intervals on the wall surface of a nozzle portion 4 of the turbine casing 1. , each of these grooves 5 is formed at an angle corresponding to the angle generally used in, for example, those with guide vanes, that is, with respect to a straight line A passing through the inner peripheral end of each groove 5 and the rotation center of the turbine impeller. It is tilted on the opposite side to the rotation direction of the turbine impeller 6. The inlet 2 is connected to an engine exhaust pipe (not shown). Exhaust gas from the engine is led to the inlet 2 through the exhaust pipe, is given a swirling component as it passes through the scroll 3, and is further given a flow velocity by the nozzle part 4, causing the turbine impeller 6 to rotate. If the nozzle part 4 is not provided with guide vanes, there is no constraint on the flow direction, so the direction of inflow at the inlet 7 of the turbine impeller 6 will be non-uniform on the circumference, and the exhaust gas of the engine will be pulsating. Because of this, there are large changes over time, resulting in a decrease in efficiency.

In the exhaust turbine supercharger of the present invention, a large number of grooves 5 are provided on the wall surface of the nozzle portion 4, and these grooves 5
is at such an angle that the turbine efficiency is good at low speeds of the engine, so the gas flow near the wall surface flows along the groove 5, and the gas flow near the wall surface also flows near the center of the nozzle section 4. , the flow at the impeller inlet 7 is made uniform, and the performance curve of the turbine follows the dashed line L in FIG.
It will be like 3. In other words, the maximum efficiency is significantly increased compared to the normal type without guide vanes (L2), and the range of high efficiency is wider than that of the type with guide vanes (L1). This improves the engine's torque characteristics. Furthermore, since the grooves 5 can be easily provided during casting of the turbine casing 1, the manufacturing cost is almost the same as that of a conventional structure without guide vanes.

As explained above, according to the embodiment of the present invention, the maximum efficiency is significantly higher than that of a conventional nozzle section without guide vanes, and the turbine performance with a relatively wide range of high efficiency can be obtained. For example, when the exhaust turbine supercharger according to the present invention is installed in an engine, if the angles of the grooves in the turbine casing and nozzle section are designed so that the operating line passes through the turbine's highest efficiency point at low engine speeds, the engine torque can be reduced. Characteristics can be improved.

As described in detail above, according to the present invention, it is possible to improve the turbine efficiency when the engine is running at low speed, and to maintain a high range of turbine efficiency over a wide range of turbine flow rates.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional side view showing a conventional exhaust turbine supercharger equipped with a guide vane, Fig. 2 is a front view of a conventional exhaust turbine supercharger without a guide vane, and Fig. 3 is a cross-sectional side view showing a conventional exhaust turbine supercharger equipped with a guide vane. 4 is a sectional side view of one embodiment of the present invention, and FIG. 5 is a sectional side view of an embodiment of the present invention.
6 is an enlarged cross-sectional view of FIG. 5, and FIG. 7 is a performance curve diagram for explanation. 1... Swirl turbine casing, 2... Inlet, 3...
Scroll, 4... Nozzle part, 5... Groove, 6... Turbine impeller.

Claims (1)

[Claims] 1. In an exhaust turbine supercharger that is equipped with a swirl turbine casing in which no guide vanes are provided in the nozzle part, a turbine impeller rotatably housed in the turbine casing, and uses engine exhaust gas as a driving source, the nozzle part is The wall surface has a large number of grooves formed at intervals, and each of these grooves has a rotation angle of the turbine impeller with respect to a straight line passing through the inner circumferential end of each groove and the rotation center of the turbine impeller. An exhaust turbine supercharger characterized by being tilted in the opposite direction.