JPS6314161B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in the exhaust turbine of an internal combustion engine using a nozzleless turbine.

The configuration of a conventional exhaust turbocharged internal combustion engine is shown in FIG. In this engine 1, exhaust gas from a cylinder 2 passes through an exhaust pipe 3 to drive an exhaust turbine 4.
The exhaust turbine 4 drives a coaxial compressor 5, which compresses atmospheric air and supplies high-pressure air to the cylinder 2 through an air supply pipe 6. A cross section of the exhaust turbine is shown in FIG.

This is a nozzleless radial turbine that is widely used as an exhaust turbine for high-speed internal combustion engines, and exhaust gas passes through an exhaust passage 11 in a volute casing 10 to drive turbine blades 12. A cross section of the volute casing 10 is shown in FIG.

The internal passage of the volute casing 10 is composed of a volute introduction part 13 from the volute inlet Aen to the volute throat At, and a spiral volute part 14 having a cross section whose inner side is partially open toward the turbine rotor blades. The passage area of the volute introduction section 13 gradually decreases from the volute inlet surface Aen toward the volute throat At, and the capacity of the exhaust turbine is determined by the size of the cross-sectional area of the volute throat At. Volute part 14
The passage area also decreases from the volute throat At to the volute tip 15.

In FIG. 1, the amount of exhaust gas discharged from the engine 1 and supplied to the exhaust turbine 4 is proportional to the rotational speed of the engine 1. By the way, the capacity of the exhaust turbine 4 is determined by the size of the cross-sectional area of the volute throat At shown in FIG. 3, as described above.

If the capacity of the exhaust turbine 4 is determined according to the maximum rotational speed of the engine 1, when the engine 1 is operated at a low rotational speed, the exhaust turbine 4 will be
becomes too large, and the amount of air supplied from the compressor 5 becomes too small, resulting in problems such as increased smoke from the engine 1.

Conversely, if the capacity of the exhaust turbine 4 is determined according to the low rotational speed of the engine 1, when the engine 1 is used at the maximum rotational speed, the exhaust turbine 4 will be
If the amount of air is too small, the amount of air supplied from the compressor 5 becomes too large, causing problems such as damage to various parts due to an increase in the maximum pressure inside the cylinders of the engine 1.

It is an object of the present invention to overcome these drawbacks of conventional exhaust turbines. According to the invention,
This is intended to improve the performance of an exhaust turbocharged internal combustion engine within a wide rotational speed range by making the capacity of the exhaust turbine variable and changing the capacity of the exhaust turbine depending on the rotational speed of the engine.

The feature is that a movable partition is provided in the passage within the volute of a nozzleless radial turbine, and by opening and closing the partition, the cross-sectional area of the passage within the volute, including the volute throat, is changed.

This allows the capacity of the turbine to be changed depending on the amount of exhaust gas.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 4 is a sectional view showing an exhaust turbine according to one embodiment of the present invention.

In the figure, a guide groove 21 is provided in the volute internal passage of a volute casing 20, and a movable partition wall 22 that moves along the guide groove 21 is attached.

FIG. 5 shows a cross section taken along the - arrow in FIG.

The guide groove 21 is installed throughout the spiral volute part 14 from the volute throat At to the volute tip 15, and communicates with a storage part 23 provided in the middle of the volute introduction part 13. Further, a driving roller 24 is installed between the volute introduction section 13 and the storage section 23.

The movable partition wall 22 is made of a thin elastic plate, and can be deformed along the guide groove 21 and deformed into a spiral shape to be stored in the storage portion 23 .

Here, the movable partition wall 22 moves along the guide groove 21 to the turbine blade 12 by the rotation of the drive roller 24.
moves in the circumferential direction, and when its tip reaches the volute tip 15, the other end still has enough length to partially remain in the storage section 23. At this time, the movable partition wall 22
The volute portion 14 is partitioned in the radial direction of the exhaust turbine rotor blade 12, and the cross-sectional area of the volute portion passage opening inward with respect to the exhaust turbine axis is as follows:
The area decreases from the partitioned volute throat At ₁ toward the volute tip 15.

Next, FIG. 6 shows a state in which the movable partition wall 22 is pulled back into the storage section 23 by the drive roller 24.

The tip of the movable partition wall 22 is pulled back into the outer wall of the volute introduction section 13.

Although the means for driving the drive roller 24 is not shown, any means may be used as long as it detects the engine rotation speed and determines the direction of rotation of the drive roller 24 based on the height of the rotation speed.

The operation in the case of the above configuration will be described.

When the drive roller 24 is rotated and the entire passage inside the volute is partitioned off by the movable partition wall 22, the exhaust turbine capacity becomes a small capacity determined by the volute throat _At1 .

In addition, the drive roller 24 is reversely rotated, and the movable partition wall 22
When the exhaust turbine is pulled back to the storage section 23, the exhaust turbine capacity becomes a large capacity determined by the volute throat At.

The present invention as described above has the following effects.

When the engine rotational speed is high, when the movable partition wall 22 is pulled back to the storage portion 23 by the drive roller 24, the capacity of the exhaust turbine 4 increases, and the amount of air supplied from the compressor 5 becomes an appropriate amount.

Next, when the engine rotation speed is low, the drive roller 24
When the movable partition wall 22 is installed along the guide groove 21 throughout the volute internal passage, the exhaust turbine capacity becomes small and the amount of air supplied from the compressor 5 does not become too small, but an appropriate amount can be ensured.

As a result of the above, the performance of the exhaust turbocharged internal combustion engine can be improved within a wide rotational speed range.

Furthermore, if the exhaust turbine capacity is reduced by the movable bulkhead 22, the volute introduction section 13 from the volute inlet Aen to the volute throat _At1
Since the passage cross-sectional area from the volute throat At ₁ to the volute tip 15 is gradually reduced, high efficiency can be maintained without decelerating the flow rate of the exhaust air midway.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing the configuration of a conventional exhaust turbocharged internal combustion engine, Fig. 2 is a sectional view showing the exhaust turbine, Fig. 3 is a sectional view taken in the direction of - arrow in Fig. 2, and Fig. 4 is the present invention. FIG. 5 is a cross-sectional view showing an exhaust turbine according to an embodiment of the present invention, and FIG.
The figure is an explanatory diagram showing a state in which the movable partition wall is pulled back. 14... volute part, 15... volute tip,
20... Volute casing, 21... Guide groove,
22...Movable bulkhead, 23...Storage section, 24...Drive roller.

Claims (1)

[Claims] 1 In the volute internal passage of a nozzleless radial turbine, the volute internal passage from the volute throat to the volute tip is divided into two by a spiral surface around the turbine axis, and the volute internal passage is divided into two along guide grooves provided on both sides of the volute internal passage. A variable capacity variable capacity characterized by comprising: a flexible movable bulkhead that slides along the movable bulkhead; and a driving means for driving the movable bulkhead to change the cross-sectional area of the passage within the volute including the volute throat. turbine.