JPS61149520A - Turbocharger - Google Patents

Abstract

PURPOSE:To prevent a turbocharger from generating abnormal sound and from being broken, and so forth, by blocking the entire periphery of downstream side of an impeller in a compressor upon predetermined decelerating operation to sufficiently restrain surge. CONSTITUTION:Intake-air to be fed into an engine 33 is pressurized by a impeller 22, and is then fed through a parallel wall diffuser 26a, a scroll type diffuser 26b and an intake-air pipe 32, and the flow rate of the intake-air is controlled by a throttle valve 31. When decelerating operation takes place, the throttle valve 31 is fully closed so that the pressure in the intake-air pipe 32 downstream of the throttle valve 31 comes to be negative. When the intake-air pressure exceeds the urging force of a spring 29, a slider 27 moves to close the inlet port of the parallel wall diffuser 22a, and therefore, the entire periphery of downstream side of the impeller 22 is blocked. Accordingly, even if air in the volume from the slider 27 to the throttle valve 31 is compressed during this period, the counterflow of compressed air to the slider 27 may be inhibited, thereby no large surge occurs.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a turbocharger, and particularly to a turbocharger provided with a surge prevention device during deceleration transition.

(Prior art) A turbocharger uses engine exhaust energy to rotate a turbine, and a compressor coaxial with the turbocharger rotates the turbine to pressurize intake air and supply it to the engine.It increases the output torque of the engine and is useful for automobiles. This improves acceleration performance, etc.

However, during operation of this turbocharger.

For example, when you take your foot off the accelerator pedal to decelerate the vehicle from a steady state of operation, the throttle valve downstream of the compressor is fully closed to reduce the amount of intake air, but the compressor, which was rotating at high speed, suddenly stops rotating at low speed. Instead, air is supplied under pressure. Since the throttle valve is fully closed, the pressurized air has no place to escape, and may flow backward through the compressor, causing a so-called surge phenomenon that impacts the compressor.

For this reason, an example has conventionally been proposed in which the return passage of the compressor is opened during deceleration transients and the compressed air is returned to the compressor inlet again to prevent surges (MT21
(See March 979 issue, pages 107-111).

As shown in FIG. 3, a cylindrical piston-type return valve 6 is provided in a return passage 5 that short-circuits between the inlet 3 and outlet 4 of the compressor 2 of the turbocharger 1. The actuator that operates is the intake manifold 7, that is, when the intake negative pressure downstream of the throttle valve 8 exceeds a certain value, this pressure is guided to the back of the valve 6 to pull up the valve body against a spring (not shown). It is something. With such a configuration, in the conventional compressor, when the throttle valve 8 is closed, the return valve 6 is opened, and pressurized air from the outlet section 4 of the compressor 2 escapes to the inlet section 3, thereby preventing surges. In addition, 9 in FIG. 3 is an engine, and 10 is a turbine of the compressor 2. Further, in FIG. 1, arrows indicate the flow of air and exhaust gas.

(Problem to be Solved by the Invention) However, in such a conventional turbocharger, the return valve is opened by the intake negative pressure downstream of the throttle valve, and the pressurized air at the compressor outlet is sent through the return passage to the inlet. Since the structure was such that surges were prevented by allowing them to escape, there was a problem in that surges could not be suppressed to a sufficiently small level.

In other words, the actuator for operating the return valve opens the valve based on the differential pressure between the intake negative pressure downstream of the throttle valve and the atmospheric pressure, so its operation is influenced by the absolute value of the intake negative pressure (the magnitude of the negative pressure). At the same time, when the return valve opens,
The intake air that has already been fed to the compressor is compressed because the throttle valve is closed, and this compressed air flows back to the compressor. The compressed air at the compressor outlet is allowed to escape to the inlet through the return passage when the return valve is opened, but it also flows back into the compressor.Furthermore, the slower the return valve opens, the more compressed air flows back into the compressor. increases. Therefore, the surge cannot be suppressed to a sufficiently low level, and if the return valve is opened with a small intake negative pressure, the actuator becomes large and cannot be installed. As a result, there have been problems in that the surge causes abnormal noise and damage to the turbocharger.

(Purpose of the Invention) Therefore, the present invention focuses on the fact that surges occur due to backflow of air into the impeller, and that the magnitude of the surge increases as the volume of air downstream of the impeller increases. By closing the entire downstream circumference of the impeller, the purpose is to suppress surges to a sufficiently low level and prevent abnormal noise and damage to the turbocharger.

(Structure of the Invention) The turbocharger of the present invention is a turbocharger that is driven by exhaust energy from an engine, pressurizes intake air by rotation of an impeller of a compressor, and supplies it to the engine. By closing the entire circumference of the side, surges are suppressed to a sufficiently small level.

(Example) Hereinafter, an example of the present invention will be described based on the drawings. FIG. 1 is a diagram showing an embodiment of the present invention. First, to explain the configuration, 21 is a turbocharger compressor,
22 is an impeller, 23 is a compressor housing, 24
25 is a compressor shroud, and 25 is a bearing housing. The compressor housing 23 and the bearing housing 25 define a parallel wall diffuser 26a on the outer periphery of the impeller, and a scroll type diffuser 26b on the outer periphery of the parallel wall diffuser 26a.

The inlet of the parallel wall diffuser 26a is opened and closed by a slider 27. The slider 27 is the compressor housing 2
3 and the compressor shroud 24
A spring 29 is compressed in the chamber 28 and biases the slider 27 in the opening direction. Intake negative pressure downstream of the throttle valve 31 is introduced into the chamber 28 through a connecting pipe 30 and an introduction pipe (not shown), and the slider 27 is actuated by the force relationship between the biasing force of the spring 29 and the negative pressure in the chamber 28. Close the inlet of the parallel wall diffuser 26a. That is, during deceleration operation when the throttle valve 31 is closed and the intake negative pressure downstream of the throttle valve 31 reaches a predetermined level (a negative pressure that overcomes the biasing force of the spring 29), the slider 27 closes the inlet of the parallel wall diffuser 26a. The entire outer circumference of the impeller 22 is closed.

On the other hand5. The intake air fed under pressure by the impeller 22 is sent to a parallel wall diffuser 26a and a scroll type diffuser 26b.
and is supplied to the engine 33 through the intake pipe 32.

The compressor housing 23 is attached to the bearing housing 25 with bolts 35 via a mounting plate 34, and the compressor shroud 24 is attached to a C-shaped head stopper 36.
It is attached to the compressor housing 25 by.

Next, the effect will be explained.

Intake air supplied to the engine 33 is pressurized by the impeller 22 and supplied through the parallel wall diffuser 26a, the scroll type diffuser 26b, and the intake pipe 32, and the flow rate is controlled by the throttle valve 3 which is linked to the accelerator pedal of the vehicle.
1. Also, the impeller 22 is connected to the engine 3.
It is rotated by a turbine (not shown) which is driven to rotate by receiving the exhaust energy of No. 3.

When the accelerator pedal is released from normal constant speed operation or acceleration operation to enter a predetermined deceleration operation, the throttle valve 31 is fully opened and the pressure in the intake pipe 32 downstream of the throttle valve 31 becomes negative pressure. When this intake negative pressure becomes larger than the biasing force of the spring 29,
As shown in FIG. 2, the slider 27 moves to close the inlet of the parallel wall diffuser 26a, and the entire downstream circumference of the impeller 22 is closed. At this time, the volume of air downstream of the impeller 22 is extremely small. Therefore, throttle valve 3
1 When fully opened, the slider 27 becomes the parallel wall diffuser 26a.
from the slider 27 to the throttle valve 31 until the inlet is closed.
Even if the air is compressed into a volume up to 100 kW, the slider 27 prevents the compressed air from flowing back to the impeller 22, and no large surge occurs. Further, since there is no volume between the impeller 22 and the slider 27, the surge of the impeller 22 is extremely slight and does not affect the turbocharger or generate abnormal noise.

(Effects of the Invention) According to the present invention, the surge in the compressor of the turbocharger can be suppressed to a sufficiently low level, so that it is possible to prevent the occurrence of breakage and damage to the turbocharger, and also to prevent the generation of abnormal noise. Can be done.

[Brief explanation of drawings]

Figures 1.2 are diagrams showing one embodiment of the turbocharger of the present invention, Figure 1 is its overall configuration diagram, and Figure 2 is a sectional view showing the state in which the entire downstream circumference of the impeller is closed. be. FIG. 3 is a schematic diagram of a conventional turbocharger. 21... Compressor, 22... Impeller. 33...Engine.

Claims (1)

[Claims] In a turbocharger that is driven by exhaust energy from an engine and pressurizes intake air by rotation of an impeller of a compressor and supplies it to the engine, the entire circumference of the downstream side of the impeller of the compressor is closed during a predetermined deceleration operation. turbocharger.