WO2015152510A1

WO2015152510A1 - Turbo charger having nvh-reducing device

Info

Publication number: WO2015152510A1
Application number: PCT/KR2015/000654
Authority: WO
Inventors: Ho Il Park; Sung-Bae Choi; Seong-sik JANG
Original assignee: Keyyang Precision Co., Ltd.
Priority date: 2014-04-01
Filing date: 2015-01-22
Publication date: 2015-10-08

Abstract

A turbo charger having a noise, vibration and harshness (NVH)-reducing device, includes: a central housing including a bore into which a shaft having a turbine wheel coupled to one side thereof and a compressor wheel coupled to another side thereof is inserted; a turbine housing disposed at the one side of the central housing, and in which an exhaust gas inlet and an exhaust gas outlet are formed and the turbine wheel is disposed; a compressor housing disposed at the other side of the central housing, and in which an air inlet and an air outlet are formed and the compressor wheel that compresses air introduced from the air inlet when the turbine wheel is rotated and moves the compressed air toward the air outlet is disposed; and an air-alleviating portion that is disposed between the air inlet and the air outlet of the compressor housing and alleviates a flow of air that occurs when the compressor wheel is rotated.

Description

TURBO CHARGER HAVING NVH-REDUCING DEVICE

The present invention relates to a turbocharger having a noise, vibration and harshness (NVH)-reducing device, and more particularly, to a turbocharger having an NVH-reducing device that is capable of minimizing abnormal NVH that occurs in the flow of air inside a compressor housing.

An internal combustion engine converts thermal energy into mechanical energy by combusting a mixture of air and fuel inside a cylinder. The internal combustion engine having this structure necessarily discharges gas combusted in the cylinder. Devices for increasing an output of an engine using an exhaust gas are well known.

In general, a turbocharger rotates a turbine using exhaust energy of the exhaust gas and rotates a suction fan of a compressor installed on the same axis as the turbine, thereby taking in air with a strong force. In this case, the turbocharger leads the intake air to a combustion chamber of the internal combustion engine so as to increase the quantity of the air that is taken in. Thus, the output of the engine can be improved compared to a naturally aspirated engine.

Since the turbocharger mounted in a diesel engine has relatively simple structure and design, most diesel cars that have been mass-produced recently are equipped with turbochargers.

As demand for improvements in fuel efficiency and improvements in output is increasing, there is a trend of turbochargers also being mounted in gasoline engines. Turbochargers can attain the effect of downsizing in which an exhaust quantity of the engine is reduced, and help to improve fuel efficiency and solve a pollution problem.

Since a turbocharger takes in air strongly by rotating a compressor wheel inside the compressor at a high speed so as to improve the output of the engine, the flow of the air causes noise, vibration and harshness (hereinafter referred to as NVH) having various forms on an air movement path inside the compressor.

The air that flows in a compressor housing is compressed by a compressor wheel. NVH that occurs in this procedure is introduced into the interior of a car.

Thus, a noise insulation material or a noise absorption material is disposed in the car so that noise is not introduced into the interior of the car. However, this blocking method may cause not only an increase in manufacturing cost of the car but also louder noise when the above-mentioned NVH is combined with other noise of the car. As a rotation speed of the engine is increased, a discharge pressure of the exhaust gas is increased. Thus, rotation speed of the compressor wheel is increased. In this case, louder noise occurs in the turbocharger.

In particular, it is known that a vortex flow occurs when the compressor collides with a blade of the compressor wheel in which the intake air rotates, when the compressor compresses the intake air and the vortex flow causes NVH when it collides with inner walls of the compressor housing in which the compressor wheel is disposed.

Generally, a distance between the compressor wheel and the compressor housing is increased so as to reduce the vortex flow. Although this method is capable of reducing NVH to an extent, compression efficiency of the air may be lowered.

The present invention provides a turbo charger that is capable of reducing noise, vibration and harshness (NVH) while preventing compression efficiency of air from being lowered.

In accordance with an aspect of the present invention, a turbo charger having a noise, vibration and harshness (NVH)-reducing device includes: a central housing including a bore into which a shaft having a turbine wheel coupled to one side thereof and a compressor wheel coupled to another side thereof is inserted; a turbine housing disposed at one side of the central housing, and in which an exhaust gas inlet and an exhaust gas outlet are formed and the turbine wheel is disposed; a compressor housing disposed at the other side of the central housing, and in which an air inlet and an air outlet are formed and the compressor wheel that compresses air introduced from the air inlet when the turbine wheel is rotated and moves the compressed air toward the air outlet is disposed; and an air-alleviating portion that is disposed between the air inlet and the air outlet of the compressor housing and alleviates a flow of air that occurs when the compressor wheel is rotated.

Extension ducts may be formed between the air inlet and the air outlet, and an expanded groove that increases a volume of the extension ducts may be formed in the extension ducts.

A first inclined surface may be formed at one end of the expanded groove, a second inclined surface may be formed at the other end of the expanded groove, and a slope of the second inclined surface may be formed to be gentler than that of the first inclined surface.

The expanded groove may have an arc-shaped cross section.

The expanded groove may be formed between the extension ducts that correspond to a front end of the compressor wheel from the air inlet.

Through holes may be formed in front and rear ends of the compressor wheel, a front end of the shaft may be disposed in the through holes to penetrate a penetration hole in the front end of the compressor wheel, and a relief groove may be formed in an end of the shaft.

In a turbo charger in accordance with an embodiment of the present invention, an vortex current that occurs when a compressor wheel is rotated is introduced into an air-alleviating portion of a compressor housing and is alleviated so that noise, vibration and harshness (NVH) that occurs when the vortex current directly collides with an inside surface of the compressor housing can be reduced.

FIG. 1 is a side cross-sectional view of a turbo charger in accordance with an embodiment of the present invention.

FIG. 2 is a cross-sectional view of essential portions of a compressor housing of the turbo charger in accordance with another embodiment of the present invention.

FIG. 3 is a cross-sectional view of essential portions of a compressor housing of the turbo charger in accordance with the embodiment illustrated in FIG. 1.

FIG. 4 is a partial cut perspective view of the compressor housing of the turbo charger in accordance with an embodiment of the present invention.

FIG. 5A is a graph showing noise that occurs in a turbo charger in accordance with an embodiment of the related art, and FIG. 5B is a graph showing noise that occurs in a turbo charger in accordance with an embodiment of the present invention.

FIG. 6 is a graph showing an air pressure ratio for comparing a case in which an air-alleviating portion illustrated in FIG. 2 is formed with a case in which no air-alleviating portion is formed in a turbo charger according to the related art.

FIG. 7 is a graph showing an air pressure ratio for comparing a case in which an air-alleviating portion illustrated in FIG. 3 is formed with a case in which no air-alleviating portion is formed in the turbo charger according to the related art.

The present invention will now be described more fully with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. The invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art, and the present invention is merely defined by the scope of the claims. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a,” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It will be understood that although the terms “first,” “second,” etc. may be used herein to describe various components, these components should not be limited by these terms. These components are only used to distinguish one component from another.

FIG. 1 is a side cross-sectional view of a turbo charger in accordance with an embodiment of the present invention, FIG. 2 is a cross-sectional view of essential portions of a compressor housing of the turbo charger in accordance with another embodiment of the present invention, FIG. 3 is a cross-sectional view of essential portions of a compressor housing of the turbo charger in accordance with the embodiment illustrated in FIG. 1, and FIG. 4 is a partial cut perspective view of the compressor housing of the turbo charger in accordance with an embodiment of the present invention.

Referring to FIG. 1, a turbo charger having a noise, vibration and harshness (NVH)-reducing device according to an embodiment of the present invention that compresses air using an exhaust gas of a car and supplies the compressed air to an engine of the car includes a central housing 8, a turbine housing 2 and a compressor housing 4 that are disposed at right and left sides of the central housing 8.

A shaft 6, opposite ends of which are disposed in the turbine housing 2 and the compressor housing 4, and to which a turbine wheel 12 and a compressor wheel 22 are coupled, is mounted in the central housing 8. A bore 8a into which the shaft 6 is inserted is formed in the central housing 8 to penetrate the left and right sides of the central housing 8.

The turbine wheel 12 coupled to a right side of the shaft 6 is surrounded by the turbine housing 2 in which an exhaust gas inlet 10 and an exhaust gas outlet 2a are formed, as illustrated in FIG. 1, and the turbine housing 2 that surrounds the turbine wheel 12 is coupled to the right side of the central housing 8.

The compressor wheel 22 coupled to a left side of the shaft 6 is surrounded by the compressor housing 4 in which an air inlet 20 and an air outlet 18 are formed, and the compressor housing 4 that surrounds the compressor wheel 22 is disposed at the left side of the central housing 8.

Thus, while the exhaust gas is introduced into the turbine housing 2 through the exhaust gas inlet 10 and is discharged through the exhaust gas outlet 2a, the exhaust gas causes the compressor wheel 22 connected to the turbine wheel 12 via the shaft 6 to be rotated. When the compressor wheel 22 is rotated, air at the air outlet 20 of the compressor housing 4 is taken into the compressor housing 4, is compressed and then is transferred to the engine through the air outlet 18.

The air introduced into the air inlet 20 is this air intake and compression procedure collides with the compressor wheel 22 or a blade B of the compressor wheel 22. Some of the colliding air collides with an inside surface of the compressor housing 4 and causes a vortex of the air.

In this case, NVH occurs. Thus, in the present invention, an air- alleviating portion 24 that alleviates the flow of air occurring when the compressor wheel 22 is rotated is configured between the air inlet 20 and the air outlet 18 of the compressor housing 4 so as to reduce NVH.

The air-alleviating portion 24 reduces NVH that occurs by accommodating and alleviating the air having a vortex shape secondarily directed toward the inside surface of the compressor housing 4 after the air that moves toward the air outlet 18 via the air inlet 20 of the compressor housing 4 collides with the compressor wheel 22.

The air-alleviating portion 24 will now be described in more detail. As illustrated in FIG. 1, extension ducts 20a that form a movement space of the air are formed between the air inlet 20 and the air outlet 18, and the air-alleviating portion 24 is formed between the extension ducts 20a so as to accommodate the air having the vortex shape by increasing a volume of each of the extension ducts 20a. Thus, a vortex that occurs when the air introduced through the air inlet 20 is compressed by the compressor wheel 22 is accommodated in the air-alleviating portion 24, and NVH that occurs when the vortex collides with the inside surface of the compressor housing 4 is reduced.

The expanded groove 24 includes a first inclined surface 24a formed at a right side of the expanded groove 24, and a second inclined surface 24b formed at a left side of the expanded groove 24 and having a gentler slope than the first inclined surface 24a, as illustrated in FIG. 2. An extension surface having a cross section approximately parallel to the inside surface of the compressor housing 4 may be formed between the first inclined surface 24a and the second inclined surface 24b to extend.

Also, the expanded groove 24 may be formed to have an arc-shaped cross section, as illustrated in FIG. 3, which illustrates another embodiment of the present invention.

The expanded groove 24 may be formed between the extension ducts 20a that correspond to a left end of the compressor wheel 22 from the air inlet 20, as illustrated in FIGS. 1 and 4. The expanded groove 24 increases the volume of each extension duct 20a, as described above. Thus, when the expanded groove 24 is formed between the extension ducts 20a corresponding to the blade B of the compressor wheel 22, compression efficiency may be lowered.

Thus, a distal end I in a direction of the compressor wheel 22 of the expanded groove 24 may be formed to be moved toward the air inlet 20 rather than the blade B of the compressor wheel 22

FIG. 5A is a graph showing noise that occurs in a turbo charger in accordance with an embodiment of the related art, and FIG. 5B is a graph showing noise that occurs in a turbo charger in accordance with an embodiment of the present invention. Comparison of the graphs will be described below.

In the graphs of FIGS. 5A and 5B, horizontal axes represent a volumetric flow at the air inlet 20 of the compressor housing 4, vertical axes represent NVH, and rpm of the compressor wheel is shown on each line. Comparing FIG. 5A with FIG. 5B, it can be seen that, when the compressor wheel is rotated at the same rpm, NVH is reduced.

For example, when the expanded groove 24 is not formed, as illustrated in FIG. 5A, an inlet volumetric flow of the compressor housing 4 is 0.06 m3/sec, and when the compressor wheel is rotated at 100,000 rpm, NVH is 72 dbA to 75 dbA, whereas, when an expanded groove according to the present invention is formed at a volumetric flow and rotation speed of the compressor wheel under the same conditions, NVH can be seen to be reduced to 65 dbA.

Thus, when the expanded groove is formed, NVH that occurs in the turbo charger is effectively reduced.

FIG. 6 is a graph showing an air pressure ratio for comparing a case in which an air-alleviating portion illustrated in FIG. 2 is formed (indicated by triangles) with a case in which no air-alleviating portion is formed in a turbo charger according to the related art (indicated by circles), and FIG. 7 is a graph showing an air pressure ratio for comparing a case in which an air-alleviating portion illustrated in FIG. 3 is formed (indicated by triangles) with a case in which no air-alleviating portion is formed in the turbo charger according to the related art (indicated by circles).

In the graphs of FIGS. 6 and 7, horizontal axes are the same as those of FIGS. 5A and 5B, and vertical axes represent the ratio of pressure at an air outlet with respect to pressure at an air inlet when pressure at the air inlet is set to P1 and pressure at the air outlet is set to P2. On each line, rpm of a compressor wheel is indicated by a number, as in FIGS. 5A and 5B.

Referring to FIG. 6, as described above, forming the air-alleviating portion having the shape of FIG. 2 is formed is advantageous to NVH reduction. However, performance of air compression is lowered compared to the turbo charger according to the related art. For example, when the compressor wheel is rotated at 188,000 rpm, the formation of the air-alleviating portion can be seen to be advantageous to NVH reduction, but performance of air compression is lowered.

On the other hand, FIG. 7 shows the case in which an air-alleviating portion having an arc shape illustrated in FIG. 3 is formed under the same conditions. NVH reduction and compression performance can both be seen to be improved compared to the turbo charger according to the related art and the turbo charger illustrated in FIG. 2.

Also, according to another embodiment of the present invention, through holes may be formed in front and rear ends of the compressor wheel 22, and a front end of the shaft 6 may be disposed in the through holes by penetrating a penetration hole in the front end of the compressor wheel 22. A relief groove is formed on front end of the shaft 6, so that a vortex may be prevented from occurring when the compressor wheel 22 is rotated.

*Explanation of Reference Numerals*

2: turbine housing 4: compressor housing

6: shaft 8: central housing

8a: bore 10: exhaust gas inlet

12: turbine wheel 18: air outlet

20: air inlet 20a: extension duct

22: compressor wheel 24: air-alleviating portion, expanded groove

24a: first inclined surface 24b: second inclined surface

Claims

A turbo charger having a noise, vibration and harshness (NVH)-reducing device, the turbo charger comprising:

a central housing 8 comprising a bore 8a into which a shaft 6 having a turbine wheel 12 coupled to one side thereof and a compressor wheel 22 coupled to another side thereof is inserted;

a turbine housing 2 disposed at the one side of the central housing 8, and in which an exhaust gas inlet 10 and an exhaust gas outlet 2a are formed and the turbine wheel 12 is disposed;

a compressor housing 4 disposed at the other side of the central housing 8, and in which an air inlet 20 and an air outlet 18 are formed and the compressor wheel 22 that compresses air introduced from the air inlet 20 when the turbine wheel 12 is rotated and moves the compressed air toward the air outlet 18 is disposed; and

an air-alleviating portion 24 disposed between the air inlet 20 and the air outlet 18 of the compressor housing 4 that alleviates a flow of air that occurs when the compressor wheel 22 is rotated.
The turbo charger of claim 1, wherein extension ducts 20a are formed between the air inlet 20 and the air outlet 18, and

an expanded groove 24 that increases a volume of the extension ducts 20a is formed in the extension ducts 20a.
The turbo charger of claim 2, wherein a first inclined surface 24a having a slope of 80 to 90 degrees from each of the extension ducts 20a is formed at one end of the expanded groove 24, and a second inclined surface 24b having a slope of 30 to 50 degrees from each of the extension ducts 20a is formed at the other end of the expanded groove 24.
The turbo charger of claim 2, wherein the expanded groove 24 has an arc-shaped cross section.
The turbo charger of claim 4, wherein the expanded groove 24 is formed between the extension ducts 20a that correspond to a front end of the compressor wheel 22 from the air inlet 20.