JP2011174477A - Supercharger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a supercharger capable of suppressing the lowering of the durability by suppressing the rise of the temperature of a bearing device for supporting a turbine shaft. <P>SOLUTION: This supercharger 1 includes the turbine shaft 3 to one end of which a turbine wheel 2 is fixed and to the other end of which a compressor impeller 4 is fixed, the bearing device 5 for rotatably supporting the turbine shaft 3, and a bearing housing 6 in which the bearing device 5 is stored while the turbine wheel 2 and the compressor impeller 4 are exposed from both end surfaces thereof in the axial direction. A ventilation passage 50 for guiding the compressed air compressed by the compressor impeller 4 to the intermediate portion of the turbine shaft 3 positioned between the turbine wheel 2 and the bearing device 5 to cool the intermediate portion by blasting air is formed in the bearing housing 6. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a supercharger.

Some engines, such as automobiles, use a supercharger that compresses the air sent to the engine using the pressure of exhaust gas and increases the output. Such a supercharger includes a turbine shaft having a turbine wheel fixed to one end and a compressor impeller fixed to the other end, a bearing device that rotatably supports the turbine shaft, and both axial end surfaces There is a turbocharger including a bearing housing in which the bearing device is housed in a state where the turbine wheel and the compressor impeller are exposed.
The turbocharger is configured to convert the pressure of exhaust gas into a rotational force by a turbine wheel, and to compress air fed into the engine by a compressor impeller that rotates integrally with the turbine wheel by a turbine shaft. Since the turbine wheel is directly exposed to the hot exhaust gas as described above, the turbine wheel has a very high temperature. The heat of the turbine wheel that has risen in temperature is transmitted to the bearing device to raise the temperature of the bearing device, which deteriorates the lubrication state of the bearing device and causes seizure, thereby reducing its durability. For this reason, the supercharger is usually configured to cool the bearing device by circulating engine oil, engine coolant, or the like inside the bearing housing that houses the bearing device.
Further, in addition to the cooling mechanism as described above, a heat shield plate is disposed between the turbine wheel and the bearing housing to prevent the heat of the turbine wheel from being transmitted to the bearing device through the bearing housing. (See, for example, Patent Documents 1 and 2).

JP 2002-105669 A (FIG. 1) JP-A-7-189724 (FIG. 1)

In the above conventional example, although an extreme temperature rise of the bearing device can be suppressed by cooling with cooling water or a heat shield, it can be said that the temperature rise is sufficiently suppressed from the viewpoint of maintaining the durability of the bearing device. Therefore, in order to suppress a decrease in the durability of the bearing device, there has been a demand for a measure for more effectively suppressing the temperature rise of the bearing device.
This invention is made | formed in view of such a situation, and provides the supercharger which can suppress effectively the temperature rise of the bearing apparatus which supports a turbine shaft, and can suppress a durable fall. With the goal.

The present invention includes a turbine shaft having a turbine wheel fixed to one end and a compressor impeller fixed to the other end, a bearing device that rotatably supports the turbine shaft, the turbine wheel from both axial end surfaces, and A turbocharger comprising a bearing housing in which the bearing device is housed with the compressor impeller exposed. In the turbocharger, compressed air compressed by the compressor impeller is supplied to the bearing housing. An air passage that leads to an intermediate portion located between the turbine wheel and the bearing device and blows and cools the intermediate portion is formed.
According to the turbocharger configured as described above, even when the heat transmitted from the turbine wheel to the turbine shaft reaches the intermediate portion of the turbine shaft and the temperature of the intermediate portion rises, the intermediate portion is removed from the compressor. Can be cooled by compressed air. That is, since the heat transmitted from the turbine wheel can be cooled before reaching the bearing device, the amount of heat transmitted to the bearing device can be reduced, and as a result, the temperature rise of the bearing device can be effectively suppressed.

It is preferable that a hollow chamber into which the compressed air is introduced is formed inside the intermediate portion.
In this case, since the compressed air guided to the intermediate portion can be brought into contact with the inner surface of the hollow chamber, the contact area with which the compressed air comes into contact with the intermediate portion can be increased. For this reason, an intermediate part can be cooled more effectively and the amount of heat transmitted to the bearing device can be further reduced.

  According to the supercharger of the present invention, since the temperature rise of the bearing device that supports the turbine shaft can be effectively suppressed, it is possible to suppress a decrease in durability of the supercharger.

It is sectional drawing of the supercharger which concerns on the reference example 1. FIG. It is sectional drawing which expanded and showed the connection part of a bearing housing and a turbine housing. It is principal part sectional drawing of the supercharger which concerns on the reference example 2. FIG. It is principal part sectional drawing of the supercharger which concerns on the reference example 3. FIG. 10 is a cross-sectional view of a main part showing a modification of the supercharger according to Reference Example 3. It is sectional drawing of the supercharger which is the 1st Embodiment of this invention. It is principal part sectional drawing which showed the modification of the supercharger which is 1st Embodiment.

Next, preferred embodiments of the present invention will be described with reference to the accompanying drawings. 1 is a cross-sectional view of a supercharger according to Reference Example 1. FIG.
In FIG. 1, a supercharger 1 is a so-called turbocharger used for an automobile engine, and a turbine wheel 2 that converts the pressure of exhaust gas of the engine into a rotational force is fixed to one end and the other end. A turbine shaft 3 to which a compressor impeller 4 for compressing air is fixed, a bearing device 5 that rotatably supports the turbine shaft 3, and a bearing housing 6 that houses the bearing device 5 therein. is doing.

The bearing housing 6 has a main body 6a whose outer periphery is substantially cylindrical, and a journal 6b in which a central hole 6b1 centering on the axis C is formed at the radial center. . As described above, the bearing device 5 that rotatably supports the turbine shaft 3 is disposed in the center hole 6b1.
The bearing device 5 is disposed in the center hole 6b1 as described above and is accommodated in the bearing housing 6. The sleeve 5a inserted into the center hole 6b1 and the inner peripheral side of the sleeve 5a in the axial direction. It is composed of a pair of rolling bearings 5b and the like arranged at a predetermined interval. The bearing device 5 supports the turbine shaft 3 so as to be rotatable around the axis C by the pair of rolling bearings 5b.
The bearing housing 6 houses the bearing device 5 with the turbine wheel 2 exposed from one end face 6a1 of the main body 6a and the compressor impeller 4 exposed from the other end face 6a2.

A cooling water jacket 6 c is formed inside the main body 6 a of the bearing housing 6. The cooling water jacket 6c is a water channel into which engine cooling water is introduced, and is formed in a spiral shape so as to surround the outer peripheral side of the journal 6b. The main body 6a is formed with a water supply / drain port (not shown) for introducing and discharging engine cooling water to and from the cooling water jacket 6c. The cooling water jacket is supplied and discharged from the water supply / drain port. The cooling water is circulated inside 6c, and the cooling water is used to cool the bearing housing 6 and the bearing device 5 disposed in the journal 6b.
In addition to the cooling water jacket 6c, a tank portion 6d in which lubricating oil to be supplied to the bearing device 5 is stored is also formed inside the main body portion 6a. The lubricating oil stored in the tank 6d can be supplied to the bearing device 5 by a lubricating oil supply mechanism (not shown). The bearing device 5 is lubricated only with the lubricating oil in the tank portion 6d.

Further, first and second flange portions 6e and 6f extending outward in the radial direction are formed on the outer peripheral surfaces of the main body portion 6a of the bearing housing 6 on the one end portion side and the other end portion side, respectively. A compressor housing 7 surrounding the compressor impeller 4 exposed at the other end surface 6a2 of the main body portion 6a is fixed to the second flange portion 6f. The compressor housing 7 is formed with a compression flow path for compressing air taken into the engine, and the compressor impeller 4 rotates to suck outside air into the compression flow path and compress it.
On the other hand, a turbine housing 8 surrounding the turbine wheel 2 exposed at one end surface 6a1 of the main body 6a is fixed to the first flange 6e. The turbine housing 8 is formed with an engine exhaust gas passage, and the turbine wheel 2 is rotated by the exhaust gas whose flow velocity is increased in the passage.

FIG. 2 is an enlarged cross-sectional view showing a connection portion between the bearing housing 6 and the turbine housing 8. The turbine housing 8 has a flange portion 8a that is abutted against the first flange portion 6e of the main body portion 6a at one end thereof. Between the flange surface 8a1 of the flange portion 8a located on the outer peripheral portion of the one end surface of the turbine housing 8 and the flange surface 6e1 of the first flange portion 6e located on the outer peripheral portion of the one end surface 6a1 of the bearing housing 6 will be described later. A heat shield member 10 that shields heat from the turbine wheel 2 is interposed. Further, an annular projecting portion 8a2 projecting in the axial direction from the flange surface 8a1 is formed on the periphery of the flange portion 8a. The tip of the protruding portion 8a2 is in contact with the flange surface 6e1 of the first flange portion 6e, and the axial position of the turbine housing 8 with respect to the bearing housing 6 is positioned.
A clamp 9 is mounted on the outer peripheral side of the flange portion 8a and the first flange portion 6e so as to fix both the flange portions 8a and 6e in a state of abutting each other. The clamp 9 presses both flange portions 8a and 6e in a direction in which the flange portions 8a and 6e are abutted with each other in the axial direction, and the bearing housing 6 and the turbine housing 8 are firmly fixed by the clamp 9.

Here, the aspect of the fixed part of the turbine wheel 2 and the turbine shaft 3 will be described in detail.
In FIG. 2, a small-diameter outer peripheral surface 31 on which the turbine wheel 2 is fitted in a contact state is formed on the outer peripheral surface of one end of the turbine shaft 3. Further, a large-diameter outer peripheral surface 32 having a larger diameter than that of the small-diameter outer peripheral surface 31 connected through the inclined surface 33 is formed on the bearing housing 6 side of the small-diameter outer peripheral surface 31.

On the other hand, the turbine wheel 2 is formed with a center hole 20 centering on an axis C which is the center of rotation, and the turbine shaft 3 is inserted into the center hole 20.
A small-diameter inner peripheral surface 21 is formed on the inner peripheral surface side of the center hole 20 as a shaft support portion in which the small-diameter outer peripheral surface 31 of the turbine shaft 3 is inserted in a contact state and fixed by welding or the like. The small diameter inner peripheral surface 21 is provided at a position where the axial position substantially coincides with the small diameter outer peripheral surface 31 of the turbine shaft 3. A large-diameter inner peripheral surface 22 having a larger diameter than the small-diameter inner peripheral surface 21 is formed on the bearing housing 6 side of the small-diameter inner peripheral surface 21 via an inclined surface 23.
The inner diameter of the large-diameter inner peripheral surface 22 is formed larger than the outer diameter of the large-diameter outer peripheral surface 32 of the turbine shaft 3, and the large-diameter inner peripheral surface 22 and the large-diameter outer peripheral surface 32 are between them. A cylindrical gap S is formed. A cylindrical gap S formed between the large-diameter inner peripheral surface 22 of the center hole 20 and the large-diameter outer peripheral surface 32 of the turbine shaft 3 is an inclined surface 33 of the turbine shaft 3 and an inclined surface 23 of the center hole 20. Is extended along the axial direction from the bottom portion formed by the end portion, and the end portion thereof opens toward the bearing housing 6 side.

Further, as shown in FIG. 2, the turbine wheel 2 is disposed in a state of being axially spaced with a predetermined dimension with respect to the one end surface 6a1 of the main body 6a, and a space K is provided between the two. It has been. Therefore, the cylindrical gap S opened toward the bearing housing 6 is connected to the space K.
The space K can shield the heat radiated from the turbine wheel 2 that is heated by receiving the exhaust gas toward the bearing housing 6 by the air layer present in the space K.

  In the space K and the cylindrical gap S that are connected to each other, the above-described heat shield member 10 is disposed. The heat shield member 10 includes a main body portion 10a disposed in the space K and a cylindrical portion 10b disposed in the cylindrical gap S by extending in the axial direction from the main body portion 10a.

  In the heat shield member 10, for example, a main body portion 10a and a cylindrical portion 10b are integrally formed by press-molding a plate material or the like made of a metal material having high heat resistance. The main body 10a is a member that shields heat between the turbine wheel 2 and the bearing housing 6 by being disposed in the space K as described above. The disk 10a1 located in the space K and the disk 10a1 A cylindrical portion 10a2 extending from the peripheral edge toward the first flange portion 6e of the bearing housing 6, and the cylindrical portion 10a2 is bent outward in the radial direction so as to contact the flange surface 6e1 of the first flange portion 6e. The bent portion 10a3 is formed.

As described above, the bent portion 10a3 serving as the outer peripheral edge of the main body portion 10a is between the flange surface 8a1 of the flange portion 8a provided in the turbine housing 8 and the flange surface 6e1 of the first flange portion 6e. It is pinched. The thickness of the bent portion 10a3 is slightly thicker than the width of the gap formed between the flange surface 8a1 and the flange surface 6e1, and the bent portion 10a3 has both flange surfaces 8a1, 6e1. Are firmly held in contact with both flange surfaces 8a1 and 6e1. The heat shield member 10 is fixed between the turbine housing 8 and the bearing housing 6 by sandwiching the bent portion 10a3 between the flange surfaces 8a1 and 6e1 as described above, and the space K and the cylindrical gap S are fixed. Placed in.
Further, by sandwiching the bent portion 10a3 between the turbine housing 8 and the bearing housing 6, the bent portion 10a3 (heat shield member 10) can be interposed therebetween, so that the turbine housing 8 and the bearing housing can be interposed. The efficiency of heat conduction to 6 can be reduced. For this reason, even if the turbine housing 8 is exposed to exhaust gas and reaches a high temperature, the amount of heat transferred from the turbine housing 8 to the bearing housing 6 and the bearing device 5 can be reduced.

The cylinder portion 10a2 connected to the bent portion 10a3 is formed so as to be externally fitted to the side surface portion 6a3 connected to the one end surface 6b from the flange surface 6e1 of the first flange portion 6e.
The disk portion 10a1 has a hole 10a4 through which the turbine shaft 3 is inserted at the center thereof. The disk portion 10 a 1 is disposed between the turbine wheel 2 and the bearing housing 6 and blocks heat radiation from the turbine wheel 2.
At the periphery of the hole 10a4 of the disk portion 10a1, the cylindrical portion 10b is extended toward the axial turbine wheel 2 side with the periphery as a base end. The cylindrical member 10b is disposed in the cylindrical gap S so as to cover the large-diameter outer peripheral surface 32 of the turbine shaft 3, and the tip of the cylindrical member 10b extends to the vicinity of the inclined surfaces 23 and 33 constituting the cylindrical gap S. It has been extended. Thus, the cylindrical member 10b is arrange | positioned over the axial direction substantially whole region of the cylindrical clearance gap S, and heat-shields between the turbine shaft 3 and the turbine wheel 2. As shown in FIG.

  According to the supercharger 1 configured as described above, the cylindrical gap S is formed between the center hole 20 of the turbine wheel 2 and the large-diameter outer peripheral surface 32 of the turbine shaft 3. The contact area between the turbine wheel 2 and the turbine shaft 3 can be reduced as compared with the case where the inner peripheral surface of the hole 20 is in contact with and fixed to the outer peripheral surface of the turbine shaft 3 over the entire axial direction. . Thereby, the efficiency of heat conduction between the turbine wheel 2 heated by the exhaust gas and the turbine shaft 3 can be reduced, and the amount of heat transmitted to the bearing device 5 via the turbine shaft 3 can be reduced. it can. As a result, a temperature rise of the bearing device 5 can be suppressed, and a decrease in durability of the supercharger 1 can be suppressed.

  In the reference example 1, the cylindrical portion 10b of the heat shield member 10 radiates from the large-diameter inner peripheral surface 22 of the center hole 20 of the turbine wheel 2 that is a heat source toward the large-diameter outer peripheral surface 32 of the turbine shaft 3. In addition to shielding the heat that is generated, heat transfer due to air convection in the cylindrical gap S can be prevented, so that an increase in temperature of the turbine shaft 3 can be suppressed. Further, the body portion 10 a of the heat shield member 10 can shield the heat radiated from the turbine wheel 2 toward the bearing housing 6, and can suppress the temperature rise of the bearing housing 6. As described above, the heat shield member 10 can suppress the temperature rise of the bearing housing 6 and the turbine shaft 3 due to the heat radiated from the turbine wheel 2. The amount of heat to be transmitted can be further reduced, and a decrease in durability of the supercharger 1 can be more effectively suppressed.

FIG. 3 is a cross-sectional view of main parts according to Reference Example 2. The main difference between the reference example 2 and the reference example 1 is that an annular sleeve 40 is interposed between the small-diameter inner peripheral surface 21 of the center hole 20 of the turbine wheel 2 and the small-diameter outer peripheral surface 31 of the turbine shaft 3. This is the point. The other points are the same as in Reference Example 1, and thus the description thereof is omitted.
The sleeve 40 is formed using a low heat conductive material such as zirconia, and the turbine wheel 2 and the turbine shaft 3 are fixed via a sleeve 40 made of a low heat conductive material. For this reason, according to the supercharger 1 of the present Reference Example 2, as in Reference Example 1, compared with the case where the small-diameter inner peripheral surface 21 and the small-diameter outer peripheral surface 31 are fixed in direct contact with each other, the turbine wheel The efficiency of heat conduction from 2 to the turbine shaft 3 can be reduced, and as a result, the amount of heat transmitted to the bearing device 5 via the turbine shaft 3 can be further reduced.

FIG. 4 is a cross-sectional view of a main part of the supercharger 1 according to Reference Example 3. The main difference between the reference example 3 and the reference example 1 is that a hole 35 is formed at one end of the turbine shaft 3 so as to open in the front end surface 34 of the turbine shaft 3 and extend in the axial direction.
In this case, since the hole portion 35 forms a gap inside one end portion of the turbine shaft 3, the substantial heat capacity at the one end portion of the turbine shaft 3 can be reduced. For this reason, the amount of heat transmitted from the turbine wheel 2 to the turbine shaft 3 can be reduced, and as a result, the amount of heat transmitted to the bearing device 5 can be reduced.
As shown in FIG. 5, an embedded member 36 that fills the inside of the hole 35 may be inserted into the hole 35. The embedded member 36 is formed using a low heat conductive member such as zirconia. In this case as well, the substantial heat capacity at one end of the turbine shaft 3 can be reduced as described above. Further, the provision of the hole 35 by the embedded member 36 can suppress a decrease in strength at one end of the turbine shaft 3 that is thin.

  FIG. 6 is a cross-sectional view of the supercharger 1 according to the first embodiment of the present invention. The main difference between the present embodiment and Reference Example 1 is that a blower passage 50 for guiding the compressed air compressed by the compressor impeller 4 to the turbine shaft 3 is provided in the bearing housing 6 and the turbine. The shaft 3 and the turbine wheel 2 are integrally formed, and a hollow chamber 61 into which the compressed air is introduced is formed inside the turbine shaft 3.

The air passage 50 has an opening 51 opened at the other end surface 6a2 of the main body portion 6a of the bearing housing 6 surrounded by the compressor housing 7 at one end, and a shaft hole formed in the main body portion 6a through which the turbine shaft 3 is inserted. An opening 52 that opens to the inner peripheral surface of 6a4 is provided at the other end, and the interior of the compressor housing 7 communicates with the inner peripheral surface side of the shaft hole 6a4.
An intermediate portion 60 located between the turbine wheel 2 and the bearing device 5 in the turbine shaft 3 is located on the inner peripheral side of the shaft hole 6a4. The intermediate portion 60 is formed with the hollow chamber 61 described above. The hollow chamber 61 is formed by closing the opening of the hole 64 formed along the axial center from the end surface of the turbine shaft 3 with the plug 65.
In addition, a circumferential groove 62 whose axial direction coincides with the opening 52 is formed on the outer peripheral surface of the intermediate portion 60, and a large number of communication holes 63 communicating the bottom portion of the circumferential groove 62 and the hollow chamber 61. Are arranged in the circumferential direction.
Further, an exhaust passage 70 having an opening 71 that opens to the inner peripheral surface of the shaft hole 6a4 and an opening 72 that opens to the outside of the main body 6a is formed inside the main body 6a. The opening 71 is provided in the shaft hole 6a4 on the opposite side of the opening 52 with the axial position substantially the same and sandwiching the shaft center.

In the supercharger 1 configured as described above, the compressed air in the compressor housing 7 is introduced into the air passage 50 from the opening 51 and is guided from the opening 52 to the inner peripheral side of the shaft hole 6a4 to blow the intermediate portion 60. Cooling. The compressed air guided to the inner peripheral side of the shaft hole 6 a 4 is also introduced into the hollow chamber 61 through the peripheral groove 62 and the communication hole 63. The compressed air is guided to the opening 71 of the exhaust passage 70 through the circumferential groove 62 and the communication hole 63, and is exhausted to the outside from the opening 72 through the exhaust passage 70.
Seal members are provided on both axial sides of the circumferential groove 62 so that compressed air does not leak to the bearing device 5 or the turbine wheel 2 side.

According to the turbocharger having the above configuration, even when the heat from the turbine wheel 2 reaches the intermediate portion 60 of the turbine shaft 3 and the temperature of the intermediate portion 60 rises, the intermediate portion 60 is compressed from the compressor impeller 4. Air can be cooled by air. That is, since the heat transmitted from the turbine wheel 2 can be cooled before reaching the bearing device 5, the amount of heat transmitted to the bearing device 5 can be reduced. As a result, a temperature rise of the bearing device 5 can be effectively suppressed, and a decrease in durability of the supercharger 1 can be suppressed.
Moreover, in this embodiment, since the compressed air guided to the intermediate part 60 can be brought into contact with the inner side surface of the hollow chamber 61, the contact area with which the compressed air comes into contact with the intermediate part 60 can be increased. it can. For this reason, the intermediate part 60 can be cooled more effectively, and the amount of heat transmitted to the bearing device 5 can be further reduced.

In addition, the supercharger of this invention is not limited to the said embodiment. In the above embodiment, the cylindrical gap S is formed by forming the large-diameter inner peripheral surface 22 in the center hole 20 and the large-diameter outer peripheral surface 32 in the outer peripheral surface of the turbine shaft 3, but for example, the center hole 20 or the turbine The cylindrical gap S can also be formed by forming a peripheral surface with a different diameter on only one peripheral surface of the shaft 3.
In the first embodiment, the mode of introducing the compressed air is not limited to the illustrated mode, and any mode may be used as long as the compressed air can be guided to the turbine shaft. In the first embodiment, the turbine wheel 2 and the turbine shaft 3 are integrally formed. However, as shown in FIG. 7, the turbine wheel 2 and the turbine shaft 3 are separated as shown in FIG. The cylindrical gap S may be formed between the two.

DESCRIPTION OF SYMBOLS 1 Supercharger 2 Turbine wheel 3 Turbine shaft 4 Compressor impeller 5 Bearing apparatus 6 Bearing housing 6a1 One end surface 8 Turbine housing 10 Thermal insulation member 10a Main body part 10b Cylindrical part 20 Center hole 21 Small diameter inner peripheral surface (shaft support part)
34 End surface 35 Hole 36 Embedded member 40 Sleeve 50 Air passage 60 Intermediate part 61 Hollow chamber S Cylindrical gap

Claims (2)

A turbine shaft having a turbine wheel fixed to one end and a compressor impeller fixed to the other end;
A bearing device for rotatably supporting the turbine shaft;
In a supercharger comprising: a bearing housing in which the bearing device is housed in a state where the turbine wheel and the compressor impeller are exposed from both end faces in the axial direction.
The bearing housing is formed with an air passage that guides compressed air compressed by the compressor impeller to an intermediate portion located between the turbine wheel and the bearing device in the turbine shaft, and blows and cools the intermediate portion. The supercharger characterized by being made.   The supercharger according to claim 1, wherein a hollow chamber into which the compressed air is introduced is formed in the intermediate portion.

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