JP2002089570A - Ball bearing for turbo-charger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ball bearing for a turbo-charger having little rotation resistance (rotating torque) and emitting little heat. SOLUTION: The radius of curvature r9a of the cross-sectional shape of an outer ring raceway 9a is 52 to 54% of the diameter d13 of each ball 13. The radius of curvature r11a of the cross-sectional shape of an inner ring raceway 11a is 53 to 55% of the diameter d13 of each ball 13. The angle α of contact of each ball 13 is 8 to 20 deg.. As a result, the area of contact at the portion of contact between the rolling surface of each ball 13, the outer ring raceway 9a and the inner ring raceway 11a is reduced and a slip which occurs at the portion of contact is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The ball bearing for a turbocharger according to the present invention is incorporated in a turbocharger for improving the output of an automobile engine, for example, and a rotating shaft connecting a turbine and an impeller is rotatable with respect to a housing. Use to support. Particularly, the present invention realizes a ball bearing for a turbocharger having a small rotation resistance (rotation torque) and a small amount of heat generation.

[0002]

2. Description of the Related Art In order to increase the output of an engine without changing the displacement, a turbocharger for compressing air sent to the engine by the energy of the exhaust is widely used. This turbocharger collects the energy of exhaust gas by a turbine provided in the middle of the exhaust passage, and rotates an impeller of a compressor provided in the middle of the air supply passage by a rotating shaft fixed to an end of the turbine. This impeller can be tens of thousands or hundreds of thousands of mi with the operation of the engine.
It rotates at a speed of n ^-1 (rpm) and compresses the air sent to the engine through the air supply passage.

FIGS. 2 and 3 show an example of such a turbocharger. The turbocharger rotates the turbine 3 fixed to one end (the left end in FIG. 2) of the rotating shaft 2 by exhaust gas flowing through the exhaust flow path 1. This rotating shaft 2
Is transmitted to the impeller 4 fixed to the other end (the right end in FIG. 2) of the rotating shaft 2, and the impeller 4 rotates in the air supply passage 5. As a result, the air sucked from the upstream end opening of the air supply passage 5 is compressed and sent into the cylinder chamber of the engine together with fuel such as gasoline or light oil. The rotation axis 2 of such a turbocharger is tens of thousands to several hundred thousand minutes.
It rotates at a speed as high as ^-1 (rpm), and its rotation speed changes frequently depending on the operating condition of the engine. Therefore, the rotating shaft 2 needs to be supported by the bearing housing 6 with a small rotation resistance.

For this reason, conventionally, the bearing housing 6
The above-mentioned rotating shaft 2 is rotatably supported by first and second ball bearings 7 and 8, each of which is a ball bearing for a turbocharger. These first and second ball bearings 7, 8
Is an angular type ball bearing as shown in FIGS. The configuration of these first and second ball bearings 7 and 8 is basically the same. However, of these two ball bearings 7, 8, the lubrication condition of the first ball bearing 7, which is close to the exhaust passage 1 through which high-temperature exhaust flows and whose temperature rises remarkably, is determined by the air supply passage 5 through which low-temperature air flows. , And the temperature rise is not so significant, which is more severe than that of the second ball bearing 8.

The first and second ball bearings 7 and 8 have an outer race 10 having an outer raceway 9 on an inner peripheral surface, an inner race 12 having an inner raceway 11 on an outer peripheral surface, and the outer race 9 and the inner race. A plurality of balls 13, 13 provided to be able to roll freely between the track 11 and
And Each of these balls 13, 13 is placed in a plurality of pockets 15 provided in an annular retainer 14, respectively.
It is held so that it can roll freely one by one. In the illustrated example, the inner ring 12 has a so-called counter bore in which one shoulder is not provided. Further, the outer peripheral surface of the cage 14 is
An outer ring guide is provided in which the diametrical position of the retainer 14 is regulated by the outer ring 10 by being opposed to the inner peripheral surface of the outer ring 10.

The first ball bearing 7 of the first and second ball bearings 7 and 8 has the outer ring 10 fitted inside one end of the bearing housing 6 and the inner ring 12 fitted with the inner ring 12. By externally fitting and fixing to one end of the rotating shaft 2, the rotating shaft 2
Is rotatably supported by the bearing housing 6. On the other hand, the second ball bearing 8 fits the outer race 10 inside the other end of the bearing housing 6 and
Is fixed to the other end of the rotating shaft 2 so that the other end of the rotating shaft 2 is rotatably supported by the bearing housing 6. Further, the first and second ball bearings 7,
The compression spring 16
Provides elasticity in a direction away from each other. That is,
Pressing rings 17, 17 are respectively butted against end faces of the outer rings 10, 10 facing each other.
The compression spring 16 is sandwiched between the members 7 and 17.
Therefore, the first and second ball bearings 7 and 8 are assembled in a state where the directions of the contact angles are reversed with each other (back-side combination (DB) type).

Further, an oil supply passage is provided in a casing 18 in which the bearing housing 6 is accommodated, and the respective ball bearings 7 and 8 are provided.
Is lubricated freely. During operation of the engine equipped with the turbocharger, the lubricating oil passes through a clearance space between the inner peripheral surface of the casing 18 and the outer peripheral surface of the bearing housing 6 after foreign substances are removed by the filter 19,
Nozzle hole 2 provided in pressing ring 17 adjacent to outer ring 10
From 0, the first ball bearing 7 is lubricated (oil jet lubrication) toward the outer peripheral surface of the inner ring 12 constituting the first ball bearing 7 obliquely from the outside in the radial direction. The lubricating oil jetted toward the first ball bearing 7 in this manner lubricates not only the first ball bearing 7 but also the second ball bearing 8,
The oil is discharged from the oil discharge port 21.

[0008]

In recent years, high turbocharging and high rotation of a turbocharger have been attempted, and accordingly, the first conventional turbocharger ball bearing as described above has been developed. The heat generated by the second ball bearings 7 and 8 cannot be ignored. Heat generation of such ball bearings 7 and 8 is as follows.
The frictional contact between the rolling surfaces of the balls 13, 13 and the outer raceway 9 and the inner raceway 11, which is also a cause of the rotational resistance, is caused to be converted into heat energy (friction heat). Therefore, if the rotational resistance is reduced, the amount of generated heat is reduced. By the way, such a calorific value is, as generally known, a contact pressure (P) at a contact portion between the rolling surface of each of the balls 13 and 13 and the outer raceway 9 or the inner raceway 11, and It greatly affects the PV value represented by the product of these balls 13 and 13 and the sliding speed (V) at the contact portion. And, the smaller the PV value, the smaller the amount of heat generated by the ball bearings 7 and 8 and the smaller the rotational resistance.

On the other hand, the contact portions between the rolling surfaces of the balls 13 and the outer ring raceway 9 and the inner ring raceway 11 are actually caused by the elastic deformation of the contact portions of these members 13, 9 and 11, resulting in a hertz. It is known that it becomes an elliptical region derived from the contact theory. Then, the sliding speed (V) is determined for each ball 1
The contact ellipse spreads in a direction perpendicular to the rolling directions of the ellipses 3 and 13 (this direction becomes the major axis of the ellipse). The contact ellipse becomes largest at the width direction (major axis direction) end, and the width (major axis) of the contact ellipse The slip velocity (V) also increases as the value increases. Also, as the width of the contact ellipse increases, the contact area also increases. The width of the contact ellipse increases as the ratio of the radius of curvature r ₉ , r ₁₁ of the cross-sectional shape of the outer race 9 and the inner race 11 to the diameter d ₁₃ of the balls 13, ₁₃ increases. Become. Therefore, the outer raceway 9
When the ratio between the radii of curvature r ₉ and r ₁₁ of the inner raceway 11 is smaller than a predetermined value, the effect of the increase in the slip speed (V) on the PV value increases, and the PV value increases. At the same time, the contact area also increases. Therefore, in order to reduce the PV value and the contact area, and to reduce the rotational resistance and the calorific value of the ball bearings 7 and 8, the ratio of the radii of curvature r ₉ and r ₁₁ of the outer ring raceway 9 and the inner ring raceway 11 is determined. It is necessary to regulate to more than a predetermined value.

On the other hand, if the ratio of the radii of curvature r ₉ , r ₁₁ of the outer raceway 9 and the inner raceway 11 to the diameter d ₁₃ of the balls 13, ₁₃ becomes too large, the contact is reduced. Although the area is small, the contact pressure (P) is large, so that the calorific value is increased, and each of the balls 13, 1
The time (separation life) until the separation occurs on the rolling surface 3 and the tracks 9 and 11 becomes insufficient. Therefore, the ball bearing 7,
In order to reduce the rotational resistance and the calorific value of the ball bearings 7 and 8 while sufficiently securing the durability of the balls 8, the balls 13, 1
For 3 diameter d _13, the outer ring raceway 9 and the inner ring raceway 1
It is necessary to restrict the ratio of the radii of curvature r ₉ and r ₁₁ of the cross-sectional shape of No. 1 to a predetermined range.

In addition, at the contact portion between the rolling surfaces of the balls 13 and the outer raceway 9 and the inner raceway 11, slip occurs due to the spin of the contact ellipse existing at the contact portion. Such a slip increases as the contact angle α between the balls 13 increases, and as a result, the temperature rise due to the generated frictional heat also increases. Also, at high speed rotation,
Due to the centrifugal force, the contact angle α of each of the balls 13, 13 becomes larger than the initially set angle, and as a result, the above-mentioned slip increases and heat generation becomes remarkable. On the other hand, if the contact angle α becomes too small, the radial clearance between the rolling surface of each of the balls 13 and the outer raceway 9 and the inner raceway 11 becomes smaller, and the contact surface of the contact portion becomes smaller. The pressure is increased, and the rotational resistance and the amount of generated heat tend to increase. Therefore, in order to reduce the rotational resistance and the amount of heat generated by the ball bearings 7 and 8 while ensuring the durability of the ball bearings 7 and 8 sufficiently, the contact angle α of each of the balls 13 and 13 is also predetermined. It is necessary to regulate within the range. SUMMARY OF THE INVENTION In view of such circumstances, the present invention has been devised to realize a ball bearing for a turbocharger having a small rotation resistance and a small amount of heat generation.

[0012]

The ball bearing for a turbocharger of the present invention has an outer raceway on its inner peripheral surface, similarly to the above-mentioned conventionally known ball bearing for a turbocharger.
An outer race supported inside the housing, an inner race having an inner raceway on the outer peripheral surface, the inner race being externally fixed to a rotating shaft connecting the turbine and the impeller, and rolling freely between the outer raceway and the inner raceway And a plurality of balls provided in the plurality. And
It is assembled between the both ends of the rotating shaft and the inner peripheral surface of the housing with the directions of the contact angles being opposite to each other.

In particular, in the turbocharger ball bearing of the present invention, the radius of curvature of the cross-sectional shape of the outer raceway is set to 52 to 54% of the diameter of each ball, and the curvature of the cross-sectional shape of the inner raceway is also set. The radius is 53 to 55% of the diameter of each ball.
And the contact angle is set to 8 to 20 °. still,
This contact angle is in the range of 8 to 20 ° at a normal temperature. Further, it is more preferable that the one that supports the turbine-side end of both ends of the rotating shaft has the contact angle of 14 to 18 °.

[0014]

With the ball bearing for a turbocharger of the present invention configured as described above, the rotation resistance (rotation torque) and the amount of generated heat can be reduced. That is, since the radius of curvature of the cross-sectional shape of the outer raceway is 52 to 54% of the diameter of each ball, the contact area and the sliding speed (V) of the contact portion between the rolling surface of each ball and the outer raceway can be reduced. . For this reason, the rotational resistance can be reduced, and the heat generation at the contact portion between the rolling surface of each ball and the outer raceway can be suppressed. If the radius of curvature is less than 52%, the contact area and the sliding speed (V) become too large, and the rotational resistance and the heat generation increase. On the other hand, when the radius of curvature exceeds 54%, the contact area becomes too small, the contact pressure (P) of the contact portion increases, the heat value increases, and the ball The rolling surface and the outer raceway are likely to be damaged such as peeling.

Since the radius of curvature of the cross-sectional shape of the inner raceway is 53 to 55% of the diameter of each ball, the contact between the rolling surface of each ball and the inner raceway is the same as in the case of the outer raceway. The contact area of the portion and the sliding speed (V) can be reduced. For this reason, it is possible to reduce the rotational resistance and suppress the heat generation at the contact portion between the rolling surface of each ball and the inner raceway. If the radius of curvature is less than 53%, the contact area and the sliding speed (V) become too large, and the rotational resistance and the heat generation increase. On the other hand, when the radius of curvature exceeds 55%, the contact area becomes too small, the contact pressure (P) of the contact portion increases, the calorific value increases, and the ball The rolling surface and the inner raceway are likely to be damaged such as peeling.

The range of the radius of curvature is slightly different between the outer raceway and the inner raceway (the range of the radius of curvature of the outer raceway is 52 to 54%, whereas the range of the radius of curvature of the inner raceway is less. The reason is as follows. That is, when the contact area between the rolling surface of each ball and the outer raceway and the inner raceway is the same, the contact pressure (P _OUT ) between the rolling surface of each ball and the outer raceway is applied to each ball. The applied centrifugal force is larger than the contact pressure (P _IN ) of the inner raceway (P _OUT > P _IN ). Therefore, the contact pressure (P
_OUT ) increases, it is necessary to secure a contact area between the rolling surface of each ball and the outer raceway to reduce the contact pressure (P _OUT ). In other words, in order to secure the contact area of the outer raceway, it is necessary to make the radius of curvature of the outer raceway smaller than the radius of curvature of the inner raceway. For this reason, the range of the radius of curvature of the outer raceway and the range of the radius of curvature of the inner raceway are slightly different as described above.

Further, since the contact angle of each ball is set to 8 to 20 °, the slip generated at the contact portion between the rolling surface of each ball and the outer raceway and the inner raceway is reduced, and the contact surface pressure is excessive. Can be prevented. For this reason, it is possible to reduce the rotational resistance and suppress heat generation at the contact portions between the rolling surfaces of these balls and the outer raceway and the inner raceway. The contact angle is 20
When the angle exceeds °, the slip becomes remarkable, and the amount of heat generated by the slip increases. On the other hand, when the contact angle is less than 8 °, the radial gap between the rolling surface of each ball and the outer raceway and the inner raceway is too small. As a result, the contact surface pressure (P) of the contact portion becomes excessive, and the rotational resistance and the amount of generated heat tend to increase.

[0018]

FIG. 1 shows a first embodiment of the present invention.
An example is shown. Ball bearing 22 for turbocharger of this example
Has an outer raceway 9a on the inner peripheral surface thereof, and has a bearing housing 6
An outer race 10 supported inside (see FIGS. 2 and 3) and an inner raceway 11a on the outer peripheral surface are externally fitted and fixed to a rotating shaft 2 (see FIGS. 2 and 3) connecting the turbine 3 and the impeller 4. And a plurality of balls 13 rotatably provided between the outer raceway 9a and the inner raceway 11a.
Each of these balls 13 is rotatably held in a plurality of pockets 15 (omitted in FIG. 1, see FIGS. 4 and 5) provided in an annular retainer 14. In the illustrated example, the inner ring 12 has a so-called counterbore without one shoulder. In addition, FIGS.
In the same manner as in the conventional structure shown in FIG. 1, by making the outer peripheral surface of the retainer 14 approach and closely face the inner peripheral surface of the outer ring 10,
An outer ring guide for restricting the diametric position of the retainer 14 by the outer ring 10 is provided. And the above-mentioned FIGS.
And between the two ends of the rotary shaft 2 of the turbocharger and the inner peripheral surface of the bearing housing 6 with the directions of the contact angles α reversed.

In particular, in the case of the turbocharger ball bearing 22 of the present invention, the radius of curvature r _9a of the cross-sectional shape of the outer raceway 9a is set to be 52 to 54% of the diameter d ₁₃ of each of the balls 13, and The radius of curvature r of the cross-sectional shape of the inner raceway 11a
The _11a is set to 53 to 55% of the diameter d ₁₃ of the balls 13. Further, the contact angle α of each of the balls 13 is set to 8 to 20 °. Note that the contact angle α is in the range of 8 to 20 ° at the time of normal temperature.

Further, when supporting the end (left end in FIG. 2) of the both ends of the rotary shaft 2 on the turbine 3 side, it is more preferable to set the contact angle α to 14 to 18 °. preferable.
That is, as shown in FIG. 2, of the two ends of the rotating shaft, the end on the turbine 3 side is disposed in an exhaust passage 1 through which high-temperature exhaust flows.
, The temperature rise is remarkable as compared with the end (the right end in FIG. 2) on the impeller 4 side near the air supply passage 5 through which low-temperature air flows. Therefore, during operation, the contact angle α of each of the balls 13 tends to change more than the initially set angle, which may make it difficult to exert the operation described below. Therefore, when supporting the end on the turbine 3 side, the range of the contact angle α needs to be more strictly regulated than when supporting the end on the impeller 4 side. For such a reason, when supporting the end on the turbine 3 side (the left end in FIG. 2), it is more preferable to set the contact angle α in the above range.

In the case of the turbocharger ball bearing of the present invention configured as described above, the rotation resistance (rotation torque) and the amount of generated heat can be reduced. That is, 52 to 54 of diameter d ₁₃ of the outer ring raceway 9a of the cross-sectional shape of the curvature radius r _9a the respective balls 13
%, The rolling surface of each ball 13 and the outer raceway 9
The contact area and the sliding speed (V) of the contact portion with the contact a can be reduced. For this reason, it is possible to reduce the rotational resistance and suppress the heat generation at the contact portion between the rolling surface of each ball 13 and the outer raceway 9a. When the radius of curvature r _9a is less than 52%,
The contact area and the sliding speed (V) become too large,
Rotational resistance and heat generation increase. On the other hand, when the radius of curvature r _9a exceeds 54%, the contact area becomes too small, the contact pressure (P) of the contact portion increases, the heat generation increases, and The rolling surface of each ball 13 and the outer raceway 9a are liable to be damaged such as peeling.

The curvature of the cross-sectional shape of the inner raceway 11a is as follows.
Radius r_11a Is the diameter d of each ball 13 ₁₃53-55% of
As in the case of the outer ring raceway 9a,
Contact area of contact portion between rolling surface of ball 13 and inner raceway 11a
And the sliding speed (V) can be reduced. Because of this, rotation resistance
And the rolling surface of each ball 13 and the inner raceway
It is possible to suppress heat generation at the contact portion with the contact 11a. The above
Radius of curvature r_11a Is less than 53%, the above contact area
And the slip speed (V) becomes too large, and the rotational resistance
The calorific value increases. On the other hand, the curvature radius r
_11a Exceeds 55%, the contact area is small.
Too much, the contact pressure (P) of this contact portion increases,
As the amount increases, the rolling surface of each ball 13 and the inner ring gauge
Damage such as peeling is likely to occur on the road.

The outer raceway 9a and the inner raceway 11a are
Radius of curvature r_9a, R_11a Regulation range is slightly different (outer ring
Radius of curvature r of orbit 9a_9aRegulation range is 52-54%
Whereas the radius of curvature r of the inner raceway 11a_11a Regulatory scope of
The reason is as follows. Immediately
The rolling surface of each ball 13, the outer raceway 9a and the inner raceway
If the contact area with the ball 11a is the same,
Pressure between the rolling surface of the outer ring and the outer raceway 9a (P_OUT ) This
And the inner raceway 11a by the centrifugal force applied to each ball 13
Contact pressure (P_IN) (P_OUT > P_IN).
Therefore, the contact pressure (P_OUT ) Is larger,
The contact area between the rolling surface of each ball 13 and the outer raceway 9a is secured.
And the contact pressure (P_OUT ) Must be reduced. Word
In other words, it is necessary to secure the contact area of the outer ring raceway 9a.
Radius of curvature r of the outer raceway 9a _9aThe above inner ring raceway 1
Radius of curvature r of 1a_11a Need to be smaller than
For this reason, the radius of curvature r of the outer raceway 9a is_9a
And the radius of curvature of the inner raceway 11a_11a Regulations
The range is slightly different as described above. In addition,
As is known, the outer raceway 9a and the inner raceway 11a have a cross-sectional shape.
Radius of curvature r_9a, R _11a Even if the same
The area of the contact ellipse for the track 9a is
Larger than the area of the contact ellipse. However, the present invention
The target turbocharger ball bearings are extremely fast
As it is operated, the value of the centrifugal force also increases,
As described above, the outer ring raceway 9a is not changed until the value of the radius of curvature is changed.
The area of the contact ellipse is defined by the area of the contact ellipse with respect to the inner raceway 11a.
Sometimes it must be larger than the product.

The contact angle α of each of the balls 13 is 8 to 20 °.
Therefore, it is possible to reduce the slip generated at the contact portion between the rolling surface of each ball 13 and the outer raceway 9a and the inner raceway 11a, and to prevent the contact area from becoming excessive. Therefore, the rotation resistance is reduced, and the heat generation at the contact portions between the rolling surfaces of the balls 13 and the outer raceway 9a and the inner raceway 11a can be suppressed. If the contact angle α exceeds 20 °, the slip becomes remarkable, and the amount of heat generated by the slip increases. On the other hand, when the contact angle α is less than 8 °, the radial gap between the rolling surface of each ball 13 and the outer raceway 9a and the inner raceway 11a is too small. As a result, the contact surface pressure (P) of the contact portion becomes excessive, and the rotational resistance and the amount of generated heat tend to increase.

[0025]

Since the present invention is constructed and operates as described above, a ball bearing for a turbocharger having a small rotation resistance (rotation torque) and a small calorific value can be realized. Because of this,
In addition to improving the response of the turbocharger, it can contribute to the improvement of the performance including durability and reliability of the turbocharger incorporating the ball bearing.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view showing an example of an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the overall configuration of the turbocharger.

FIG. 3 is an enlarged view of a portion A in FIG. 2;

FIG. 4 is a sectional view showing an example of a conventional structure.

FIG. 5 is an enlarged top view of FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Exhaust flow path 2 Rotating shaft 3 Turbine 4 Impeller 5 Supply flow path 6 Bearing housing 7 First ball bearing 8 Second ball bearing 9, 9a Outer ring track 10 Outer ring 11, 11a Inner ring track 12 Inner ring 13 Ball 14 Cage 15 Pocket 16 Compression spring 17 Press ring 18 Casing 19 Filter 20 Nozzle hole 21 Oil drain 22 Ball bearing

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Norifumi Ikeda 5-5-150 Kumeinuma Shinmei, Fujisawa-shi, Kanagawa F-term in NSK Ltd. (reference) 3G005 EA16 FA28 GB55 JA17 3J101 AA02 AA42 AA54 AA62 BA53 BA54 CA07 FA34 FA41 GA29

Claims (2)

[Claims] 1. An inner race having an outer raceway on an inner peripheral surface and supported inside a housing, and an inner race having an inner raceway on an outer peripheral surface and externally fitted and fixed to a rotating shaft connecting a turbine and an impeller. And a plurality of balls provided rotatably between the outer raceway and the inner raceway, and the directions of the contact angles between both ends of the rotating shaft and the inner peripheral surface of the housing are mutually changed. In a turbocharger ball bearing incorporated in an inverted state, the radius of curvature of the cross-sectional shape of the outer raceway is 52 to 54% of the diameter of each ball, and the radius of curvature of the cross-sectional shape of the inner raceway is A ball bearing for a turbocharger, characterized in that the diameter of each ball is 53 to 55% and the contact angle is 8 to 20 °. 2. The ball bearing for a turbocharger according to claim 1, wherein a contact angle is set to 14 to 18 ° to support a turbine-side end of both ends of the rotating shaft.