JPS634056A - Floating bearing of turbo charger - Google Patents

Abstract

PURPOSE:To improve the seizure resistance, wear resistance and durability of a floating bearing of a turbo charger made of a copper alloy by providing many grooves to the outside peripheral surface of the floating bearing and coating the surface thereof with TiN or TiCN having specific roughness. CONSTITUTION:The floating bearing 1 of the turbo charger is made of the copper alloy such as phosphor bronze and the many grooves 21 extending in the peripheral direction are formed to the outside periphery thereof. Projecting parts 22 thereof are formed to a trapezoidal sectional shape and top surfaces 23 thereof are formed flat. The outside surface of such bearing 1 is coated with a layer 24 consisting of TiN or TiCN to 2-10mum thickness by an ion plating method, etc. The surface roughness Rz of the coating layer 24 is specified to 5-20mum, and the surface roughness Rz of the peak surface 25 of the projecting parts 22 is specified to <=1mum. The seizure resistance, wear resistance and durability of the floating bearing 1 are remarkably improved by the presence of the ceramic coating layer consisting of the TiN, TiCN, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a floating bearing for a turbocharger.

[Conventional technology]

In turbochargers, floating bearings are used to support the drive shaft (for example, Japanese Patent Application Laid-Open No. 60-56035).

Some floating bearings have a metal base material with a ceramic coating applied to the surface. Prior art documents related to ceramic-coated floating bearings include 9, for example, Japanese Utility Model Application Publication No. 1862-1983.
3. Utility model 1986-119425, Utility model 56-9192
1. There is a Utility Model Publication No. 57-196822.

The reason for applying ceramic coating is to improve the seizure resistance, wear resistance, and durability of floating bearings.

(Problems to be Solved by the Invention) Conventional floating bearings coated with ceramic have had problems in that the coating layer cracks and peels off, or the coating layer wears out. Cracks appear in the coating layer because there is a difference in thermal expansion coefficient between the coating layer and the metal base material.

In order to prevent cracks from forming in the coating layer, the coating layer may be made thin.

On the other hand, the problem of the coating layer being worn away can be solved by making the coating layer thicker, but this will cause the problem that the coating layer will crack and peel off. Therefore, there is a trade-off regarding the thickness of the coating layer.

The present invention solves these problems of the conventional technology.

Technical illumination of the present invention! ! The object of the present invention is to prevent the coating layer from peeling off and to extend the life of a ceramic-coated floating bearing (that is, to prevent wear and tear).

[Means for solving problems]

In order to achieve this technical problem, the following measures are taken in the present invention.

In other words, the floating bearing for a turbocharger according to the present invention is a floating bearing for a turbocharger whose base material is made of a copper alloy, and at least the outer circumferential surface of the base material of the floating bearing has a large number of parts extending in the circumferential direction. A groove is provided, and a coating layer of titanium nitride or titanium carbonitride with a film thickness of 2 to 10 μm is provided on the entire outer peripheral surface of the base material, and the surface roughness of the outermost surface of the coating layer is Rz 1 μm. It is characterized by the following.

In addition, the floating bearing for a turbocharger according to the nine combined inventions is a floating bearing for a turbocharger whose base material is made of a copper alloy, and the floating bearing has a small amount of material (extending in the circumferential direction) on the outer peripheral surface of the base material of the floating bearing. A large number of striations are provided, and a coating layer of titanium nitride or titanium carbonitride with a thickness of 2 to 10 μm is provided on the entire outer peripheral surface of the base material, and the surface roughness of the outermost surface of the coating layer is characterized in that Rz is 1 μm or less.

Further, the floating bearing for a turbocharger according to the combined invention is a floating bearing for a turbocharger whose base material is made of a copper alloy, and at least the outer peripheral surface of the base material of the floating bearing has a surface roughness of Rz 5. ~20 μm, and a coating layer of titanium nitride or titanium carbonitride with a thickness of 2 to 10 μm is provided on the entire outer peripheral surface of the base material, and the surface roughness of the outermost surface of the coating layer is It is characterized by having an Rz of 1 μm or less.

[Effect]

When using the floating bearing of the present invention, initially only the outermost coating layer is in contact with the mating member, but after a while of use, the outermost coating layer wears out and the base material comes out. Become.

However, even if this happens, in the floating bearing of the present invention, the side surfaces of the groove, the side surfaces of the groove, or the Rz
Since there is always a coating layer on the side surface of the unevenness of 5 to 20 μm, the same lubrication state as before wear can be maintained by the coating layer on the side surface. That is, it has been experimentally confirmed that it is sufficient to provide a coating layer of titanium nitride or titanium carbonitride on the side surfaces of grooves, grooves, or irregularities with an Rz of 5 to 20 μm.

In the present invention, the thickness of the coating layer is approximately 2 to 10
It is said to be μm and has a relatively thin film thickness.

It will not crack or peel due to the difference in thermal expansion coefficient with the base material.

Thus, according to the present invention, there are two ceramic coated floating bearings.

Peeling of the coating layer is not caused, and the service life can be extended. In other words, according to the present invention, it is possible to further improve the seizure resistance, wear resistance, and durability of the floating bearing compared to conventional bearings.

The reason why the present invention requires a coating on the outer circumferential surface of the floating bearing is that, in general, in floating bearings for turbochargers, wear, seizure, etc. are more likely to occur on the outer circumferential surface than on the inner circumferential surface. This is because they tend to occur.

The reason why the coating ceramic is limited to titanium nitride or titanium carbonitride in the present invention is that other types of materials would easily wear out themselves or wear out the other side, that is, the center housing. In the present invention, the roughness of the outermost surface is Rz 1 μm or less, because if the roughness of the outermost surface is Rz 1 μm or more, it will damage the mating member.

〔Example〕

FIG. 1 is an enlarged longitudinal sectional view of a portion of a floating bearing of a turbocharger according to the present invention. FIG. 1 is an enlarged longitudinal cross-sectional view of the portion indicated by the arrow 2 in FIG.

FIG. 3 is a longitudinal sectional view of a floating bearing of a turbocharger according to the present invention.

In Figure 3, 1 is the entire floating bearing,
9 represents an oil hole. The floating bearing 1 has a hollow cylindrical shape.

FIG. 4 is a longitudinal sectional view of a turbocharger equipped with the floating bearing of FIG. 3.

The explanation will start from FIG. In FIG. 4, 11 is a center housing, 12 is a compressor wheel housing, and 13 is a turbine housing.

An exhaust turbine 14 is housed in the turbine housing 13, and the compressor wheel housing 12
A compressor wheel 15 is housed inside. The exhaust turbine 14 and compressor wheel 15 are connected by a drive shaft 16. The drive shaft 16 is supported by a floating bearing 1. Floating bearing 1 is supported by center housing 11. 9 is an oil hole.

The drive shaft 16 is rotatable relative to the floating bearing 1, and the floating bearing 1 is also rotatable relative to the center housing 11. Therefore, if the drive shaft 16 rotates at, for example, 100.000 rpm, the floating bearing 1 rotates at about 3 to 50.00 rpm relative to the center housing 11.

In this way, the floating bearing 1 is not fixed to the center housing 11, which is why it is called the floating bearing 1.

Returning to FIG. 3, the base material of the floating bearing 1 is made of a copper alloy 9, such as special high-strength brass (phosphor blue 1) or aluminum brass for gears.

As can be seen from Figure 3, floating bearing 1
A large number of grooves 21 extending in the circumferential direction are provided on the outer periphery. The protrusion 22 constituting the groove 21 has a trapezoidal cross-sectional shape, and the top surface 23 of the protrusion 22 is flat.

The height from the bottom of the groove 21 to the top surface 23 of the protrusion 22 is 1
．． The width of the groove 21 at the top surface 23 is 1.5 mm, and the width of the top surface 23 is 1.5 mm.

In FIG. 1, 21 is a groove, 22 is a protrusion, and 23 is a top surface.

As can be seen from Figure 3, floating bearing 1
A ceramic coating is applied to the outer peripheral surface (that is, the groove 21 and the protrusion 22) of the ceramic coating layer 2.
4 is formed. The thickness of the ceramic coating layer 24 is approximately 2 to 10 μm. The roughness of the outermost surface 25 of the coating layer is approximately Rz 1 μm in 10-point average roughness.

Titanium nitride or titanium carbonitride is used as the ceramic for the coating. Coating methods include physical vapor deposition (P, V, D methods), chemical vapor deposition (C9v, D methods), and laser chemical vapor deposition (
laser C0V-D method).

There are plasma chemical vapor deposition methods (plasma C, V, D methods), etc. In this embodiment, the coating is applied by an ion blating method, which is one of the physical vapor deposition methods (F', V, D methods).

The operation of this embodiment will be explained.

In this example, as shown in FIG. Only the outermost surface 25 is in contact with the center housing 11 (see FIG. 4), but after use for a while, the outermost surface 25 will wear out and the base material will be exposed as shown in FIG.

However, even if the state shown in FIG.
The coating layer 24 on the side surface 29 of the floating bearing 1 of this embodiment can maintain a lubricated state similar to that before wear, that is, as shown in FIG. That is, the coating layer 24 of titanium nitride or titanium carbonitride covers the protrusion 2.
It has been experimentally confirmed that the presence on the side surface 29 of 2 is sufficient.

In this embodiment, the thickness of the coating layer 24 is approximately 2
It is said to be ~10 μm and is relatively thin.

It will not crack or peel due to the difference in thermal expansion coefficient with the base material.

Thus, according to the present embodiment, it is possible to prevent the coating layer 24 from peeling off and to extend the life of the ceramic-coated floating bearing 1. In other words, according to the two embodiments, it is possible to further improve the seizure resistance, wear resistance, and durability of the floating bearing l compared to conventional ones.

The reason why the ceramic coating is applied to the outer circumferential surface of the floating bearing 1 in this embodiment is that - In general, in floating bearings for turbochargers, wear, seizure, etc. tend to occur more on the outer circumferential surface than on the inner circumferential surface. This is because it is in

The reason why the coating ceramic is limited to titanium nitride or titanium carbonitride in this example is that other types of materials would easily wear out themselves or wear out the other side, that is, the center housing. This is because it may get lost. On the other hand, titanium nitride or titanium carbonitride itself is less likely to wear out, and it is also less likely to wear out its counterpart.

In this regard, the applicant has provided a test piece 1 coated with titanium nitride or titanium carbonitride, a test piece 2 coated with silicon carbide or titanium carbide,
Experiments were conducted on test piece 3 coated with silicon nitride or aluminum oxide. The experiment consisted of 4 in series
Using a diesel engine with 2000 cc cylinders, the test was carried out for a long time equivalent to a mileage of 200,000 km. The test conditions were to run the engine at 5000 rpm for 30 minutes at full load.

Next, stop for 30 minutes and then return to full load for 30 minutes at B50.
Run the engine at 00 rpm and stop for 30 minutes.
I started and stopped it repeatedly. This is to simulate the fact that the temperature of a turbocharger increases mainly when the engine is stopped.

FIG. 5 shows the results of this experiment. FIG. 5 illustrates the amount of wear on the test piece 1.2.3 and the amount of wear on the mating member (center housing).

In FIG. 5, the white area represents the amount of wear on the component itself, and the hatched area represents the amount of wear on the mating member.

From FIG. 5, it can be seen that although silicon carbide or titanium carbide (test piece 2) itself does not wear out quickly, it causes severe wear on the mating member. Furthermore, it can be seen that although silicon nitride or aluminum oxide (test piece 3) hardly wears out the mating member, it itself wears out quickly. On the other hand, it can be seen that titanium nitride or titanium carbonitride (test piece 19 of this example) does not wear itself or the mating member.

In this embodiment, the coating layer 24 (see FIG. 1) t
-2 to 10 μm is because the coating layer 24
This is because if the coating layer 24 is too thick, cracks will occur due to the difference in thermal expansion coefficient with the metal base material, and the coating layer 24 will peel off.On the other hand, if the coating layer 24 is too thin, it will wear out early. The coating layer 24 preferably has a thickness of 2 to 4 μm.

In this embodiment, the roughness of the outermost surface 25 of the coating layer of the protrusion 23 is approximately Rz 1 μm in 10-point average roughness, and this is for the following reason.

That is, if the roughness of the outermost surface 25 is R) 1 μm or more, the mating member (center housing) will be damaged until the state shown in FIG. 2 is reached.

In that sense, the smaller the roughness of the outermost surface 25, the better.

As a practical matter, it cannot be made too small, so R21μ
I made it about m.

Regarding this point as well, the applicant has developed a test piece l coated with titanium nitride or titanium carbonitride at an Rz of 0.8 μm, and a test piece l coated with titanium nitride or titanium carbonitride at an Rz of 2 μm.
Experiments were conducted on test piece 2 coated with m and test piece 3 coated with titanium nitride or titanium carbonitride with an Rz of 3 μm. The experiment was conducted for a long time equivalent to a mileage of 200,000 km using an in-line 4-cylinder 2000 cc diesel engine. The test conditions were to run the engine at 5 QOO rpm for 30 minutes at full load.

Then stop for 30 minutes 9 then return to full load for 30 minutes 50
Run the engine at 00 rpm and stop for 30 minutes.
I started and stopped it repeatedly. As mentioned earlier, this is to simulate the actual operating conditions of the turbocharger.

FIG. 6 shows the results of this experiment. FIG. 6 shows the wear amount of the mating member (center housing) for test pieces 1, 2.3.

From FIG. 6, it can be seen that when Rz is 2 μm or more (test piece 2), the amount of wear on the mating member is too large, and when Rz O is about 8 μm (test piece 1), it is satisfactory. Therefore,
As mentioned above, in this embodiment, Rz was set to about 1 μm.

In this example, the strawberry material is made of copper alloy 9, such as special high-strength yellow w.
4 (phosphor blue m>) The reason why we limited it to aluminum brass for gears is due to the following two reasons. Namely, when coating, the temperature is raised to about 500°C, but the base material is lead bronze. In lead bronze, low melting point metals such as lead and tin exist alone without being alloyed, so at 500℃ (leprosy), metal particles of lead or tin jump out to the surface and destroy the coating layer. Because it will break through.

FIG. 7 is a longitudinal sectional view of a floating bearing of a turbocharger according to a second embodiment of the present invention. 7th
In the figure, 1 is the entire floating bearing, and 9 is an oil hole.

In the one shown in FIG. 7, grooves 21 are provided not only on the outer circumferential surface but also on the inner circumferential surface. A coating layer of titanium nitride or titanium carbonitride is provided on the outer peripheral surface and the inner peripheral surface.

Since all other matters regarding the device shown in FIG. 7 are exactly the same as those of the first embodiment, the reference numerals shown in FIG. 2 will only be given and further explanation will be omitted.

FIG. 8 is a longitudinal sectional view of a floating bearing of a turbocharger according to a third embodiment of the present invention. 8th
In the figure, 1 is the entire floating bearing, and 9 is an oil hole.

In the one in Figure 8, the outer peripheral surface of the base material is finished with streaks 8,
A coating layer of titanium nitride or titanium carbonitride is provided over the entire outer peripheral surface. Regarding the striation finishing, the pitch is 0.1 to lrnm and the depth is about 10 μm.

All other matters regarding the device shown in FIG. 8 are exactly the same as those of the first embodiment, so further explanation will be omitted.

FIG. 9 is an enlarged longitudinal sectional view of a portion of the outer surface of a floating bearing of a turbocharger according to a fourth embodiment of the present invention.

In the one shown in FIG. 9, the outer peripheral surface of the base material of the floating bearing 1 is plateau finished, and a coating layer 24 of titanium nitride or titanium carbonitride is provided on the entire outer peripheral surface. Plateau finish is a puff finish on the surface after blasting. The surface roughness of the outer peripheral surface of the floating bearing 1 of this embodiment is R25 to 20 μm as a 10-point average roughness.

All other matters regarding the one in FIG. 9 are the same as those in the first embodiment, so further explanation will be omitted.

Although nine specific embodiments of the present invention have been described above, the present invention is not limited to these embodiments (various embodiments are included within the scope of the claims).

〔Effect of the invention〕

According to the present invention, it is possible to achieve the effect that a floating bearing coated with a ceramic coating does not cause peeling of the coating layer and has a long service life.

[Brief explanation of the drawing]

FIG. 1 is an enlarged longitudinal cross-sectional view of a portion of a floating bearing of a turbocharger according to a first embodiment of the present invention (an enlarged longitudinal cross-sectional view of a portion indicated by arrow Z in FIG. 3). FIG. 2 is an enlarged vertical sectional view of a portion of the floating bearing of the turbocharger according to the first embodiment of the present invention, the outermost surface of which has been worn. FIG. 3 is a longitudinal sectional view of a floating bearing of a turbocharger according to a first embodiment of the present invention. FIG. 4 is a longitudinal sectional view of a turbocharger equipped with the floating bearing of FIG. 3. FIG. 5 is a graph showing the amount of wear measured for test pieces 1 to 3. FIG. 6 is a graph showing the amount of wear of the mating member for test pieces 1 to 3. FIG. 7 is a longitudinal sectional view of a floating bearing of a turbocharger according to a second embodiment of the present invention. FIG. 8 is a longitudinal sectional view of a floating bearing of a turbocharger according to a third embodiment of the present invention. FIG. 9 is an enlarged vertical sectional view of a portion of the outer surface of a floating bearing of a turbocharger according to a fourth embodiment of the present invention. 1---------Floating bearing 8--
-111・Stroke 21-・-Groove 24・・・・・・Coating layer 25・−・・Outermost surface Fig. 1 Fig. 2 Fig. 8 Fig. 8 -Q? ? −

Claims (3)

[Claims] (1) A floating bearing for a turbocharger whose base material is made of a copper alloy, wherein at least the outer peripheral surface of the base material of the floating bearing is provided with a large number of grooves extending in the circumferential direction, and the outer peripheral surface of the base material A floating turbocharger characterized in that the entire surface is provided with a coating layer of titanium nitride or titanium carbonitride with a thickness of 2 to 10 μm, and the outermost surface of the coating layer has a surface roughness of Rz 1 μm or less. bearing. (2) A floating bearing for a turbocharger whose base material is made of a copper alloy, in which at least the outer peripheral surface of the base material of the floating bearing is provided with a large number of circumferentially extending grooves, and the outer periphery of the base material A turbocharger characterized in that a coating layer of titanium nitride or titanium carbonitride with a thickness of 2 to 10 μm is provided on the entire surface, and the surface roughness of the outermost surface of the coating layer is Rz1 μm or less. floating bearing. (3) A floating bearing for a turbocharger whose base material is made of a copper alloy, and at least the outer peripheral surface of the base material of the floating bearing has a surface roughness of Rz5 to 2.
0 μm, and a film thickness of 2 on the entire outer peripheral surface of the base material.
A floating bearing for a turbocharger, characterized in that a coating layer of titanium nitride or titanium carbonitride of ~10 μm is provided, and the surface roughness of the outermost surface of the coating layer is Rz1 μm or less.