WO2019097781A1 - Aluminum alloy floating metal bearing - Google Patents

Abstract

This sliding bearing integrally bears an intake side and an exhaust side of a turbine shaft of an exhaust-turbine-type turbocharger. The material used for the sliding bearing is an aluminum alloy that contains prescribed amounts of silicon (Si), iron (Fe), copper (Cu), manganese (Mn), magnesium (Mg), zinc (Zn), and titanium (Ti) and, of other elements, no more than 0.10 weight% of each and no more than 0.15 weight% total, the remainder being aluminum (Al). In order to reduce bearing loss, the sliding bearing uses low-specific-gravity aluminum and is thereby lighter weight. The sliding bearing also improves rotational tracking, reduces turbo lag, suppresses self-excited vibration, and reduces noise.

Description

Aluminum alloy floating metal bearing

The present invention relates to a slide bearing, and more particularly, to a floating metal bearing technology based on a lightweight aluminum alloy as a bearing of a turbine shaft of an exhaust gas turbine turbocharger for automobiles.

Automotive exhaust turbine turbochargers increase the density of air and send more oxygen to the combustion chamber, allowing aircraft to fly at altitudes as low as oxygen concentration in the atmosphere, to automotive internal combustion engines It is a technology diverted as a supercharging device to be used. Exhaust gas turbine turbochargers for automobiles have undergone many changes from the beginning of development to the present, and the objective of development initially is to improve the output power. BMW's 2002 Turbo equipped with a turbocharger is an appearance that has achieved about 30% power improvement, and then in Japan, in combination with DOHC (double overhead camshaft), further increase of power by intercooler, turbine blade In the era of high power competition among car makers, there are backgrounds such as the use of ceramic for ceramic and adoption of ball bearings for turbine shaft.

As described above, although technology related to exhaust turbine turbochargers has been enhanced, the recent needs have been focused on the avoidance of fossil fuel exhaustion, the environmental impact of exhaust gases, and the reduction of environmental impact, There is an urgent need to develop exhaust-turbine turbochargers that are suitable for small diesel engines mainly in Europe, and small displacement gasoline engines that are being promoted in Japan, and that can be supplied from a low speed range.

In general, exhaust turbines are exposed to extremely high temperature combustion gas exceeding 800 ° C. on the exhaust side impeller, and exhaust gases from bearings are also used because exhaust gas from the internal combustion engine is used as a motive power. Heat transfer causes temperature rise, temperature rise and fall repeatedly, temperature change is intense, and it must always withstand ultra-high-speed rotation as high as 200,000 rotations, always in a harsh environment In order to be able to withstand, it is necessary to carefully consider the selection of the material.

Furthermore, the sliding bearing has a large frictional resistance during acceleration / deceleration, and the follow-up ability of supercharging from opening the accelerator to raising the intake pressure is inferior to that of the ball bearing, which causes a problem that the time lag of supercharging occurs. In some cases, the fuel consumption may be reduced by depressing the accelerator. In addition, some racing cars and the like that require follow-up performance use a ball bearing with low bearing loss due to contact, but there are problems with vibration and cost due to the increase in moment of inertia due to the rotating body around the turbine shaft. have.

Also, the turbine shaft is usually supported by floating bearings or ball bearings at two locations, outside and inside the intake and exhaust sides, but these two bearings It must be processed so that the core does not shift. Misalignment of the processing accuracy causes vibration and noise. Therefore, in some exhaust turbine turbochargers, two ball bearings are integrated and provided in the bearing portion of the bearing housing. According to the configuration, it is considered that the vibration can be suppressed without the shaft core being shaken. However, in the ball bearing, the moment of inertia generated in the rotating body around the axis becomes large, causing a problem that self-excited vibration occurs, and the problem that the generation of noise is caused due to this is not solved.

In addition, conventionally, in order to solve the above-mentioned problems, various technical proposals have been made from other than the present inventor. For example, there is disclosed a technology in which the title of the invention is referred to as "Turbocharger" (see Patent Document 1). Specifically, “a shaft connecting a turbine and a compressor, a bearing housing having a bearing portion for rotatably supporting the shaft, and a slide bearing interposed between the shaft and the bearing portion A turbocharger, wherein the bearing portion is formed of an aluminum-based material, the shaft is formed of a steel material, and the slide bearing is formed of a copper-based material. It has become a technology. However, the technology described in Patent Document 1 has not yet solved the weight reduction by using the aluminum alloy product, which is the subject of the present invention.

In addition, a technology in which the title of the invention is "a bearing provided with a floating metal" is disclosed (see Patent Document 2). Specifically, “a floating metal provided so as to have a first sliding surface gap with the outer periphery of the rotating shaft and a second sliding surface gap with the inner periphery of the bearing chamber. And at least one of the first sliding surface gap and the second sliding surface gap at a cut that is centered on and cut at a plane perpendicular to the rotation axis is not constant on the circumference, A bearing having a floating metal is disclosed, characterized in that it has a shape consisting of individual tapers, and an oil supply hole for supplying oil to the sliding surface clearance is provided at the maximum position of the clearance. It is a well-known technology. However, the technology described in Patent Document 2 has not yet solved the weight reduction by using the aluminum alloy product, which is the subject of the present invention.

Further, a technology is disclosed in which the title of the invention is "a manufacturing method of a thrust bearing for a turbocharger and a thrust bearing for a turbocharger" (see Patent Document 3). Specifically, “the method of manufacturing a thrust bearing for a turbocharger has a step of obtaining a dust core, a step of supplying the dust core into the mold, and a molding step of compression molding, It is a process of forming a flow path of oil and forming a green compact, having a sintering process, bonding a part corresponding to metal powder, and being excellent in slidability and abrasion resistance. A method of manufacturing a scurass bearing for a turbocharger is disclosed in the related art. However, the technology described in Patent Document 3 has not yet solved the weight reduction by using the aluminum alloy, which is the subject of the present invention.

Furthermore, in floating metal bearings that have already been produced and put into practical use, in order to reduce the moment of inertia of the rotating body and to propose shaft vibration, turbine wheels made of titanium aluminum alloy, impellers and turbine shafts are used. Some are made of magnesium alloy. These have commercialized technologies that succeeded in reducing the rotational moment of the rotating body by 42% and further increasing the bending resonance rotational speed of the shaft by 44%. However, none of the bearings themselves use an aluminum alloy, and the weight reduction of a bearing metal that rotates as a part of a rotating body is still at present made of a steel alloy or the like. The appearance of the floating metal bearing made of aluminum is expected.

JP 2013-209934 JP-A-1-93409 WO2014010429A1 Patent No. 5477930

In order to solve the problem of reducing the bearing loss described above, the present invention aims to reduce the weight of the bearing by using aluminum having a small specific gravity, and to pay attention to enhancing the followability of rotation and reducing the turbo lag. On the other hand, because of the properties of aluminum, which has lower heat resistance and wear resistance compared to cast iron and other alloys of nonferrous metals, etc., as a material for bearings used in exhaust turbine turbochargers that are conventionally used at high temperatures, There is a current situation that it is difficult to select, and it is an object of the present invention to provide a technology that can be used as a metal bearing for an exhaust turbine turbocharger that solves these problems.

In addition, in the case where a floating metal bearing is generally adopted as a turbine shaft, there is a problem that self-excited vibration is easily generated because the rotation speed of the shaft becomes high. In this respect, on the other hand, the inventor of the present invention has developed a sliding bearing having a portion with different roundness at the equiangular isotropic position of the bearing and has already patented the floating metal bearing having a high damping effect. There is. In order to further enhance such technology, a synergetic effect can be expected by combining it with the technology that enables realization of weight reduction by using the aluminum alloy, which is the problem of the metal bearing, and it contributes to the solution of the problem. It can be said that there is.

The present invention is a slide bearing integrally bearing the intake side and the exhaust side of a turbine shaft of an exhaust turbine turbocharger, and the material is silicon (Si) in a weight ratio of 10.0 to 11.5%. Iron (Fe): not more than 0.50%, copper (Cu): 2.0 to 3.0%, manganese (Mn): not more than 0.10%, magnesium (Mg): 0.20 to 0.50% Zinc (Zn): 0.10% or less, titanium (Ti): 0.10% or less, and each other 0.10% or less, and the total of the other is 0.15% or less, the balance being aluminum (Al) The composition was made of an aluminum alloy.

Further, the present invention is a slide bearing integrally bearing the intake side and the exhaust side of a turbine shaft of an exhaust turbine type turbocharger, and the material is silicon (Si) in weight ratio: 9.5 to 11. 5%, iron (Fe): 0.50% or less, copper (Cu): 4.0 to 5.0%, manganese (Mn) 0.3% or less, magnesium (Mg) 0.40 to 0.80% Zinc (Zn) 0.5% or less, titanium (Ti) 0.2% or less, each other 0.10% or less, and the total of the other is 0.15% or less, the balance being composed of aluminum (Al) It is also possible to adopt a configuration made of an aluminum alloy.

Further, according to the present invention, it is also possible to adopt a configuration in which a plurality of areas having different fluid lubrication conditions are continuously provided equidistantly isotropically from the shaft core by changing the roundness to the surface of the bearing hole.

Further, the present invention can also adopt a configuration in which the number of regions having different fluid lubrication conditions is six.

According to the aluminum alloy floating metal bearing according to the present invention, by using the aluminum alloy as the raw material, the specific gravity is approximately one third that of the conventional copper-based one, so that weight reduction can be realized, and rotation can be realized. It exhibits the excellent effect of reducing the inertial force of objects, improving response and reducing turbo lag.

Further, according to the aluminum alloy floating metal bearing according to the present invention, it is possible to exhibit an excellent effect of solving the problem which can not be solved by the integrated ball bearing developed in recent years. That is, in the integral type ball bearing, the moment of inertia generated in the rotating body around the axial center becomes large, and self-excited vibration is easily generated, and generation of noise caused by this is not solved, either. In the case of aluminum alloy, the result of weight reduction achieved by using aluminum alloy and the use of a floating metal bearing with a small moment of inertia around the axial center, so self-excited vibration is less likely to occur, and the integrated core is free from axial centering It is because it becomes the composition which pulls out.

In addition, by combining the above-described effects of the aluminum alloy floating metal bearing according to the present invention with the technology relating to the suppression of vibration, which the present inventor has already patented, mutual effects are exhibited synergistically, It has an excellent effect that makes it possible to provide a high-performance exhaust turbine turbocharger.

BRIEF DESCRIPTION OF THE DRAWINGS It is structure explanatory drawing which shows the basic composition of the aluminum alloy floating metal bearing which concerns on this invention. It is structure explanatory drawing explaining the structure of the exhaust gas turbine using the aluminum alloy floating metal bearing which concerns on this invention. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a layout configuration explanatory view for explaining the entire configuration of an exhaust turbine turbocharger using the present invention.

The present invention makes it possible to improve the rotational response of the turbine, reduce the turbo lag, and suppress the vibration by reducing the weight by using an aluminum alloy having a small specific gravity for the turbine shaft metal bearing for the exhaust turbine turbocharger 10. Is the biggest feature. The following description will be made based on the drawings and tables. However, the present invention is not limited to the shapes and configurations described in the drawings and tables, and can be changed within the range in which the effects exhibited as the creation of the technical idea of the present invention can be obtained.

FIG. 1 is an explanatory view for explaining an outline of an aluminum alloy floating metal bearing 1 according to the present invention, and FIG. 1 (a) is an entire view for explaining the whole configuration of an integrated floating metal bearing 20 according to the present invention. It is an explanatory view, Drawing 1 (b) is an AA 'cross section showing thrust collar 22 concerning the present invention, and Drawing 1 (c) shows B-B showing floating metal bearing 20 concerning the present invention. FIG. 1 (d) is a cross-sectional view taken along the line CC 'showing the thrust bearing 21 according to the present invention.

The slide bearing used for the bearing of the turbine shaft 31 is composed of a full floating metal bearing 20, a thrust bearing 21 or a thrust collar 22 as usual.

The thrust bearing 21 is a bearing for supporting an axial pressure due to air pressure, gas pressure and vibration applied to the turbine shaft 31, and since the exhaust pressure is at most 1.5 kgf / cm ² (150 kPa), the thrust is The pressure applied to the bearing 21 is not so high, and the mechanical characteristics of the aluminum alloys AA1 and AA2 according to the present invention can sufficiently cope with the reduction of the weight of the exhaust turbine 30 in combination with the floating metal bearing 20. Is desirable.

The thrust collar 22 may be used as a conventional separate type slide bearing, but the integral type aluminum alloy floating metal bearing 1 according to the present invention does not require the thrust collar 22.

The floating metal bearing 20 is a cylindrical bearing and is rotatable while maintaining a clearance between the inner and outer shafts and the bearing housing 40. Moreover, the oil film of the inner and outer collecting has a high damping effect and the relative speed is low, which is suitable for high speed bearings. Therefore, the present invention solves these problems and can be said to be a technology necessary for turbocharging an engine equipped with a downsized small displacement internal combustion engine which will be further increased in the future.

The oil supply groove 24 is a groove which is provided around the outer periphery and connects the plurality of oil supply holes 25 and holds lubricating oil supplied from the engine side with the bearing housing 40 and improves the floating property. It is an effective structure to

The oil supply holes 25 are holes for oil supply provided from the outer periphery to the bearing hole 26 at a plurality of equiangular and equiangular positions from the axial center. It is desirable that six oil supply holes 25 be arranged. However, the present invention is not limited to the number of such arrangements, and as long as the effect of suppressing the centering effect and the self-excited vibration can be obtained by the presence of the regions having different fluid lubrication conditions, which should be referred to The arrangement number can be set freely.

The surface of the bearing hole 26 is internally machined so that a plurality of areas having different fluid lubrication conditions are continuously provided equidistantly and equidistantly from the axial center, and the areas having different fluid lubrication conditions are substantially round. In the surface of the bearing hole 26, a substantially convex narrow flow channel extending in the axial direction is formed in the film-like oil flow channel formed by the clearance with the surface of the substantially perfect circular shaft It is desirable to adopt a configuration that exhibits a high centering effect from a low rotation area and reduces noise generation by slightly changing the degree and causing a change in hydraulic pressure in the slight membrane-like flow path.

FIG. 2 is a configuration explanatory view illustrating the configuration of an exhaust turbine 30 using the aluminum alloy floating metal bearing 1 according to the present invention. As shown in FIG. 2, the exhaust turbine 30 is shown to be configured by an exhaust side impeller 32, an intake side impeller 33, a turbine shaft 31, and an integrated floating metal bearing 20.

The exhaust turbine 30 is a rotating body on which the exhaust side impeller 32 and the intake side impeller 33 are disposed and fixed at both ends of the turbine shaft 31.

The exhaust side impeller 32 is an impeller for absorbing the energy of the exhaust gas as rotational motion, and transmits the energy to the intake side impeller 33 provided at the opposite end through the turbine shaft 31. In order to efficiently absorb the working fluid from the exhaust gas and convert it into rotational motion, the plurality of blades are formed into a shape suitable for supercharging, and in a gasoline engine, the temperature of the exhaust gas exceeds 1000 ° C. In some cases, materials that can withstand such temperatures are required. Although ceramic materials and titanium alloys are conventionally used in some racing vehicles, etc., although ceramics are excellent in heat resistance, they are easily cracked etc., and titanium alloys are expensive and have problems in cost. doing. Therefore, in the present invention, by using an aluminum alloy for the bearing, the purpose is to improve the response of supercharging by the inertial force of the rotating body, so the exhaust side impeller 32 rotating on the same axial center is also possible. It is effective to reduce the weight as much as possible.

The intake side impeller 33 is an impeller for rotating the exhaust side impeller 32 by the rotational driving force rotated by the exhaust gas, increasing the natural air pressure flowing from the atmosphere and the flow velocity, and pushing it into the cylinder. is there. In addition, since the turbine has a high rotation speed as high as 200,000 rpm, the speed near the tip of the blade of the impeller 32 becomes higher than the speed of sound, and it is also heated by air resistance.

In the design of the slide bearing, it is necessary to clearly grasp various conditions such as operating temperature, load, sliding speed, material of the mating material, torque, accuracy, environment, movement pattern, expected life and the like. In the aluminum alloy floating metal bearing 1 according to the present invention, it is necessary to consider the operating temperature, the material of the mating material, the lubrication condition, etc., while taking into consideration the allowable surface pressure and the allowable sliding speed of the bearing material.

Using the PV value expressed as the product of the surface pressure P (Pa) and the sliding velocity V (m / min), the usable operation allowable range of the bearing material is determined. However, the surface pressure and the sliding speed also have respective allowable values, and the usable range is a PV curve that defines the respective allowable values for the surface pressure and the sliding speed. The equation for calculating the slip velocity V can be obtained by V = π × d × n × 10 ⁻³ .

FIG. 3 is a schematic explanatory view of a state in which the aluminum alloy floating metal bearing 1 according to the present invention is incorporated into the exhaust turbine type turbocharger 10, in a bearing housing 40 for bearing the exhaust side and the intake side of the turbine shaft 31. The integrated floating metal bearing 20 is shown.

The turbine housing 50 is a component that encloses the exhaust side impeller 32 and is configured by an introduction portion and an exhaust portion of the exhaust gas, and plays a role of accelerating the exhaust gas from the engine and guiding it to the exhaust side impeller 32. is there. Such a turbine housing 50 is always exposed to high temperature in order to direct exhaust gas directly, and is generally made of cast iron having characteristics such as heat resistance, heat dissipation, and thermal expansion resistance.

The bearing housing 40 is located at the center of the turbine housing 50 and the compressor housing 60, includes a bearing of the turbine shaft 31, and has a function of connecting and supporting the two housings. The configuration of the aluminum alloy floating metal bearing 1 according to the present invention exemplifies a case where one floating metal bearing 20 in which the intake side and the exhaust side are integrated is supported by the bearing housing 40.

The compressor housing 60 wraps the intake side impeller 33 and is constituted of an air intake portion and an air discharge portion to guide the air and has a function of converting dynamic pressure given by the intake side impeller 33 into static pressure. .

As shown in FIGS. 1 to 3, the present invention appears in appearance to be the same as a conventional floating metal bearing 20. However, the technical main part of the present invention is not that it can be judged from the appearance, and is that it can be used by improving an aluminum alloy which can not be used conventionally, and the compounding ratio for its configuration is shown in Table 1 It is street.

Table 1 shows the ratio of various metals to be incorporated into the base metal, and the invention according to claim 1 or 2 according to the present invention is shown as aluminum alloys AA1 and AA2 in order from the top, and below that, A copper-based alloy conventionally used for the turbine shaft 31 is shown and can be compared.

Silicon (Si) suppresses expansion due to heat by containing to improve wear resistance, and the content is within the range of 9.5 Wt% to 11.5 Wt%, more preferably 10 It is desirable to be within the range of 0. 0 Wt% to 11.5 Wt%.

Iron (Fe) is contained to prevent seizure. However, increasing the iron content will lower the strength. The content is desirably 0.5 wt% or less.

Copper (Cu) is contained to improve the strength, and by further adding nickel, the strength can be further improved. The content is preferably in the range of 2.0 Wt% to 5.0 Wt%, preferably in the range of 2.0 Wt% to 3.0 Wt%, or 4.0 Wt% to 5.0 Wt%. .

Manganese (Mn) can improve the strength while maintaining the corrosion resistance of aluminum as it is, and further improves the strength by containing magnesium (Mg). It is desirable that the content is within the range of 0.3 wt% or less, and more preferably 0.1 wt% or less.

By containing magnesium (Mg), strength and corrosion resistance can be improved. However, if it is cold-worked, stabilization processing is performed because its strength decreases with age. In particular, in the exhaust turbine turbocharger 10 used at high temperature, there is a problem of stress corrosion cracking, so the right side of the soft material is required. Furthermore, the inclusion of magnesium (Mg) and silicon (Si) at a constant content ratio contributes to age hardening by heat treatment. The content is within the range of 0.2 Wt% to 0.8 Wt%, preferably 0.2 Wt% to 0.5 Wt, and heat treatment results in the highest strength alloy among the aluminum alloys. The content is desirably in the range of 0.5 wt% or 0.4 wt% to 0.8 wt%.

Zinc (Zn) is preferably contained together with magnesium (Mg), and more preferably 0.1 wt% or less.

Titanium (Ti) can be used for grain refinement, mechanical property improvement, or prevention of shrinkage cracking with an Al—Cu-based alloy or the like. However, when the content is excessive, there arises a problem that the viscosity of the molten metal increases. The content is within the range of 0.2 Wt% or less, more preferably 0.1 Wt% or less.

The aluminum alloys AA1 and AA2 according to the present invention have the above-mentioned composition. White metals, copper alloys, steel alloys and the like have been used as metals used in conventional slide bearings. Such white metal is excellent in seizure resistance at room temperature, adaptability, and burying ability, and can be said to be an optimum material if it is used for a static load bearing. However, the material of the bearing used for the turbine shaft 31 of the exhaust gas turbine turbocharger 10 exposed to high temperature has a low limit.

Copper-lead alloys or lead-bronze alloys, etc., have been studied as materials for bearings instead of the above-mentioned white metals, and they are metals that can improve white metal defects and have higher wear resistance etc. It is. However, many copper-based alloys are problematic because copper penetrates into the shaft, and are now coated on the surface to solve such problems, so the cost is high. As a result, there is a problem that the labor and time in the manufacturing process become large.

Therefore, bearings made of an aluminum alloy having a small specific gravity have also been developed, and are also used as Al-SA, AlCu, etc. in which soft elements of tin and lead are present as independent components. In Japan, as a technology of alloy based on aluminum, when aluminum alloy is used for bearing, it is possible to combine the characteristics of both strength and softness, and it can be usually used without plating It exerts an advantageous effect that conventional products do not have. In the aluminum alloy according to the present invention, the content of tin is increased, and an Al—Sn-based alloy excellent in seizure resistance and corrosion resistance, and an Al—Sn—Si-based alloy containing silicon (Si) of a hard substance have wear resistance and It has excellent fatigue resistance and is the mainstream of bearings for automobile engines, and it is also a kind of alloy added to ISO standard by Japanese proposal.

Therefore, if an aluminum alloy with a low specific gravity can be used for bearings at high temperatures, a lightweight exhaust turbine 30 can be configured, and many problems such as the following problem and heat conduction can be solved. It can be said. However, the melting point of aluminum (Al) is about 660 ° C, the recrystallization temperature is as low as about 200 ° C, and a creep reaction occurs at 180 ° C. It can not be used as a bearing for bearing the turbine shaft 31.

Therefore, in the present invention, the lubricating oil in the vicinity of the turbine shaft 31 of the exhaust turbine turbocharger 10 may rise from 130 ° C. to about 150 ° C. Therefore, at least about 150 ° C., preferably about 200 ° C. It can be said that it is necessary to use an alloy which does not cause creep and does not deteriorate mechanical properties such as strength and hardness.

Therefore, the present inventor has researched and developed a raw material of an aluminum alloy floating metal bearing 1 that solves all the respective problems described above, and has completed the aluminum alloy floating metal bearing 1 according to the present invention.

Table 2 shows the results of investigation of the mechanical properties of the aluminum alloy according to the present invention. The materials to be investigated are those after tempering (T6 treatment) of the extruded material at room temperature. The survey items are tensile strength (MPa), 0.2% proof stress (MPa), elongation (%), and hardness (HRB).

Refining is performed on the assumption that the product is used at 150 ° C. and 200 ° C. for 100 hours, and hardness and tensile strength are measured after T6 treatment. Note that such T6 treatment is a heat treatment combining treatment for artificially carrying out precipitation aging in order to improve the mechanical properties, strength, hardness and machinability of the aluminum alloy. Hardening and tempering are performed.

The linear expansion coefficient is a characteristic of the material necessary for the design of the clearance, and indicates an expansion ratio which expands and contracts in a specific direction, and the coefficient changes depending on the shape unlike the thermal expansion coefficient which expands with a change in volume. In the present invention, the expansion in the specific direction of the gap between the bearing and the shaft becomes a problem, but the aluminum alloys AA1 and AA2 have linear expansion coefficients of 22.2 × 10 ⁻⁶ / ° C. and 20.810 ^{−6 respectively.} / ° C, and is used for metal bearings made of typical copper alloys of the conventional product (C1100: tensile strength 215 N / mm ² to 315 N / mm ² , elongation 2% to 10%, hardness 80 or less) It has an approximately the same linear expansion coefficient as 17.7 × 10 ⁻⁶ / ° C., and exhibits an expansion characteristic equivalent to 20.5 × 10 ⁻⁶ / ° C. made of the most popular brass. It is shown that the effect of the change in clearance is similar to that of a conventional copper alloy or brass slide bearing. However, such numerical values take into consideration the expansion characteristics corresponding to the turbine shaft 31 which is the counterpart of a slide bearing made of brass or the like conventionally used, and if the material of the turbine shaft 31 changes, the material It is obvious that the aluminum alloy floating metal bearing 1 according to the present invention can be used depending on AA1 and AA2.

The hardness of the floating metal bearing 20 is in contact in the initial stage of rotation, and the bearing is mounted on the oil film when rotation starts, so that the structure is advantageous in terms of wear resistance against friction, and high durability is obtained. On the other hand, a hardness difference is required in relation to the turbine shaft 31 as appropriate. When the difference in hardness is small, it becomes easy to wear. Therefore, in the present invention, copper alloys used in conventional turbine shaft journal bearings for turbochargers, for example, BM-9E (75HRB), YZ5X (72HRB), P-31C (83HRB), AT-3E (90HRB), In the present invention, AA1 is 79 HRB, AA2 is 85 HRB, and some decrease in hardness is seen at 200 ° C, but it has a hardness of 60 HRB for AA1 and 71 HRB for AA2. It can be seen that sufficient performance is maintained as compared to the copper alloy.

The tensile strength of BM-9E (490N / mm ² ), YZ5X (250N / mm ² ), P-31C (590N / mm ² ), and AT-3E (660N / mm ² ) have a wide range. the present invention, AA1 at 200 ° C. is AA1 at 426N / mm ² AA2 is at 458N ^/ mm 2, 150 ℃ is AA2 is a 393N / mm ² at 359N / mm ^2, have a tensile strength in this range doing. In addition, since the load of a radial direction is small to the turbine shaft 31 in the exhaust turbine type turbocharger 10 as a pressure received from exhaust gas, this does not require high tensile strength.

The mechanical properties of the aluminum alloys AA1 and AA2 according to the present invention in the heated state are shown in Table 3. As for mechanical properties at normal temperature, T6 treatment is performed as a temper after T6 treatment, but the T6 treatment is the mechanical properties, strength, hardness and machinability of the aluminum alloy. In order to improve it, it is a heat treatment that combines the process of artificially performing precipitation aging, which is solution heat treatment, quenching treatment, tempering treatment, and it is assumed that the product is used at 150 ° C and 200 ° C for 100 hours. It is an experimental result performed.

In addition, after investigating the mechanical property as shown in Table 2 to the alloy comprised from aluminum alloy AA1, AA2 shown in Table 1, the change of the mechanical property under high heat was investigated by the following procedure. Specifically, after solution treatment, artificially age-hardened ones are not actively cold-worked, tempered (T6 (JIS standard)), and then left while returning to room temperature, and tensile specimen processing After that, the test temperature was heated at 150 ° C. and 200 ° C. for 100 hours with the heater of the tensile tester and the measurement at ordinary temperature, and the tensile test and the like in the heated state were performed.

From the measurement results of the mechanical properties described above and changes in mechanical properties at normal temperature and in the 150 ° C. or 200 ° C. heating condition, it is considered to adopt the exhaust turbine turbocharger 10 using the aluminum alloys AA1 and AA2 according to the present invention Do. The temperature to which the bearings are subjected usually rises only to about 150 ° C. because the temperature of the engine oil is the upper limit. It is not heated from the lubricating oil temperature to at least 150 ° C, preferably 200 ° C. Therefore, it has been confirmed that self-excited vibration and noise are not generated in the temperature range, and it is possible to reduce the turbo lag accompanied by the weight reduction and improve the response. In addition, in the worn state after use for about 100 hours, no influence was observed on the surface roughness and the roundness in the measurable range.

While the present inventors are reviewing various processing conditions such as surface roughness and roundness, even if the high-accuracy roundness characteristics and surface roughness characteristics are improved, the generation of noise from the turbine is quite difficult. That is, it may be possible to suppress the generation of the vibration by slightly changing the roundness on the inner surface of the bearing hole 26 to a polygonal position because it is difficult to suppress the generation of the vibration causing the noise. Based on the idea of changing the roundness variously, repeat the experiment on the presence or absence of vibration and noise generation, technology to reduce the generation of vibration "low vibration type floating metal bearing" (see Patent Document 4) (below, Low-vibration sliding bearing)), and using the aluminum alloy AA1 and AA2 materials of the aluminum alloy floating metal bearing 1 according to the present invention. By a sliding bearing, it is possible to synergistically effective resulting from mutual technology.

That is, although the invention according to the low vibration slide bearing can obtain the high centering effect and the generation of noise from the low rotation region to the high rotation region, the effect of the invention is generated from the start of the rotation Therefore, by reducing the weight of the floating metal bearing 20 which is one of the parts constituting the rotating body, the weight of the entire turbine can be reduced, and suppression of turbo lag, improvement of response, self-excited vibration, noise, etc. Generation of noise can be suppressed.

Therefore, the surface of the bearing hole 26 of the aluminum alloy floating metal bearing 1 according to the present invention is provided with a plurality of regions having different fluid lubrication conditions equidistantly equidistant from the axis, and the clearance is slightly changed on the surface of the bearing hole 26 It is desirable to adopt a configuration that causes a change in hydraulic pressure by forming a substantially convex narrow membrane-like flow path in the axial direction in the oil flow path.

Furthermore, the clearance is changed so that the regions having different fluid lubrication conditions gently connect the substantially convex narrow membranous flow channel toward the axial center and the substantially concave wide membranous flow channel toward the outer peripheral direction. It is also effective to

The centering property (self-centering function), which is an effect of the configuration, is rotated as in the distribution of pressure generated from the Reynolds equation, when a portion having a slightly different roundness is disposed at the same circular peripheral edge of the equiangular position. Because the pressure changes that occur are always of the same magnitude and occur at equal intervals on the same circumference, the pressure difference generates a force toward the center of the turbine shaft 31 at all times, and the centering effect is rotation even if the rotational speed is low. Occurs almost simultaneously with Therefore, if the weight of the turbine and the rotating bearing can be reduced, the problems of the present invention are solved, and the response is improved, the turbo lag is reduced, the self-excited vibration is suppressed, and the generation of noise due to the vibration is reduced. It is possible to provide the exhaust turbine turbocharger 10.

With the above configuration, the weight and size can be reduced, and the performance as a bearing is not reduced due to the deterioration of the mechanical properties of the aluminum alloy under high temperature which has been regarded as the most problematic. It has been confirmed by various measurement results and experiments that the effect of reducing vibration and noise at high rotation speed is exhibited.

According to the aluminum alloy floating metal bearing according to the present invention, it is possible to provide an exhaust turbine type turbocharger capable of achieving an improvement in the response due to the reduction of vibration and the reduction of weight by integration. Their availability in the automotive industry is considered to be high.

DESCRIPTION OF SYMBOLS 1 aluminum alloy floating metal bearing 10 exhaust turbine type turbocharger 20 floating metal bearing 21 thrust bearing 22 thrust collar 24 oil supply groove 25 oil supply hole 26 bearing hole 30 exhaust turbine 31 turbine shaft 32 exhaust side impeller 33 intake side impeller 40 bearing Housing 50 Turbine housing 60 Compressor housing AA1 Aluminum alloy AA2 Aluminum alloy

Claims (4)

A slide bearing integrally bearing an intake side and an exhaust side of a turbine shaft (31) of an exhaust turbine turbocharger (10),
The material is in weight ratio,
Silicon (Si): 10.0 to 11.5%,
Iron (Fe): 0.50% or less,
Copper (Cu): 2.0 to 3.0%,
Manganese (Mn): 0.10% or less,
Magnesium (Mg): 0.20 to 0.50%,
Zinc (Zn): 0.10% or less,
Titanium (Ti): 0.10% or less,
Others are each 0.10% or less, and the other total is 0.15% or less,
The balance is aluminum (Al)
An aluminum alloy floating metal bearing (1) characterized in that it is made of an aluminum alloy (AA1) composed of A slide bearing integrally bearing an intake side and an exhaust side of a turbine shaft (31) of an exhaust turbine turbocharger (10),
The material is in weight ratio,
Silicon (Si): 9.5 to 11.5%,
Iron (Fe): 0.50% or less,
Copper (Cu): 4.0 to 5.0%,
Manganese (Mn) 0.3% or less,
Magnesium (Mg) 0.40 to 0.80%,
Zinc (Zn) 0.5% or less,
Titanium (Ti) 0.2% or less,
Others are each 0.10% or less, and the other total is 0.15% or less,
The balance is aluminum (Al)
An aluminum alloy floating metal bearing (1) characterized in that it is made of an aluminum alloy (AA2) composed of A plurality of areas having different fluid lubrication conditions by continuously changing the circularity on the surface of the bearing hole (26) are provided equidistantly isotropically from the shaft core. The aluminum alloy floating metal bearing (1) described in. The aluminum alloy floating metal bearing (1) according to any one of claims 1 to 3, wherein the number of the regions having different fluid lubrication conditions is six.

Images