JPS6238417B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Field of Application) The present invention relates to floating bearing materials used in turbochargers. (Prior art) Floating bearings are used in the bearings of turbochargers installed in internal combustion engines.
Immediately after the internal combustion engine stops operating, the temperature reaches around 300℃ due to heat conduction from the turbine, and the lubricating engine oil adhering to the bearing surface is heated above its heat-resistant temperature. As a result, the following problems occur, for example. That is, (1) Corrosive acidic substances are generated in the engine oil, which selectively corrodes lead contained in bearings, increasing wear on the bearings. (2) As engine oil deteriorates, deposits form in the oil holes used to supply lubricating oil to the bearings, which block the oil holes and cause an oil film to run out, causing bearing wear due to poor lubrication. growing. (3) The wear of the bearing increases due to friction with peeled pieces of the deposit formed above or with metal chips remaining on the surface due to insufficient cleaning of the engine body or turbocharger oil hole. As the wear of the bearing increases, the eccentricity of the rotating shaft of the turbine wheel increases, resulting in interference between the turbine wheel and the turbine housing, causing problems such as abnormal noise and damage to the turbine wheel. will occur. Conventionally, lead bronze (e.g. LBC3, LBC4, LBC5), whose main components are copper, tin, and lead, has been mainly used as a material for floating bearings in turbochargers, but it has poor wear resistance and seizure resistance after lubrication stops. I was not completely satisfied with my sexuality. (Object of the Invention) The present invention is intended to solve the above-mentioned problems in the prior art, and its purpose is to provide a bearing material for turbochargers that is superior in wear resistance and seizure resistance to conventional lead bronze turbocharger bearing materials. The purpose of this project is to provide bearing materials for turbochargers. (Structure of the Invention) That is, the turbocharger bearing material of the present invention contains 55 to 65% copper and 25 to 65% zinc by weight.
35%, aluminum 2 to 6%, nickel 0.2 to 3%, iron 0.5 to 4%, titanium 1
to 2.5%, lead 2 to 10%, manganese 2 to 4%, silicon 0.5 to 2%, zirconium 0.5
It is made of an alloy component containing at least one to five types of impurities of 1 to 2% and the remainder, and has intermetallic compound particles with a maximum length of 5 to 30μ and a Vickers hardness of 400 or more on the surface with an area ratio of 3 to 15%. It is characterized by letting it come out. The preferred composition of the bearing material is 55 to 65% copper and 25% zinc by weight.
A base material containing 2 to 35% of aluminum and 2 to 6% of aluminum, further 2 to 4% of iron, and 1.5 to 1.5% of titanium.
Add 2.5% or add lead 2 in addition to the above ingredients.
Examples include alloys with 10% to 10% added. Another preferred bearing material has a base material containing 55 to 65% copper, 25 to 35% zinc, and 2 to 6% aluminum, to which 0.2 to 3% nickel and 1 to 2% titanium are added. Examples include alloys that are Another preferable bearing material has a base material containing 55 to 65% copper, 25 to 35% zinc, and 2 to 6% aluminum by weight, and further 0.2 to 3% nickel, 2 to 4% manganese,
Examples include alloys containing 0.5 to 2% silicon. Another preferable bearing material has a base material containing 55 to 65% copper, 25 to 35% zinc, and 2 to 6% aluminum, further 0.2 to 3% nickel, 0.5 to 2% iron, silicon
Add 0.5 to 2%, zirconium 0.5 to 2%, or add 2 to 10% lead in addition to the above ingredients.
Examples include alloys with added . Since the bearing material of the present invention contains a predetermined amount of nickel, iron, titanium, zinc, manganese, silicon, etc., a hard intermetallic compound consisting of these components is generated, but this intermetallic compound is By casting, setting the solidification start temperature to 900 to 950°C, and cooling to room temperature at an average cooling rate of about 100°C/min, it can be precipitated in the form of needles or blocks in the base alloy. This intermetallic compound has a Vickers hardness (Hv) of 400 or more, which is much higher than the 160 to 230 Vickers hardness of a uniform alloy layer, so it has excellent wear resistance. By uniformly dispersing particles having a maximum length, the wear resistance of the base alloy can be improved. The maximum length is about 5 to about 30
μ, particularly preferably about 15μ. Further, the area ratio where the intermetallic compound crystallizes is preferably 3 to 15%. Therefore, by using this alloy, a bearing with excellent wear resistance can be obtained. Further, the wear resistance of the bearing can be further improved by utilizing the characteristics of the bearing material of the present invention. That is, after polishing the sliding surface of a bearing material formed into a desired shape, for example, a cylindrical shape, etching the sliding surface using an appropriate etching agent, such as various acids or salts, creates a bond between metals such as iron and titanium. Since the compound particles are not easily corroded, they remain exposed on the sliding surface. For this reason, the sliding surface has a structure having continuous or intermittent recesses, and by filling these with lubricating oil to form oil pools, lubricity is increased and wear resistance is improved. Especially the initial scuff (scuff,
wear) can be reduced. The depth of the recess, that is, the exposed height of the intermetallic particles, is about 0.5μ to about 5μ, preferably about 1μ, because if it is too large, the intermetallic particles will peel off, and if it is too small, it will not be possible to obtain a sufficient lubrication effect. It is preferable to set the thickness to about 3μ. Another method for obtaining the same effect as above is to arrange grooves in the form of grooves at predetermined intervals along the circumferential direction on the inner and outer peripheral surfaces of a cylindrical bearing material. It's okay. Furthermore, when the surface etc. are precision-machined to create a final product bearing, these grooves not only have an oil retaining effect for storing lubricating oil such as engine oil, but also divide the bearing sliding surface along its axis. For example, even if sludge is generated on each divided sliding surface due to engine oil deterioration, the adhesion force is weakened because the adhesion area is small. Therefore, the sludge is easily broken by the rotation of the bearing, and problems such as sticking to the sliding surface are eliminated. In addition, in the case of the bearing material of the present invention, hard intermetallic compound particles are exposed on the sliding surface, which is also effective in scraping off sludge, and together with the effect of the grooves, it is extremely difficult for sludge to form. Become something. Furthermore, by providing grooves, the flow rate of engine oil flowing in the axial direction of the bearing increases when the turbocharger moves, increasing the lubrication and cooling effect and suppressing the rise in bearing temperature, reducing the generation of sludge and wear of the bearing. can be reduced. It is even more effective to use a combination of etching the sliding surface and providing grooves. The size of the cylindrical bearing, that is, the height, inner diameter, and outer diameter of the cylinder, are optimally selected according to the turbocharger. A hole having a desired size and shape may be formed in a part of the cylindrical side surface for the purpose of preventing deformation, increasing cooling efficiency, supplying engine oil, etc. The cross-sectional shape of the groove can be various shapes, such as V-shaped, U-shaped, rectangular, or semicircular. In addition, the groove spacing, width, and depth are optimally selected taking into account the strength of the bearing, the amount of engine oil retained, workability, etc., but for turbocharger bearings used for normal purposes, the groove spacing should be approximately It is preferable that the width is about 1 mm to about 5 mm, the width is about 0.5 mm to 3 mm, and the depth is about 0.5 mm to about 3 mm. (Example) The present invention will be explained in further detail in the following example. Note that the present invention is not limited to the following examples. Example 1: Zinc (Zn) 32.0% by weight, aluminum (Al)
5.7% by weight, iron (Fe) 3.0% by weight, titanium (Ti)
The raw materials were mixed at a ratio of 2.2% by weight and the balance was copper (Cu), put into a melting furnace, melted at 1150°C, poured at a pouring temperature of 1000°C, and water cooled at an average cooling rate of 100°C.
It was cooled to room temperature at a rate of °C/min to obtain bearing material 1 for turbocharger. At this time, the solidification start temperature is
It was 950℃. Examples 2 to 7 The raw materials were blended in the component proportions shown in the table, and Example 1
Bearing materials 2 to 7 were obtained in the same manner as above. Chemical components of the bearing materials for turbochargers of the present invention obtained in Examples 1 to 7 above and conventional materials for comparison, and wear resistance and seizure occurrence time (seizure resistance) of bearings manufactured using these materials.
are summarized in the table. The wear resistance shown in the table is LFW
-1 It shows the wear depth of various bearing materials at relatively low rotation speeds and low loads using a wear tester, and the smaller the value, the better. In addition, the seizure resistance shown in the table assumes a state of poor lubrication, which is a problem unique to turbocharger bearings, and was measured using a mechanical testing laboratory type friction and wear tester during break-in operation at low load and high rotation speed under lubrication. It shows the time from when lubrication is stopped until seizure occurs, and the longer the time, the better.

【table】

[Table] As is clear from the table, the bearing material of the present invention has a much smaller wear depth and significantly improved wear resistance than conventional lead bronze. Furthermore, the time required for seizure to occur has become longer, and the seizure resistance has also improved. The reason why the bearing material of the present invention has excellent wear resistance is that hard intermetallic compound particles are crystallized in the base material, and A390 in the table is a typical example of a material with a similar structure. There are high-silicon aluminum alloys. However, although this alloy has excellent wear resistance, it has low seizure resistance under conditions of insufficient lubrication. This is because the base material is aluminum (Al), which has a low heat resistance temperature, and is susceptible to plastic flow due to an increase in the temperature of the friction surface due to poor lubrication. The superiority of the inventive material is that the base material is copper (Cu).
This is because it has a higher heat resistance temperature than aluminum and is less likely to undergo plastic flow. Conventional lead bronze LBC3, 4, and 5 have excellent seizure resistance because they contain lead (Pb), as can be seen when compared with the comparative material PBP, and the lead contained in the alloy structure absorbs frictional heat. This is because it is eluted and exhibits a lubricating effect. However, the wear resistance is poor because hard intermetallic compound particles are not crystallized in the alloy structure as in the material of the present invention. In the material of the present invention, the same effect as described above is produced by adding lead, and the seizure resistance is further improved. FIG. 1 is a partially enlarged sectional view of the surface of the turbocharger bearing material of the present invention after polishing and etching. After polishing the sliding surface of the cylindrical bearing material, add 105 g of sodium chloride/
, etching is performed for several minutes at room temperature using an aqueous solution containing 30 g of ammonium chloride to form intermetallic compound particles 2 on the surface of the base material 1 from 1 to 3 from the surface.
μ exposed. FIG. 2 is a cross-sectional view of an embodiment of a bearing manufactured using the turbocharger bearing material of the present invention having grooves on its sliding surface. Turbocharger bearing 3 has an inner diameter of 10 mm, an outer diameter of 16 mm, and a height of 9.
It has a cylindrical shape with a diameter of mm, and has six holes 4 in its axial center. Furthermore, grooves 5 having a V-shaped cross section and a width of 1 mm and a depth of 1 mm are provided on the inner circumferential side surface and the outer circumferential side surface at intervals of 3 mm along the circumferential direction. Providing such striated grooves 5 reduces the contact area, which increases the pressure per unit area (surface pressure), which causes increased wear and problems with bearings made from conventional materials. Since the bearing material of the invention has excellent wear resistance, even if the surface pressure increases, the wear hardly increases and there is no problem. FIG. 3 is an enlarged sectional view of a portion surrounded by a dashed line in FIG. 2. FIG. (Effects of the Invention) As described above, the bearing material for turbochargers of the present invention has intermetallic compound particles having an appropriate average particle size and a much greater hardness than the base metal alloy exposed on the surface, so it has a hardness that is higher than that of the conventional lead alloy. Compared to bearing materials for turbochargers such as bronze, it has improved wear resistance and seizure resistance, and has a significant effect on improving the reliability and quality of turbochargers.

[Brief explanation of the drawing]

Fig. 1 is a partially enlarged sectional view of the surface of the turbocharger bearing material of the present invention after polishing and etching, and Fig. 2 is manufactured using the turbocharger bearing material of the present invention with grooves provided on the sliding surface. A sectional view of one embodiment of the bearing shown in FIG.
FIG. 3 is an enlarged cross-sectional view of a portion surrounded by a dashed line in the figure. In the figure, 1...base material, 2...intermetallic compound particles,
3... Bearing for turbo charger, 4...
Hole, 5...groove.

Claims (1)

[Claims] 1. Copper 55 to 65%, zinc 25 to 35% by weight
%, aluminum 2 to 6%, nickel 0.2 to 3%, iron 0.5 to 4%, titanium 1
to 2.5%, lead 2 to 10%, manganese 2 to 4%, silicon 0.5 to 2%, zirconium 0.5
It is made of an alloy component containing at least one to 5 types of impurities of 3 to 2% and the remainder, and has intermetallic compound particles on the surface with a maximum length of 5 to 30μ and a Vickers hardness of 400 or more in an area ratio of 3 to 15%. A bearing material for turbochargers characterized by crystallization. 2. The bearing material for a turbocharger according to claim 1, wherein the intermetallic compound particles are exposed at a predetermined height on the surface.