BRPI0901936A2 - cylinder block, internal combustion engine, conveying apparatus and method of producing cylinder block - Google Patents

Abstract

CYLINDER BLOCK, INTERNAL COMBUSTION ENGINE, TRANSPORT DEVICE AND METHOD FOR PRODUCING CYLINDER BLOCK. The cylinder block according to the present invention is a cylinder block composed of a silicon-containing aluminum alloy, the cylinder block including a cylinder wall with a sliding surface. The cylinder block according to the present invention includes a plurality of crystalline silicon grains on the sliding surface such that the ten point average roughness Rz ~ JIS ~ of the sliding surface and the load length ratio Rmr (30 ) of the sliding surface at a cutting level of 30% is larger on the upper 1/4 of the sliding surface than on the lower 1/4 of the sliding surface.

Description

"CYLINDER BLOCK, INTERNAL COMBUSTION ENGINE, TRANSPORT DEVICE AND METHOD FOR PRODUCING CYLINDER BLOCK"

Background of the Invention

1. Technical Field

The present invention relates to a cylinder block and a method of producing this and, in particular, a cylinder block which is made of an aluminum alloy which includes silicon and a method of production thereof. The present invention also relates to an internal combustion engine and a conveying apparatus incorporating a cylinder block such as this.

2. Description of Related Technology

In recent years, in an attempt to reduce the weight of internal combustion engines, there has been a tendency to use an aluminum alloy for cylinder blocks. Since a cylinder block is required to have high mechanical strength and high abrasion resistance, it is expected that aluminum alloys containing a large amount of disillusion, that is, aluminum-silicon alloys having a hypereutectic composition, are alloys. promising aluminum blocks for cylinder blocks.

In a cylinder block composed of an aluminum - silicon alloy, crystalline silicon grains located on the sliding surface will contribute to the improvement of mechanical strength and abrasion resistance. An example of a technique for obtaining silicon crystalline grains exposed on the surface of an alloy base metal is a grinding process to allow crystalline silicon grains to stand out (called "embossing"). In addition, Japanese patent 2885407 discloses a technique for performing a chemical etching process to allow crystalline silicon grains to protrude on the surface of an aluminum - silicon alloy and subsequently to perform anodic oxidation to form an oxide layer and, additionally to flame-spray a fluorplastic onto this oxide layer to form a fluorplastic resin layer.

As a lubricant is trapped between the silicon crystalline grains that remain surging on the sliding surface (ie in the recesses between the silicon crystalline grains that function as oil pools), better lubricity is obtained when a piston slides in the cylinder, according to the design. that the abrasion resistance and the sticking resistance of the cylinder block are improved.

However, further improvements in abrasion resistance and breakthrough resistance are necessary when using the aluminum alloy cylinder block prescribed for certain types of internal combustion engines.

Conventionally, aluminum alloy cylinder blocks have been used in internal combustion engines that are mounted on four-wheeled automobiles. In a four-wheeled automobile, a mechanism (eg, an oil pump) for propulsively supplying a lubricant to the cylinder block and piston is provided on the internal combustion engine, and the internal combustion engine is operated at a speed relatively low revolution speed (specifically at a maximum revolution speed of 7,500 rpm or less), in which case the above problems will not occur. However, in an internal combustion engine that is operated at a relatively high revolution speed (specifically, at a maximum revolution speed of 8,000 rpm or more) or an internal combustion engine in which a lubricant is supplied to the cylinder only by means of lubricant splash associated with crankshaft rotation (ie, the oil pump is omitted, as in the case of an internal combustion engine that is mounted on a motorcycle), the aluminum alloy cylinder block may become stuck and / or significant abrasion. Moreover, when a piston made of an aluminum alloy is used to achieve additional weight reduction of the internal combustion engine as a whole, slippage occurs between the aluminum alloy surfaces and thus a greater likelihood of binding occurs.

In order to further improve the abrasion resistance and sticking resistance of the cylinder block, it is necessary to improve the lubricity at the start of the internal combustion engine, which requires good retention of the lubricant on the sliding surface. Studies have shown that a cylinder block that has been subjected to the above embossing process or chemical etching process can not achieve sufficient lubrication retention so that there is adequate lubricity when high speed operation is achieved immediately after starting. of the internal combustion engine.

Therefore, the inventors have proposed in Japanese patent application 2007-329164 a technique for improving the ability of a sliding surface to retain lubricant. In this technique, as a parameter which represents the surface roughness of a sliding surface, attention is given to an average roughness of ten points Rzj | S and a length of charge length Rmr. By adjusting these parameters over a specific range, a sliding surface is designed in which a large number of fine crystalline silicon grains remain protruding, thus contributing to lubricant retention. As a result, a cylinder block with excellent abrasion resistance and binding resistance can be obtained.

However, the inventors conducted an additional study to find that during the use of the technique disclosed in the Japanese patent application 2007-329164, the slip surface is immersed in an embossing liquid, thus causing the entire slip surface to be uniformly recorded. As a result, although the abrasion resistance and binding resistance of the cylinder block are improved on an upper part (near the top dead center) of the sliding surface, a new problem occurs where, on a lower part of the sliding surface, The fine crystalline silicon grains that remain protruding on the sliding surface become trapped during piston sliding, thus increasing friction loss.

Summary of the Invention

The present invention has been made in view of the above problems, and its purpose is to provide a cylinder block with excellent abrasion resistance and resistance to binding and with a small friction loss as well as a production method. of this one.

A cylinder block according to the present invention is a silicon-containing aluminum alloy cylinder block, comprising: a cylindrical wall with a sliding surface on which a piston slides, and a plurality of crystalline silicon grains on the sliding surface, where an average roughness has ten points Rzj | S of the sliding surface and a load length ratio R-mr (30) of the sliding surface at a cutting level of 30% is greater in one part 1 / 4 upper of the sliding surface than on a 1/4 lower part of the sliding surface.

In a preferred embodiment, on the upper 1/4 of the sliding surface, the average ten point roughness Rzj | S is 0.54 µm or more, and the load length ratio Rmr (30) at a cutting level of 30% is 20% or more.

In a preferred embodiment, on the upper 1/4 of the sliding surface, the average roughness of ten points Rzj | S is 2.0 µm or less.

In a preferred embodiment, on the upper 1/4 of the sliding surface, the load length ratio Rmr (30) at a 30% shear level is 55% or less.

In a preferred embodiment, on the lower 1/4 of the sliding surface, ten point average roughness Rzj | S is less than 0.54 µm and the load length ratio Rmr (30) at a 30% cut-off level. is 15% or less.

In a preferred embodiment, the sliding surface has been subjected to a chemical etching process.

Another cylinder block according to the present invention is a silicon-containing aluminum alloy cylinder block, comprising: a sliding wall with a sliding surface on which a piston slides, and a plurality of crystalline grains of silicon on the sliding surface, wherein, on an upper 1/4 part of the sliding surface, an average roughness of ten points Rzj | S of the sliding surface is 0,54 one or more, and a load length ratio Rmr (30) of the sliding surface at a cut level of 30% is 20% or more, and a coating is provided on at least a 1/4 lower portion of the sliding surface.

In a preferred embodiment, on the upper 1/4 of the sliding surface, the average roughness of ten points Rzj | S is 2.0 µm or less.

In a preferred embodiment, on the upper 1/4 of the sliding surface, the load length ratio Rmr (30) at a 30% shear level is 55% or less.

In a preferred embodiment, the plurality of crystalline silicon grains includes a plurality of primary crystal silicon grains and a plurality of siliconeutectic grains.

In a preferred embodiment, the plurality of primary crystal silicon grains has an average crystalline grain size of no less than 12 µm and no more than 50 µm.

In a preferred embodiment, the plurality of eutectic silicon grains has an average crystalline grain size of 7.5 µm or less.

In a preferred embodiment, the plurality of silicon crystalline grains has a grain size distribution with a first peak existing in a crystalline grain size range of no less than 1 µm and no more than 7.5 µm and a second peak existing. having a crystalline grain size range of not less than 12 µm and not more than 50 µm.

In a preferred embodiment, a frequency in the first peak is at least five times higher than a frequency in the second peak.

In a preferred embodiment, the aluminum alloy contains: not less than 73.4 mass% and not more than 79.6 mass% of aluminum, not less than 16 mass% and not more than 22 mass% silicon, and not less than 2.0% by weight and not more than 5.0% by weight of copper.

In a preferred embodiment, the aluminum alloy contains no less than 50 ppm mass and no more than 200 ppm mass phosphorus and no more than 0.01% mass calcium.

An internal combustion engine according to the present invention comprises: the cylinder block of the exposed construction, and a sliding piston, still contacting the sliding surface of the cylinder block.

In a preferred embodiment, the piston is composed of an aluminum alloy. A conveying apparatus according to the present invention comprises an internal combustion engine of the exposed construction.

A method for producing a cylinder block according to the present invention is a method for producing a cylinder block that includes a cylinder wall, the cylinder wall having a sliding surface on which a piston slides, the method comprising: step of providing a molded part that is composed of a silicon-containing aluminum alloy, a step of polishing a region of the surface of the molded part to become the sliding surface by using a finisher with a granularity of 1,500 or more, and a first chemical etching step to record only part of the polished region.

In a preferred embodiment, the method for producing a cylinder block according to the present invention further comprises, after the first chemical attack step, a second chemical attack step for etching the entire region.

In a preferred embodiment of the method for producing a cylinder block according to the present invention, no additional chemical etching steps for etching the region is performed prior to the first etching step.

Another method for producing a cylinder block according to the present invention is a method for producing a cylinder block which includes a cylinder wall, the cylinder face with a sliding surface on which a piston slides, the method comprising: a step of providing a molded part that is composed of a silicon-containing aluminum alloy, a step of polishing a surface region of the molded part to become the sliding surface by using a finisher with a granularity of 1,500 or more, a step chemical etching to engrave the polished region, and a step to provide a coating on only a portion of the engraved region.

In the following, the functions and effects of the present invention will be described. In a cylinder block according to the present invention, the average ten point roughness Rzj | S of the sliding surface and the load length ratio R-mr (30 ) of the sliding surface at a cutting level of 30% is larger at the top 1/4 of the sliding surface than at the bottom 1/4. As a result, it is possible to increase the lubricant retention capacity of the sliding surface on the upper 1/4 of the sliding surface, while lowering the coefficient of friction on the lower 1/4 of the sliding surface. Therefore, friction loss can be reduced while still ensuring excellent abrasion resistance and binding resistance.

In order to sufficiently improve the lubricant retention capacity to obtain excellent abrasion resistance and binding resistance, it is preferable that, on the upper 1/4 of the sliding surface, the average roughness of ten points Rzj | Is 0.54 µm or plus and that the charge length ratio Rmr (30) at a 30% deceleration level is 20% or more.

However, from the point of view of preventing the gradual decline of the crystalline silicon grains and any significant counterpart abrasion (piston ring and / or piston) as a function of the crystalline silicon grains that remain protruding, it is preferable that average aridness of ten points Rzj | S is 2,0 one or less on the top 1/4 of the sliding surface.

Moreover, from the point of view of counterpart damage and abrasion reduction, it is preferred that the load length ratio Rmr (30) is 55% or less at the upper 1/4 of the sliding surface.

Furthermore, in order to sufficiently reduce the frictional loss by sufficiently decreasing the coefficient of friction, it is preferable that the average ten point roughness Rzj | is less than 0.54 µm and that the load length ratio Rmr (30) at a 30% cut-off level is 15% or less on the bottom 1/4 of the sliding surface.

Typically, the sliding surface of the cylinder block according to the present invention has been subjected to a chemical etching (etching) process.

In another cylinder block according to the present invention *; at the upper 1/4 of the sliding surface, the average ten point roughness Rzj | S is 0.54 um or more and the load length ratio Rmr (30) at a 30% cut-off level is 20% or more and furthermore coating is provided on at least a 1/4 part below the sliding surface. As a result, it is possible to increase the lubricant-holding ability of the sliding surface on the upper 1/4 of the sliding surface, while lowering the coefficient of friction on the lower 1/4 of the sliding surface. Therefore, friction loss can be reduced while still ensuring excellent abrasion resistance and binding resistance.

From the standpoint of preventing the gradual decline of the silicon crystalline grains and any significant counterpart abrasion (piston ring and / or piston) as a function of the remaining crystalline silicon grains, it is preferable that the average ten point roughness Rzj | S is 2,0 one or less on the upper 1/4 of the sliding surface.

Moreover, from the point of view of counterpart damage and abrasion reduction, it is preferred that the load length ratio Rmr (30) is 55% or less at the top 1/4 of the sliding surface.

Typically, the plurality of crystalline silicon grains includes a plurality of primary crystal silicon grains and a plurality of eutectic silicon grains. Thus, since not only primary crystal silicon grains but also eutectic silicon grains remain prominent on the sliding surface, the average roughness of ten Rzjis points and the load length ratio Rmr (30) can increase sufficiently.

From the point of view of improving abrasion resistance and mechanical block cylinder strength, it is preferable that the average crystalline grain size of the plurality of primary crystal silicon grains be not less than 12 µm and not more than 50 µm, and that average crystalline grain size of the plurality of eutectic silicon grains is 7.5 um or less. Moreover, it is preferable that the plurality of crystalline silicon grains have a grain size distribution with a first peak existing in a crystalline grain size range of not less than 1 µm and not more than 7.5 µm and a second peak existing in a crystalline grain size range of no less than 12 µm and no more than 50 µm, and it is further preferable that the frequency at the first peak be at least five times greater than the frequency at the second peak.

In order to sufficiently increase the abrasion resistance and mechanical strength of the cylinder block, it is preferable that the aluminum alloy contain: not less than 73,4% by weight and not more than 79,6% by weight of aluminum, not less than 16% by weight and not more than 22% by weight of silicon, not less than 2,0% by weight and not more than 5,0% by weight of copper.

Moreover, it is preferable that the aluminum alloy contain no less than 50 ppm mass and no more than 200 ppm mass phosphorus, and no more than 0.01% mass calcium. When the aluminum alloy contains no less than 50 ppm by weight and no more than 200 ppm by weight of phosphorus, it is possible to reduce the tendency for the disilicon crystalline grains to become gigantic, thus allowing for the uniform dispersion of the crystalline silicon grains in the alloy. On the other hand, when the calcium content in the aluminum alloy of the guarantee is 0.01 wt% or less, the effect of providing fine crystalline silicon grains on phosphorus is ensured, and a structure can be obtained. metallurgical with abrasion resistance.

A cylinder block according to the present invention may be suitably used in internal combustion engines for various types of conveyor apparatus and particularly suitably used in an internal combustion engine whose piston is made of an aluminum alloy as a reduction of Weight.

In a method of producing a cylinder block according to the present invention, after performing a step of polishing a surface region of a molded part to become a sliding surface by the use of a 1,500 granularity polisher. or more, a first chemical attack step to engrave only one part of the polished region is performed. As a result, both the average ten point roughness Rzjis and the charge length ratio Rmr (30) may differ between the one recorded through the first chemical etching step and the other part. Therefore, the average ten point roughness Rzj | S and the load length ratio Rmr (30) of the sliding surface may become larger in the upper 1/4 than in the lower 1/4, whereby a Cylinder block with excellent abrasion resistance and binding resistance and a small friction loss can be produced.

After the first chemical etching step, a second chemical etching step to engrave the entire region to become the sliding surface can be performed. When a second chemical attack stage such as this is performed, the entire sliding surface will undergo a chemical attack process (although the part that is recorded through the first chemical attack stage will suffer a greater amount of chemical attack than in the other one). part). As a result, recesses between the crystalline silicon grains (which act as oil puddles to retain the lubricant) are properly formed across the entire sliding surface, thereby further improving abrasion resistance and corrosion resistance. Binding resistance on the entire surface of the slip.

Alternatively, after the first chemical etching step, no additional chemical etching step to etch the region to become the sliding surface can be performed. In the event that an additional chemical attack step such as this is taken, the number of steps is reduced, whereby the cost of production can be reduced and the production steps can be simplified.

In another method for producing a cylinder block according to the present invention, after performing a step of polishing a surface region of a molten part to become a sliding surface by the use of a coarse-grained finisher. 1,500 or more, a chemical etching step for etching the polished region is performed, after which, a step of providing a coating only on a part of the etched region is additionally performed. As a result, both the average roughness of ten points Rzj | S and the load length ratio Rmr (30) may become different between the coated part and the other part. Therefore, the average ten point roughness Rzj | If the load length ratio Rmr (30) of the sliding surface may become larger in the upper 1/4 part than in the lower 1/4 part, according to which -produce a cylinder block with excellent abrasion resistance and jamming resistance and a small friction loss.

In any of the above described production methods, a surface region of a molded part to become a sliding surface is polished by the use of a polisher of 1,500 or more granularity and thereafter at least one part of the polished region is etched. . As a result, in the engraved part, a surface is created where not only a large number of primary crystal silicon grains, but also a large number of eutectic silicon grains remain protruding (projecting), and oil depths of sufficient depth are formed with a fine oscillation. Therefore, abrasion resistance and binding resistance on a part of the slip surface can be significantly improved.

In accordance with the present invention there is provided a cylinder block with excellent abrasion resistance and binding resistance and a small friction loss as well as a production method thereof. Furthermore, according to the present invention there is also provided an internal combustion engine and a transport apparatus incorporating a cylinder block such as this.

Other features, elements, processes, steps, features and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments of the present invention in relation to the accompanying drawings.

Brief Description of the Drawings

Fig. 1 is a perspective view schematically showing a decylinder block 100 according to a preferred embodiment of the present invention.

Figure 2 is a cross-sectional view schematically showing a cylinder block 100 according to a preferred embodiment of the present invention.

Figure 3 is a plan view schematically showing an image of a slide surface of the cylinder block 100.

Figure 4 is a cross-sectional view schematically showing an enlarged image of a sliding surface of the cylinder block 100.

Figure 5 is a diagram for explaining an average roughness of ten points Rzj | S.

Figure 6 is a diagram for explaining a load length ratio R-mr (c).

Figure 7 is a graph showing an exemplary relationship between a crank angle (degrees) and a gas pressure (MPa) and a frictional force (N) in a conventional internal combustion engine.

Figures 8A and 8B are diagrams to explain why the frictional force acting on a sliding surface is increased immediately after the explosion.

Figure 9 is a flow chart showing production steps for cylinder block 100.

Figure 10 is a flow chart showing production steps for cylinder block 100.

Figures 11A through 11E are step-by-step cross-sectional views schematically showing partially the production steps for cylinder block 100.

Figures 12A and 12B are step-by-step cross-sectional views schematically showing partially the production steps for cylinder block 100.

Figure 13 is a flow chart showing the production steps for cyberblock block 100.

Figure 14 is a cross-sectional step view schematically showing a part of the production steps for cylinder block 100. Figure 15 is a flow chart showing the production steps for cylinder block 100.

Figures 16A through 16C are step-by-step cross-sectional views schematically showing partially the production steps for cylinder block 100.

Figures 17A through 17C are diagrams to explain why eutectic silicon grains do not contribute to lubricant retention when a embossing process is performed.

Figures 18A through 18C are diagrams explaining why eutectic silicon grains do not contribute to lubricant retention when a chemical process is performed without first performing a mirror-finish honing process.

Figure 19 is a diagrammatic diagram showing a braid test machine 30 which is used to measure a coefficient of friction.

Figure 20 is a graph in which Examples 1 to 3 and Comparative Examples 1 to 11 are graphically represented on a horizontal geometric axis representing

an average roughness of ten points Rzj | S and on a vertical geometrical axis representing a load length ratio Rmr (30) at a cutting level of 30% relative to an upper 1/4 of the sliding surface.

Figure 21 is a cross-sectional view schematically showing a sliding surface in which not only primary crystal silicon grains but also eutectic silicon grains remain protruding.

Figure 22 is a cross-sectional view schematically showing a sliding surface in which substantially nothing except crystalline silicon grains remains protruding.

Figure 23 is a diagram for explaining why a constant height of relief cannot be obtained when a embossing process is employed.

Figure 24 is a diagram to explain why a constant height of relief is obtained when a chemical etching process is employed.

Figure 25 is a graph in which Examples 1 to 3 and Comparative Examples 1 to 11 are graphically represented on a horizontal geometric axis representing an average roughness of ten points Rzj | S and on a vertical geometric axis representing a ratio of the length of load Rmr (30) at a cut-off level of 30%, relative to a lower 1/4 of the sliding surface.

Figure 26 is a graph showing an example of a preferred grain size distribution of crystalline silicon grains.

Fig. 27 is a cross-sectional view schematically showing an internal combustion engine 150 with cylinder block 100.

Figure 28 is a side view schematically showing a motorcycle incorporating internal combustion engine 150 shown in figure 27.

Detailed Description of Preferred Modalities

In the following, embodiments of the present invention will be described with respect to the drawings. Although the following descriptions are directed to a cylinder block for a water-cooled internal combustion engine as an example, the present invention is not limited thereto. The present invention is also suitably used in a cylinder block for an air-cooled internal combustion engine.

Figure 1 and Figure 2 show a cylinder block according to the present embodiment (which may also be referred to as a "cylinder body") 100. Figure 1 and Figure 2 are a perspective view and a view cross-section showing schematically the cylinder block 100. The cylinder block 100 is made of a silicon-containing aluminum alloy and, more specifically, an aluminum-silicon alloy of a large composition containing a large amount of silicon.

As shown in FIG. 1 and FIG. 2, the cylinder block 100 includes: a wall portion (referred to as a "cylinder wall") 103 defining a cylinder bore 102, and a wall portion (referred to as a "cylinder wall"). as an "outer wall") 104, surrounding the wall of cylinder 103 and defining the outer contour of cylinder block 100. Between the wall of cylinder 103 and outer wall 104, a water jacket 105 is provided for retaining Great soda. While the present embodiment illustrates a single cylinder cylinder block 100, the cylinder block 100 may have multiple cylinders.

A cylinder wall surface 101 facing the cylinder bore 102 (ie, the inner peripheral surface) defines a sliding surface on which a piston slides (i.e., the sliding surface is in contact with a piston) . The sliding surface 101 is shown enlarged in Figure 3. Figure 3 is a plan view showing schematically the sliding surface 101.

As shown in Figure 3, the cylinder block 100 with the cylinder wall 103 with the sliding surface 101 includes a plurality of crystalline silicon grains 1 and 2 on the sliding surface 101. These crystalline silicon grains 1 and 2 are present. dispersed in a matrix (alloy base metal) 3 of solid solution containing aluminum.

Crystalline silicon grains, which are the first to be formed during an aluminum-silicon alloy melt having a hypereutectic composition, are referred to as "primary crystal silicon grains". Crystalline silicon grains, which are then formed, are referred to as "eutectic silicon grains". Among the crystalline silicon grains 1 and 2 shown in Figure 2, the relatively large crystalline silicon grains 1 are the primary crystal silicon grains. The relatively small crystalline silicon grains present among the primary crystal silicon grains are the eutectic silicon grains.

Figure 4 shows a cross-sectional structure of the sliding surface101. As shown in Figure 4, the plurality of crystalline silicon grains 1 and 2, including primary crystal silicon grains 1 and eutectic silicon grains 2, protrude (i.e. remains protruding) from a matrix 3 The recesses 4 formed between the crystalline silicon grains 1 and 2 act as oil puddles in which a lubricant will be retained.

The inventors have studied the reasons why the conventional rebinding honing process or chemical etching process cannot obtain sufficient lubricant-holding capacity. Thus, it has been found that most eutectic silicon grains are actually removed from the sliding surface according to these conventional techniques, such that hardly any contribution of eutectic silicon grains to lubricant retention can be obtained. thus resulting in a low lubricant retention capacity.

Thus, as the parameters representing the surface roughness of the sliding surface 101, the inventors paid attention to an average roughness of ten points Rzj | S and a load length ratio Rmr (30) at a cutting level of 30%, and have found that adjusting these parameters to be within specific ranges can greatly improve the ability of the sliding surface 101 to hold a lubricant.

The average roughness of ten points Rzj | S is, relative to a part taken from a cross-sectional profile, the part extending at a reference length L (as shown in Figure 5), a difference between an average value of heights R1 , R3, R5, R7 and R9 of the five highest summits and an average value of the heights R2, R4, R6, R8 and R10 of the lower five valleys, as expressed by equation 1 below. Therefore, an average ten point roughness Rzj | S means that oil puddles 4 have a sufficient depth.

Equation 1

(R1 + R3 + R5 + R7 + R9) - (R2 + R4 + R6 + R8 + R10)

A ratio of the load length Rmr (c) at a given shear level c is, in relation to a part taken from a roughness profile, the part extending over an evaluation length In (as shown in Figure 6), a ratio of the sum of the cutting lengths when the roughness profile is cut to a cutting level c that is parallel to a line connecting the apexes (i.e. load length) M1 (c) , by the length of valuation In, as expressed by equation 2 below.

Equation 2 <formula> formula see original document page 14 </formula>

Therefore, the charge length ratio Rmr (c) is an index indicating how many silicon grains 1 and 2 remain protruding on the sliding surface 101. A high charge length ratio Rmr (c) means that a large number of disilicon grains 1 , 2 (and in particular eutectic silicon grains 2) remains outstanding. At an early stage of operation of an internal combustion engine, the outermost surface of the sliding surface 101 is abraded (expressed as "suitability"), approaching to a depth corresponding to a cutoff level of 30%. Therefore, it can be assumed that a load length ratio Rmr (30) at a cutoff level of 30% serves as a parameter indicating how many eutectic silicon grains 2 remain protruding during an actual operation.

As stated, a large average roughness of ten points Rzj | S means that the oil pieces 4 have sufficient depth, and a high head length ratio Rmr (30) means that a large number of silicon grains 1, 2 , protrudes on the sliding surface 101 (that is, they remain without gradual decline). Therefore, by ensuring that the ten point average roughness Rzj | S and the slack surface ratio Rmr (30) of the sliding surface 101 are greater than certain levels, the sliding surface lubricant retention capacity 101 However, if the average ten-point roughness Rzj | S and the load-length ratio Rmr (30) of the sliding surface 101 are simply increased, that is to say, uniformly over the entire sliding surface 101, the large number of eutectic desilicon grains 2 that remain protruding on the sliding surface 101 will induce greater friction loss.

In the cylinder block 100 of the present embodiment, each of the ten point average roughness Rzj | S and the load length ratio Rmr (30) at a 30% shear level differs between an upper 1/4 part 101a and a part 1. / 4 lower 101b of the sliding surface 101 (see figure 2). Specifically, the ten point average roughness Rzj | S of the sliding surface 101 and the load length ratio Rmr (30) of the sliding surface 101 at a cutting level of 30% are greater in the upper 1/4 part101a of the sliding surface. sliding surface 101 than on the lower 1/4 part 101b of the sliding surface 101. Since the surface roughness of the sliding surface 101 has such a distribution, the frictional loss can be reduced while still ensuring excellent abrasion resistance. and resistance to binding. Hereafter, the reasons will be described.

Needless to say, the "upper side" of the sliding surface 101 means the cylinder head side (i.e. the top dead center side), while the "lower side" of the sliding surface 101 means the crankcase side (ie the dead center base side). Specifically, when the entire sliding surface 101 is equally divided into four parts along the direction of the piston side (the direction of the central geometric axis of the bore of the device 102), the upper 1/4 part 101a of the sliding surface 101 relates to one. region that is closest to the cylinder head, while the lower 1/4 portion 101b of the sliding surface 101 relates to a region that is closest to the crankcase.

Figure 7 shows an exemplary relationship in a conventional 4 stroke internal combustion engine between crank angle, gas pressure (cylinder pressure) and frictional force occurring between a piston (including a piston ring). piston) and the sliding surface of the cylinder block. Note that, as for the crank angle, the top dead center of the compression is set to 0 °. As for the frictional force, any frictional force that occurs in the opposite direction of rotation in favor of the crankshaft is indicated with a positive value. When considering the influence of a frictional force occurring between the piston and the sliding surface of the cylinder block, only the absolute value of the frictional force shown in figure 7 needs to be considered. The reason the frictional force is substantially 0 at the crank angles ± 360 °, ± 180 °, 0 ° is that when the crank angle is close to either angle, the piston movement is very small relative to changes in the crank angle, so that any frictional force is unlikely to occur.

As shown in Figure 7, during the inlet step, the frictional force occurring between the piston side face and the sliding surface of the cylinder block is substantially constant, such that the frictional force is greater near an angle of - 270 ° when the sliding speed increases. Similarly, during the compression step, the frictional force is substantially constant, so that the frictional force is greater near a -90 ° crank angle as the sliding velocity increases.

On the other hand, during the blast step, the frictional force acting on the sliding surface of the cylinder block varies greatly, such that the frictional force takes the highest value for all four steps near a crank angle of 0 ° C. ° when the gas pressure becomes maximum (a region R1 surrounded by a dotted line in figure 7). In other words, immediately after the explosion, the frictional force is greater, and the sliding surface of the cylinder block and the piston (more specifically, the piston ring and piston skirt) come into strong and direct contact. One reason why frictional force becomes large immediately after the explosion is that, as shown in Figure 8A, flue gas enters between the piston and the piston ring as a function of the explosion pressure (ignition pressure), thus pressing the piston ring against the sliding surface of the cylinder block. Another reason is that, as shown in Figure 8B, the piston is inclined to the cylinder bore immediately after explosion. In this state, the piston ring is strongly pressed against the sliding surface of the cylinder block (region A surrounded by a broken line in figure 8B), so that the piston skirt is pressed tightly against the sliding surface of the block. cylinder (region B surrounded by a broken line in figure 8B). As a result, a large frictional force occurs not only between the piston ring and the sliding surface of the cylinder block, but also between the piston skirt and the sliding surface of the cylinder block. Furthermore, when the piston and the sliding surface of the cylinder block rub strongly against each other, the relative movement speed of the piston relative to the sliding surface decreases so that proper retention of an oil film to reduce the force friction does not occur on the surface of the sliding surface, thereby further increasing the frictional force.

On the other hand, since the gas pressure subsequently decreases, the aortic force decreases (region R2 surrounded by a dotted line in figure 7). In other words, except for the very early stage of the blast step, the contact pressure between the sliding surface of the cylinder block and the piston is low.

Therefore, on the sliding surface of the cylinder block, any part that contacts the piston near the top dead center of the compression (specifically, a crank angle range of - 45 ° to + 45 °) It must have high abrasion resistance and binding resistance. Compared to other parts, surface smoothness, that is, having a low coefficient of friction, is more important than having excessive abrasion resistance and binding resistance.

In the cylinder block 100 of the present embodiment, the ten point average roughness Rzjis of the sliding surface 101 and the load length ratio Rmr (30) of the sliding surface 101 at a cutting level of 30% are greater in the part. 1/4 upper 101a of the sliding surface 101 than in the lower 1/4 part 101b of the sliding surface 101. As a result, it is possible to increase the lubricant retention capacity of the sliding surface 101 on the part Upper 1/4 101a of the sliding surface 101, while still decreasing the coefficient of friction on the lower 1/4 part 101b of the sliding surface 101. Therefore, frictional loss can be reduced while still ensuring excellent abrasion resistance and resistance to binding.

In order to obtain excellent abrasion resistance and binding resistance by sufficiently improving lubricant retention capacity (ie, allowing eutectic silicon grains 2 on the sliding surface 101 to contribute sufficiently to lubricant retention), it is preferable that the average roughness of ten points Rzj | Is 0,54 æm or more and the load length ratio Rmr (30) at a 30% sloping level is 20% or more on the upper 1/4 part 101a of the sliding surface101. However, in the case of the production of cylinder block 100 by a production method involving a chemical etching process, as will be described later, the large amount of crystalline silicon grains that remain protruding may cause significant damage or abrasion to the counterpart (piston ring and / or piston) if the load length ratio Rmr (30) exceeds 55% and therefore preferably the load length ratio Rmr (30) is 55% or less. In addition, from the point of view of further increasing the lubricant holding capacity, it is more preferable that the average ten point roughness Rzj | S is 0.7 one or more and, from the point of view of preventing the gradual decline of eutectic silicon 2 and any significant counterparty abrasion, it is preferable that the average roughness of ten points Rzj | S be 2.0 µm or less.

Furthermore, in order to sufficiently reduce the frictional loss by sufficiently decreasing the coefficient of friction, it is preferable that the average ten point roughness Rzj | is less than 0.54 µm and that the load length ratio Rmr (30) at a 30% cut-off level is 15% or less at the lower 1/4 part 101b of the sliding surface101. Note that, from the point of view of further reducing frictional loss, the average ten point roughness Rzj | S and the charge length ratio Rmr (30) are more preferably in the numerical ranges mentioned above in part 1/2. more preferably in the above numerical bands in the lower part 3/4 of the sliding surface 101.

As described above, in the cylinder block 100 of the present embodiment, the surface roughness of the sliding surface 101 has a distribution. On the other hand, in a conventional cylinder block, substantially the same surface roughness exists across the entire sliding surface. In other words, the present invention was based on an entirely novel concept of purposely introducing a difference in surface roughness (specifically, the average ten point roughness Rzjis and the load length ratio Rmr (30) at a cutoff level of 30%. ) between a part and another part of the sliding surface 101.

A method for producing a cylinder block 100 of the present embodiment will be described with reference to figures 9 to 12B. Figure 9 and Figure 10 are flow charts showing production steps for cylinder block 100. Figures 11A through 11E and Figures 12A and 12B are cross-sectional views schematically showing the production steps.

First, a molded part that is made of a silicon-containing aluminum alloy is provided (step S1). This molded part includes primary crystal silicon grains and near-surface eutectic silicon grains. Step S1 of providing the molded part may include, for example, steps S1a through S1e shown in Figure 10.

First, a silicon-containing aluminum alloy is prepared (step S1a). In order to ensure sufficient abrasion resistance and mechanical strength of cylinder block 100, it is preferable to use an aluminum alloy containing: not less than 73.4 mass% and not more than 79.6 mass% aluminum; not less than 16% by weight and not more than 22% by weight of silicon; and not less than 2.0% by mass and not more than 5.0% by mass copper.

Thereafter, the prepared aluminum alloy is heated and melted in a melting furnace, whereby a melting is formed (step S1b). It is preferred that about 100 ppm by weight of phosphorus be added to the aluminum alloy prior to melting or melting. If the aluminum alloy contains no less than 30 ppm by weight and no more than 200 ppm by weight of phosphorus, it becomes possible to reduce the tendency of the crystalline silicon grains to become gigantic, thus allowing the uniform dispersion of the crystalline grains of naliga silicon. On the other hand, if the calcium content in the aluminum alloy is 0.01 wt% or less, the effect of providing fine crystalline grains of silicon as a function of phosphorus is assured, and a metallurgical structure can be obtained with Excellent abrasion resistance. In other words, the aluminum alloy preferably contains no less than 50 ppm by weight and no more than 200 ppm by weight of phosphorus, and no more than 0.01% by weight of calcium.

Next, casting is performed by using the aluminum alloy liquid bath (stepS1c). In other words, the liquid bath is cooled in a mold to form a molded part. At this time, the portion to become the sliding surface 101 of cylinder wall 103 is cooled at a high cooling rate (e.g., not less than 4 ° C / sec and no more than 50 ° C / sec), according to Thus, a molded part is obtained which includes crystalline silicon grains that contribute to the abrasion resistance near its surface. This casting step S1c may be performed by the use, for example, of a casting apparatus which is disclosed in International Publication2004 / 002658.

Next, the molded part that has been removed from the mold is subjected to one of the heat treatments commonly known as "T5", "T6" and "T7" (step S1d). A T5 treatment is a treatment in which the molded part is rapidly cooled (with water or the like) immediately after it is removed from the mold and subsequently subjected to artificial aging at a predetermined temperature for a predetermined period of time. -Determined for best mechanical properties and dimensional stability, followed by air cooling. A T6 treatment is a treatment in which the molded part is subjected to a solution treatment at a predetermined temperature for a predetermined period after it has been removed from the mold, then cooled with water and subsequently subjected. artificial aging at a predetermined temperature for a predetermined period of time, followed by air cooling. A T7 treatment is a treatment to cause a stronger degree of aging than the T6 treatment, although the T7 treatment may provide better dimensional stability than the T6 treatment, the resulting hardness will be lower than that obtained from the T6 treatment.

Then predetermined machining is performed on the molded part (step S1e). Specifically, a surface that rests on a cylinder head and a surface that rests on a crankcase are subjected to grinding or the like.

After the molded part is prepared in the above manner as shown in Figure 11A, the surface of the molded part, specifically, the inner peripheral surface of the cylinder wall 103 (i.e. the surface to become the sliding surface101) undergoes a fine drilling process for dimensional precision adjustment (stepS2).

Thereafter, as shown in Figure 11B, the surface that has undergone a hole drilling process is subjected to a coarse honing process (step S3). In other words, the surface to become the sliding surface 101 is polished by the use of a polisher with a relatively small roughness value (specifically, with a granularity of no less than 600 and no more than 1,000). This coarse honing process can be accomplished by the use of a honing apparatus disclosed in Japanese Open Patent Publication 2004-268179, for example.

Next, as shown in Fig. 11C, a mirrored finishing honing process is performed (step S4). In other words, the region of the surface of the molded part to become the sliding surface 101 is polished by the use of a polisher with a relatively large roughness value (specifically with a roughness value of 1,500 or more). This mirror-finishing honing process can also be accomplished by the use of a honing apparatus such as that disclosed in Japanese Open Patent Publication 2004-268179.

Next, as shown in Figure 11 D, only part of the polished region is recorded (step S5). In the part that has been subjected to the chemical etching process (for example, an alkaline chemical etching process), the matrix 3 near the surface is removed to a predetermined thickness, whereby the recesses are formed between the grains. of primary crystal silicon 1 and eutectic silicon grains 2. As shown in Figure 12A, this chemical etching step is performed by installing an elementocylindrical 11 in the cylinder bore 102 of a molded part 100 'which is installed in an inverted position (that is, upside down relative to how it will be installed when an internal combustion engine is mounted), the cylindrical sliding element 11 with a diameter smaller than that of the cylinder bore 102. In this state, an embossing liquid 12 is used for filling between the outer peripheral surface of the cylindrical element 11 and the inner peripheral surface of the cylinder wall 103 to a predetermined height. Note that the chemical etching process in this localized chemical etching step must be performed for at least the upper 1/4 of the region to become the sliding surface 101 (in Figure 12A, this portion corresponds to the lower 1/4 of the peripheral surface). inside the cylinder wall 103, since the molded part 100 'is in an upside down position).

Thereafter, as shown in Fig. 11E, the entire region to become the sliding surface 101 is recorded (step S6). Through the chemical etching process, in the region of the region to become the sliding surface 101, the matrix 3 near the surface is removed to a predetermined thickness, whereby the sliding surface 101 is formed with the sliding surface 101. primary crystal silicon grains 1 and eutectic desilicon grains 2 projecting therefrom. The recesses 4 between the primary crystal silicon grains 1 and the eutectic silicon grains 2 function as oil pools. As shown in Figure 12B, this general chemical etching step is performed by adding more chemical etching 12 to fill the space between the outer peripheral surface of the cylindrical element 11 and the inner peripheral surface of the cylinder wall 103 with the product. the chemical attack 12 to a height such that the entire inner peripheral surface of the cylinder wall 103 is immersed in the chemical attack 12 (i.e. the maximum height). The upper end of the cylindrical element 11 is thus opened allowing the chemical attack product 12 to be collected through the interior of the ecirculate cylindrical element 11.

Note that the sizing steps to be performed prior to the mirror finish sanding process (step S4) are not limited to the two steps exemplified above, ie a fine drilling process (step S2) and a rough sanding process (step S4). S3). Sizing can be done in one step, or sizing can be done in three or more steps.

According to the production method of the present embodiment, after performing a localized chemical etching (first chemical etching) step of only engraving a portion of the region to become the sliding surface 101, a general chemical etching step ( second chemical attack) to engrave the entire region to become the sliding surface 101. As a result, although a portion of the region becoming the sliding surface 101 is subjected to two chemical attack processes, the other part is subjected only to to a chemical attack process. Therefore, a distribution can be entered into the average roughness dimension of ten points Rzjis and the load length ratio Rmr (30) on the sliding surface 101 and therefore each average ten point roughness Rzj | S and the length ratio of The load Rmr (30) of the sliding surface 101 may differ between the upper 1/4 part 101a and the lower 1/4 part 101b of the sliding surface 101. As a result, the ten-point average roughness Rzj S and the load length ratio Rmr (30) of the sliding surface 101 may become larger in the upper 1/4 part 101a than in the lower 1/4 part 101b.

The average roughness of ten points Rzjis and the charge length ratio R-mr (30) of each part undergoing a chemical etching process and the part undergoing two chemical etching processes can be adjusted based on concentration and temperature of the chemical etching product, chemical etching time (immersion time) and congeners of the localized etching and general etching stage.

Note that, as shown in figure 13, the general chemical attack step may be omitted. In other words, after the localized chemical etching (first chemical attack) step S5, there is no need to perform an additional etching step to record the region to become the sliding surface 101. In this case, as shown in Figure 14, the The localized chemical etching step is performed by using a cylindrical element 11, which is lower than the cylindrical element 11 shown in Figure 12, and by means of an open upper end of the cylindrical element 11, the product of the chemical band 12 It is collected through the interior of the cylindrical element 11 and allowed to circulate.

Even when the general chemical etching step is omitted, each of the ten point average roughness Rzj | S and the charge length ratio Rmr (30) may become different between the part undergoing a process. chemical attack in the localized chemical attack stage and the other part that is not subjected to any chemical attack process at all. Therefore, the average ten point roughness Rzj | S and the load length ratio Rmr (30) of the sliding surface 11 may become larger in the upper 1/4 part 101 than in the lower 1/4 part 101b. However, where the overall chemical etching step is omitted, it is preferable to adjust the amount of chemical etching at the localized etching step so that the average ten point roughness Rzjis and the charge length ratio Rmr (30) of the sliding surface 101 become large enough through the chemical etching process of the localized chemical etching step only.

Moreover, the cylinder block 100 of the present embodiment may also be produced by using a production method shown in Figure 15, which does not include a localized chemical attack step. The production method shown in Fig. 15 is identical to the production methods shown in Fig. 9 and Fig. 13 up to the mirror finish polishing step (step S4). In the production method shown in Figure 15, after the mirror-finish honing method, as shown in Figure 16A, a general chemical etching step to engrave the region to become the sliding surface 101 (the entire region) is performed ( step S7). Subsequently, a coating is provided only in part of the recorded region (step S8).

In this partial coating step, first as shown in Figure 16B, a cylindrical mask element 14 with substantially the same diameter as the bore 102 is installed in the cylinder bore 102. Thereafter, as shown in Figure 16C, an internal trigger 16 is inserted into the bore of cylinder 102, and a lining material is flame-sprinkled from the inner trigger 16, thereby providing an unmasked coating of the inner peripheral surface of the cylinder wall 103. The coating at least in the lower 1/4 of the region to become the sliding surface 101 (which corresponds to the upper 1/4 of the inner peripheral surface of the cylinder wall 103 in figure 16C because the molded part 100 'is in a inverted position).

By carrying out a partial coating step after a general chemical bonding step, it can be ensured that each of the ten point average roughness Rzj | If and of the charge length ratio Rmr (30) is different between the part coated and the parthenon coated. Specifically, each of the ten point average roughness Rzj | S and the portion of load length Rmr (30) may become smaller in the coated part than in the uncoated part. Thus, the average ten point roughness Rzj | S and the load length ratio Rmr (30) of the sliding surface 101 may become larger in the upper 1/4 part 101a than in the lower 1/4 part 101b.

As the coating material, a wide range of materials which are unlikely to adhere to the piston material and which have excellent lubricity can be used. A mixture of imide polyamide and molybdenum disulfide is suitably used as the coating material because it exceeds in thermal resistance, low friction and direct contact binding resistance. It is noted that the coating material is not limited to this. For example, ceramics (cemented carbide, etc.) may be used.

In either of the above described production methods, a chemical etch is performed after polishing using a polisher with a granularity of 1,500 or more. In other words, a surface smoothing process (through a mirror-finish polishing process) is performed first. and then a chemical grinding (by chemical attack) is performed, whereby recesses 4 surrounding oil puddles are formed. By forming the sliding surface 101 in this manner (i.e. the sliding surface 101 is a sliding surface that has undergone a chemical etching process), eutectic silicon grains 2 are allowed to remain on the sliding surface 101 without gradual decline. , so that eutectic silicon grains 2 can contribute sufficiently to lubricant retention. In other words, the average roughness of ten points Rzj | S and the ratio of the discharge length Rmr (30) in the part (upper 1/4 part) of the sliding surface 101 where abrasion resistance and binding resistance are required may become sufficiently large. On the other hand, with a conventional embossing process and the chemical chemical process, it is difficult to make the average roughness of ten points Rzj | S and the reason for the load length Rmr (30) sufficiently large. The following will describe the reasons behind this.

In the event that a embossing process is employed to form the sliding surface 101, a molded part with primary crystal silicon grains and eutectic silicon grains near its surface is first prepared (same step as step S1 shown in figure 9). and then the surface of the molded part undergoes a fine drilling process as shown in figure 17A. Then, after performing a coarse honing process as shown in Fig. 17B, an embossing process is carried out as shown in Fig. 17C. The embossing process is carried out by the use of a resin brush to which abrasive grains are adhered, and is carried out in such a way that mainly die 3 is cut. However, the embossing process, which is a mechanical grinding process, will inevitably remove a portion of the eutectic silicon grains 2 together with the matrix 3, as shown schematically in Figure 17C. Therefore, eutectic silicon grains2 do not contribute much to lubricant retention.

On the other hand, in the event that the sliding surface 101 is formed by a chemical etching process that is not preceded by a mirror-finish honing process, a piece of primary crystal silicon grains and Eutectic silicon grains near its surface are first prepared (same step S1 as shown in Figure 9) and then the surface of the molded part is subjected to a fine drilling process shown in Figure 18A. Thereafter, a buffing process is performed as shown in Figure 18B and thereafter a chemical process is performed as shown in Figure 18C. In this case, these eutectic desilicon grains 2, the surfaces of which have been damaged by the grinding process (ie cracked or broken), will remain protruding. Accordingly, such eutectic silicon grains 2 gradually decline on the sliding surface of the shape shown schematically in Figure 18C. Therefore, eutectic silicon grains 2 do not contribute much to lubricant retention.

In the present embodiment, a mirror-finish honing process is performed prior to a chemical etching process, in which case the chemical etching process (which is a chemical grinding process) does not remove silicon eutectic grains 2 along with matrix 3, unlike embossing process (which is a mechanical grinding). Furthermore, since the surface is smoothed by the mirror-finish honing process (which also covers the eutectic silicon grain surface 2) prior to the chemical etching process, the gra-dual decline of the silicon grain Eutectic 2 occurs less frequently than in the case where the chemical attack process is performed immediately after a coarse honing process. Therefore, eutectic silicon grains 2 contribute sufficiently to lubricant retention.

Note that in all of the above methods the mean roughness of ten points Rzjis and the load length ratio Rmr (30) of the resulting sliding surface 101 vary in two steps, from the upper side towards the lower side. However, the average ten point roughness Rzj | S and the load length ratio Rmr (30) of the sliding surface 101 may vary in a greater number of steps, or vary gradually (for example, linearly).

In the following, results of the actual prototyping of the cylinder blocks 100 according to the present embodiment and their subjection to a binding resistance evaluation test and friction coefficient measurements will be described.

Using an aluminum alloy of the composition shown in Table 1, a molten part to become a cylinder block 100 was produced by a high pressure molten casting technique similar to that disclosed in International Publication2004 / 002658.

Table 1

<table> table see original document page 24 </column> </row> <table>

By using the moldings produced, the cylinder blocks 100 were produced by the respective production methods which were described with reference to Fig. 9, Fig. 13 and Fig. 15 (Examples 1 to 3).

The honing processes (coarse honing process and mirrored finishing honing process) were carried out by the use of a honing apparatus disclosed in Japanese open patent publication 2004-268179, still supplying cooling oil to the surface to be polished (ie wet honing). A roughness 600 grinder was used for the coarse honing process, while a 2,000 roughness grinder was used for the mirror finish honing process. Note that a higher roughness value indicates that the burner has finer abrasive grains and, therefore, the polished surface will achieve greater smoothness. However, as the abrasive grains become thinner, the cutting speed slows, resulting in longer processing times and lower productivity. In other words, the production method according to the present embodiment dares to carry out the mirror-finishing lapping process, which is disadvantageous in terms of productivity.

Both in the localized chemical etching stage and the general chemical etching stage, the chemical etching process was carried out by the use of a 5% by mass sodium hydroxide solution under conditions such that the temperature of the solution was 70 ° C. ° C. The amount of chemical attack (depth of chemical attack) was adjusted by varying immersion time.

An internal combustion engine was assembled by using cylinder block 100 as well as an aluminum alloy piston which was separately produced by forging.

Immediately after a state in which the internal combustion engine was still cold and the lubricant had not permeated the cylinder, this internal combustion engine was operated for 5 minutes at a revolution speed of 8,000 rpm, and hazards occurring in the upper 1/4 101a of the sliding surface 101 (i.e. wear) were observed by visual inspection to determine if the cylinder block is qualified for use.

The results (ie, results of the binding resistance evaluation) are shown in Table 2 below.

Table 2 also shows results of friction coefficient measurements on the lower 1/4 part 101b of the sliding surface 101. Friction coefficient measurements were taken by employing a scratch test machine 30 shown in Fig. 19. The scratch test machine 30 includes a stylus 31, an acoustic emission (AE) sensor 32, a pressure depth sensor (not shown) and the like. During the application of a predetermined vertical load FN to the stylus 31, a sample 35 is moved horizontally as a result of which the stylus 31 scrapes on the surface of the sample 35. Thus, the frictional force FT is detected, and The coefficient of friction can be measured. Here, a SUJ2 ball was used as the stylus 31, and a small portion that was cut off by cylinder block 100 was used as sample 35. Measurements were made during oil dripping onto the surface of sample 35.

In addition, Table 3 shows an average roughness of ten Rzjis points and a Rmr load length reason (30) at a cutoff level of 30% of the slip surface 101, measured by using SURFCOM 1400D manufactured by TOKYOSEIMITSU CO., LTF, relative to the upper 1/4 part 101a and lower 1/4 part 101b of the sliding surface 101. As already described, the ten point average roughness Rzjis is a parameter that can be used to assess the depth of the oil puddles. 4, while the load length ratio Rmr (30) is a parameter that can be used to assess the number of eutectic silicon grains 2 that remain protruding (that is, remaining without gradual decline) on the sliding surface 101.

Table 2 <table> table see original document page 26 </column> </row> <table>

TABLE 3

<table> table see original document page 26 </column> </row> <table> Example 2 1.28 43 0.28 10

<table> table see original document page 27 </column> </row> <table>

In addition, Table 2 and Table 3 also show similar evaluation and measurement results for cylinder blocks that were produced as Comparative Examples. In Comparative Example 1, after a coarse honing process and a mirrored finishing honing process, neither a raised honing process nor a chemical etching process were performed. In Comparative Examples 2 to 5, a embossing process was carried out after a coarse grinding process and a mirror-finish grinding process. In Comparative Examples 6 to 11, the entire sliding surface was subjected to a chemical etching process after a coarse honing process and a mirror finish honing process.

As can be seen from Table 2 and Table 3, in all Examples 1 to 3, the ten point average roughness Rzj | S of the sliding surface 101 and the load length ratio Rmr (30) of the sliding surface 101 at a cut-off level of 30% is greater on the upper 1/4 part 101a of the slip surface 101 than on the lower 1/4 part 101b, whereby excellent binding resistance and reduced friction loss ( here, up to a coefficient of friction of 0.15 or less) is performed.

Furthermore, for all Examples 1 to 3, the average roughness of ten Rzjis points is 0.54 µm or more and the load length ratio Rmr (30) is 20% or more in the upper 1/4 part 101a. of the sliding surface 101. This indicates that in order to obtain excellent binding resistance it is preferable that the average roughness of ten points Rzj | S is 0.54 µm or more and that the load length ratio Rmr (30) 20% or more on the upper 1/4 part 101a of the sliding surface 101. Moreover, in all Examples 1 to 3, the average ten point roughness Rz-jis is less than 0.54 µm and the ratio of the Load length Rmr (30) is 15% or less in the lower 1/4 portion 101b of the sliding surface 101. This indicates that in order to obtain a sufficient reduction in frictional loss (here, up to a coefficient of friction of 0.15 or less), it is preferable that the average roughness of ten points Rzj | S is less than 0.54 um and that the load length ratio Rmr (30) is 15% or less in the lower 1/4 part 101b of the sliding surface 101.

In all Comparative Examples 1 to 11, the average roughness of ten Rzjis points and the load length ratio Rmr (30) at a cut-off level of 30% of the sliding surface are substantially the same across the entire surface. thus substantially the same between the upper 1/4 and lower 1/4 of the sliding surface. Therefore, a lower binding resistance or greater friction loss (here, a coefficient of friction of 0.2 or more) was obtained. Specifically, in Comparative Example 1, neither a chemical attack process nor a embossing process after a mirrored finishing process, and in Comparative Examples 2 to 5, where a embossing process was performed after a mirrored finishing process, the coefficient of friction was low, but wear and tear occurred.

Moreover, in Comparative Examples 7 to 11, where the entire surface was subjected to a chemical etching process after a mirrored co-honing process, no wear occurred, but the coefficient of friction was large. Moreover, in Comparative Example 6, where the entire sliding surface was subjected to a embossing process after a mirror-finishing polishing process, but for a shorter chemical etching time than in Comparative E-Examples 7 to 11, wear occurred and the coefficient of friction was also high.

Figure 20 is a graph in which Examples 1 to 3 and Comparative Examples 1 to 11 are graphically plotted on a horizontal geometry axis representing ten point average roughness RzjiS and on a vertical geometry axis representing load length ratio Rmr ( 30) relative to the upper 1/4 of the sliding surface.

As can be seen from Figure 20, Examples 1 to 3, and Comparative Examples 7 to 11, where no wear occurred, the average roughness of ten Rzjis points was 0.54 µm or more and the ratio load length Rmr (30) was 20% or more. On the other hand, in comparative Examples 1 to 6, which have been worn out, at least one of the ten point average roughness Rzj | S and the load length ratio Rmr (30) falls outside the above mentioned range (s). number (s). Therefore, it can be seen that the lubricant holding capacity on the upper 1/4 part 101a of the sliding surface 101 is improved and wear is prevented under conditions where the average Rzjis ten point roughness is 0.54 µm. or more and the load length ratio R-mr (30) at a 30% cutoff level is 20% or more. Note that when the ten point average roughness Rzj | S is significantly large (specifically, exceeding 4.0 µm), significant gradual decline of fine eutectic silicon grains 2 may occur so that fine voids for lubricant retention ( oil puddles 4 with a slight wobble) may decrease. Therefore, the average roughness of ten points Rzj | S is preferably 4.0 um or less and more preferably 2.0 um or less.

As stated, a high lubricant retention capacity is obtained when only primary crystal silicon grains 1, but also a large number of eutectic silicon grains 2, still protrude on the sliding surface 101. From the form shown schematically in Figure 21 sufficient depths of oil 4 are formed with a fine oscillation when large numbers of eutectic silicon grains 2 remain protruding, whereby lubricant retention capacity is improved and binding resistance is improved. enhanced. Since a large number of eutectic silicon grains 2 remain protruding, the area of the parts that actually comes in contact with piston ring 122a increases compared to the case where only primary crystal silicon grains 1 remain protruding. . As a result, the load per unit area that is applied during a slip is reduced, whereby better abrasion resistance is obtained.

On the other hand, as shown schematically in Figure 22, when substantially nothing except the primary crystal silicon grains 1 remain protruding, the oil puddles 4 are formed with a coarse oscillation, resulting in lower retention capacities. lubricant and binding resistance. Since hardly any grain of eutectic silicon 2 remains protruding, the area of the parts actually in contact with piston ring 122a is small, thus resulting in low abrasion resistance.

As already described above, with the conventional embossing process, it is difficult to sufficiently increase the average roughness of ten points Rzjis and arazão of load length Rmr (30). The reason for this will be described in relation to figure 23.

In a embossing process, which is a mechanical grinding process, the amount of grinding differs between regions where crystalline silicon grains 1 and 2 are sparse and regions where they are dense. Specifically, from the shape shown on the right side in Figure 23, deep grinding occurs in a region where crystalline silicon grains 1 and 2 are sparse, thus resulting in a large relief height h. However, as shown on the left side in figure 23, only surface grinding occurs in a region where crystalline silicon grains 1 and 2 are dense, thus resulting in a small height of relief h. Therefore, it is difficult to obtain a large average roughness of ten points Rzj | S over the entire sliding surface101. Moreover, since the eutectic silicon grains 2 will be ground together with the matrix 3, it is also difficult to obtain a large R-mr load length ratio (30). Moreover, since a embossing process is a mechanical grinding process, relative to the apex of each silicon crystal grain 1 or 2, it is difficult to gouge deeply into the aluminum alloy (matrix 3) present in the around each grain of silicon crystal 1 or 2. Therefore, around each grain of silicon crystal 1 or 2, there is aluminum alloy up to a height that is not much different from its apex, thus resulting in a holding capacity of lubricant that is smaller than in the case of a chemical attack process.

On the other hand, in a chemical etching process (which is a chemical grinding process), as shown in figure 24, grinding occurs at a constant depth, regardless of whether silicon crystalline grains 1 and 2 are sparse. or so, and thus a constant relief height h is obtained. Therefore, by adjusting the concentration and temperature of the chemical attack product and the time of the chemical attack, the average ten point roughness Rzj | S can easily increase. Furthermore, since eutectic silicon grains 2 will not be ground together with matrix 3, the load length ratio Rmr (30) can easily increase.

Figure 25 is a graph in which Examples 1 to 3 and Comparative Examples 1 to 11 are graphically plotted on a horizontal geometry axis representing ten point average roughness Rzj | S and on a vertical geometry axis representing load length reasoning. Rmr (30) with respect to the lower 1/4 of the sliding surface.

As can also be seen from Figure 25, in all Examples 1 to 3 and Comparative Examples 1 to 4, which showed a small coefficient of friction (0.15 or less), the average roughness of ten points Rzj | S is less than 0.54 µm and the load length ratio Rmr (30) is 15% or less. On the other hand, in Comparative Examples 6 to 11, which showed a large coefficient of friction (0.2 or more), at least one of the average roughness of ten points Rzjis and the load length ratio Rmr (30) of above (s) numeric range (s). This indicates that, by ensuring that the average ten point roughness Rzj | S is less than 0.54 µm and that the load length ratio Rmr (30) at a 30% cut-off level is 15%. or less, the coefficient of friction on the lower 1/4 part 101b of the sliding surface 101 may become sufficiently small, and the frictional loss may be further reduced. Note that in Comparative Example 5, the coefficient of friction is small, although the average roughness of Rzj | S points is 0.54 µm or more. This is because the ratio of the discharge length Rmr (30) is as small as 3%.

Furthermore, it can be seen from Table 2 that the coefficient of friction on the lower 1/4 part 101b of the sliding surface 101 is the smallest (and thus the frictional loss is the smallest) in Example 3, followed by Example 2 and then Example 1. Therefore, from the point of view of reducing frictional losses, it is preferable to employ the production method described in relation to Figure 15, that is, a production method in which a reversing step - Partial cementing is performed after a general chemical attack step.

In the case where the production method described in relation to Fig. 13 is used, that is, a production method in which no additional chemical attack step is conducted after performing a localized chemical attack step, the number of eta-pas is reduced. Therefore, a reduction in production costs and simplification of production steps are possible.

In the case where the production method described with respect to Figure 9 is used, that is, a production method in which a general chemical etching step is conducted after performing a localized chemical etching step, the entire sliding surface101 is subjected to a chemical etching process (although the amount of chemical etching is not constant), so that the lubricant retention capacity of the entire sliding surface 101 is improved. Thus, a high effect of improving abrasion resistance and binding resistance is achieved across the entire sliding surface 101.

In the following, preferred average crystal grain sizes and preferred grain size distributions of crystalline silicon grains 1 and 2 will be described on the sliding surface 101. The inventors conducted a detailed study of the relationship between the specific implementation of crystalline grains 1 and 2 on the sliding surface 101 and the abrasion resistance and mechanical strength of cylinder block 100. As a result, it has been found that abrasion resistance and mechanical strength can be greatly improved by adjusting the average dimensions. of crystal grain of crystalline silicon grains 1 and 2 in the specific ranges, and / or by prescribing grain-specific size distributions for crystalline silicon grains 1 and 2.

First, by adjusting the average crystalline grain size of the primary crystalline silicon grains 1 to be in the range of not less than 12 µm and not more than 50 µm, the abrasion resistance of cylinder block 100 can be improved.

If the average crystalline grain size of the primary crystal silicon grains 1 exceeds 50 µm, the number of the primary crystal silicon grains 1 per unit area of the sliding surface 101 becomes small. Therefore, a large charge will be applied to primary crystal silicon cadre 1 during operation of the internal combustion engine, so that the primary crystal silicon grains 1 can be destroyed. Waste from the destroyed primary crystal silicon grains 1 will act as abrasive particles, possibly causing considerable abrasion of the sliding surface 101.

If the average crystalline grain size of the primary crystal silicon grains 1 is less than 12 µm, the portion of each primary crystal silicon grain 1 that is buried in the matrix 3 will be small. Therefore, it is likely that the gradual decline of primary decrystalline silicon grains 1 will occur during internal combustion engine operation. Gradually declining primary crystal desilicon grains 1 will act as abrasive particles, possibly causing considerable abrasion of the sliding surface 101.

On the other hand, when the average crystalline grain size of primary crystalline silicon grains 1 is not less than 12 µm and not more than 50 µm, there is a sufficient number of primary crystal silicon grains 1 per unit surface area. sliding Therefore, the load applied to each primary crystal silicon grain 1 during internal combustion engine operation will be relatively small, whereby the destruction of the primary crystal silicon grain 1 is suppressed. Since the portion of each primary crystal silicon grain 1 that is buried in the matrix 3 is sufficiently large, the gradual decline of the primary crystal silicon grain 1 is reduced, whereby the abrasion of the sliding surface 101 as a function of Primary decrystalline silicon grains 1 with gradual decline is also suppressed.

Moreover, eutectic silicon grains 2 serve to reinforce matrix 3.

Therefore, by providing fine grains of eutectic silicon 2, the abrasion resistance and mechanical strength of cylinder block 100 can be improved. Specifically, by ensuring that eutectic silicon grains 2 have an average crystalline grain size of 7.5 µm or less, an abrasion resistance and mechanical strength enhancing effect is obtained.

Furthermore, by prescribing grain size distributions for crystalline silicon grains 1 and 2 such that crystalline silicon grains peak within a crystalline grain size range of not less than 1 µm and not more than 7 µm. 1.5 um and having another peak in a crystalline grain size range of no less than 12 µm and not more than 50 µm, the abrasion resistance and mechanical strength of the decylinder block 100 can be greatly improved. Figure 26 shows an example of preferred grain size distributions. Crystalline silicon grains whose crystal grain dimensions fall in the range of not less than 1 æm and not more than 7.5 μm are eutectic desilicon grains 2, while crystalline silicon grains whose size of the crystalline grain fall in the range of less than 12 µm and no more than 50 µm are primary decrystalline silicon grains 1. Moreover, from the point of view of allowing more eutectic silicon grains 2 to contribute to the creation of oil pools 4, as is shown in Figure 26, it is preferable that the frequency at a first peak existing in the crystalline grain size range of not less than 1 µm and not more than 7.5 µm (i.e., the peak associated with eutectic silicon grains 2) is at least five times the frequency at a second peak in the crystalline grain size range of not less than 12 µm and not more than 50 µm (ie the peak associated with primary crystal silicon grains 1) .

In order to control the average crystal grain size of the primary decrystalline silicon grain 1 and the eutectic silicon grain 2, the cooling rate of the part to render the sliding surface 101 can be adjusted at the casting step of the molded part (the step S1c shown in figure 10). Specifically, by performing the above-mentioned casting so that the part to become the sliding surface 101 is cooled to a cooling rate of not less than 4 ° C / second and not more than 50 ° C / second, the crystalline silicon grains 1 and 2 will be deposited in a manner that the primary crystal silicon grains 1 have an average crystal grain size of not less than 12 µm and not more than 50 µm and that the eutectic silicon grains 2 have a size average crystalline grain of 7,5 µm or less.

As described above, the cylinder block 100 of the present embodiment has excellent abrasion and sticking resistance as well as a small friction loss, and therefore can be suitably used in internal combustion engines for various types of conveyor apparatus. . In particular, cylinder block 100 is suitably used in any internal combustion engine that is operated at a high revolution speed (specifically, at a maximum revolution speed of 8,000rpm or more), for example a Internal combustion engine of a motorcycle, according to which, the durability of the internal combustion engine can be greatly improved.

Fig. 27 shows an exemplary internal combustion engine 150 incorporating cylinder oblique 100 according to the present invention. Internal combustion engine 150 includes a crankcase 110, a cylinder block 100 and a cylinder head 130.

A crankshaft 111 is accommodated in the crankcase 110. The crankshaft 111 includes a big nut 112 and a crank arm 113.

Cylinder block 100 is provided above the crankcase 110. A piston 122 is inserted into a bore of cylinder 102 of cylinder block 100. Piston 122 slides into bore of cylinder102, still in contact with sliding surface 101 of cylinder block. cylinder100. Piston 122 is made of an aluminum alloy (typically an aluminum alloy containing silicon). Piston 122 may be formed by forging, as disclosed, for example, in USP 6205836.

No cylinder sleeve is inserted into cylinder bore 102, and no plating is provided on the inner surface of cylinder wall 103 of cylinder block 100. In other words, primary crystal silicon grains 1 and eutectic silicon grains 2 are exposed on the inner surface, i.e. the sliding surface 101, of the wall of the cylinder bore 103.

A cylinder head 130 is provided above cylinder block 100. Along with piston 122 in cylinder block 100, cylinder head 130 defines a combustion chamber 131. Cylinder head 130 includes an inlet port 132 and an exhaust port 133. An inlet valve 134 for supplying fuel-air mixture in the interior combustion chamber 131 is provided in the inlet port 132, and an exhaust valve 135 for carrying out the combustion chamber 131 is provided in the exhaust hole 133.

Piston 122 and crankcase 111 are connected by means of a connecting rod 140. Specifically, a piston pin 123 of piston 122 is inserted into a through hole in a small end 142 of connecting rod 140, and crankshaft sleeve 1121 it is inserted into a through hole at a large end 144, whereby piston 122 and crankshaft 111 are connected to one another. Rolling bearings 114 are provided between the inner peripheral surface of the large end bore 144 through the bore 112.

The internal combustion engine 150 shown in Fig. 27 is of excellent durability because the cylinder block 100 of the present embodiment is incorporated despite the lack of an oil pump for compulsory supply of a lubricant. Since cylinder bevel 100 of the present embodiment is characterized by a high resistance to sliding surface 101, there is no need for a cylinder sleeve. Therefore, the production steps of the internal combustion engine 150 can be simplified. Thus, the weight of the internal combustion engine 150 may be reduced, and the cooling performance may improve. Moreover, since metallization is unnecessary for the inner surface of the cylinder bore wall 103, it is also possible to reduce the production cost. In addition, because the internal combustion engine 150 includes cylinder oblique 100 of the present embodiment, a lower friction loss and therefore better fuel consumption is obtained.

Figure 28 shows a motorcycle incorporating the internal combustion engine 150 shown in Figure 27. On a motorcycle, the internal combustion engine 150 will be operated at a high revolution speed.

On the motorcycle shown in Figure 28, a pickup tube 302 is provided at the front end of a chassis 301. On the pickup tube 302, a front fork 303 is attached to swing in the right - left direction of the vehicle. At the lower end of the front fork 303, a front wheel 304 is supported for rotation.

A seat rail 306 is attached to an upper end of the rear end chassis 301 to extend in the rear direction. A fuel tank 307 is provided on chassis 301, and a main seat 308a and a coupled seat 308b are provided on seat rail 306.

Rear arms 309 extending in the rear direction are attached at the rear end of the chassis 301. At the rear end of the rear arms 309, a ratchet 310 is supported for rotation.

In the central part of the chassis 301, the internal combustion engine 150 shown in figure 27 is locked. Cylinder block 100 of the present embodiment is used for the internal combustion engine 150. A radiator 311 is provided in front of the internal combustion engine 150. An exhaust pipe 312 is connected to an internal combustion engine exhaust port 150. , and a muffler 313 is attached to the rear end of the exhaust pipe 312.

A transmission 315 is connected to the internal combustion engine 150. Drive sprockets 317 are attached to an output shaft 316 of the transmission 315. By means of a belt 318, drive sprockets 317 are attached to the wheels. rear wheel sprockets 319 from rear wheel 310. The transmission 315 and belt 318 act as a transmission mechanism for transmitting the driving energy generated from the internal combustion engine 150 to the drive wheel.

In accordance with the present invention there is provided a cylinder block with excellent abrasion resistance and binding resistance and a small friction loss as well as a production method thereof.

The cylinder block according to the present invention may be suitably used in internal combustion engines for various types of conveyor apparatus, and may be suitably used particularly for internal combustion engines operating at high revolution speeds and for combustion engines. Internal lubricant is not compulsorily supplied to a cylinder by means of a pump.

While the present invention has been described with respect to its preferred embodiments, it will be apparent to those skilled in the art that the disclosed invention may be modified in a number of ways and may take on many different modalities from those specifically described above. Accordingly, the appended claims are intended to cover all modifications of the invention that fall within the true spirit and scope of the invention.

Claims (16)

1. Cylinder block consisting of a silicon-containing aluminum alloy, characterized by the fact that it comprises: a cylinder wall with a sliding surface on which a piston slides, and a plurality of crystalline grains on the sliding surface; where an average roughness of ten points Rzj | S of the sliding surface and a portion of the load length Rmr (30) of the sliding surface at a cut level of 30% are greater on an upper 1/4 of the surface. than a bottom 1/4 of the sliding surface. Cylinder block according to Claim 1, characterized in that the fattech on the top 1/4 of the sliding surface has an average roughness of ten Rzjis points of 0.54 µm or more and the charge length ratio Rmr (30) at a 30% cutoff level is 20% or more. Cylinder block according to claim 2, characterized in that on the upper 1/4 of the sliding surface the average roughness of ten Rzjis points is 2.0 µm or less. Cylinder block according to claim 2 or 3, characterized in that on the upper 1/4 of the sliding surface the load length ratio Rmr (30) at a cut-off level of 30% is 55% or less. Cylinder block according to any one of claims 1 to 4, characterized in that in the lower 1/4 of the sliding surface ten point average roughness Rzj | S is less than 0.54 µm and the ratio of the Rmr (30) load length at a cut level of 30% is 15% or less. Cylinder block according to any one of claims 1 to 5, characterized in that the sliding surface has been subjected to a chemical etching process. 7. A silicon-containing aluminum alloy cylinder block, characterized in that it comprises: a cylinder wall with a sliding surface on which a piston slides, and a plurality of crystalline silicon grains on the surface of where an upper 1/4 part of the sliding surface has a mean roughness of ten points Rzj | S of the sliding surface is 0.54 µm or more and a load length ratio Rmr (30) of the sliding surface slip at a cutoff level of 30% is -20% or more; A coating is provided on at least an upper 1/4 of the sliding surface. Cylinder block according to claim 7, characterized in that at the top 1/4 of the sliding surface the ten point average roughness Rzjis is 2.0 µm or less. Cylinder block according to claim 7 or 8, characterized in that on the upper 1/4 of the sliding surface the load length ratio Rmr (30) at a cut-off level of 30% is 55% or less. Internal combustion engine, characterized in that it comprises: the cylinder block of any one of claims 1 to 9; It is a sliding piston still in contact with the sliding surface of the cylinder block. Internal combustion engine according to claim 10, characterized in that the piston is composed of an aluminum alloy. Conveyor apparatus, characterized in that it comprises the internal combustion engine of claims 10 or 11. 13. Method for producing a cylinder block including a cylinder wall, the cylinder face with a sliding surface on which a piston slides, characterized by the fact that the method comprises: a step of providing a molded part that is composed of a silicon-containing aluminum alloy: a step of polishing a region of the surface of the molded part to become the sliding surface by the use of a polisher of 1,500 or more granularity; a first stage of chemical attack to record only part of the polished region. Method for producing a cylinder block according to claim 13, characterized in that it further comprises, after the first chemical etching step, a second chemical etching step for etching the entire region. A method of producing a cylinder block according to claim 13, characterized in that no additional chemical etching step to engrave the region is performed after the first chemical etching step. A method for producing a cylinder block including a cylinder wall, the cylinder face with a sliding surface on which a piston slides, characterized by the fact that the method comprises: a step of providing a molded part that is composed of a silicon-containing aluminum alloy; a step of polishing a region on the surface of the molded part to become the sliding surface by the use of a finisher of 1,500 or more granularity; a chemical etching step to etch the polished region; A step of providing a coating on only part of the recorded region.