JP2005249127A - Shaft of low friction sliding device, crank shaft, cam shaft, and engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shaft of a low friction sliding device capable of reducing friction loss, in regard to a sliding device to be used for a crank shaft of an engine. <P>SOLUTION: The sliding device 1 is structured of the shaft 10 rotating around the shaft center and a sliding bearing formed from a cylinder for supporting the shaft 10 and lubricated with interposed oil. A surface of the shaft 10 is formed with a recessed part 10a having a function for propelling a flow of the oil having a component in a rotating direction when rotating the shaft 10. For example, when rotating at high speed, low friction effect is shown to improve seizure-resistance. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention reduces friction generated in a sliding device by providing a concave portion on the outer surface of the shaft in a sliding device composed of a shaft and a sliding shaft made of a cylinder supporting the shaft. And to improve the seizure resistance of the sliding device.

  Conventionally, a sliding device has been used in, for example, a crank pin provided in an engine and a bearing metal that supports the crank pin, and friction generated on a sliding surface when the crank pin slides on the bearing metal. In order to reduce this, there is one in which a concave portion whose longitudinal direction is orthogonal to the sliding direction is provided on the surface of the shaft with the groove depth changed according to the portion of the shaft surface (see Patent Document 1). This is because the recess holds the lubricating oil so that the lubricating oil intervening between the shaft and the bearing metal is evenly moistened to the sliding surface during reciprocating sliding of the shaft whose sliding direction and sliding speed change. In addition, it is based on exhibiting a function of providing lubricating oil to the sliding surface in the vicinity of the recess during sliding (hereinafter referred to as a function of retaining the lubricating oil).

However, the sliding device described in Patent Document 1 is not a sliding device whose shaft rotates and slides. In a sliding device where the shaft rotates and slides on the inner surface of a cylindrical slide bearing such as a crankshaft, the shaft crankpin rotates around the shaft center in the cylinder of the crankshaft, which is a slide bearing. Slide. At that time, in order to reduce the friction generated on the sliding surface, it is assumed that the lubricating oil is wound around the rotating shaft and forms a layer that forms an oil film and flows stably in the rotational direction of the shaft. It becomes. Generally, when the shaft rotates at a low speed, the lubricating oil stably flows in the direction of rotation of the shaft as described above. However, when the shaft rotates at a high speed, compared to when rotating at a low speed, the shaft does not rotate the shaft center stably and comes in contact with the bearing more frequently, and the frictional force generated on the sliding surface during the contact also increases. large. Due to this friction, the flow of the lubricating oil is disturbed and may not be caught in the shaft as in the case of low speed rotation and may not flow stably in the rotation direction of the shaft. Thus, when disturbance occurs in the flow of the lubricating oil, the premise for reducing the friction described above is lacking. Under such circumstances, there is a problem that the effect of low friction is not always sufficiently exhibited only by providing a conventional concave portion on the surface of the shaft.
JP 2002-235852 A

  Accordingly, an object of the present invention is to provide an effect of low friction and improve seizure resistance even in the above-described situation that may occur when the shaft rotates at high speed in a sliding device in which the shaft rotates and slides. Is to provide a simple sliding device. A further object is to provide an engine system in which the frictional resistance in the rotating portion is reduced by using the sliding device for reducing the friction in this way.

  The object of the present invention is achieved by the following means.

(1) It has a shaft rotatable about an axis and a cylindrical slide bearing for supporting the shaft via oil, and one or more recesses are provided on the outer surface of the shaft. The low friction sliding device is characterized in that the concave portion is formed so as to promote the flow of the oil having a component in the rotational direction of the shaft when the shaft rotates.

  (2) The shaft in a low friction sliding device having a shaft rotatable around an axis and a cylindrical slide bearing for supporting the shaft via oil, the outer surface of the shaft Among the unit surfaces having one or more recesses and having a unit area in the surfaces constituting the recesses, the sum of the areas of the unit surfaces whose normal line has a component in the rotation direction of the axis is the normal line A shaft of a low friction sliding device characterized by being larger than the total area of unit surfaces having a component in a direction opposite to the rotational direction of the shaft.

  (3) The shaft in a low friction sliding device having a shaft rotatable around an axis and a cylindrical slide bearing for supporting the shaft via oil, the outer surface of the shaft The shaft of the low-friction sliding device is characterized in that one or more recesses are provided in the shaft, and the recesses are inclined with respect to a direction perpendicular to the rotation direction of the shaft.

  (4) A crankshaft to which the shaft of the low friction sliding device according to any one of (1) to (3) is applied.

  (5) A camshaft to which the shaft of the low friction sliding device according to any one of (1) to (3) is applied.

  (6) An engine in which the shaft of the low friction sliding device according to any one of (1) to (3) is applied to at least a part.

  According to the present invention, the concave portion provided on the surface of the shaft has a function of holding the lubricating oil and a function of promoting the flow of the lubricating oil having a component in the rotation direction of the shaft when the shaft rotates. In addition, the lubricating oil is moistened on the sliding surface, the disturbance of the lubricating oil flow that may occur when the shaft rotates at high speed is reduced, and the effect of reducing the friction generated in the sliding device is exhibited.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, an embodiment of the present invention will be described below. FIG. 1 is a schematic view of a sliding device 1 according to an embodiment of the present invention. FIG. 1 shows a sliding device 1 including a columnar shaft 10 that rotates about an axis a and a slide bearing 11 that is a cylinder that supports the shaft 10. In addition, the dimension of the length of the axis | shaft 10 may be suitably extended from what is shown in a figure. Further, lubricating oil (not shown) is supplied between the surface of the shaft 10 and the inner surface of the sliding bearing 11. In order to reduce the friction generated on the sliding surfaces of the shaft 10 and the slide bearing 11, it is important that the lubricating oil is present in an appropriate amount on the sliding surfaces. For this reason, conventionally, for example, in a sliding device in which a shaft reciprocally slides on a sliding bearing, it is known to provide a recess having a function of holding lubricating oil on the surface of the shaft. Also in the present embodiment, a plurality of recesses 10 a are provided on the surface of the shaft 10.

  In the sliding device 1 in which the shaft 10 rotates and slides in the cylinder of the slide bearing 11, the lubricating oil flows as the shaft 10 rotates. In order to reduce the friction generated on the sliding surface, as described above, the lubricating oil may be wound around the shaft 10 and flow stably as a layer forming an oil film in the rotation direction of the shaft 10. It is a premise. Therefore, in the present embodiment, the shaft 10 has a function of holding the conventional lubricating oil in the recess 10a so that the lubricating oil flows stably in the rotation direction of the shaft 10 even when the shaft 10 rotates at high speed. The function of promoting the flow of lubricating oil toward the rotation direction was added. The function of promoting the flow is classified into a function of guiding the flow of the lubricating oil in the rotation direction of the shaft 10 and a function of pushing the lubricating oil in the rotation direction of the shaft 10.

  First, a preferable mode for the recess 10a to have a function of guiding the flow of the lubricating oil in the rotation direction of the shaft 10 will be described. FIG. 2 shows a side view of the shaft 10 in the present embodiment. (A) in a figure is a basic pattern of arrangement | positioning of the recessed part 10a provided on the surface of the axis | shaft 10 in this embodiment, and (A) is demonstrated first. It should be noted that the arrangement of the recesses 10a shown in the figure includes a plurality of components proposed by the present invention with respect to the arrangement of the recesses 10a, and is described by disassembling each component for convenience. It shall be.

  A plurality of recesses 10 a are formed on the surface of the shaft 10. The shaft 10 rotates in the cylinder of the slide bearing 11 in the direction of arrow A shown in the drawing. As described above, in order to reduce the friction generated on the sliding surface, it is assumed that lubricating oil (not shown) flows stably in the rotation direction A of the shaft 10. Here, the concave portion 10a is considered to induce the lubricating oil in the longitudinal direction of the concave portion 10a by refracting the flow of the lubricating oil flowing into the concave portion 10a by the side wall. Therefore, in order for the lubricating oil to flow in the rotation direction A of the shaft 10, the longitudinal direction of the recess 10 a is not directed in the direction perpendicular to the rotation direction A of the shaft 10 as shown in the prior art. The recess 10a is formed so as to be inclined with respect to the orthogonal direction.

  The angle at which the longitudinal direction of the recess 10a is inclined with respect to the direction orthogonal to the rotation direction of the shaft 10 is preferably greater than 0 ° and 60 ° or less, and more preferably 30 ° or more and 60 ° or less. By providing the angle within this range, the recess 10a can have both a function of guiding the flow of the lubricating oil and a function of holding the lubricating oil.

  Next, in order to reduce the friction generated in the sliding device 1, it is preferable that the lubricating oil is evenly moistened on the sliding surface. In order to realize this situation, it is important to control the flow of the lubricating oil induced by the recess 10a described above. Therefore, in the present embodiment, the flow of the lubricating oil induced by the recess 10a reaches a wide range without interfering with each other, and evenly spreads over the entire sliding surface. And decided to control. As a result, the flow of the lubricating oil induced by the recess 10a disappears by interfering with each other, or the lubricating oil flow is induced only in a specific direction, and the lubricating oil stays only at a specific portion of the sliding surface. And the occurrence of an imbalance in the lubrication of the lubricating oil on the sliding surface is considered to be prevented. Below, each component in arrangement | positioning of the recessed part 10a of this embodiment which produces the said effect is described concretely.

  On the extension line in the longitudinal direction of each recess 10a, one or more other recesses 10a that are parallel in the longitudinal direction are arranged. As a result, the flow line of the lubricating oil guided by one concave portion 10a in the longitudinal direction of the concave portion 10a is further extended by the other concave portion 10a located on the extended line in the longitudinal direction, and the lubricating oil is directed in the same direction. This streamline can be secured in a wide area of the sliding surface.

  Further, with respect to the plane b perpendicular to the axis of the axis 10, the other recess 10 a exists so as to be a mirror image (surface object) with each other, and is positioned in each region divided into the plane b. The concave portions 10a are arranged so that the longitudinal directions thereof are all parallel. Thereby, the flow of the lubricating oil induced by the recess 10a flows symmetrically with respect to the plane b, so that the lubricating oil supplied to each region divided into the plane b can be balanced, Lubricating oil flows induced by the recess 10a in the region are parallel and do not interfere with each other.

  Furthermore, each recessed part 10a was arrange | positioned inclining the longitudinal direction so that the front part with respect to the rotation direction A of the axis | shaft 10 of the said recessed part 10a might be separated from the plane b rather than the rear part. Thereby, it becomes possible to flow lubricating oil so that it may diffuse to the whole sliding surface. Note that the position of the plane b in the longitudinal direction of the shaft 10 is appropriately determined according to the sliding condition in the cylinder of the sliding bearing 11 of the shaft 10.

  The arrangement of the recess 10a can be applied to the arrangements shown in (B) and (C) based on the arrangement of (A). That is, as shown in (B) and (C), a plurality of recess groups shown in (A) are arranged in the longitudinal direction of the shaft 10. As a result, the effect in (A) described above is exhibited, and the distance between both ends of the row of recesses 10a whose longitudinal direction is on the same extension line can be reduced more compactly, and each recess 10a in the row of recesses 10a can be reduced. It is possible to further strengthen the linkage of the lubricating oil flow. Further, the flow of the lubricating oil guided to each row of the recesses 10a can be aggregated for each recess group as a flow toward an equal direction centered on the plane c, and the lubricating oil that can be generated during high-speed rotation It becomes possible to reduce that the flow of the lubricating oil induced by the recess 10a is disturbed against the flow disturbance.

  Next, with reference to FIGS. 3 and 4, a preferable embodiment for the recess 10 a to have a function of pushing the lubricating oil in the rotation direction A of the shaft 10 will be described. FIG. 3 is an enlarged cross-sectional view when the recess 10a is cut along a plane perpendicular to the axis a, and FIG. 4 is an enlarged perspective view of the recess 10a as viewed from above.

  Here, the recessed part 10a can be formed in arbitrary cross-sectional shapes including what is shown in FIG. Among them, the common elements of the recess 10a that can exert the function of pushing the lubricating oil in the rotation direction A of the shaft 10 will be described below. The surface constituting the recess 10a has a unit area and can be regarded as an aggregate of unit surfaces having independent normal directions. It can be said that the unit surface whose normal has a component in the rotation direction A of the shaft 10 pushes the lubricating oil in the rotation direction A of the shaft 10 as the shaft 10 rotates. Therefore, it is considered that the concave portion 10a in which many such unit surfaces exist has a function to push the lubricating oil. Therefore, the total area of the unit surfaces whose normals have a component in the rotational direction of the axis 10 is larger than the total area of unit surfaces whose normals have a component in the direction opposite to the rotational direction of the axes. In addition, the concave portion 10a is formed.

  The two-dot chain line arrows shown in each recess 10a in FIG. 3 indicate one or two unit surfaces on the surface constituting each recess 10a, and indicate the normal B on the unit surface. The normal B shown in (a), (b), and (c) has a component in the rotation direction A, and the normal is the same as the normal B in the surface constituting the recess 10a. The sum of the areas of the unit surfaces having the above component is larger than the sum of the areas of the unit surfaces having the normal component in the direction opposite to the rotation direction A. On the other hand, the normal B shown in (e) has a component in the opposite direction to the rotation direction B, and the normal is opposite to the rotation direction A in the same way as the normal B on the surface constituting the recess 10a. The total area of the unit surfaces having the direction component is larger than the total area of the unit surfaces having a normal component having the rotation direction A component. In (d), it can be said that the two areas are substantially equal. Therefore, since the concave portion 10a has a function of pushing the lubricating oil in the rotation direction of the shaft 10, the cross-sectional shape of the concave portion 10a is preferably the cross-sectional shapes shown in (a), (b), and (c) of FIG. The cross-sectional shapes shown in d) and (e) are not preferred.

  Furthermore, as described above, there is a recess 10 a shown in FIG. 4 as an example in which the recess 10 a is formed so that the longitudinal direction of the recess 10 a is inclined from the direction orthogonal to the rotation direction A of the shaft 10. The alternate long and short dash line shown in the figure is a cutting line C that cuts into the cross section of FIG. 3, and therefore, the cross-sectional shape of the recess 10a is the shape shown in FIG. In the example of the concave portion 10a shown in FIG. 4, the surface I and the surface II shown in the drawing correspond to the surface whose normal line has the component in the rotational direction of the shaft 10, and the surface III and the surface IV have the normal line described above. Corresponds to a surface having a component in the direction opposite to the rotational direction of the shaft. Therefore, it is preferable that the concave portion 10a is formed so that the total area of the surfaces I and II exceeds the total area of the surfaces III and IV.

  In addition, by making the shape which the recessed part 10a opens to the outer surface of the axis | shaft 10 into a rectangular shape and an oval shape, the effect of making lubricating oil flow in continues more and the effect of friction reduction is exhibited.

  Furthermore, the shape in which the recess 10a is opened on the outer surface of the shaft 10 is such that the width dimension in the direction orthogonal to the longitudinal direction is 50 to 150 μm, and the length dimension in the longitudinal direction is twice or more the width dimension. It is preferable to make it 10 times or less. When the opening shape of the recess 10a is provided within this range, sufficient lubricating oil is allowed to flow into the sliding surface, a friction reducing effect is exhibited under sliding conditions, and a slide bearing It is possible to suppress damage such as friction and seizure at the 11 end.

  In addition, it is preferable that the total area of the recesses 10 a opening on the outer surface of the shaft 10 is 0.3% or more and 10% or less of the surface area of the shaft 10. When the ratio is less than 0.3%, a sufficient seizure improvement effect cannot be obtained, and when it exceeds 10%, the load capacity is reduced and a problem of metal contact may occur.

  As described above, according to the present embodiment, the concave portion 10a provided on the outer surface of the shaft 10 has a function of holding the lubricating oil and the flow of the lubricating oil toward the rotation direction of the shaft 10 when the shaft 10 rotates. In addition, the lubricating oil is moistened to the sliding surface, and the disturbance of the lubricating oil flow that may occur during the high-speed rotation of the shaft 10 is reduced, and the friction generated in the sliding device 1 is reduced. Demonstrate the effect.

  The shaft 10 is applicable to engine sliding devices such as a crankshaft and a camshaft. Furthermore, the engine can be a variable compression ratio engine. This variable compression ratio engine is an engine that improves energy consumption and the like by controlling the stroke length of the piston according to the operating state, thereby saving energy.

  FIG. 5 shows a schematic diagram of a variable compression ratio engine 2 to which the shaft 10 of the present invention can be applied. A first connecting rod 23 is connected to a piston 21 that reciprocates in the cylinder 20 via a piston pin 22. Below that, the first connecting rod 23 is swingably connected to the second connecting rod 25 by a connecting pin 24 between connecting rods, and further below, the second connecting rod 25 is connected to the crankshaft by a crank pin 26. 27 is rotatably connected. The second connecting rod 25 is swingably connected to the control rod 29 by an inter-control rod connecting pin 28 located in the vicinity of the connecting rod connecting pin 24. The control rod 29 is connected to the control mechanism 31 by a control mechanism connecting portion 30 located on the opposite side of the control rod connecting pin 28. The control mechanism 31 can change the position of the control mechanism connecting portion 30.

  With the above configuration, the first connecting rod and the second connecting rod are connected in the connecting rod connecting portion according to the trajectory drawn by the connecting rod connecting portion 24 within the swing range of the control rod 29 in accordance with the stroke of the piston 21. The power is transmitted to the crankshaft 27 by bending in a U-shape. When the control mechanism 31 changes the position of the control mechanism connecting portion 30, the degree of bending in the shape of the character is adjusted, and the stroke length of the piston 21 is controlled. In the variable compression ratio engine 2, the shaft 10 in the present embodiment can be applied to the piston pin 22, the connecting rod connecting pin 24, the control rod connecting pin 28, and the crank pin 26.

  The connecting rod connecting pin 24 and the control rod connecting pin 28 may be a single pin, and the first connecting rod 23, the second connecting rod 25, and the control rod may be connected by the same pin.

<Example>
Next, as an embodiment of the present invention, it is possible to specify the preferred angle at which the longitudinal direction of the recess 10a described above is inclined with respect to the direction orthogonal to the rotation direction of the shaft 10, and the recess 10a having the cross-sectional shape shown in FIG. For the purpose of confirming that the material is effective in reducing friction, a sliding device was actually manufactured and a friction test was performed. Specifically, with respect to the angle inclined with respect to the direction orthogonal to the direction of the longitudinal axis, and the cross-sectional shape, the concave portion 10a having various forms is provided with the cylindrical shaft 10 (axis 10) provided on the outer surface. Then, a test body of the sliding device 1 composed of the cylindrical bearing metal 11 (slide bearing 11) is manufactured, and the cylinder shaft 10 is rotated in the cylinder of the bearing metal 11 to generate friction generated on the sliding surface. A friction test was performed to calculate the coefficient.

  The manufacturing process of the test body used for the test will be specifically described below.

  FIG. 6 is a vertical and horizontal sectional view of the sliding device 1 used in the test. The bearing metal 11 is obtained by press-fitting an aluminum metal 11a having an inner diameter of 45 mm into a steel cylinder having an outer diameter of φ60. On the other hand, the column shaft 10 is a carburizing and tempering material of steel (SCM420H steel) having a cylindrical shape, an outer diameter of φ43, and an axial curvature radius of R700 mm. The widths 10a and 11b of the cylindrical shaft 10 and the bearing metal 11 are both 20 mm.

  On the surface of the cylindrical shaft 10, a recess 10 a having a diameter of 43 mm was formed by microindent processing and mask blasting. In the micro indent process, an indenter was manufactured to form a desired recess 10a, and the recess 10a was formed by pressing the indenter against the cylindrical surface and plastic processing. Also, in microblasting, optical microlithography is used to form a concave fine shape on a resin mask, and after the resin mask is affixed to the cylindrical surface, alumina abrasive grains having an average particle diameter of 20 μm are applied from the projection nozzle. The distance to the workpiece was set to 100 mm, and projection was performed under the conditions of a projection flow rate of 100 g / min and a projection pressure of 0.4 Mpa to obtain a recess 10a. After forming the recess 10a using various methods, the bulge formed at the edge of the recess 10a was removed with a tape wrap film having a particle size of 9 μm and subjected to the test.

  Table 1 shows the form of the recess 10a produced as described above and provided on the surface of the cylindrical shaft 10 of each test specimen, and the test results described later.

まず、各試験体において、凹部１０ａの開口部は矩形状を呈し、開口部の短辺は５０〜１５０μｍであり、長辺は、短辺の２倍以上１０倍以下であり、前述した好ましい範囲内に形成されている。

First, in each test body, the opening of the recess 10a has a rectangular shape, the short side of the opening is 50 to 150 μm, the long side is 2 to 10 times the short side, and the preferred range described above Is formed inside.

  Further, the total area where the recesses 10a are opened on the surface of the shaft 10 is formed to be 0.3% or more and 10% or less of the surface area of the shaft 10, and is formed within the preferable range described above.

  Next, regarding the cross-sectional shape of the recess 10a, Examples 1 to 5 are shown in (a) of FIG. 3, Examples 6 to 8 and Comparative Examples 1 and 2 are shown in (d), and Comparative Example 3 is (e). Is provided. That is, Examples 1-5 are provided in the preferable cross-sectional shape in this embodiment.

  In addition, the angle at which the longitudinal direction of the recess 10a is inclined with respect to the direction orthogonal to the rotation direction of the shaft 10 (longitudinal inclination angle in the table) is provided at various angles of 0 ° or more in each specimen. ing.

  In addition, arrangement | positioning of the recessed part 10a provided in the surface of the cylindrical axis | shaft 10 of each test zone was unified into the form shown to (A) of FIG. This is because the arrangement pattern of the recesses 10a provided on the surface of the shaft 10 exists innumerably in addition to this embodiment, and the arrangement of the recesses 10a in this embodiment has an effect on friction compared to the other. It is impossible to identify and prove that it is the form of the arrangement to be exhibited, and for the sake of comparison, each specimen is inclined with respect to the direction perpendicular to the direction of rotation of the longitudinal axis 10. For conditions other than the cross-sectional shape, it is necessary to manufacture the same. The fact that the arrangement of the recesses 10a in the present invention is effective in reducing the friction, as described above, claims that the action generated by the arrangement of the recesses 10a is an effect that is naturally brought about.

  Next, the apparatus used for the test will be described.

  FIG. 7 is a schematic view of an inscribed two-cylinder testing machine used for the test. In a sliding device composed of a shaft and a slide bearing used for a crankshaft of a car engine or the like, the slide bearing is usually fixed and only the shaft rotates. In this embodiment, in order to reproduce the rotational speed of a shaft used for a crankshaft or the like, the cylindrical shaft 10 is rotated into the cylinder of the bearing metal 11 and the sliding bearing 11 is also opposite to the rotational direction A of the shaft 10. By rotating in the direction D, the relative rotational speed obtained by adding the absolute values of both rotational speeds was set to be approximately the same as the rotational speed of the shaft in the crankshaft. Therefore, an AC servo motor (not shown) is attached to each of the cylindrical shaft 10 and the bearing metal 11 so that the rotation can be controlled independently. An oil film was formed between the cylindrical shaft 10 and the bearing metal 11 by immersing the cylindrical shaft 10 and the bearing metal 11 in an oil bath (not shown) containing 5W30 of lubricating oil. The frictional torque generated during the relative rotational motion is measured by a torque sensor (not shown) attached to the cylindrical shaft 10 so that the friction coefficient can be calculated.

  Next, Table 2 shows test conditions in this example.

本試験における、円柱軸１０と軸受メタル１１との相対回転速度の測定可能範囲は、０〜１２ｍ／ｓであり、円柱軸１０および軸受メタル１１の平均転がり速度は、０〜２ｍ／ｓである。実験は、ラジアル荷重２０ｋｇの荷重条件下で行い、使用した潤滑油は５Ｅ３０ＳＪであり、油温度は８０℃である。

In this test, the measurable range of the relative rotational speed of the cylindrical shaft 10 and the bearing metal 11 is 0 to 12 m / s, and the average rolling speed of the cylindrical shaft 10 and the bearing metal 11 is 0 to 2 m / s. . The experiment was performed under a load condition of a radial load of 20 kg, the lubricating oil used was 5E30SJ, and the oil temperature was 80 ° C.

  Next, a test pattern and a test evaluation method will be described.

  As shown in Table 1, the test was performed under two rotation conditions (conditions A and B). The rotational speeds of the cylindrical shaft 10 and the bearing metal 11 shown in Table 1 indicate that the rotational direction of the cylindrical shaft 10 is positive. The relative rotational speed between the cylindrical shaft 10 and the bearing metal 11 is the sum of the absolute values of the rotational speeds of the cylindrical shaft 10 and the bearing metal 11 shown in the table, and is 6 m / s in the condition A and 12 m / s in the condition B. It is.

  The evaluation of the friction generated on the sliding surface of each test specimen is performed based on the coefficient of friction obtained by a testing machine. The test specimen serving as a reference for comparison was defined as Comparative Example 1. The concave portion 10a in Comparative Example 1 is not provided in a preferable form in both because the sectional shape of the concave portion 10a is (d) and the angle inclined with respect to the longitudinal direction is 0 °. Compared with the comparative example 1, in the recess 10a, either the cross-sectional shape or the angle at which the longitudinal direction is inclined is compared with the friction coefficients of Examples 1 to 8 provided in a preferable form in the present embodiment. In the table, the friction coefficient of each specimen is changed to a ratio divided by the friction coefficient of Comparative Example 1.

  Next, test results will be described.

  As a result of the test, in Examples 1 to 5, the ratio of the friction coefficient is lower than that of Comparative Example 1 in which the cross-sectional shape is (d) and also in Comparative Example 3 in which the cross-sectional shape is (e). Therefore, it is confirmed that (a) is the cross-sectional shape of the recessed part 10a which reduces friction most among the cross-sectional shapes of the recessed part 10a shown in FIG.

  In Examples 6 to 8, the ratio of the coefficient of friction is lower than that in Comparative Example 1 and also in Comparative Example 2 in which the angle of inclination in the longitudinal direction is 70 °. It has been confirmed that the angle at which the longitudinal direction is inclined with respect to the direction orthogonal to the rotation direction of the shaft 10 is preferably greater than 0 ° and 60 ° or less, and more preferably 30 ° or more and 60 ° or less. The

  Further, in Example 5, both the angle and the cross-sectional shape in which the longitudinal direction is inclined are manufactured in the above-described preferred form, but the friction coefficient is lower than that of all the other examples, and the friction is reduced. It can be said that this is the test body that has been most effective.

  In addition, the test was performed with the relative speed changed under the conditions A and B. In Examples 1 to 5, the ratio of the coefficient of friction decreased as the speed increased, and thus the friction reduction effect increased. ing. This is because the cross-sectional shape of the concave portion 10a in Examples 1 to 5 is formed in (a) shown in FIG. 3, and the concave portion 10a is increased as the relative rotational speed between the shaft 10 and the bearing metal 11 increases. It is considered that the function of flushing the lubricating oil of 10a was further amplified.

  Since the recess 10a has a function of accelerating the flow of the lubricating oil in the rotation direction of the shaft, the recess 10a has a function of inducing the flow of the lubricating oil in the rotation direction of the shaft 10 and lubricates in the rotation direction of the shaft 10. It is not necessary to have both of the function of flushing out oil, and it may be provided in the above-described preferred form so as to have any one function. In addition, as shown in Example 5, when the recessed part 10a is formed so as to have both functions, the effect of further reducing friction is exhibited.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims.

  In addition, the recessed part 10a in this embodiment may be provided in the cylindrical inner surface of the slide bearing 11. FIG.

  Further, although the plain bearing in the present embodiment is assumed to have a cylindrical shape, it may be configured to be disassembled into two semi-cylindrical shapes in consideration of use for a crankshaft or the like.

It is the schematic of the sliding apparatus 1 in embodiment of this invention. 3 is a side view of the shaft 10. FIG. It is an expanded sectional view at the time of cut | disconnecting the recessed part 10a by the surface orthogonal to the axial center a. It is the expansion perspective view which looked at the recessed part 10a from the top. 1 is a schematic view of a variable compression ratio engine 2 to which a shaft 10 of the present invention can be applied. It is the vertical and horizontal sectional drawing of the sliding apparatus 1 used for the test in the Example of this invention. It is the schematic of the inscribed 2 cylinder test machine used for the test in the Example of this invention.

Explanation of symbols

1 sliding device,
2 variable compression ratio engine,
10 axes (cylinder axis),
10a recess,
11 Sliding bearing (bearing metal),
21 piston,
23 first connecting rod,
24 Connecting rod connecting pin,
25 Second connecting rod,
28 Inter-control connecting pin,
30 Control mechanism coupling part,
31 control mechanism,
A axis (cylinder axis) rotation direction,
B Normal of the unit surface in the surface constituting the recess.

Claims (18)

An axis rotatable around the axis, and
The shaft in a low friction sliding device having a cylindrical slide bearing for supporting the shaft via oil,
One or more recesses are provided on the outer surface of the shaft;
The shaft of the low friction sliding device, wherein the recess is formed so as to promote the flow of the oil having a component in the rotation direction of the shaft when the shaft rotates. An axis rotatable around the axis, and
The shaft in a low friction sliding device having a cylindrical slide bearing for supporting the shaft via oil,
One or more recesses are provided on the outer surface of the shaft;
Of the unit surfaces having a unit area in the surface constituting the recess, the sum of the areas of the unit surfaces whose normal line has a component in the rotation direction of the axis is a component whose normal line is in a direction opposite to the rotation direction of the axis. A shaft of a low-friction sliding device characterized by being larger than the total area of unit surfaces.   The cross-sectional shape of the recess cut along a plane perpendicular to the axis is a triangle, and the front of the two sides of the triangle extending from the apex located at the bottom of the recess is forward with respect to the rotation direction of the shaft. The side of the low friction sliding device according to claim 2, wherein a side located at the side is shorter than a side located rearward with respect to the rotation direction of the shaft.   The shaft of the low friction sliding device according to claim 3, wherein a cross-sectional shape of the recess is a right triangle. An axis rotatable around the axis, and
The shaft in a low friction sliding device having a cylindrical slide bearing for supporting the shaft via oil,
One or more recesses are provided on the outer surface of the shaft;
The shaft of the low-friction sliding device, wherein the concave portion is inclined with respect to a direction perpendicular to the rotation direction of the shaft.   The shaft of the low friction sliding device according to claim 5, wherein an angle at which the longitudinal direction of the concave portion is inclined with respect to a direction orthogonal to the rotation direction of the shaft is set to be greater than 0 ° and equal to or less than 60 °. .   A plurality of the recesses are provided on the outer surface of the shaft, and arranged such that one or more other recesses having a longitudinal direction parallel to the longitudinal direction of the recesses exist on an extension line in the longitudinal direction of one recess. The shaft of the low friction sliding device according to claim 5, wherein the shaft is a low friction sliding device.   6. A recess group composed of a plurality of recesses arranged so as to be mirror images of each other with respect to a plane perpendicular to the axis is provided on the outer surface of the shaft. The shaft of the low friction sliding device as described in 1.   The shaft of the low friction sliding device according to claim 8, wherein a plurality of the recess groups are provided in a longitudinal direction of the shaft.   The concave portions located in each region divided by the plane among the plurality of concave portions constituting the concave group are arranged so that all of the longitudinal directions thereof are parallel to each other. The shaft of the low friction sliding device described.   The plurality of recesses constituting the recess group are formed such that a front portion of the recess with respect to the rotation direction of the shaft is separated from the plane than a rear portion of the recess with respect to the rotation direction of the shaft. The shaft of the low friction sliding device according to any one of claims 8 to 10.   The shaft of the low-friction sliding device according to any one of claims 1 to 11, wherein the shape of the recess opening on the outer surface of the shaft is either an elliptical shape or a rectangular shape.   The shape in which the concave portion opens on the outer surface of the shaft has a width dimension in the direction perpendicular to the longitudinal direction of 50 to 150 μm, and a length dimension in the longitudinal direction of 2 to 10 times the width dimension. The shaft of the low friction sliding device according to claim 1, wherein the shaft is a low friction sliding device.   14. The low area according to claim 1, wherein the total area in which the recesses open to the outer surface of the shaft is 0.3% to 10% of the surface area of the shaft. Friction sliding device shaft.   A crankshaft to which the shaft of the low friction sliding device according to any one of claims 1 to 14 is applied.     A camshaft comprising the shaft of the low friction sliding device according to any one of claims 1 to 14.   An engine, wherein the shaft of the low friction sliding device according to any one of claims 1 to 14 is applied to at least a part thereof. The engine is a variable compression ratio engine in which a crankshaft and a piston that reciprocates in a cylinder are connected via a first connecting rod and a second connecting rod,
The first connecting rod and the second connecting rod are connected by a connecting pin between connecting rods,
The second connecting rod is swingably connected to the control rod by a control rod connecting pin,
The control rod is connected to the control mechanism by a control mechanism connecting portion located on the opposite side of the inter-control rod connecting pin,
The variable compression ratio engine according to claim 17, wherein the control mechanism controls a stroke length of a piston by changing a position of the control mechanism connecting portion.

Images