JP5376798B2 - Roller bearing cage and design method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a retainer for a rolling bearing capable of reducing the friction and wear of the retainer and a race, and increasing an applicable operation limit by setting the width dimension of a retainer outer diameter excluding pocket width and improving a lubrication state on a retainer outer diameter surface and a race inner diameter surface. <P>SOLUTION: The minimum oil film thickness h balanced with an obtained contact force is obtain based on a fluid lubrication theory. A combined surface roughness &sigma; of the retainer outer diameter surface 11A and an outer race 14 facing the retainer outer diameter surface 11A is obtained. The minimum width dimension b<SB>1</SB>making the minimum oil film thickness h equal to the combined surface roughness &sigma; is obtained. The width dimension b of a cylindrical surface is set not smaller than the minimum width dimension b<SB>1</SB>. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a rolling bearing retainer used at a connecting rod large end and a design method thereof.

Roller bearing cage guide types include a rolling element guide system that guides with rolling elements made of balls or rollers, and a raceway guide system that guides with an inner ring or an outer ring. In the raceway guide system, the cage and the raceway are in sliding contact. In this raceway guide system, when the cage is strongly pressed against the raceway due to centrifugal force or the like, a sufficient oil film is not formed, and the contact portion between the cage and raceway may be worn, resulting in a malfunction. As a countermeasure, for example, a technique has been proposed in which an oil reservoir is provided in a part of the cage and sufficient lubricating oil is supplied to the contact portion (see, for example, Patent Document 1).
JP 7-167135 A Muraki and Kimura Study on traction characteristics of lubricating oil (2nd report), Lubrication, 28, 10 (1983) 753-760. RS Zhou and MR Hoeprich Torque of Tapered Roller Bearings, Trans. ASME, J. Trib., 113, 7 (1991) 590. Yamamoto / Kaneda Tribology, Science and Technology (1998) 88 Hashimoto Tribology Learned from Fundamentals, Morikita Publishing (2006) 94 Japanese Standards Association JIS Handbook Machine Element, Japanese Standards Association (1997) 1165-1166 Muraki and Kimura Study on traction characteristics of lubricating oil (1st report), Lubrication, 28, 1 (1983) 67-73

  In the raceway guide system, even if an oil reservoir is provided in a part of the cage, when the cage is strongly pressed against the raceway by centrifugal force or the like, a sufficient oil film is not formed, and the cage and The contact part of the bearing ring may be worn out, resulting in a malfunction.

  An object of the present invention is to set the width dimension excluding the pocket width of the outer diameter surface of the cage, and improve the lubrication state between the outer diameter surface of the cage and the inner surface of the raceway ring, thereby improving the friction between the cage and the raceway ring. It is an object of the present invention to provide a rolling bearing retainer capable of reducing wear and improving an applicable operation limit, and a design method thereof.

A rolling bearing cage of the present invention is a rolling bearing cage incorporated at the connecting rod large end, and is a substantially cylindrical shape having a plurality of pockets for holding rolling elements. The width dimension of one side of the cylindrical surface continuous in the circumferential direction formed on both sides in the cage axial direction of the pocket among the outer diameter surfaces of the cage is b, and the outer ring raceway facing the cylindrical surface and the cylindrical surface The minimum oil film thickness between the surface and h is defined as h, and the contact force between the outer diameter surface of the cage and the outer ring raceway surface is defined by equation (1),
Using the following equation (1a) based on the fluid lubrication theory, the value of the contact force F and the oil film force W is obtained as equivalent values by using the following equation (1a) based on the fluid lubrication theory,
Where η is the viscosity, Pa · s, N ′ is the shaft speed, rps, L is the bearing width, m, c is the radial clearance, m, R is the bearing radius, m,
Obtain the combined surface roughness σ of the outer diameter surface of the cage and the outer ring raceway surface facing the outer diameter surface of the cage,
The relationship between the minimum oil film thickness h and the rotational speed of the crankshaft is expressed by equation (2),
In the formula (2), when the minimum oil film thickness h is equal to the synthetic surface roughness σ between the outer diameter surface of the cage and the outer raceway surface facing the outer diameter surface of the cage, the width dimension b The minimum width dimension b ₁ is obtained, and the width dimension b of the cylindrical surface is set to be equal to or greater than the minimum width dimension b ₁ .
The synthetic surface roughness is a total value obtained by adding a value obtained by squaring the root mean square surface roughness (Rq) of the outer ring raceway surface to the square mean surface roughness (Rq) of the outer ring raceway surface. This is synonymous with the roughness calculated by taking the square root of the total value.

According to this configuration, determining the minimum oil film thickness h, determining the minimum width b ₁ of the minimum oil film thickness h is equal to the synthetic surface roughness sigma, the width b of the cylindrical surface of the minimum width b ₁ Since the lower limit is set, the oil film forming property is improved, the wear of the cage and the bearing ring can be suppressed, and the life of the bearing can be extended. That is, based on a report by Muraki et al. (See Non-Patent Document 1) that the amount of wear rapidly increases when the value obtained by dividing the minimum oil film thickness h by the synthetic surface roughness σ is smaller than 1, that is, h / σ <1. And 1 ≦ h / σ. Further, the structure of the cage can be simplified and the degree of freedom in design can be increased as compared with the case where an oil sump is provided in a part of the conventional cage. Therefore, the manufacturing cost can be reduced.

In this inventions, in the formula representing the relation between the width b of one side of the cage outer diameter as the previous SL minimum oil film thickness h (2), the minimum oil film thickness h is, and the cage outer diameter surface this The width dimension b when the outer ring raceway surface facing the cage outer diameter surface is equal to the composite surface roughness σ is defined as the minimum width dimension bmin. In the above formula (2), the minimum oil film thickness h is the width b of the case where the cage outer diameter surface and three times the combined surface roughness σ of the outer ring raceway surface that faces to the cage outer diameter surface and the maximum width bmax., the width of the front Symbol cylindrical surface The dimension b may be set to be not less than the minimum width dimension bmin. And not more than the maximum width dimension bmax .

According to this configuration, in the above equation (2), the width dimension b of the cylindrical surface is expressed in the form of an implicit function of the minimum oil film thickness h. Since it cannot be expressed in the form of an explicit function with respect to the minimum oil film thickness h, it is necessary to perform convergence calculation in order to obtain the minimum oil film thickness h under specific conditions. Rather than calculating the oil film pressure, the minimum oil film thickness h can be estimated easily. Further, since the minimum width dimension bmin. In which the minimum oil film thickness h is equal to the synthetic surface roughness σ is obtained, and this minimum width dimension bmin. Is set as the lower limit value of the width dimension of the cylindrical surface, the oil film forming property is improved. In addition, the wear of the cage and the bearing ring can be suppressed, and the life of the bearing can be extended.
Here, when 1 ≦ h / σ ≦ 3, the wear amount decreases as h / σ increases, but the wear amount hardly changes when 3 <h / σ. When the width dimension b is increased, the roller length decreases and the load capacity of the bearing decreases. When 3 <h / σ, there is no merit in reducing the amount of wear and there is only a demerit in reducing the load capacity. Therefore, the maximum width dimension bmax. Where the minimum oil film thickness h is three times the synthetic surface roughness σ is obtained. The maximum width dimension bmax. Was set to the upper limit value of the width dimension of the cylindrical surface. Other operations and effects similar to those of the first invention are provided.

  The cross section of the cage viewed by cutting along an axial plane may be substantially gate-shaped or substantially M-shaped. When the substantially gate-shaped cross-sectional shape is used, a cage that has excellent column strength and does not fall off can be realized. When the substantially M-shaped cross-sectional shape is used, the shape can be simplified and a cage that does not fall off can be realized.

  It is good also as a holder | retainer by which a pocket is punched and manufactured by a press process. It is manufactured by punching a pocket in a band-shaped member by pressing, rounding it into a ring shape with one end and the other end in the longitudinal direction facing each other, and welding and joining the one end and the other end in the longitudinal direction. It is good also as a cage. In these cases, the manufacturing cost of the cage can be reduced. In the finishing process of the outer diameter surface of the cage, grinding may be used.

  At least the cylindrical surface of the cage may be subjected to soft metal plating treatment or resin coating treatment. As the soft metal, silver or copper is often used. As the resin film, polyamideimide or the like is preferable in terms of heat resistance and wear resistance. When the cylindrical surface is subjected to a soft metal plating treatment or a resin coating treatment, it has excellent conformability between the outer diameter surface of the cage and the outer raceway surface (improvement of surface roughness). This is especially effective in applications where this is a problem.

The cage design method of the present invention is formed in a substantially cylindrical shape having a plurality of pockets for holding rolling elements, and in the cage design method for crank motion, among the substantially cylindrical cage outer diameter surfaces, The minimum oil film thickness between the cylindrical surface and the outer ring raceway surface facing the cylindrical surface is defined as b, where b is a width dimension on one side of the circumferentially continuous cylindrical surface formed on both sides of the pocket in the cage axial direction. And the relationship between the minimum oil film thickness h, the crank radius r _cr and the crank angular velocity w _cr is expressed by equation (3),
A step of obtaining the minimum oil film thickness h based on the formula (3), a step of obtaining a composite surface roughness σ of the cage outer diameter surface and an outer ring raceway surface facing the cage outer diameter surface , in the above following formula (3) representing the relation between the width b of one side of the minimum oil film thickness h and the retainer outer diameter, the minimum oil film thickness h is, the cage outer diameter surface and the cage outer diameter surface the minimum width dimension the width b of the case before Symbol synthetic surface ing equal to roughness σ of the outer ring raceway surface facing the bmin. and then, in the above formula (3), the minimum oil film thickness h is, the retainer the method comprising the width b of the case where the outer diameter surface and ing tripled before Symbol synthetic surface roughness σ of the outer ring raceway surface that faces to the cage outer diameter surface and the maximum width bmax., said cylindrical surface The width dimension b is set to be not less than the minimum width dimension bmin. And not more than the maximum width dimension bmax., And the minimum width dimension bmin. And the maximum width dimension bmax. Those having.

  According to this configuration, in particular, the minimum oil film thickness h determined based on the formula (3) is determined to obtain the minimum width dimension bmin. That is equal to the synthetic surface roughness σ, and the minimum oil film determined based on the formula (3) above. Since the maximum width dimension bmax. In which the thickness h is three times the synthetic surface roughness σ was determined and the lower limit value and the upper limit value of the width dimension of the cylindrical surface were set, the oil film forming property was improved, The wear of the bearing ring can be suppressed, the bearing life can be extended, and the load capacity of the bearing can be minimized. In addition, the same operations and effects as the first and second inventions are exhibited.

A rolling bearing cage of the present invention is a rolling bearing cage incorporated at the connecting rod large end, and is a substantially cylindrical shape having a plurality of pockets for holding rolling elements. The width dimension of one side of the cylindrical surface continuous in the circumferential direction formed on both sides in the cage axial direction of the pocket among the outer diameter surfaces of the cage is b, and the outer ring raceway facing the cylindrical surface and the cylindrical surface The minimum oil film thickness between the surface and h is defined as h, and the contact force between the outer diameter surface of the cage and the outer ring raceway surface is defined by equation (1),
Using the following equation (1a) based on the fluid lubrication theory, the value of the contact force F and the oil film force W is obtained as equivalent values by using the following equation (1a) based on the fluid lubrication theory,
Where η is the viscosity, Pa · s, N ′ is the shaft speed, rps, L is the bearing width, m, c is the radial clearance, m, R is the bearing radius, m,
Obtain the combined surface roughness σ of the outer diameter surface of the cage and the outer ring raceway surface facing the outer diameter surface of the cage,
The relationship between the minimum oil film thickness h and the rotational speed of the crankshaft is expressed by equation (2),
In the formula (2), when the minimum oil film thickness h is equal to the synthetic surface roughness σ between the outer diameter surface of the cage and the outer raceway surface facing the outer diameter surface of the cage, the width dimension b The minimum width dimension b ₁ is determined, the width dimension b of the cylindrical surface is set to be equal to or greater than the minimum width dimension b ₁ , and the lubrication state of the outer diameter surface of the cage and the inner diameter surface of the bearing ring is improved. In addition, the friction and wear of the bearing ring can be reduced, and the applicable operating limit can be improved.

The cage design method of the present invention is formed in a substantially cylindrical shape having a plurality of pockets for holding rolling elements, and in the cage design method for crank motion, among the substantially cylindrical cage outer diameter surfaces, The minimum oil film thickness between the cylindrical surface and the outer ring raceway surface facing the cylindrical surface is defined as b, where b is a width dimension on one side of the circumferentially continuous cylindrical surface formed on both sides of the pocket in the cage axial direction. The relationship between the minimum oil film thickness h, the crank radius r _cr and the crank angular velocity ω _cr is expressed by equation (3).
A step of obtaining the minimum oil film thickness h based on the formula (3), a step of obtaining a composite surface roughness σ of the cage outer diameter surface and an outer ring raceway surface facing the cage outer diameter surface , in the above following formula (3) representing the relation between the width b of one side of the minimum oil film thickness h and the cage outer diameter, the minimum oil film thickness h is, the cage outer diameter surface and the cage outer diameter surface the minimum width dimension the width b of the case before Symbol synthetic surface ing equal to roughness σ of the outer ring raceway surface facing the bmin. and then, in the above formula (3), the minimum oil film thickness h is, the retainer the method comprising the width b of the case where the outer diameter surface and ing tripled before Symbol synthetic surface roughness σ of the outer ring raceway surface that faces to the cage outer diameter surface and the maximum width bmax., said cylindrical surface The width dimension b is set to be not less than the minimum width dimension bmin. And not more than the maximum width dimension bmax., And the minimum width dimension bmin. And the maximum width dimension bmax. Therefore, by setting the width dimension excluding the pocket width on the outer diameter surface of the cage, and suppressing the decrease in the load capacity of the bearing, the lubrication state of the outer diameter surface of the cage and the inner surface of the bearing ring is improved. It is possible to reduce the friction and wear of the vessel and the race, and to improve the applicable operating limit.

An embodiment of the present invention will be described with reference to FIGS.
This embodiment is applied to a needle bearing (needle roller bearing) used at the connecting rod large end. In this embodiment, the needle bearing retainer is applied. However, the present invention is not necessarily limited to the needle bearing retainer. For example, it can be applied to a cage of a cylindrical roller bearing. In addition, the following description also includes the description about the design method of a holder | retainer.
This needle bearing has a cage 15A (15B) and a plurality of rolling elements T. As shown in FIG. 2, the needle bearing NJ according to the present embodiment is provided in the fitting hole CRa of the connecting rod large end CR. The connecting rod large end portion CR in which the fitting hole CRa is formed serves as a race ring, that is, an outer ring, and the inner diameter surface of the fitting hole CRa corresponds to the outer ring raceway surface. The needle bearing according to this embodiment does not have a raceway as a constituent feature. However, the raceway may be a constituent requirement in applications other than the connecting rod. A cross section of the cage 15A (15B) viewed by cutting along an axial plane is substantially M-shaped as shown in FIG. 1 (A) or substantially portal-shaped as shown in FIG. 1 (B). However, the substantially M shape includes an M shape, and the approximate gate shape includes a gate shape.

  In the cage under the crank motion, the outer diameter surface of the cage comes into contact with the inner diameter of the connecting rod large end by centrifugal force. As a result of calculating the contact force at this time by a dynamics calculation program to be described later under the following assumptions (i) to (ix), the interference force F between the cage and the outer ring as shown in FIG. It became clear that it was almost equal to (1). In FIG. 3, the dimensions of the needle bearing indicate the inner diameter circle diameter φ26 mm, the outer diameter circle diameter φ33 mm, the width 13.8 mm, 16 rollers, the engine specifications: the displacement of 125 cc, and the interference force F in a single cylinder. The interference force F is synonymous with forces that interfere with each other including a frictional force component.

The assumption conditions will be described.
(I) Rollers, cages and connecting rods have three degrees of freedom (two translational displacements and one degree of angular freedom).
(Ii) The piston has only translational freedom in the reciprocating direction. However, the connecting rod is joined at its small end by a smooth rotary joint.
(Iii) The center of the crank is fixed and rotates at a constant angular velocity.
(Iv) A load due to in-cylinder pressure acts on the piston.
(V) Consider elastic deformation of the cage. However, only deformation modes that are plane-symmetric with respect to the radial plane at the center of the bearing are considered.
(Vi) The contact force at each interference portion between the roller and raceway surface, between the roller and cage, and between the cage and raceway surface conforms to the elastic contact theory.
(Vii) Traction characteristics conform to Muraki's formula (see Non-Patent Document 1).
(Viii) The rolling viscous resistance (see Non-Patent Document 2) due to the EHL oil film exists at the contact portion between the roller and the raceway surface.
(Ix) The lubrication mode of the contact part between the outer diameter part of the cage and the outer ring raceway and between the cage pillar and the roller is assumed to be boundary lubrication.

The dynamic calculation program and the like will be described.
The dynamic analysis system of the cage stress of the three-dimensional rolling bearing can be applied to various rolling bearings. However, in the three-dimensional dynamic analysis, since all the six degrees of freedom of each part and the three-dimensional degree of freedom of elastic deformation of the cage are simultaneously numerically integrated, the calculation cost is high. By the way, in a needle bearing, a cylindrical roller bearing, etc., there are cases where it is desired to handle only the behavior of an object on a radial plane. In this case, the dynamic analysis considering all the three-dimensional degrees of freedom is not efficient. In addition, although the degree of freedom of movement of the rigid parts can be easily constrained, it is difficult to constrain the axial displacement of the cage handled as an elastic body and the angular displacement around two axes excluding rotation.

Therefore, in the dynamic analysis program for the cage stress of the rolling bearing according to the present embodiment, the degree of freedom of elastic deformation of the cage is limited to two dimensions, and the degree of freedom of motion of the rolling elements and the races is also two-dimensional. By limiting to the above, the processing amount required for numerical integration is reduced. As a result, the calculation of the cage stress of the rolling bearing can be completed in a shorter time than in the case of performing the three-dimensional analysis.
As shown in FIG. 4, the cage stress analysis system 1 in which the dynamic analysis program is stored includes an input unit 2, a calculation unit 3, and an output unit 4. The calculation means 3 is provided with a dynamic analysis model of a rolling bearing in which the bearing component is regarded as a rigid body, and the dynamic elastic deformation characteristics of the cage can be input to the dynamic analysis model based on a mode synthesis method. The dynamic analysis characteristics are included by simultaneously numerically integrating the analysis model setting unit 3a, the degree of freedom of elastic deformation input by the analysis model setting unit 3a, and the degree of freedom of movement of the predetermined bearing components. A stress calculation unit 3b that calculates a deformation history of the cage, converts the calculated deformation history into a stress distribution, and an output processing unit that outputs the cage stress converted by the stress calculation unit 3b to the output unit 4. 3c, and is configured to limit the degree of freedom of elastic deformation of the cage and the motion of the rolling element, the raceway, and the rigid body mode of the cage to two dimensions.

  4A and 4B are block diagrams showing an electrical configuration of the stress analysis system according to the embodiment of the present invention. The stress analysis system 1 mainly includes an input unit 2, a calculation unit 3, and an output unit 4. The input unit 2 is realized by, for example, a keyboard or a pointing device. The calculation means 3 includes an analysis model setting unit 3a, a stress calculation unit 3b, and an output processing unit 3c. The analysis model setting unit 3a sets the above-described dynamic analysis model, and inputs the dynamic elastic deformation characteristics (natural deformation mode and its frequency) of the cage based on the mode synthesis method to the dynamic analysis model. It is possible.

  The stress calculation unit 3b includes deformation dynamic characteristics by simultaneously numerically integrating the degree of freedom of elastic deformation input by the analysis model setting unit 3a and the degree of freedom of movement of the predetermined bearing component (roller). It has a deformation history calculation unit 3ba that calculates the deformation history of the cage, and a stress distribution conversion unit 3bb that converts the calculated deformation history into a stress distribution. The output processing unit 3c outputs the stress distribution converted by the stress distribution conversion unit 3bb to the output unit 4. The computing means 3 is, for example, a micro that includes a central processing unit 5 (abbreviated as CPU: Central Processing Unit), a read only memory 6 (abbreviated as ROM: Read Only Memory), and a random access memory 7 (abbreviated as RAM: Random Access Memory). It has a computer, a bus 8, an input / output interface 9, and a drive circuit 10 for driving the output means 4.

  CPU 5, ROM 6, and RAM 7 are electrically connected to the input / output interface 9 via the bus 8. The input means 2 is electrically connected to the input / output interface 9, and the output means 4 is electrically connected via the drive circuit 10. The output unit 4 is realized by, for example, a display or a printer capable of display output. For example, the ROM 6 stores a program for calculating the deformation history of the cage including the above-described dynamic characteristics of the deformation, and converting the calculated deformation history into a stress distribution. The RAM 7 temporarily stores input values, calculated values, and the like. Arithmetic is executed with the CPU 5 as the controlling entity.

  According to this configuration, dynamic elastic deformation characteristics of the cage are introduced into the dynamic analysis model based on the mode synthesis method, and the degree of freedom of elastic deformation and the degree of freedom of motion of the bearing components are numerically integrated simultaneously. Thus, the deformation history of the cage including the dynamic characteristics of the deformation can be obtained. Cage stress can be obtained based on the deformation history. In particular, the structure that restricts the elastic deformation of the cage and the motion of the rolling element, the raceway, and the rigid body mode of the cage to two dimensions in a shorter time than the case of the three-dimensional analysis. Calculation results can be obtained.

Next, a method for calculating the oil film thickness of the outer diameter portion of the cage will be described.
As shown in FIG. 1, the outer diameter portion 11 of the cage is classified into a pocket column portion 12 that is formed at regular intervals in the circumferential direction, that is, an intermittent pocket column portion 12 and a cylindrical portion 13 that is continuous in the circumferential direction. Is done. The oil film generated in the pocket column 12 was calculated using a numerical calculation program for obtaining the oil film pressure based on the Ray Nozzle equation, but the effect was not recognized.
On the other hand, the oil film produced in the cylindrical portion 13 has a relatively large load capacity. Therefore, the width dimension b of the cylindrical portion 13 may be determined by paying attention only to the minimum oil film thickness in the cylindrical portion 13 continuous in the circumferential direction. This width dimension b is the remaining width dimension of the cylindrical surface of the cylindrical part 13 excluding the width dimension Lc of the chamfered part 13c.

As described above, with the aid of the numerical calculation program, it is possible to obtain the minimum oil film thickness h at which the force by the oil film based on the fluid lubrication theory balances with the load on the cage outer diameter portion 11 of Equation (1). A width dimension b ₁ is determined such that the minimum oil film thickness h is equal to the combined surface roughness σ of the cage outer diameter surface 11A and the outer ring raceway surface 14 opposed thereto. If the width dimension b ₁ is set as the minimum width dimension, the ratio of the load supported by the oil film increases, so that the wear of the outer diameter surface 11A of the cage can be reduced.
The synthetic surface roughness σ is a sum obtained by adding a value obtained by squaring the root mean square surface roughness (Rq) of the outer ring raceway surface 14 to a value squared by the root mean square surface roughness (Rq) of the cage outer diameter surface 11A. It is the roughness which calculated | required the value and calculated by taking the square root of this total value. Specifically, when the root mean square surface roughness (Rq) of the cage outer diameter surface 11A is α (μm) and the root mean square surface roughness (Rq) of the outer ring raceway surface 14 is β (μm), the synthetic surface roughness. σ is obtained by √ (α ² + β ² ).
As will be described later, when the crank rotational speed increases, the minimum oil film thickness h of the retainer outer diameter surface 11A decreases. What is necessary is just to determine a width dimension.

  By the way, generally, the width-diameter ratio of the main cylindrical portion 13 in the cage is small. That is, the ratio of the width dimension of the cylindrical portion 13 to the entire width dimension L of the cage is small. In that case, it is considered that the force by the oil film, that is, the minimum oil film thickness h can be calculated based on the infinitesimal width bearing theory (see Non-Patent Document 3). The force by the oil film is represented by the following formula (2). The application condition of the infinitesimal width bearing theory is when the ratio of the width dimension to the cage diameter dimension D is 0.25 or less (see Non-Patent Document 3).

The crankpin corresponds to the inner ring raceway of the rolling bearing, and the inner ring raceway rotates with the crankshaft at a crankshaft rotational speed ω _cr . Normally, the cage of the rolling bearing that rotates on the inner ring rotates at a speed approximately 0.4 times the inner ring, and therefore the cage of the needle bearing at the large end of the connecting rod also has a crankshaft rotational speed ω _cr of about 0. Rotate at 0.4ω _cr multiplied by 4.
By the way, the contact between the cage 15A (15B) and the raceway is constantly generated in the cage outer diameter portion 11 radially outward from the center of the crank due to centrifugal force. Therefore, when the inertial coordinate system is used as a reference, the crank angular velocity ω It is rotating at _cr . Looking at the contact position between the cage outer diameter surface 11A and the outer ring raceway surface 14 as a reference, the cage 15A (15B) moves at about −0.6ω _cr and the outer ring 16 moves at −ω _cr .

In the above formula (2), since the force of the oil film of the cage outer diameter portion 11 is proportional to the sum of the surface velocities, the shaft rotational speed N ′ = 1.6ω _cr / 2π may be set.
For the above formula (2), the bearing width L is the width b of the cage 15A (15B), the bearing radius R (not shown) is half the cage outer diameter D, N ′ = 1.6Ω. _If 1/2 of the cage load according to the above equation (1) is substituted for _cr / 2π and the oil film force, the cylindrical portion 13 on one side in the axial direction of the cage 15A (15B) and the outer ring 16 that is the raceway ring The relationship between the minimum oil film thickness existing between and the rotation speed of the crankshaft is obtained, and the following equation (3) is obtained.

In the equation (3), when only the width dimension b is left on the left side, the equation (4) is obtained.

  In the above equation (4), the width dimension b is expressed in the form of an implicit function of the minimum oil film thickness h. Since an expression cannot be expressed in the form of an explicit function with respect to the minimum oil film thickness h, it is necessary to perform a convergence calculation to obtain the minimum oil film thickness h under specific conditions. However, according to the above equation (4), the minimum oil film thickness h can be estimated more easily than calculating the oil film pressure by the above-described numerical calculation program. Therefore, the width dimension b can be easily obtained. The obtained width dimension b is output by the output means 4 of FIG.

FIG. 5 shows a calculation example of the minimum oil film thickness h of the cage outer diameter portion 11 with respect to the crank rotation speed according to the above equation (4). This will be described with reference to FIG. Since the load on the outer diameter surface 11A of the cage increases due to the increase in the crank rotation speed, the minimum oil film thickness h decreases. It can also be seen that the minimum oil film thickness h is large when the width dimension b of the continuous cylindrical portion 13 of the cage outer diameter surface 11A is large. Specifically, under the conditions of the lubricant viscosity grade ISO VG22 130 ° C., the radial clearance between the cage outer diameter surface 11A and the outer ring raceway surface 0.1 mm, for example, when the crank rotation speed is 2000 rpm, the width dimension b is 1 In the case of 0.0 mm, the minimum oil film thickness h is about 0.26 μm. Under the same conditions, when the crank rotation speed is 2000 rpm, the minimum oil film thickness h is about 0.74 μm when the width dimension b is 2.0 mm.
Therefore, if an appropriate width dimension b of the cage 15A (15B) is selected at the maximum rotation speed of the crankshaft, an oil film always exists between the cage 15A (15B) and the outer ring 16, and the cage 15A ( 15B) and the wear of the outer ring 16 can be reduced.

The validity of the above equation (4) will be described.
FIG. 6, FIG. 7 and Table 1 show the results of visual confirmation of wear of the outer diameter surface 11A of the cage by changing some of the width dimension b of the cage 15B in a test apparatus that performs crank motion simulating an engine. . The operating conditions were a rotational speed of 5000 rpm, a test time of 1 hour, and lubricating oil viscosity grade ISO VG22 was applied. The cages 15B subjected to the test are all made of steel and have no surface coating. The number of tests is two for each of the same width dimension b.

When the annular width, that is, the width dimension b of the cage 15B is 2.2 mm as shown in FIG. 6 (a), no wear marks were observed on the outer diameter surface 11A of the cage. In Table 1, this state is indicated as “◎” as the cage wear state. Minor wear was observed when the width dimension b was 1.8 mm, and this state was indicated as “◯” as the cage wear state in Table 1. In the case where the width dimension b is 1.5 mm, adhesive wear is partially recognized, and this state is indicated as “Δ” in Table 1 as the cage wear state. When the width dimension b was 1 mm, severe adhesive wear was observed over almost the entire width of the annular portion, and this state was indicated as “x” in Table 1 as the cage wear state.
According to this test result, with the increase in the width dimension b of the cage 15B, wear marks that can be visually confirmed on the outer diameter surface 11A of the cage decreased. From this experiment, it was confirmed that the retainer 15A (15B) of the actual connecting rod large end needle bearing also increased the oil film thickness of the outer diameter surface 11A of the cage due to the increase in the width dimension b of the cage 15A (15B). it can.

Further, when the cage was operated under the outer ring stationary condition and the metal contact rate was measured during that time, it was as shown in FIG. In FIG. 8, the horizontal axis film thickness ratio is obtained by dividing the minimum oil film thickness h obtained based on the above equation (2) by the measured roughness σ of the cage outer diameter surface 11A and the outer ring raceway surface 14 measured. Is. The metal contact ratio on the vertical axis is the applied voltage V _I , the potential difference between the outer ring and the cage is V _B ,

Is defined as follows.
When the film thickness ratio is “3” or more, the metal contact ratio is almost constant at 10% or less. However, when the film thickness ratio is less than “3”, the metal contact ratio increases rapidly and greatly varies with respect to the film thickness ratio. There was almost no linear change. The synthetic surface roughness σ is a standard deviation of the projection height of the surface roughness. When the minimum oil film thickness h exceeds three times the synthetic surface roughness σ, the cage 15A (15B) is almost stochastically. And the outer ring 16 should not come into contact with each other. The metal contact rate measurement results are in good agreement with this finding.
From the two test results shown in FIGS. 6, 7, and 8, it is considered that the oil film thickness of the retainer outer diameter surface 11 </ b> A substantially matches the above formula (4).

  In the above equation (4), the width b of the cylindrical surface is expressed in the form of an implicit function of the minimum oil film thickness h. Since it cannot be expressed in the form of an explicit function with respect to the minimum oil film thickness h, it is necessary to perform convergence calculation in order to obtain the minimum oil film thickness h under specific conditions. Rather than calculating the oil film pressure, the minimum oil film thickness h can be estimated easily.

  The minimum width bmin. Where the minimum oil film thickness h obtained by the above equation (4) is equal to the composite surface roughness σ is obtained, and the minimum oil film thickness h obtained by the above equation (4) is the synthetic surface roughness. The maximum width dimension bmax. that is three times σ is obtained. If the width dimension b of the cylindrical surface of the cage 15A (15B) is set to the minimum width dimension bmin. Or more, the load supported by the oil film increases, wear is reduced, and the maximum width dimension bmax. For example, the load can be almost completely supported by the oil film, and a decrease in the load capacity of the bearing can be minimized, so that the life of the bearing can be extended. When the crank rotational speed is increased, the minimum oil film thickness h of the retainer outer diameter surface 11A is decreased. Therefore, the minimum rotational width bmin. Must be determined for the crank rotational speed using the use limit speed.

The cage 15 </ b> A (15 </ b> B) described above is made of steel and has no surface coating or the like. As another embodiment of the present invention, the surface of the cage may be subjected to soft metal plating treatment or resin coating treatment. As the soft metal, silver or copper is applied. For example, a cage with an outer diameter of 32.9 mm with copper plating on the cage surface, a bearing width of 13.8 mm, a width dimension b = 1.475 mm, and a surface roughness of about 0.4 μm is incorporated at the connecting rod large end, and crank rotation The roughness of the contact portion of the cage outer diameter portion 11 and the connecting rod large end inner diameter after operating at several 10000 rpm for 5 hours was approximately 0.15 μm and 0.07 μm, respectively. Therefore, the synthetic surface roughness σ is obtained as √ (0.15 ² +0.07 ² ) = 0.17 μm.

  Since the surface roughness of soft metal plating is easily reduced by contact, the width dimension b where the minimum oil film thickness h of the outer diameter surface 11A of the cage is 0.17 μm is set to the lower limit regardless of the roughness during manufacture. bmin. As an upper limit value bmax. Of the width dimension b, 0.25D which is an application limit of the infinitesimal width bearing theory is adopted. Alternatively, “0.51” that is three times 0.17 μm obtained as the combined surface roughness σ is employed as the upper limit value bmax of the width dimension b. Adopting such lower and upper limits of the width dimension b is preferable in terms of wear resistance.

As the resin coating, polyamideimide or the like is preferable in terms of heat resistance and wear resistance. However, the resin coating is not limited to polyamideimide.
As described above, when the retainer 15A (15B) is subjected to a soft metal plating process or a resin coating process, the conformability between the retainer outer diameter surface 11A and the outer ring raceway surface 14, that is, the surface roughness is excellent. . For this reason, it is particularly effective in applications where wear of the cage outer diameter portion 11 becomes a problem. In this embodiment, the entire cage 15A (15B) is subjected to a soft metal plating process or a resin film process, but the present invention is not limited to this form. For example, only the cylindrical surface of the cage outer diameter surface 11A may be subjected to a soft metal plating process or a resin coating process. As shown in FIG. 1, the cage side surface 11B and the cylindrical surface may be subjected to a soft metal plating process or a resin film process. Even in such a case, the same effects as described above can be obtained.

As shown in FIG. 1A, when the cage 15A has a substantially M-shaped cross section, the shape can be simplified and a cage that does not roll off can be realized. As shown in FIG. 1B, when the cage 15B has a substantially gate-like cross-sectional shape, a cage that has excellent column strength and does not fall off can be realized.
The cage 15A (15B) may be manufactured by punching the pocket Pt from the ring-shaped member by press working. By punching, the pocket Pt is punched into the band-shaped member, the longitudinal end of the band-shaped member is opposed to the other end and rounded into a ring shape, and the longitudinal end and the other end are welded to each other. It is good also as a cage to be used. Moreover, you may manufacture using a shaving process as needed. In these cases, the manufacturing cost of the cage can be reduced. Note that grinding may be used in the finishing process of the cage outer diameter surface 11A.
The rolling bearing cage 15A (15B) described above may be provided at a place where the crank motion is performed other than the large end of the connecting rod. In this case, the friction and wear of the cage 15A (15B) and the race can be reduced, and the applicable operating limit can be improved.

(A) It is sectional drawing of the retainer of the substantially M-shaped cross-sectional shape which concerns on one Embodiment of this invention, (B) It is sectional drawing of the retainer of the substantially portal-shaped cross-sectional shape which concerns on one Embodiment of this invention. is there. It is a top view of the connecting rod in which the same holder is assembled. It is a figure showing the interference force of the holder outer diameter surface with respect to a crankshaft rotational speed. (A) It is a block diagram which represents roughly the electrical structure of the stress analysis system which concerns on embodiment of this invention, and the block diagram which mainly represents the calculating means of the same stress analysis system. It is a figure showing the minimum oil film thickness of the holder outer diameter surface with respect to a crankshaft rotational speed. It is a figure showing the external appearance after the test of the cage | basket ring width under a crank motion, FIG. 6 (a) is a figure showing the external appearance with an annular width of 2.2 mm, FIG.6 (b) is an annular width of 1.8 mm. FIG. It is a figure showing the external appearance after a test of the cage ring width under the crank motion, FIG. 7 (a) is a view showing the external appearance with an annular width of 1.5 mm, and FIG. 7 (b) is the external appearance with an annular width of 1 mm. FIG. It is a figure showing the relationship between the film thickness ratio by the calculation of the outer diameter part of a holder | retainer in a stationary outer ring, and a metal contact rate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Cage outer diameter part 11A ... Cage outer diameter surface 13 ... Cylindrical part 14 ... Outer ring raceway surface 15A, 15B ... Cage 16 ... Outer ring b ... Width dimension

Claims (7)

A rolling bearing retainer incorporated into the connecting rod large end, wherein the retainer is formed in a substantially cylindrical shape having a plurality of pockets for retaining rolling elements.
The width dimension of one side of the cylindrical surface continuous in the circumferential direction formed on both sides in the cage axial direction of the pocket of the substantially cylindrical outer diameter surface of the pocket is b, and the cylindrical surface and the cylindrical surface The minimum oil film thickness between the opposing outer ring raceway surface is h,
The contact force between the outer diameter surface of the cage and the outer ring raceway surface is defined by equation (1),
Using the following equation (1a) based on the fluid lubrication theory, the value of the contact force F and the oil film force W is obtained as equivalent values by using the following equation (1a) based on the fluid lubrication theory,
Where η is the viscosity, Pa · s, N ′ is the shaft speed, rps, L is the bearing width, m, c is the radial clearance, m, R is the bearing radius, m,
Obtain the combined surface roughness σ of the outer diameter surface of the cage and the outer ring raceway surface facing the outer diameter surface of the cage,
The relationship between the minimum oil film thickness h and the rotational speed of the crankshaft is expressed by equation (2),
In the formula (2), when the minimum oil film thickness h is equal to the synthetic surface roughness σ between the outer diameter surface of the cage and the outer raceway surface facing the outer diameter surface of the cage, the width dimension b The minimum width dimension b ₁ is
The width b of the cylindrical surface, the cage of the rolling bearing which is set to the minimum width dimension b ₁ or more. In Claim 1, in said Formula (2) showing the relationship between the said minimum oil film thickness h and the width dimension b of one side of a cage outer diameter, the minimum oil film thickness h is the said cage outer diameter surface and this holding | maintenance. The width dimension b in the case where it is equal to the composite surface roughness σ with the outer ring raceway surface facing the outer diameter surface of the vessel is defined as the minimum width dimension bmin. In the formula (2), the minimum oil film thickness h is The width dimension b when the outer surface of the cage and the outer ring raceway surface facing the cage outer diameter surface is three times the synthetic surface roughness σ is the maximum width dimension bmax.
A rolling bearing cage in which a width dimension b of the cylindrical surface is set to a minimum width dimension bmin. Or more and a maximum width dimension bmax.   The rolling bearing retainer according to claim 1 or 2, wherein a cross section of the retainer cut along an axial plane is substantially a gate shape or a substantially M shape.   The rolling bearing retainer according to any one of claims 1 to 3, wherein a pocket is formed by punching a ring-shaped member by pressing.   The pocket according to any one of claims 1 to 3, wherein a pocket is punched into the band-shaped member by pressing, the one end and the other end in the longitudinal direction of the band-shaped member are opposed to each other, and are rounded into a ring shape. A rolling bearing cage manufactured by welding one end and the other end.   The rolling bearing retainer according to any one of claims 1 to 5, wherein at least the cylindrical surface of the retainer is subjected to a soft metal plating treatment or a resin coating treatment. In a method of designing a cage that is formed in a substantially cylindrical shape having a plurality of pockets that hold rolling elements and that performs a crank motion,
Of the substantially cylindrical cage outer diameter surface, the width dimension on one side of the circumferentially continuous cylindrical surface formed on both sides in the cage axial direction of the pocket is b, and the cylindrical surface and the cylindrical surface Where h is the minimum oil film thickness between the outer ring raceway surface facing
The relationship between the minimum oil film thickness h, the crank radius r _cr and the crank angular velocity ω _cr is expressed by equation (3),
Obtaining the minimum oil film thickness h based on the equation (3);
A process of obtaining a composite surface roughness σ of the cage outer diameter surface and the outer ring raceway surface facing the cage outer diameter surface;
In the above formula (3) representing the relationship between the minimum oil film thickness h and the width dimension b on one side of the cage outer diameter, the minimum oil film thickness h is applied to the cage outer diameter surface and the cage outer diameter surface. The width dimension b when the outer ring raceway surface facing the synthetic surface roughness σ is equal to the minimum width dimension bmin., And in the above equation (3), the minimum oil film thickness h is equal to the cage outer diameter surface. A process of setting the width dimension b to be the maximum width dimension bmax when the synthetic surface roughness σ of the outer ring raceway surface facing the outer diameter surface of the cage is three times the synthetic surface roughness σ;
Setting the width dimension b of the cylindrical surface to a minimum width dimension bmin. Or more and a maximum width dimension bmax. Or less, and outputting the minimum width dimension bmin. And the maximum width dimension bmax.
Method for designing a cage having