JPH09144761A - Ball bearing, and pulley and fan provided with the ball bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the abnormal noise in a pulley in a cold condition by improving the lubricating performance of grease in a cold condition. SOLUTION: A holder 2d is of Snap-On type formed by injection molding of the synthetic resin, and provided with a plurality of pockets 3 at equal intervals on the circumference. One side in the axial direction of the pockets 3 is an annular base part 4 and the other side in the axial direction of the pockets is an opening part 5. A peripheral edge of the pockets 3 is formed of a recessed spherical surface, and the pockets 3 are of the inclined shape from the annular base part 4 to the opening part 5 toward the axis.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ball bearing, a pulley and a fan having the bearing. This pulley is mainly locked to the timing belt of the engine of the automobile, the belt for driving the auxiliary equipment, etc., and the fan is
It means to forcibly cool the cooling water of the engine.

[0002]

2. Description of the Related Art Pulleys are arranged in a timing belt of an engine of an automobile, a belt for driving an auxiliary machine, or the like, in order to increase a winding angle of the belt and apply an appropriate tension to the belt. As the pulley, the pulley peripheral surface with which the belt contacts is provided directly on the outer diameter of the outer ring of the ball bearing (shade outer ring).
However, as shown in FIG. 6, a structure in which a pulley main body (11) having a pulley peripheral surface (11c) and a ball bearing (12) are integrally fitted is often used.

The pulley body (11) is made of a steel plate press and has an outer diameter cylindrical portion (11a) for hanging a belt and an inner diameter cylindrical portion (11b) into which the outer ring (12a) of the ball bearing (12) is fitted.
The pulley peripheral surface (11c) is provided at the outer diameter of the outer diameter cylindrical portion (11a). The ball bearing (12) includes an outer ring (12a) fitted to the inner diameter cylindrical part (11b) of the pulley body (11), an inner ring (12b) fitted to a fixed shaft (not shown), and inner and outer rings (12b). ),
Multiple balls (12
c), a retainer (12d) for holding the balls (12c), and a pair of seals (12e) for sealing the grease.

In this type of pulley, when the pulley body (11) rotates by receiving a rotational driving force from the belt, the outer ring (12a) of the ball bearing (12) fitted to the pulley body (11) rotates.
And rotate together.

In the pulley described above, a ball bearing (1
The retainer (12d) of 2) is a snap-on type made of synthetic resin, and holds the ball (12c) in a pocket whose peripheral edge is a concave spherical surface. The diameter of this pocket is usually
It is set by adding a pocket clearance of about 0.2 mm to 0.3 mm to the diameter D of the ball (12c), and the housed and held ball (12c) can freely roll.

[0006]

By the way, when the above pulley is operated in cold weather, a peculiar sound (whistling sound) may be generated depending on the pulley specifications and operating conditions.
This peculiar sound during cold weather, so-called abnormal noise during cold, does not always occur 100% in the market, is affected by temperature and the like, and occurs only in a very limited area in Japan (such as Hokkaido). In addition, it occurs in a very short time (about 1 minute even for a long one) from the start of the engine of the automobile, and then none. Since the abnormal noise during cold has such a complicated property and is difficult to reproduce, the cause of its occurrence has not been clarified yet. Moreover, since pulleys used in automobiles are driven at high temperature and high speed, and durability is one of the important characteristics, it is not possible to take measures to reduce durability. For these reasons, the actual situation is that at present, no effective means that is decisive as a measure against the abnormal noise when the pulley is cold is provided.

Conventionally, as a measure against abnormal noise during cold use, grease having excellent low temperature characteristics (an oil film is formed evenly in the contact portion between the ball and the raceways of the inner and outer rings even in cold weather) is used. Is being considered. This countermeasure is intended to suppress the generation of abnormal noise during cold by improving the lubrication performance of grease during cold weather, and can be expected to have a considerable effect. However, since the viscosity of the grease decreases, there is a concern about lubrication performance at high temperatures, which may lead to a decrease in durability.

Therefore, the present invention intends to provide a means capable of effectively suppressing or preventing the generation of abnormal noise at the time of cold, taking into consideration the durability and the cost while ensuring the function as a pulley. It is a thing.

[0009]

The applicant of the present invention has confirmed several phenomena shown below in a cold abnormal sound reproduction test. (1) The pulley (outer ring) vibrates in the axial direction when abnormal noise occurs in the cold state. Further, this frequency component coincides with the acoustic frequency of the cold noise. (2) This frequency component is not recognized when no abnormal noise is generated during cold. (3) The frequency component when the abnormal noise is generated in the cold is the pulley end face 18
It has the same phase at two fixed positions on the 0 ° side.

Although the mechanism of generation of abnormal noise during cold has not been completely clarified yet, from the above verification, the source of abnormal noise during cold is the bearing, and this is also due to the self-excited vibration of the ball. It is thought that That is, in cold weather, unevenness of the oil film on the raceway surface due to increase in viscosity of the base oil of the grease and decrease in consistency are likely to occur, which causes a minute periodic change in the friction coefficient between the ball and the raceway surface. Self-excited vibration occurs on the ball. Then, it is considered that such self-excited vibration of the ball is transmitted to the outer ring and an abnormal noise is generated. In addition, the self-excited vibration of the ball may be transmitted to the pulley main body through the outer ring, resonate with the natural vibration of the pulley main body, be amplified, and may be expanded as a resonance sound.

Based on the above reasoning, the present invention directs the pocket of the synthetic resin cage from the annular base to the opening in order to effectively suppress self-excited vibration of the ball as a measure against abnormal noise during cold. To gradually incline toward the axis.

The cage made of synthetic resin according to the present invention is a so-called snap-on type in which one side of the pocket in the axial direction is an annular base portion and the other side in the axial direction is an opening. The contraction displacement in the inner diameter direction on the opening side becomes slightly larger, and conversely, when the temperature rises, the expansion displacement in the outer diameter direction on the opening side becomes slightly larger than that in the annular base part. Due to such a temperature change on the opening side,
The displacement in the outer diameter direction occurs due to the difference in thermal displacement due to the difference in rigidity between the annular base and the opening in this type of shape. The present invention utilizes the displacement of the opening side due to the temperature change to elastically contact or bring the outer peripheral edge of the pocket of the cage into contact with or close to the ball at the time of cold start to maintain the behavior of the ball. While controlling the self-excited vibration of the ball by this device, it provides an appropriate pocket clearance during normal operation (when the bearing temperature rises) to ensure free rolling of the ball, which contributes to durability. The basic idea is to avoid unfavorable effects on the environment.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION A pulley shown in FIG. 1 is an idler pulley used for an accessory drive belt of an automobile, which is fitted to a pulley body (1) made of a steel plate press and an inner diameter of the pulley body (1). And a single row ball bearing (2). The pulley body (1) includes a cylindrical portion (1a), a flange portion (1b) extending from one end of the cylindrical portion (1a) to the outer diameter side, and an outer diameter cylindrical portion (1c) extending axially from the flange portion (1b). ), A ring body composed of a flange portion (1d) extending from the other end of the cylindrical portion (1a) to the inner diameter side.
The outer ring (2a) of the ball bearing (2) is fitted to the inner diameter of the cylindrical portion (1a), and the pulley circumferential surface (1e) where a belt (not shown) contacts the outer diameter of the outer diameter cylindrical portion (1c). ) Is provided. A belt (not shown) comes into contact with the peripheral surface (1e) of the pulley to serve as an idler.

As shown in FIG. 2, the ball bearing (2) has an outer ring (2) fitted to the inner diameter of the cylindrical portion (1a) of the pulley body 1.
a), an inner ring (2
b), a plurality of balls (2c) incorporated between the raceways of the inner and outer rings (2b), (2a), cages (2d) that hold the balls (2c) at equal intervals on the circumference, and grease It consists of a pair of seals (2e).

As shown in FIG. 3, the cage (2d) is of a so-called snap-on type formed by, for example, injection molding a synthetic resin, and has a plurality of pockets (3) at equidistant positions on the circumference. The pocket (3) has an annular base (4) on one side in the axial direction and an opening (5) on the other side in the axial direction. A space between the pockets (3) is partitioned by a pillar portion (7), and an opening (5) is formed by a pair of claws (6) extending in an arc shape from the tip of the pillar portion (7). The opening (5) is set smaller than the diameter of the ball (2c), and the claw (6) is formed thin so as to be elastically deformable. When assembled, the tips of the pair of claws (6) are pressed against the ball (2c) installed between the raceways of the inner and outer rings (2b) (2a), and the opening (5) is elastically moved by the ball (2c). The ball (2c) is accommodated in the pocket (3) while pushing it out. After the ball (2c) is housed, the retainer (2d) is prevented from falling off by the pair of elastically restored claws (6).

In this embodiment, the peripheral edge of the pocket (3) is drawn as a concave spherical surface, and the diameter of the pocket (3) is the usual value in this type of cage, that is, the ball (2
It is set by adding a pocket clearance of about 0.2 mm to 0.3 mm to the diameter D of c). However, the diameter of the pocket (3) is not limited to this, and may be optimally set according to usage conditions and the like.

As shown in FIG. 3 (b), the pocket (3) of the retainer (2d) has a shape inclined from the annular base (4) to the opening (5) toward the axis, and the pocket (3) is formed. The center O of the opening (5) is δ0 (design value: a value at normal temperature state) on the axial center side with respect to the center O ′ on the side of the annular base (4). Yes.) Is offset. As described above, in this type of retainer (2d), the contraction displacement in the inner diameter direction on the side of the opening (5) is slightly larger than that of the annular base portion (4) when the temperature decreases, and when the temperature rises, the annular shape The expansion displacement in the outer radial direction on the side of the opening (5) is slightly larger than that of the base (4). Since such a displacement on the side of the opening (5) occurs, the offset amount fluctuates according to the temperature change, and when the ball (2c) is housed in the pocket (3), the gap between the minimum value zero and the maximum value pocket clearance is about. It can be a value within the range. The general standard for determining the initial offset amount δ0 is the self-excitation of the ball, which causes cold noise at the time of cold start, from the viewpoint of achieving the trade-off requirements of suppressing cold noise and ensuring durability. The vibration can be effectively suppressed, and an appropriate pocket clearance can be provided to ensure the free rolling of the ball during normal driving. In this embodiment, as shown in FIG. As shown, at the time of cold start, the outer peripheral edge (3a) of the pocket (3) (particularly the tip region of the claw 6) elastically contacts the ball (2c) (offset amount δ), and during normal operation (illustration) In (omitted), the initial offset amount δ0 is set so that the maximum pocket clearance is secured (zero offset amount). This is set in consideration of the expansion / contraction displacement amount on the opening (5) side, the value of the pocket clearance, etc., which are determined by the material, shape, and dimensions of the cage (2d) and the operating temperature range.

At the time of cold start shown in FIG. 4, the outer peripheral edge (3a) of the pocket (3) elastically contacts the ball (2c) (offset amount δ), and the behavior of the ball (2c) changes. Since it is restrained by 2d), the self-excited vibration of the ball (2c) that causes the abnormal noise during cold is effectively suppressed. Further, during normal operation, the opening (5) side is displaced in the outer diameter direction, and the pocket (3) holds the ball (2c) at the neutral position (zero offset amount), so that the maximum pocket clearance is provided. Free rolling of 2c) is secured. Therefore, the durability of the bearing is not adversely affected. Even when the outer peripheral edge (3a) of the pocket (3) does not elastically contact the ball (2c) at the time of cold start, the self-excited vibration of the ball (2c) can be reduced by reducing the pocket clearance. Quite suppressed.

As the synthetic resin forming the cage (2d) as described above, for example, polyamide (PA), polyacetal (POM), polyether sulfone (PE) is used.
S), polyetheretherketone (PEEK), polyamideimide (PAI), polyetherimide (PE
I), polyphenylene sulfide (PPS), thermoplastic resin such as thermoplastic polyimide, phenol resin,
A thermosetting resin such as wholly aromatic polyimide (PI) can be used. However, from the viewpoint of ensuring durability, it has excellent mechanical properties, wear properties, and thermal properties, it can secure the necessary amount of displacement in the inner and outer radial directions on the opening (5) side, and the viewpoint of reducing manufacturing costs. Considering that it is desirable to be a material that is inexpensive and has excellent moldability, it is considered that among these synthetic resins, polyamide resin (PA) and polyether ether ketone resin (PEEK) are preferable. Polyamide resin (PA) is considered to be particularly preferred. Examples of the polyamide include polyamide 6, polyamide 6-6, polyamide 4-6, polyamide 6-10, polyamide 6-12, and polyamide 1.
1, polyamide 12, etc. can be used.

Further, in order to assist the lubrication with the internal grease, the polyamide resin may contain a fluorine resin or the like. When the cage (2d) and the ball (2c) come into contact with each other, a fluororesin transfer coating having good lubricity is formed on the surface of the ball (2c) or the like, so the ball (2c)
It is effective in preventing stick-slip that causes self-excited vibration of the. Examples of the fluorine-based resin include polytetrafluoroethylene resin (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin (PFA), tetrafluoroethylene-hexaprolopropylene copolymer resin (FEP),
Tetrafluoroethylene-ethylene copolymer resin (ET
FE), polychlorotrifluoroethylene resin (PCTF
E), polyvinyl fluoride resin (PVF), etc. can be used, and among them, PTFE, PFA, FE
P and ETFE are desirable, and among these, PTFE (dynamic friction coefficient 0.10) having the lowest friction coefficient is particularly desirable.

Further, various fillers may be blended within a range that does not impair the effects of the present invention. Fillers include glass fiber, carbon fiber, aramid fiber, potassium titanate whisker, wollastonite, aluminum borate whisker,
Reinforcing material such as calcium sulfate whisker, inorganic powder such as molybdenum disulfide, graphite, carbon, calcium carbonate, talc, mica, kaolin, iron oxide, glass beads, phosphate compound, polyimide resin, aromatic polyester resin, polyether Various fillers such as resin powder such as ketone resin, polyphenylene sulfide resin, and silicone resin, and internal lubricant such as silicone oil, fluorine oil, wax, and stearic acid compound can be exemplified. Retainer (2d) depending on the filling ratio of the reinforcement material
In addition to adjusting the mechanical strength and the like, the amount of displacement (offset amount) on the side of the opening (5) can also be adjusted (since the linear expansion coefficient of the material changes depending on the mixing ratio of the filler).

As a method of molding the above polyamide resin,
Although various known molding methods such as injection molding, extrusion molding, monomer casting, and powder molding can be adopted, injection molding is preferable in consideration of low cost, work efficiency, and the like. Further, heat treatment and heat treatment may be performed after the molding. The heat treatment is performed to relieve the residual stress of the molded product, enhance dimensional stability, enhance crystallinity, and enhance mechanical properties. As the heat treatment agent, water, liquid paraffin, quenching oil or the like can be used. The tempering treatment is a treatment for forcibly absorbing water up to the equilibrium water content in a short time in order to enhance dimensional stability. It is recommended to use boiling water or an aqueous solution of potassium acetate.

By the way, the above-mentioned abnormal noise during cold may occur not only in the pulley but also in the cooling fan for forcibly cooling the cooling water of the radiator. As shown in FIGS. 7 (a) and 7 (b), the fan (30) has a plurality of blades (31) radially mounted around an annular case (rotating member) (35). Ball bearing (32) outer ring (32
It is fitted to a) and is rotatably attached to a main shaft (33) driven by an engine (for example, bolted to a flange portion such as a pump shaft). A temperature-compatible clutch mechanism (3) that switches between transmission and disconnection between the main shaft (33) and the fan (30) according to changes in the outside air temperature.
4) is interposed, and torque is transmitted from the main shaft (33) to the fan (30) via the clutch mechanism (34). One structural example of the clutch mechanism (34) will be described below.

A drive disk (36) which rotates integrally with the main shaft (33) is fitted and fixed to the tip of the main shaft (33). A disk-shaped plate (37) is arranged on the tip side of the drive disk (36).
Forms a first chamber (39) serving as a torque transmission chamber with the case (35). Between the plate (37) and the cover (38), oil (a viscous fluid for torque transmission:
The second chamber (40), which serves as a reservoir for silicon oil, etc.
A leaf spring (42) having a valve (41) attached to one end and the other end fixed to a plate (37) is arranged in the second chamber (40). Cover (38)
A bimetal (43) is fixed to the bimetal (43), and a piston (44) is attached to the bimetal (43) so as to match the axis (OO) of the main shaft (33).

In the above construction, when the outside air temperature is low, the bimetal (43) hardly bends as shown in FIG. 7 (a), so that the piston (44) presses the leaf spring (42) to the right in the drawing. ing. At this time, the valve (41) attached to the leaf spring (42) penetrates the hole (45) provided in the outer diameter portion of the plate (37), and is inserted into the front surface of the drive disk (36) in the first chamber (39). We are in pressure contact. As shown in FIG. 8, the hole (45) includes an insertion hole (45a) and a flow hole (45b) continuous with the insertion hole (45a), and the valve (41) has an insertion hole (45).
a). Since there is always a relative speed between the drive disk (36) and the case (35) side, that is, between the valve (41), the oil (spray) between the drive disk (36) and the plate (37) (Shown by dots) is swept out by a valve (41) serving as a weir, and sent into the second chamber (40) through the flow hole (45b). In this state, most of the oil in the first chamber (39) enters the second chamber (40), and only a very small amount of oil remains in the first chamber (39). The rotation speed of the fan (30) decreases. The arrow in FIG. 8 indicates the direction of rotation of the drive disk (36).

When the outside air temperature is high, as shown in FIG.
Since the bimetal (43) bends, the valve (41) moves to the left side of the drawing, and the piston (4) moves due to the elasticity of the leaf spring (42).
4) escapes from the hole (45). Therefore, the above-mentioned scraping action is eliminated, and the oil in the first and second chambers (39) (40) becomes the same oil level through the hole (45). At this time,
Since the oil is filled in the effective transmission surface of the first chamber (39), a predetermined torque is transmitted, and the rotation speed of the fan (30) increases.

In the above fan (30), the ball bearing (3
Ball cage (2) cage (2)
If a structure similar to that of d) is adopted, it is possible to reliably prevent the generation of abnormal noise when cold.

[0028]

The present invention has the following specific effects. (1) The self-excited vibration of the ball is effectively suppressed by restricting the behavior of the ball by elastically contacting or approaching the outer peripheral edge of the pocket of the cage at the time of cold start so as to be in contact with or close to the ball. Therefore, it is possible to suppress or prevent the generation of abnormal noise when cold. Also, during normal operation, the pocket opening side of the cage is displaced toward the outer diameter side, so that an appropriate pocket clearance is provided and free rolling of the ball is ensured, which has an unfavorable effect on durability. It can be avoided. (2) Since the effects as described above can be obtained regardless of the type of the grease to be filled, there is no fear of lowering the high temperature durability unlike the conventional pulley using grease having excellent low temperature characteristics. (3) Since the generation of abnormal noise during cold can be suppressed or prevented with a simple configuration, it is also advantageous in cost.

In order to confirm the above effects, a test was conducted, and extremely good results as shown in FIG. 5 were obtained.
Note that FIG. 5A shows the test conditions of the cold abnormal sound generation reproduction test, and FIG. 5B shows the result.

The effects (1) to (3) are similarly achieved when the present invention is applied to a fan for forcibly cooling engine cooling water.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of the ball bearing shown in FIG.

FIG. 3 is a plan view (FIG. A) showing the periphery of the pocket of the cage;
It is sectional drawing (FIG. B).

FIG. 4 is a front view (partially sectional view) showing the vicinity of a pocket of a cage.

FIG. 5 is a diagram showing test conditions (FIG. A) and results (FIG. B) of a cold abnormal sound reproduction test.

FIG. 6 is a cross-sectional view showing a conventional pulley.

FIG. 7 is a cross-sectional view showing one structural example of a cooling fan.

FIG. 8 is an enlarged front view showing the shape of holes provided in the plate of the clutch mechanism.

[Explanation of symbols]

 1 pulley body 2 ball bearing 2c ball 2d cage 3 pockets 4 annular base 5 opening 30 fan 31 blade 32 ball bearing 33 main shaft

Claims (5)

[Claims] 1. A cage made of synthetic resin, wherein a plurality of pockets for accommodating and holding balls are formed, a peripheral edge of the pocket is a concave spherical surface, and one side in the axial direction of the pocket is an annular base and the other side in the axial direction is an opening. The ball bearing, wherein the pocket of the cage has a shape that is gradually inclined from the annular base portion toward the opening toward the axial center side. 2. A pulley comprising: a pulley main body having a pulley peripheral surface with which the belt comes into contact; and the ball bearing according to claim 1 fitted to the pulley main body. 3. The pulley according to claim 2, wherein the outer raceway surface of the ball bearing is directly formed on the inner diameter of the pulley body. 4. A fan characterized in that a rotary member having a plurality of blades is fitted to the outer diameter of the outer race of the ball bearing according to claim 1. 5. A plurality of pockets made of synthetic resin for accommodating and holding balls are formed, a peripheral edge of the pocket is a concave spherical surface, one axial side of the pocket is an annular base portion, and the other axial side is an opening portion. A cage for a ball bearing, wherein the pocket has a shape that is gradually inclined from the annular base portion toward the opening toward the axial center side.