JPH08178023A - Idler pulley - Google Patents

Abstract

PURPOSE: To effectively suppress the generation of noises in the cold state by offsetting the load center of a belt load applied to a ball bearing and the center line of the ball bearing in an idler pulley with a pulley main body coupled with the outer diameter of the outer ring of the ball bearing. CONSTITUTION: This idler pulley used for an auxiliary machine drive belt is constituted of a pulley main body 1 and a ball bearing 2 coupled with its inner diameter. The pulley main body 1 is a ring body constituted of a cylinder section 1a and a flange section 1b, the outer ring 2a of the ball bearing 2 is coupled with the inner diameter of the cylinder section 1a, and a conical tapered pulley peripheral face 1a1 is provided on the outer diameter. The distribution Wa of the belt load applied to the ball bearing 2 when the belt is brought into contact with the pulley peripheral face 1a1 is increased on the large diameter side of the pulley peripheral face 1a1, and the load center W is offset relative to the bearing center line Y by a size δ to the large diameter side. A ball 2c is kept in contact with the raceway surfaces of the inner and outer rings 2a, 2b at the prescribed face pressure or above.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an idler pulley,
In particular, the present invention relates to an idler pulley that is locked to a timing belt of an automobile engine and a belt for driving auxiliary equipment.

[0002]

2. Description of the Related Art An idler pulley is arranged in a timing belt of an automobile engine, a belt for driving an auxiliary machine or the like so as to increase a wrapping angle of the belt and to give an appropriate tension to the belt. As the idler pulley, there is one in which the pulley peripheral surface with which the belt contacts is directly provided on the outer diameter of the outer ring of the ball bearing (capsule outer ring), but as shown in FIG. 12, the pulley main body 11 having the pulley peripheral surface 11a1 is provided. The one in which the ball bearing 12 and the ball bearing 12 are fitted and integrated is often used.

The pulley body 11 is made of a steel plate press,
It has an outer diameter cylindrical portion 11a for hanging a belt and an inner diameter cylindrical portion 11b for fitting an outer ring 12b of the ball bearing 12. The pulley peripheral surface 11a1 is provided on the outer diameter of the outer diameter cylindrical portion 11a. The ball bearing 12 is a deep groove ball bearing, and has an outer ring 12b fitted to the inner diameter cylindrical portion 11b of the pulley body 11, an inner ring 12a fitted to a fixed shaft (not shown), and inner / outer rings 12a, 12b.
A plurality of balls 12c incorporated between the raceways of the
It has a holder 12d for holding 2c and a seal 12e for sealing grease.

In this type of idler pulley, when the pulley body 11 is rotated by receiving the rotational driving force from the belt, the outer ring 12b of the ball bearing 12 fitted to the pulley body 11 causes the pulley body 11 to rotate.
Rotates together with.

In the above idler pulley, it is customary to design the load center position of the belt load acting on the ball bearing 12 to coincide with the axial center line Y of the ball bearing 12. This is done in order to avoid the belt load acting as an unbalanced load on the ball bearing 12 and causing an unfavorable influence on the ball bearing 12, which is a basic design matter that has been followed from the past. It is something to say.

[0006]

By the way, when the above idler pulley is operated in cold weather, a peculiar sound (whistling sound) may be generated. This peculiar sound during cold, so-called abnormal noise during cold, does not always occur 100% in the market, is affected by temperature, etc., and occurs only in a limited area such as Hokkaido in Japan. In addition, it occurs in a very short time (about 1 minute even for a long one) from the time of starting 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 idler pulleys used in automobiles and the like are driven at high temperature and high speed, and their durability is one of the important characteristics, it is impossible to take measures to reduce durability. For these reasons, the actual situation is that at present, as a countermeasure against the abnormal noise of the idler pulley when it is cold, no effective means that is the decisive factor is provided.

Conventionally, as a measure against abnormal noise during cold, a grease excellent in low temperature characteristics (an oil film is formed evenly in the contact portion between the rolling elements and the raceways of the inner and outer rings even in cold weather) Is being considered for use. 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 grease becomes low, there is concern about lubrication performance at high temperatures,
It may lead to a decrease in durability.

[0008] Further, it has been reported that the generation of abnormal noise during cold is suppressed by increasing the radius of curvature of the raceway surfaces of the inner and outer rings and increasing the bearing clearance. The increase in clearance results in amplification of angular runout of the pulley body, which may impair the function of the idler pulley.

Further, an example in which a member (rubber-like elastic body) having a sound absorbing effect is attached to the outer diameter of the boss portion of the pulley body (the portion to which the outer ring of the ball bearing is fitted) (actual flat blade 3-41247).
No.), or an elastic body is interposed between the inner diameter of the pulley body and the outer diameter of the bearing case into which the ball bearing is fitted (Japanese Utility Model Laid-Open No. 62-91056). These cases try to absorb the self-excited vibration of the bearing, which is considered to be a cause of abnormal noise during cold, by utilizing the internal damping of the elastic body. Since it is considered that the internal damping property will decrease, it is not certain that a sufficient effect can be expected as a measure against abnormal noise during cold weather.

Therefore, the present invention provides means for effectively suppressing or preventing the generation of abnormal noise in the cold state, while ensuring the durability of the idler pulley and the function as the pulley, while also considering the cost. Is what you are trying to do.

[0011]

In the present invention, the load center of the belt load acting on the ball bearing is offset from the bearing center line of the ball bearing.

During cold weather, the unevenness of the oil film on the raceway surface and the unevenness are likely to occur due to an increase in the viscosity of the base oil of the grease and a decrease in the consistency. If there is oil film unevenness / unevenness, the friction coefficient between the rolling element and the raceway surface undergoes a minute periodical change, which causes self-excited vibration in the rolling element. In particular, when there is an oil film break, the rolling element causes stick-slip at that part, and because the rolling and sliding state changes are repeated periodically, the amplitude of the self-excited vibration of the rolling element is more constant at a certain frequency. growing. Moreover, in deep groove ball bearings, the behavior becomes particularly unstable at the moment when the rolling element shifts from the load range to the non-load range or from the non-load range to the load range due to the radial load (the rolling element is delayed and advanced). Etc.), which further promotes self-excited vibration. Then, it is considered that abnormal noise is generated at the contact portion between the rolling element that vibrates in such a self-excited manner and the raceways of the inner and outer rings. Further, the self-excited vibration of the rolling element may be transmitted to the pulley main body via the outer ring, resonate with the natural vibration of the pulley main body, be amplified, and may expand as a resonance sound.

Although the mechanism of generation of abnormal noise during cold weather has not been completely clarified, it is considered that the self-excited vibration of the rolling elements is a major factor as described above. When several verifications were attempted based on such inference, the following events were found (see Tables 1 and 2).

(1) Compared to an idler pulley incorporating a bearing B (deep groove ball bearing), a bearing A (double-row angular ball bearing)
The idler pulley that incorporates is less likely to make noise when cold (see Table 1).

(2) The idler pulley in which grease having high viscosity at low temperature is enclosed has a higher frequency of abnormal noise during cooling than the idler pulley in which grease having low viscosity is enclosed (see Table 2).

[0016]

[Table 1]

[0017]

[Table 2]

From the above-mentioned events (1) and (2), it is proved that the degree of freedom of the behavior of the rolling elements and the oil film formation state of the raceway surface at the time of cold have a great influence on the generation of abnormal noise at cold. .

Based on the above inference and verification results, the present invention adopts a configuration in which the load center of the belt load and the bearing center line of the ball bearing are offset from each other, whereby abnormal noise is generated during cold It is effectively suppressed or prevented.

[0020]

By offsetting the load center of the belt load and the bearing center line of the ball bearing, a moment load acts on the ball bearing and the outer ring tilts and rotates. When the outer ring tilts with respect to the bearing center line, a skewed state occurs between the raceway surface of the outer ring and the raceway surface of the inner ring. Rolls while contacting at a contact angle (at a position off the groove bottom). The behavior of such rolling elements is supported by the following analysis results.

FIG. 9 shows the relationship between the offset amount (the axial shift amount between the load center position and the bearing center line) and the contact angle distribution,
10 and 11 show the relationship between the offset amount and the contact surface pressures of the outer ring and the inner ring. These analysis results are for the case where a deep groove ball bearing is used as the ball bearing, and the configuration with the offset amount = 0 corresponds to the conventional idler pulley. Further, the circumferential angle (phase angle) in these figures is taken around the fixed axis from the contact center position of the belt (circumferential center position at the contact portion with the pulley peripheral surface) as a reference (0 °). It is an angle.

First, from the results shown in FIG. 9, the contact angle of the rolling elements is zero in all circumferential angles in the configuration with the offset amount = 0, whereas in the configuration with the offset amount, the rolling elements are It contacts the inner and outer raceway surfaces with contact angles at almost all circumferential angles. Moreover, the contact angle of the rolling element differs depending on the circumferential angle, which means that the axis of rotation of the rolling element changes momentarily with the revolution.

From the results shown in FIGS. 10 and 11, the contact surface pressure becomes zero in the non-load region of the belt load (the region near the angle of 100 ° to 250 ° in the circumferential direction) when the offset amount is 0. On the other hand, in the structure in which the offset amount is provided, the rolling elements come into contact with the raceways of the inner and outer rings with a contact surface pressure of a predetermined value or more in the entire area including the non-loaded area. In particular, it is characteristic that a small peak state of the contact surface pressure appears at a position at an angle of 180 ° in the circumferential direction farthest from the contact center position of the belt. This state corresponds to the contact angle distribution of FIG.

As is clear from the above analysis results, in the idler pulley of the present invention, all rolling elements are
Contact with the raceway surface of the outer ring with a contact angle above a certain surface pressure,
The rotation axis (contact angle) of each rolling element changes momentarily with its revolution movement.

Since all the rolling elements come into contact with the raceways of the inner and outer rings at a contact angle of a predetermined surface pressure or more, the behavior of the rolling elements is suppressed, especially the behavior in the axial direction.
Even if any vibration factor acts, self-excited vibration is unlikely to occur. Moreover, since the rotation axis of each rolling element changes momentarily as it revolves, new lubricant adhering to the rolling element is constantly supplied to the contact portion with the raceway surface, and an oil film is easily formed. Periodic changes in the friction coefficient that cause vibration and stick slip of rolling elements are less likely to occur. In the present invention, the mechanism by which the generation of abnormal noise during cold is effectively suppressed or prevented is such a behavior suppressing function of rolling elements,
It is considered that this is due to the interaction of the oil film formation promoting functions.
And, as is clear from FIGS. 9 to 11, the contact angle and the magnitude of the contact surface pressure are related to the offset amount. Therefore, by managing the offset amount, the optimum setting according to the surrounding environment, the operating condition, etc., Changes and the like can be made extremely easily.

The above shows the most preferable state for preventing the abnormal noise generation in the cold state, and it is not always necessary that all the rolling elements correspond to the above state, and at least the load range of the belt load (circumferential direction) If the rolling elements in the angles of 0 ° to 100 ° and 250 to 360 ° are applicable to the above state, a considerable suppressing effect can be expected.

[0027]

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

The idler pulley shown in FIG. 1 is used for an accessory drive belt of an automobile. The idler pulley is composed of, for example, a steel pipe shaving pulley main body 1 and a ball bearing 2 fitted in the inner diameter of the pulley main body 1.
The pulley body 1 is a ring body including a cylindrical portion 1a and a flange portion 1b extending from the right end of the cylindrical portion 1a to the outer diameter side. The outer ring 2a of the ball bearing 2 is fitted to the inner diameter of the cylindrical portion 1a, and the outer peripheral diameter of the cylindrical portion 1a is provided with a pulley peripheral surface 1a1 with which a belt (not shown) contacts. In this embodiment, the pulley peripheral surface 1a1 is a conical taper surface having a large diameter on the left end side and a small diameter on the right end side. Flange 1b
Are provided for guiding the belt that contacts the pulley peripheral surface 1a1. The belt comes into contact with the pulley peripheral surface 1a1 to function as an idler.

The ball bearing 2 is a deep groove ball bearing, and has an outer ring 2a fitted to the inner diameter of the cylindrical portion 1a of the pulley body 1, an inner ring 2b fitted to a fixed shaft (not shown), and inner / outer rings 2a, 2b.
A plurality of balls 2c incorporated between the orbital surfaces, and a retainer (not shown) for holding the balls 2c at equal intervals around the circumference,
It is composed of a pair of seals (not shown) for sealing grease.

A belt peripheral surface 1a1 having a conical taper belt
Of the belt load acting on the ball bearing 2 when it comes into contact with
a becomes large on the large diameter side (left end side) of the pulley peripheral surface 1a1, and the load center W thereof deviates from the bearing center line Y of the ball bearing 2 by the dimension δ on the large diameter side (left end side). In this way, the load center W and the bearing center line Y are offset from each other by δ in the axial direction, so that the moment load acts on the ball bearing 2 and the outer ring 2a tilts and rotates. And
When the outer ring 2a tilts with respect to the bearing center line Y, a skewed state occurs between the raceway surface of the outer ring 2a and the raceway surface of the inner ring 2b, so that all the balls 2c are moved to the inner / outer rings 2a, 2b.
Rolls while making contact with the raceway surface at a contact angle above the specified surface pressure (at a position off the groove bottom). As a result, generation of abnormal noise during cold is prevented based on the mechanism described above.

Tests were conducted on the idler pulley having the above structure. The results are shown in Tables 3 and 4 and FIGS. 6, 7 and 8.

First, in Tables 3 and 4, the offset amount δ (m
m) and the occurrence rate (%) of cold noise.
Table 3 shows the test results when the grease A is filled in the ball bearing 2, and Table 4 shows the test results when the grease B is filled in the ball bearing 2.
Both operating conditions are the same.

[0033]

[Table 3]

[0034]

[Table 4]

In Tables 3 and 4, the offset amount δ =
At 2.0 mm, the generation rate of abnormal noise during cold drastically decreases, δ = 3.0
It is zero at mm and above.

Next, FIGS. 6 to 8 show the offset amount δ.
(Mm) and the sound pressure level (dB) of sound are shown. Sound with a sound pressure of N dB or higher is abnormal noise when cold. Figure 6
Shows the test results when grease C is filled in the ball bearing 2, FIG. 7 shows the test results when grease D is filled in the ball bearing 2, and FIG. 8 shows the test results when grease E is filled in the ball bearing 2. All operating conditions are the same.

6 to 8, the offset amount δ =
When 2.0 mm or less, abnormal noise was observed in the cold, but 2
In the region of mm <δ, the generation of abnormal noise during cold is completely prevented. The data at the right end in FIGS. 6 to 8 are re-evaluated for the configuration with the offset amount δ = 0 mm.

From the above test results, it became clear that by setting the offset amount δ to a value equal to or larger than a predetermined value, it is possible to completely prevent the generation of abnormal noise during cooling, regardless of the type of grease filled. On the other hand, by setting the offset amount δ to a value equal to or smaller than a predetermined limit value, it is considered that it is possible to achieve a balance with requirements such as durability.

In the idler pulley shown in FIG. 2, the rigidity of the pulley main body 1 in the radial direction is made different from each other so that the load center W of the belt load and the bearing center line Y of the ball bearing 2 are axially separated by a dimension δ. It is offset. The pulley main body 1 of this embodiment has an inner diameter cylindrical portion 1 into which a ball bearing 2 is fitted.
c, an outer diameter cylindrical portion 1d for hanging a belt, a connecting portion 1e for radially connecting the right ends of the inner diameter cylindrical portion 1c and the outer diameter cylindrical portion 1d, and a flange portion extending from the left end of the inner diameter cylindrical portion 1c to the inner diameter side. It is a ring composed of 1f. The wall thickness of the connecting portion 1f is thicker than the other portions. An outer ring 2a of the ball bearing 2 is fitted to the inner diameter of the inner diameter cylindrical portion 1c, and a pulley peripheral surface 1d1 with which the belt contacts is provided on the outer diameter of the outer diameter cylindrical portion 1d.

Since the right ends of the inner diameter cylindrical portion 1c and the outer diameter cylindrical portion 1d are connected to each other by the thick connecting portion 1e, the rigidity of the pulley main body 1 in the radial direction becomes large on the right end side. Therefore, the distribution Wa of the belt load acting on the ball bearing 2 becomes large on the right end side of the pulley body 1, and the load center W
Is δ on the right end side with respect to the bearing center line Y of the ball bearing 2.
It just shifts. In this way, the load center W and the bearing center line Y are offset from each other by δ in the axial direction, so that the same effect as that of the configuration shown in FIG. 1 is achieved.

In the idler pulleys shown in FIGS. 3 (a) and 3 (b), the center of belt load W and the ball bearing 2 are made different by tightening the pulley main body 1 and the outer ring 2a of the ball bearing 2 differently. The bearing center line of is offset in the axial direction by a dimension δ. The pulley main body 1 of these examples has an inner diameter cylindrical portion 1g into which the ball bearing 2 is fitted, an outer diameter cylindrical portion 1h for hanging a belt, and a connection that radially connects the inner diameter cylindrical portion 1g and the outer diameter cylindrical portion 1h. It is a ring body composed of a portion 1j and a flange portion 1k extending from the right end of the inner diameter cylindrical portion 1c to the inner diameter side. The inner diameter of the cylindrical portion 1g has a cylindrical surface. The pulley peripheral surface 1h1 is provided on the outer diameter of the outer diameter cylindrical portion 1h.

As for the outer diameter of the outer ring 2a of the ball bearing 2 in FIG. 3 (a), the predetermined area from the left end is the cylindrical surface 2a1, the predetermined area from the right end is the conical taper surface 2a2, and the cylindrical surface 2a.
1 and the conical taper surface 2a2 are smoothly continuous. Further, the outer diameter of the outer ring 2a of the ball bearing 2 in FIG.
Predetermined areas from the left and right ends are conical taper surfaces 2a3,
2a4, and the conical taper surface 2a3 and the conical taper surface 2a4 are smoothly continuous via the cylindrical surface 2a5. The center of the cylindrical surface 2a5 is displaced from the bearing center line Y of the ball bearing 2 to the left end side.

When the outer diameter of the outer ring 2 having the above-described shape is fitted to the inner diameter of the inner diameter cylindrical portion 1g of the pulley body 1, the interference between the pulley body 1 and the outer ring 2a becomes large on the left end side. . Therefore, the distribution W of the belt load acting on the ball bearing 2
a becomes large on the left end side, and its load center W is
The ball bearing 2 is displaced from the bearing center line Y by a dimension δ toward the left end. In this way, the load center W and the bearing center line Y are offset from each other by δ in the axial direction, so that the same effect as that of the configuration shown in FIG. 1 is achieved.

In the idler pulley shown in FIG. 4, the tightening margin between the pulley body 1 and the outer ring 2a of the ball bearing 2 is limited to only one of the left and right ends, so that the load center W of the belt load is reduced.
And a bearing center line Y of the ball bearing 2 are offset in the axial direction by a dimension δ. Pulley body 1 of this embodiment
Is a ring body including a cylindrical portion 1m, a flange portion 1n extending from the left end of the cylindrical portion 1m to the outer diameter side, and a flange portion 1p extending from the right end of the cylindrical portion 1m to the inner diameter side. In the inner diameter of the cylindrical part 1m,
An outer ring 2a of the ball bearing 2 is fitted, and a pulley peripheral surface 1m1 with which the belt contacts is provided on the outer diameter of the cylindrical portion 1m.

The outer diameter of the outer ring 2a of the ball bearing 2 is provided with a recessed portion 2a6 extending from the right end to a predetermined area.

When the outer diameter of the outer ring 2a having the above-described shape is fitted to the inner diameter of the cylindrical portion 1m of the pulley body 1, the tightening margin between the pulley body 1 and the outer ring 2a is not provided with the recessed portion 2a6. Only in the left end side area. Therefore, ball bearing 2
The belt load acting on is concentrated in a region having this interference, and the center W of the load is displaced from the bearing center line Y of the ball bearing 2 by the dimension δ to the left end side. In this way, the load center W and the bearing center line Y are offset from each other by δ in the axial direction, so that the same effect as that of the configuration shown in FIG. 1 is achieved.

In the idler pulley shown in FIG. 5, the load center W of the belt load and the bearing center line Y of the ball bearing 2 are offset in the axial direction by a dimension δ by making the tension of the belt 3 different from each other. Is. Therefore, the same operational effect as the configuration shown in FIG. 1 is achieved. As means for varying the tension of the belt 3 from right to left, for example, as shown in FIG. 5 (b), a configuration in which the wire diameter of the reinforcing wire of the belt 3 is varied from left to right, and as shown in FIG. 5 (c), It is conceivable that the sectional height H of the belt 3 is different between the left and right. In addition, the pulley body 1 of this embodiment is a ring body including a cylindrical portion 1q,
The outer ring 2a of the ball bearing 2 is fitted to the inner diameter of the cylindrical portion 1q, and the pulley 3a is in contact with the outer diameter of the cylindrical portion 1q with the belt 3.
1 is provided.

Although the pulley main bodies 1 having various shapes are illustrated in the above embodiments, the shape of the pulley main body is not particularly limited in the present invention. Further, the present invention can be similarly applied to an idler pulley in which the pulley peripheral surface with which the belt contacts is directly provided on the outer diameter of the outer ring (capsular outer ring) of the ball bearing.

[0049]

As described above, according to the present invention, since the center of the belt load and the center line of the bearing of the ball bearing are offset from each other, the idler pulley has the following unique effects.

(1) By providing the offset, the rolling elements, which are at least in the load range of the belt load, come into contact with the raceways of the inner and outer rings with a contact angle at a predetermined surface pressure or more,
The contact angle (spin axis) of each rolling element changes momentarily with its orbital movement, so that the rolling element's behavior is suppressed, and a new lubricant is added to the raceway surface as the rolling axis of the rolling element changes. Is constantly supplied to promote the formation of an oil film. The interaction of the rolling element behavior suppressing function and the oil film formation promoting function as described above effectively suppresses or prevents the generation of abnormal noise during cold.

(2) In particular, it has been confirmed by an experiment that the occurrence of cold noise can be completely prevented by setting the offset amount to a predetermined value or more. We were able to realize the complete prevention of sound generation.
It has extremely great technical significance.

(3) Only by managing the offset amount, it is possible to extremely easily perform optimum setting and change according to the surrounding environment, operating conditions, and the like.

(4) Since the above effect can be realized regardless of the type of grease to be filled, there is no fear of lowering the high temperature durability as in the conventional structure using low temperature grease or the like.

(4) There are few factors that complicate the structure,
It is also advantageous in terms of cost.

[Brief description of drawings]

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

FIG. 2 is a sectional view showing an embodiment of the present invention.

FIG. 3 is a sectional view showing an embodiment of the present invention.

FIG. 4 is a sectional view showing an embodiment of the present invention.

FIG. 5 is a sectional view showing an embodiment of the present invention.

FIG. 6 is a diagram showing a relationship between an offset amount (δ) and a sound pressure level.

FIG. 7 is a diagram showing a relationship between an offset amount (δ) and a sound pressure level.

FIG. 8 is a diagram showing a relationship between an offset amount (δ) and a sound pressure level.

FIG. 9 is a diagram showing a relationship between an offset amount and a contact angle distribution.

FIG. 10 is a diagram showing a relationship between an offset amount and a contact surface pressure of an outer ring.

FIG. 11 is a diagram showing the relationship between the offset amount and the contact surface pressure of the inner ring.

FIG. 12 is a sectional view showing a conventional idler pulley.

[Explanation of symbols]

 1 pulley body 2 ball bearing Y bearing center line W load center δ offset amount

Claims (1)

[Claims] 1. A pulley main body having a pulley peripheral surface with which the belt contacts is fitted to the outer diameter of the outer ring of the ball bearing, or has a pulley peripheral surface with which the belt contacts with the outer diameter of the outer ring of the ball bearing. In the idler pulley, an idler pulley in which a load center of the belt load acting on the ball bearing and a bearing center line of the ball bearing are offset from each other.