JP2002039333A - Pulley - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To prevent early breakage of a bearing applied to a small diameter pulley. SOLUTION: A pulley 10 is formed in a cylindrical shape by a metal member, and a plurality of vertical grooves 16 are formed on an inner peripheral surface 14 over the entire circumference to increase the surface area. The longitudinal groove 16 is open at both ends, and forms a gap between the outer ring when the outer ring of the radial ball bearing is fitted and fixed to the inner peripheral surface 14. The frictional heat generated in the radial ball bearing is conducted to the inner peripheral surface 14 and the vertical groove 16. The radiation of the pulley 10 prevents early damage of the radial ball bearing due to thermal fatigue.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a relatively small-diameter pulley applied to an idler, a tensioner pulley, and the like.

[0002]

2. Description of the Related Art In a belt system mechanism for transmitting rotation of an output shaft of an engine to an auxiliary shaft such as an alternator or an air conditioner by a belt, a driving pulley and a driven pulley, as well as a running direction and a contact angle of the belt are adjusted. A single endless belt is suspended on idlers that run idle and tensioner pulleys that tension the belt appropriately.
Generally, an idler or a tensioner pulley is rotatably supported by a shaft member via a radial ball bearing, and is formed to have a smaller diameter than the drive pulley to save space, and rotates at a higher speed than the drive pulley. For example, if the radius of the driving pulley is 13
If 0 mm and the radius of the idler is 55 mm, the idler rotates at a speed approximately 2.4 (= 130/55) times the speed of the driving pulley.

[0003] The radial ball bearing includes an inner ring and an outer ring fixed to a shaft member and a pulley, respectively, and a plurality of rolling elements rolling while frictionally sliding between the inner ring and the outer ring. As a result, the outer ring or pulley rotates relative to the inner ring or shaft member. The inner ring, the outer ring, and the rolling elements are formed of a metal member such as steel, and an oil film is formed by lubricating oil between the parts that come into sliding contact with each other.

[0004]

However, the operating environment temperature of the belt system is generally as high as about 90 ° C., and the temperature of the radial ball bearing is further increased by frictional heat generated by frictional sliding of the rolling elements. In particular, if the pulley diameter is reduced and the number of revolutions increases, the frictional heat increases, so that the temperature of the radial ball bearing tends to increase. Therefore, the radial ball bearing is damaged early due to thermal fatigue. More specifically, the lubricating oil is deteriorated and an oil film cannot be formed. This phenomenon is particularly remarkable when the pulley is formed of a synthetic resin that easily stores heat.

[0005] The present invention has been made in view of such a point, and an object of the present invention is to provide a small-diameter pulley capable of preventing early damage of a radial ball bearing even at high speed rotation.

[0006]

SUMMARY OF THE INVENTION A pulley according to the present invention comprises:
It is rotatably supported by a shaft member via a bearing, is formed of a material having good thermal conductivity, and has a longitudinal groove extending in the axial direction and opened at both ends. It is characterized in that a plurality are formed. As a result, the efficiency of heat conduction from the bearing to the pulley can be improved, the surface area on the side of the contact surface with the bearing can be increased, and the heat generated in the bearing due to friction or the like can be efficiently radiated. Therefore, thermal fatigue of the bearing can be suppressed, and durability can be improved.

The longitudinal groove of the pulley may be formed by serration, whereby a plurality of grooves can be formed simply, inexpensively and in a short time.

Preferably, the pulley is specifically formed of a metal material such as carbon steel. Metals have better thermal conductivity than resins and the like, easily radiate heat, and are easy to process.

[0009] The bearing may be a radial ball bearing. In this case, the deterioration of the lubricating oil inside the bearing and the seizure between the rolling element and the inner and outer rings due to insufficient formation of the oil film are prevented.

[0010] The pulley may be a V-ribbed pulley having a plurality of V-grooves arranged in the axial direction formed on the outer peripheral surface, and the V-groove and the vertical groove may be formed simultaneously by, for example, roller rolling. This makes it possible to form the vertical groove very easily.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a pulley according to the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a pulley 10 according to an embodiment together with a belt 20 and a shaft member 30. The left side of the dashed line at the center is a front view, and the right side is a sectional view. The pulley 10 is rotatably supported by a cylindrical shaft member 30 via a radial ball bearing 40, and the belt 20 contacts the outer peripheral surface of the pulley 10. Although not shown, the shaft member 30 is fixed at one end.

The belt 20 is a V-ribbed belt, and a plurality of V-shaped protrusions 22 extending in the longitudinal direction are arranged on one surface in the width direction. The pulley 10 is a V-ribbed pulley.
The same number of grooves 12 as the V-shaped protrusions 22 are arranged in the axial direction. V
A ribbed pulley and a V-ribbed belt are often used in a small space because they have less mutual slip compared with a flat pulley and a flat belt and can set a large contact angle, which is the center angle of an arc of contact between the belt and the pulley. Therefore, it is formed with a relatively small diameter with respect to the flat pulley and rotates at a high speed.

The radial ball bearing 40 is a double shielded ball bearing, and is fixed to the outer peripheral surface 32 of the shaft member 30 by press-fitting without being fastened to the inner ring 42 and the inner peripheral surface 14 of the pulley 10 by press-fitting. An outer ring 44, which is fixed without being fastened and rotates integrally with the pulley 10, is provided. Inner ring 4 arranged coaxially
A groove having a semicircular cross-section is formed over the entire surface of the second and outer rings 44 facing each other, and a rolling element 46, which is a steel ball, is sandwiched between the grooves of both the rings 42 and 44 in a rollable state. I have. A plurality of rolling elements 46 are arranged along the circumferential direction, and are slidably held by a holder 48 in order to restrict movement in the circumferential direction. The space between the inner ring 42 and the outer ring 44 is sealed by two seals 50 provided at both ends,
Lubricating oil is sealed in the closed space. This makes inner ring 4
2. An oil film is formed between the outer ring 44 or the retainer 48 and the rolling element 46, and the rolling element 46 rolls smoothly. Due to the rolling operation of the plurality of rolling elements 46, the outer ring 44 relatively rotates around the axis C with respect to the inner ring 42, that is, the pulley 10 relatively rotates with respect to the shaft member 30.

FIG. 2 is a plan view of the pulley 10, and FIG. 3 is a perspective view showing a part of the pulley 10 cut out. The pulley 10 is made of an iron-based metal member, for example, carbon steel, and is integrally formed into a substantially bowl shape by pressing a flat metal plate (rolled steel plate) over several steps. It is removed by processing and formed into a substantially cylindrical shape. The plurality of V grooves 12 on the outer peripheral surface are formed by roller rolling. At both ends of the pulley 10, flanges 18 are formed to regulate both sides of the belt 20 and prevent the belt 20 from coming off the pulley 10.

On the inner peripheral surface 14 of the pulley 10 which is in close contact with the radial ball bearing 40, a number of longitudinal grooves 16 parallel to the axis are formed at regular intervals, and these longitudinal grooves 16 are open at both ends. The vertical groove 16 is formed by serration. The vertical groove 16 may be formed by cutting serration, but it is easier and inexpensive to form the vertical groove 16 at the same time as the V groove 12 by roller rolling. This is because, in the present embodiment, serrations are provided in order to ensure the escape of excess thickness during roller rolling.

More specifically, referring to FIG. 4, an intermediate formed body 10 'having a general shape of the pulley 10 is set on a core roll 50 by press working, and a high-speed rotating roll 60 is pressed from the side with a constant load P. By doing, the intermediate molded body 1
0 'is plastically deformed to form a V-groove 12' on its outer peripheral surface. Vertical grooves are formed on the outer peripheral surface 52 of the core roll 50 at a predetermined pitch over the entire periphery, and extra thickness generated by plastic deformation of the intermediate molded body 10 ′ moves into the vertical grooves of the outer peripheral surface 52, Serrated serrations are formed on the inner peripheral surface of the intermediate molded body 10 'according to the shape of the outer peripheral surface 52 of the core roll 50. By providing the serrations on the inner peripheral surface as a relief for the excess thickness, the formability of the V-groove 12 'is improved. The convex surface of the serration formed on the inner peripheral surface of the intermediate molded body 10 'corresponds to the inner peripheral surface 14', and the concave portion corresponds to the vertical groove 16 '. After the formation of the serrations, the inner peripheral surface 14 'is subjected to broaching or lathing to improve roundness and cylindricity.

As described above, since the vertical grooves 16 'are formed simultaneously with the formation of the V-grooves 12', only the step of cutting the inner peripheral surface 14 'need be added to the conventional rolling process.
The inner peripheral surface 14 'and the vertical groove 16' can be formed with a very simple operation in a short time. V-groove 1 of intermediate molded body 10 '
2 ', the inner peripheral surface 14', and the vertical groove 16 'correspond to the V groove 12, the inner peripheral surface 14, and the vertical groove 16 of the pulley 10 shown in FIGS.

The cross-sectional shape of the vertical groove 16 is not limited to the trapezoid of this embodiment (see FIG. 2), but may be triangular or semicircular. The size of the vertical groove 16 is not particularly limited, but is set so that the inner peripheral surface 14 has a sufficient area for fitting and fixing the outer ring 44 of the radial ball bearing 40.

When the pulley 10 rotates relatively, the rolling element 46 frictionally slides with the inner race 42, the outer race 44 and the retainer 46, so that the temperature of the radial ball bearing 40 is reduced to the environmental temperature (about 90 ° C.) by frictional heat. It is known to be higher.
The lubricating oil exhibits an optimum viscosity for forming an oil film in a range of an ambient temperature in which the belt system can be used (about -40 ° C to 120 ° C), but when the temperature of the radial ball bearing 40 becomes higher than the upper limit value of 120 ° C, Cannot be formed, and the inner ring 42, the outer ring 44 or the retainer 46 and the rolling element 46 are seized. When the retainer 46 is made of a synthetic resin such as a nylon resin, the melting point (nylon 4
If it exceeds 6, 260 ° C.), it will melt. In particular, a V-ribbed pulley formed with a relatively smaller diameter than a flat pulley has a high rotation speed, and the radial ball bearing 40 tends to become hot.

Therefore, in this embodiment, the pulley 1
0 is formed of a metal material having good heat conductivity to increase the heat transfer efficiency and prevent the radial ball bearing 40 from storing heat.
Further, by providing the vertical groove 16 on the inner peripheral surface 14 which is in close contact with the radial ball bearing 40, the surface area on the inner peripheral surface 14 side is increased, so that heat transmitted from the radial ball bearing 40 can be effectively radiated. Further, since both ends of the vertical groove 16 are opened, the gap formed by the vertical groove 16 and the outer ring 44 communicates with the outside in the state of close contact between the outer ring 44 and the inner peripheral surface 14, so that outside air flows. The heat radiation effect is further enhanced. As described above, by using the pulley 10 of the present embodiment, thermal fatigue can be suppressed without changing the configuration of the radial ball bearing 40 from the conventional one, and the durability thereof can be improved. In other words, it is possible to obtain the radial ball bearing 40 that can sufficiently withstand the high-speed rotation of the pulley 10.

In this embodiment, the bearing is a double shielded ball bearing. However, other types of radial ball bearings may be used, or a radial roller bearing may be used.

[0023]

According to the present invention, it is possible to obtain a small-diameter pulley capable of preventing early breakage of the radial ball bearing even at high speed rotation.

[Brief description of the drawings]

FIG. 1 is a view showing an embodiment of a pulley according to the present invention, and is a partially cutaway front view shown together with a shaft member, a belt, and a radial ball bearing.

FIG. 2 is a plan view of a pulley.

FIG. 3 is a partial perspective view of a pulley.

FIG. 4 is a diagram schematically showing a process of manufacturing a longitudinal groove of a pulley.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Pulley 14 Inner peripheral surface 16 Vertical groove 20 Belt 30 Shaft member 40 Radial ball bearing

Claims (5)

[Claims] 1. A shaft which is rotatably supported by a shaft member via a bearing, is formed of a material having good thermal conductivity, and has a longitudinal groove which extends in the axial direction and is opened at both ends. A plurality of pulleys are formed around the circumference. 2. The pulley according to claim 1, wherein the plurality of vertical grooves are formed by serration. 3. The pulley according to claim 1, wherein the pulley is formed of a metal material. 4. The pulley according to claim 1, wherein said bearing is a radial ball bearing. 5. The pulley according to claim 1, wherein a plurality of V-grooves arranged in the axial direction are V-ribbed pulleys formed on an outer peripheral surface, and the vertical grooves and the V-grooves are formed simultaneously.