JP2001330062A - One-way clutch and pulley with built-in clutch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a one-way clutch with the excellent durability having an engaging element with the excellent abrasion resistance. SOLUTION: An engaging element 28 assembled between an inner member 21 and an outer member 25 is formed of a steel material composed of the following element components. This engaging element is hardened or carbonized for hardening, and thereafter, tempered so as to obtain 58 or more of the temper hardness HRC and 8 μm or less of the maximum carbide dimension. Percentage content of the alloy element is as follows: C: 0.6-1.3, Si: 0.3-3.0, Mn: 0.2-1.5, P: <=0.03, S: <=0.03 Cr: 0.3-5.0, Ni: 0.1-3.0, Al: <=0.050, Ti: <=0.003, O: <=0.0015, N: <=0.015, and a residual part has Fe and the inevitable impurities.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention incorporates an engaging member between an outer member and an inner member, and transmits and interrupts rotation torque between the outer member and the inner member by displacement of the engaging member. And a one-way clutch.

[0002]

2. Description of the Related Art In general, in an internal combustion engine, rotation of an engine crankshaft is transmitted to a rotating shaft of an engine accessory such as an alternator by a belt transmission to drive the engine accessory.

[0003] In the above-described drive device for an engine accessory, when the engine is rapidly decelerated, the pulley attached to the rotating shaft of the engine accessory also attempts to rapidly decelerate. However, when the engine accessory is an alternator, the rotating shaft of the alternator has a large inertial force, so the pulley mounted on the rotating shaft tries to keep rotating at a constant speed, and the pulley on the crankshaft and the alternator rotate. A large rotation speed difference is generated between pulleys on the shaft, and the tension of the belt increases, so that the belt is easily broken.

Further, the angular speed of the crankshaft fluctuates during one rotation, and the angular speed fluctuation causes slippage between the pulley and the belt on the rotating shaft of the engine accessory, and the slippage causes the belt to wear. As a result, the durability is reduced.

In order to solve such inconvenience, in a belt transmission described in Japanese Patent Application Laid-Open No. 61-228153, a one-way clutch is incorporated between a rotation shaft of an engine accessory and a pulley. When the rotation speed of the pulley becomes lower than the rotation speed of the rotating shaft, the pulley is rotated freely by releasing the lock of the one-way clutch to prevent the belt tension from increasing and to prevent slippage between the pulley and the belt. ing.

Here, if the pulley and the one-way clutch are assembled separately, it takes much time and effort to assemble. In order to facilitate the assembly, the applicant has already proposed a pulley with a built-in clutch shown in FIG. FIG.
The clutch built-in pulley shown in FIG. 1 has a pair of bearings 41 mounted on the outer periphery of an inner member 40 mounted on a rotating shaft of an engine accessory, and the pair of bearings 41 rotatably supports the pulley 42 and a pair of bearings 41. A one-way clutch 43 is incorporated between them.

The one-way clutch 43 has a clutch outer ring 44 which is press-fitted into the inner peripheral surface of the pulley 42, and a plurality of circumferentially extending retainers 45 incorporated between the clutch outer ring 44 and the inner member 40. The pockets 46 are formed at equal intervals, and the engagement members 47 made of sprags are formed in each pocket 46, and the arcuate surfaces 48 at both ends of the engagement members 47 are formed by the cylindrical inner surface 49 of the clutch outer ring 44 and the cylindrical outer surface of the inner member 40. A spring 51 for pressing the engaging element 47 in a direction engaging with the outer ring 50 is incorporated. When the clutch outer ring 44 rotates in the direction of the arrow shown in FIG. 5 (II), the clutch outer ring 44 comes into contact with the cylindrical inner surface 49 of the clutch outer ring 44. The engagement member 47 is raised to engage the arcuate surfaces 48 at both ends with the cylindrical inner surface 49 of the clutch outer race 44 and the cylindrical outer surface 50 of the inner member 40, and the rotation of the pulley 42 causes the inner member 4 to rotate.
I try to tell 0. When the rotation speed of the inner member 40 exceeds the rotation speed of the clutch outer ring 44,
The contact with the inner member 40 causes the engaging element 47 to fall down in the circumferential direction, and the arc surfaces 48 at both ends are disengaged from the cylindrical inner surface 49 of the clutch outer ring 44 and the cylindrical outer surface 50 of the inner member 40. Thus, the pulley 42 is rotated freely.

In the belt transmission device having the above-structured pulley with a built-in clutch attached to the rotating shaft of an auxiliary engine, when the automobile engine is a four-cycle four-cylinder engine, the engine is driven at a rate of two per rotation of the crankshaft.
Since one explosion stroke is involved, the one-way clutch 43 repeatedly locks and unlocks twice per rotation of the crankshaft.

For this reason, the one-way clutch 43 frequently locks and unlocks in a high-speed rotation range of 3000 rpm or more of the engine. When the hardness of the engagement member 47 of the one-way clutch 43 is low, the engagement member 47 The clutch outer race 44 is worn by contact with the cylindrical inner surface 49 of the clutch outer ring 44 and the cylindrical outer surface 50 of the inner member 40, and the abrasion increases the strut angle.

When the engine is suddenly decelerated, the engagement member 47 of the one-way clutch 43 is disengaged and slides on the inner cylindrical inner surface 49 of the clutch outer ring 44 and the cylindrical outer surface 50 of the inner member 40, The slip causes friction on the engagement element 47.

Therefore, the engaging element 47 of the one-way clutch 43, especially the sprag which does not rotate unlike the roller, is required to have excellent wear resistance.

[0012]

The engaging member 47 of the conventionally known one-way clutch 43 is usually
Made of high carbon chromium steel such as SUJ2 and quenched, or SCM420, SNCM420, SNC
M815 is made of case hardened steel and subjected to AS treatment (carbonitriding treatment) to increase hardness. However, like the one-way clutch 43 incorporated in the clutch built-in pulley,
In the case where a large slippage occurs in the engaging member during deceleration of the engine, or when the locking and unlocking are frequently performed, the wear resistance of the engaging member 47 is not sufficient, and the engagement of the one-way clutch is not sufficient. It is necessary to improve the wear resistance of the joint 47.

An object of the present invention is to provide a one-way clutch and a pulley with a built-in clutch which are improved in abrasion resistance of an engaging element and have excellent durability.

[0014]

In order to solve the above-mentioned problems, in a one-way clutch according to the present invention, an inner member, an outer member and both members are assembled between the two members. A clutch that is displaced from the unlocked position to the locked position by a relative rotational movement in the direction and is displaced from the locked position to the unlocked position by the relative rotational movement in the other direction. Of the member, the outer member, and the engaging element, at least the engaging element has an alloy element content of mass% and C of 0.6 or more.
3 or less, Si is 0.3 or more and 3.0 or less, Mn is 0.2 or more and 1.5 or less, P is 0.003 or less, S is 0.003 or less, Cr is 0.3 or more and 5.0 or less, Ni is 0.1 or more and 3.0 or less, Al is 0.050 or less, and Ti is 0.003.
Hereinafter, O 0.0015 or less, include N 0.015 or less and the balance formed of steel having Fe and inevitable impurities, the surface hardness and H _R C58 or higher by tempering after quenching or carbonitriding treatment, And the largest carbide size is 8
Therefore, a configuration of less than μm was adopted.

Here, the steel material of the engaging element may contain B (boron), W (tungsten) or other elements in addition to the listed elements.

Note that the inner member and the outer member are S
It may be formed of UJ2 or SCM415 or the like, and may be quenched or carburized and quenched to increase the hardness. Alternatively, it may be formed of the same material as the engaging element and subjected to the same heat treatment as the engaging element. Is also good.

In the one-way clutch according to the present invention,
The engagement element may be a sprag having arcuate surfaces at both ends, or may be a roller. When a sprag is adopted, a cylindrical outer surface is formed on the inner member, a cylindrical inner surface is provided on the outer member, and the arcuate surfaces at both ends of the sprag are engaged with the cylindrical outer surface and the cylindrical inner surface. The sprag is pressed by the elastic member.

When a roller is used, a cylindrical surface is formed on one of the outer periphery of the inner member and the inner periphery of the outer member, and a wedge-shaped space is formed between the other and the cylindrical surface. A roller is pressed by an elastic member toward a narrow portion of a wedge space formed by the cam surface and the cylindrical surface.

By forming the engaging member from a steel material having the above composition, the engaging member is quenched and tempered, whereby an engaging member excellent in wear resistance and heat resistance can be obtained. The tempering temperature is 180 ° C. or more and 350 ° C.
C. or less is preferred.

By performing carbonitriding instead of quenching and tempering, the wear resistance and heat resistance of the engaging element can be further improved.

Further, by the engaging element has the above composition, may be at an elevated temperature (e.g. 350 ° C.) be subjected to tempering, to obtain the H _R C58 or higher and high hardness. Thus, it is possible to reduce the amount of retained austenite by performing tempering treatment at a high temperature, it is possible to it is possible to obtain dimensional stability in a high-temperature environment to obtain the H _R C58 or higher and high hardness.

Hereinafter, the reasons for limiting the chemical components of the engaging element of the one-way clutch according to the present invention will be described. (1) Content of C (0.6% or more and 1.3% or less) C is an essential element for securing strength, and is required to maintain the hardness after a predetermined heat treatment. % Or more. For this reason, the lower limit of the C content is limited to 0.6%. In the present invention, carbides play an important role in the fatigue life as described later, but when the C content is 1.0.
When the content exceeds 3%, it has been found that large-sized carbides are generated and the fatigue life is reduced. Therefore, the upper limit of the C content is limited to 1.3%. (2) Si content (0.3% or more and 3.0% or less) Si is added because it has an effect of suppressing softening in a high temperature range and improving the heat resistance of the clutch of the one-way clutch. Is desirable. However, since the effect cannot be obtained if the Si content is less than 0.3%, the lower limit of the Si content is limited to 0.3%. Although the heat resistance is improved with an increase in the Si content, the effect is saturated even if the Si content is large in excess of 3.0%, and the hot workability and machinability are reduced. , The upper limit of the Si content is limited to 3.0%. (3) Content of Mn (not less than 0.2% and not more than 1.5%) Mn is an element used for deoxidation when producing steel, and is an element that improves hardenability. Since it is necessary to add 0.2% or more to obtain, the lower limit of the Mn content is limited to 0.2%. However, when contained in a large amount exceeding 1.5%, the machinability is greatly reduced.
The upper limit of the Mn content was limited to 1.5%. (4) Content of P (0.03% or less) Since P segregates at the austenite grain boundary of steel and causes reduction in toughness and fatigue life, it is limited to 0.03%. (5) S content (0.03% or less) S impairs the hot workability of steel and forms nonmetallic inclusions in the steel to reduce toughness and fatigue life. S
The upper limit of the content was set. S has a harmful surface as described above, but also has an effect of improving the machinability. Therefore, it is desirable to reduce S as much as possible.
% Is acceptable. (6) Content of Cr (0.3% or more and 5.0% or less) Cr is an element that plays an important role in the present invention.
It is added to improve hardenability, secure hardness by carbide and improve life. 0.3% to obtain the specified carbide
Since the above addition is necessary, the lower limit of the Cr content is set to 0.1.
Limited to 3%. However, if it is contained in a large amount exceeding 5.0%, large-sized carbides are formed and the fatigue life is reduced, so the upper limit of the Cr content is limited to 5.0%. (7) Al content (0.050% or less) Al is used as a deoxidizing agent in the production of steel, but hard oxide inclusions are generated and the fatigue life is shortened. Is desirable. In addition, exceeding 0.050%
When a large amount of was contained, a noticeable decrease in fatigue life was observed, so the upper limit of the Al content was limited to 0.050%.

If the Al content is suppressed to less than 0.005%, the production cost of steel increases, so the lower limit of the Al content is preferably limited to 0.005%. (8) Ti content (0.003% or less), O content (0.0015% or less), N content (0.015% or less) Ti, O and N are oxides in steel. , Forming a nitride and serving as a starting point of fatigue fracture as a non-metallic inclusion, thereby reducing fatigue life.
%, N: 0.015% was set as the upper limit of each element. (9) Ni content (0.1% or more and 3.0% or less) Ni suppresses a change in the structure in a fatigue process particularly when used in a high-temperature environment, and has a low hardness in a high-temperature region. It has the effect of suppressing the decrease and improving the fatigue life. In addition, N
i is effective in improving toughness and life in a foreign substance environment, and also in improving corrosion resistance. For this reason, since it is necessary to contain 0.1% or more of Ni, the lower limit of the Ni content is limited to 0.1%. However, if a large amount of Ni is contained in excess of 3.0%, a large amount of retained austenite is generated during the quenching treatment, and a predetermined hardness cannot be obtained, and the cost of steel material increases. Limited to 3.0%.

Next, the temper hardness and carbide of the engaging element according to the present invention will be described. (10) Tempering Hardness One-way clutches are generally subjected to a tempering treatment at a temperature equal to or higher than the environmental temperature in order to stabilize the dimensions in an operating environment. The present inventors have conducted a detailed investigation on the tempering hardness and fatigue life in a temperature environment,
A correlation was found between the tempering hardness and the fatigue life, and it was confirmed that the higher the tempering hardness, the longer the fatigue life tends to be. In particular, when the tempering hardness is the same, the engagement element whose tempering treatment is performed at a higher temperature has a longer life, and the engagement element whose tempering hardness is higher even when tempering is performed at a high temperature has a longer life. I found it. Furthermore, the hardness after tempering is less than H _R C58, tend to rapidly life may be shortened, also was found that variations in the lifetime increases. To improve the life at high temperatures, in order to reduce the variation, it is necessary to maintain the H _R C58 or higher hardness and tempering temperature at this time is preferably as high as possible. (11) Carbide Carbide was found to be effective in maintaining the hardness during the tempering treatment, suppressing the structural change during operation, and improving the fatigue life. At this time, 0.1 m from the surface of the engagement element
As a result of investigating the maximum size and the fatigue life of carbide at a depth of m, the life tends to decrease when large carbides are present, and the life sharply decreases when large carbides having a maximum size exceeding 8 μm remain. Therefore, the maximum dimension of the carbide was set to 8 μm.

In the above-described engagement element of the one-way clutch,
Steel material is 0.05% or more and less than 0.25 Mo by mass%.
And at least one of V of 0.05% or more and 1.0% or less is preferable.

Thus, the fatigue life in a high temperature environment can be further improved, and the hardness after tempering can be improved.

The reasons for limiting the chemical components will be described below. (12) Mo content (0.05% or more and less than 0.25%) Mo has the effect of improving the hardenability of steel and preventing softening during tempering by forming a solid solution in carbide. . In particular, Mo has been found to have an effect of improving the fatigue life in a high-temperature range, and is therefore added. However, 0.
If Mo is contained in a large amount of 25% or more, the cost of steel increases, and the hardness does not decrease during the softening treatment for facilitating the cutting work, and the machinability is greatly deteriorated. The amount was limited to less than 0.25%. Also Mo
If the content of is less than 0.05%, there is no effect on carbide formation, so the lower limit of the Mo content was limited to 0.05%. (13) Content of V (0.05% or more and 1.0% or less) V combines with carbon to precipitate fine carbides, promotes refinement of crystal grains, and has an effect of improving strength and toughness. In addition to having V, it has the effect of improving the heat resistance of the steel by suppressing the softening after high-temperature tempering, improving the fatigue life, and reducing the variation in the life. Since the V content at which this effect is obtained is 0.05% or more, the lower limit of the V content is limited to 0.05%. However, when V is contained in a large amount exceeding 1.0%, machinability and hot workability are deteriorated. Therefore, the upper limit of the V content is limited to 1.0%.

The pulley with a built-in clutch according to the present invention employs a structure in which an outer member of the one-way clutch is press-fitted into a cylindrical inner surface formed on the pulley.

In the clutch built-in pulley having the above structure, a pair of bearings are provided on both sides of the one-way clutch to support the inner member and the outer member so as to be relatively rotatable, thereby acting on the pulley. Since the radial load and the moment load can be supported by the pair of bearings, it is possible to prevent an eccentric load from acting on the one-way clutch. The engagement can be released.

Here, a rolling bearing having a retainer can be adopted as the pair of bearings. In this case, by integrating the retainer in one rolling bearing and the retainer in the one-way clutch, during idling of the one-way clutch, the revolving motion of the bearing retainer is used to make the inner member side of the engaging element and the outer member reciprocate. Since the side member can be slid evenly, friction of the clutch can be reduced.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows a belt transmission for transmitting rotation of a crankshaft to a rotation shaft of an engine accessory. This belt transmission device is provided at one end of a four-cylinder four-cycle engine 1 mounted on an automobile, and has a drive pulley 3 attached to a crankshaft 2 that rotates with a slight change in angular velocity caused by an explosion stroke of the engine 1. And a V-ribbed belt 5 as a transmission belt between a plurality of driven pulleys attached to the rotating shafts of a plurality of engine accessories including the drive pulley 3 and the alternator 4.
, A so-called serpentine layout.

More specifically, as the above-mentioned driven pulleys, the tension pulleys 6 of the auto tensioner are arranged in the order of travel from the drive pulley 3 to the V-ribbed belt 5 as indicated by arrows.
A pulley 7 for power generation of the alternator 4, a pulley 8 for a hydraulic pump of a power steering device, an idler pulley 9, a pulley 10 for a compressor of an air conditioner, and a pulley 11 for an engine cooling fan are arranged.

Here, the rotating shaft 4a of the alternator 4 has a relatively large inertia torque, and if the pulley 7 for power generation is directly mounted on the rotating shaft 4a, the belt 5 is rapidly decelerated when the engine is rapidly decelerated.
The belt is damaged at an early stage due to an increase in the tension of the V-ribbed belt 5, and a slip occurs between the power generation pulley 7 and the V-ribbed belt 5 due to the minute angular speed fluctuation of the crankshaft 2, and the V-ribbed belt 5 is easily worn. Become.

In order to eliminate such inconvenience, a pulley with a built-in clutch is employed as the power generation pulley 7.

FIGS. 2 and 3 show a pulley 7 with a built-in clutch.
Is shown. The pulley 7 with a built-in clutch includes an alternator 4
A pair of bearings 23 and a one-way clutch 24 are incorporated between an inner member 21 attached to the rotary shaft 4a and a pulley 22 provided outside the inner member 21.

The pair of bearings 23 includes an outer ring 23a and an inner ring 23.
The rolling element 23c composed of a ball is incorporated between the balls b, and the rolling element 23c is formed of a rolling bearing held by a retainer 23d. The pair of bearings 23 support a radial load and a moment load acting on the pulley 22, and prevent an unbalanced load from acting on the one-way clutch 24 incorporated between the pair of bearings 23.

The one-way clutch 24 has a clutch outer ring 25 as an outer member, and a retainer 26 is assembled between the clutch outer ring 25 and the inner member 21 and is formed at equal intervals in a circumferential direction of the retainer 26. An engaging element 28 is incorporated in the pocket 27.

The engaging element 28 is made of sprags and has arcuate surfaces 28a and 28b at both ends. Further, one side surface of the engagement element 28 has a pair of inclined surfaces 28c which are inclined in opposite directions,
28d, and a pair of inclined surfaces 28c, 28
V formed on one side of the pocket 27 at the intersection of
The protrusions 29 face each other, and the engaging element 28 can swing about the V-shaped protrusion 29.

The engaging element 28 includes arcuate surfaces 28a at both ends,
28b is pressed by the elastic member 30 in a direction to engage with the cylindrical outer surface 21a formed on the inner member 21 and the cylindrical inner surface 25a provided on the clutch outer ring 25.

Here, the retainer 26 of the one-way clutch 24
And the retainer 23d of the one bearing 23 are integrated,
When the one-way clutch 24 idles, the inner member side and the outer member side of the engagement element 28 in the one-way clutch 24 are evenly slid by utilizing the revolution of the bearing retainer.

When the one-way clutch built-in pulley 7 having the above structure is mounted on the rotating shaft 4a of the alternator 4 and the crankshaft 2 is rotated, the pulley 22 and the clutch outer ring 25 rotate in the direction of the arrow in FIG.

Here, the crankshaft 2 rotates with a slight variation in the angular velocity. When the angular velocity increases, the engaging element 28 of the one-way clutch 24 is raised in the circumferential direction by contact with the clutch outer ring 25 rotating together with the pulley 22. Then, the arcuate surfaces 28 a and 28 b at both ends engage with the cylindrical inner surface 25 a of the clutch outer race 25 and the cylindrical outer surface 21 a of the inner member 21. Therefore, the one-way clutch 24 is locked, the rotation of the pulley 22 is transmitted to the inner member 21, and the rotation shaft 4a of the alternator 4 rotates.

Further, the angular velocity of the crankshaft 1 is reduced, and the rotational speed of the pulley 22 is reduced by the rotating shaft 4 of the alternator 4.
When the rotation speed is lower than the rotation speed of the inner member 2,
The clutch outer ring 25 is tilted in the circumferential direction by contact with the clutch outer ring 25.
Cylindrical inner surface 25a and cylindrical outer surface 2 of inner member 21
The engagement with 1a is released, and the one-way clutch 24 is released. For this reason, the pulley 22 rotates freely with respect to the inner member 21, and the slip between the V-ribbed belt 5 and the pulley 22 is prevented from occurring.
Wear is prevented.

Here, when the engine is a four-cycle four-cylinder engine, the angular speed of the crankshaft 2 fluctuates twice per rotation. Therefore, when the engine is rotated at a high speed, the clutch 28 of the one-way clutch 20 is rotated. The engagement and disengagement are frequently repeated, and the engaging element 28 generates heat by slipping between the inner member 21 and the clutch outer ring 25, and the heat softens the material, thereby easily causing abrasion.

When the engine is rapidly decelerated from the high-speed rotation state, the engagement member 47 of the one-way clutch 24 is disengaged, and the cylindrical inner surface 25a of the clutch outer race 25 and the inner cylindrical inner surface 21a of the inner member 21 are released. The upper part slides, and the sliding causes wear on the engagement element 28.

Therefore, the engagement element 28 of the one-way clutch 24 is required to have wear resistance and heat resistance. In order to meet the demand and find an engaging element 28 having excellent wear resistance and heat resistance, a steel material having the elemental components shown in Table 1 was melted by a vacuum induction furnace and cast into a steel ingot having a weight of 150 kg. A hot forging was carried out by heating and holding at a temperature of 3 ° C. for 3 hours to produce a round bar having a diameter of 50 mm. After keeping the round bar material at 850 ° C for 1 hour as a normalizing process, it is subjected to an air cooling process, and further kept at 790 ° C for 6 hours as a softening process for facilitating cutting, and then up to 650 ° C at 10 ° C. A cooling treatment was carried out at a cooling rate of 1 hour / hour, and the material was subjected to a softening treatment in which it was allowed to cool down to room temperature in the air to obtain materials for various investigations.

[0047]

[Table 1]

<Hardness Investigation> In order to measure the tempered hardness after quenching and the tempered hardness after carbonitriding, a diameter of 5 mm was measured.
A cylindrical test piece having a diameter of 20 mm and a length of 100 mm was prepared from a 0 mm material by machining.

The quenching treatment was performed by heating in a salt furnace, heating at 850 ° C. for 30 minutes, and then quenching in oil at 80 ° C. Thereafter, as a tempering treatment, heating was performed in the same manner in a salt furnace, followed by holding at 350 ° C. for 2 hours and then performing a cooling treatment by air cooling.

In the carbonitriding treatment, a gas atmosphere furnace used in a normal production process is used, and a carbon potential is set to 1.0 to 1.2% and an added amount of NH ₃ is set to 5 to 10% in an RX gas atmosphere. After being kept at 850 ° C. for 60 minutes, it was quenched in oil. Thereafter, tempering was performed at 350 ° C. for 120 minutes.

A 10 mm-thick disk-shaped test piece was cut from the center of the quenched and tempered test piece or the test piece subjected to tempering treatment after carbonitriding, and both sides were polished by wet polishing. A test piece for measuring hardness was prepared.

When measuring the hardness, a Rockwell hardness tester was used to measure the hardness at a position 2 mm deep from the surface of the cross section of the test piece, and the average value at seven points was determined as the tempered hardness.

<Carbide> Thrust-type rolling fatigue life test pieces were used for the measurement of carbides present in steel. A cross section of the ring was cut from a test piece processed into a thrust rolling fatigue life test piece by performing various heat treatments to produce a micro test piece for structure observation. This test piece was mirror-finished and further corroded with a picral etchant to observe carbides. In this micro sample, carbide was observed at a depth of 0.1 mm from the surface layer of the rolling surface with an engineering microscope, and the largest carbide was measured in a visual field area of 50 mm ² .

<Abrasion Test> In order to measure the amount of abrasion after quenching and tempering and carbonitriding, a 50 mm diameter material made of a No. 1 material (STJ2) shown in Table 1 was machined to a diameter of 40 mm and a thickness of 4 mm. 6 disk-shaped test pieces (No. 1-1 to No. 1-6) were prepared. As a comparative example, a material having a diameter of 50 mm made of the material No. 13 (SUJ2) shown in Table 1 was machined to obtain two test pieces (No. 13-1 and No. 13) having the same size as the above-mentioned test pieces. −
2) was created.

In the quenching treatment and the carbonitriding treatment, heat treatment was performed under the same conditions as those of the hardness test piece. After the completion of the heat treatment, one surface of the test piece was polished to a mirror finish.
In addition, in the test piece subjected to carbonitriding, the machining allowance at the time of polishing was set to 0.1 mm.

For the abrasion test, a Savan type abrasion tester was employed. Here, as shown in FIG. 4 (I), the Savan-type abrasion tester contacts a rotating specimen with an oiling pad, contacts a fixed specimen, which is a wear specimen, with the rotating specimen. The rotating test piece is rotated in one direction while a load is applied to the piece in the direction of the arrow, and the width dimension of the wear mark formed on the fixed test piece is measured as shown in FIG. 4 (II). Table 2 shows the conditions of the test.

The measurement results of the above 350 ° C. tempering hardness and the maximum carbide size are shown in Tables 3 and 4, and the measurement result of the wear amount is shown in Table 5.

[0058]

[Table 2]

[0059]

[Table 3]

[0060]

[Table 4]

[0061]

[Table 5]

[0062] From the results of Tables 3 and 4 above, in the present invention example having a composition range of the present invention, be subjected to tempering of 350 ° C., the hardness was found to be a H _R C58 or higher. In the example of the present invention, 0.1 m from the surface layer of the rolling surface.
It was found that the maximum dimension of the carbide at a depth of m was 8.0 μm or less. Further, from the results in Table 5, it was found that in the examples of the present invention, the wear amount was small and the wear resistance was excellent.

The inner member 2 in the one-way clutch
One or both of the clutch outer ring 25 and the clutch outer ring 25 may be formed of the same material as the engagement element 28, and may be subjected to the same heat treatment as that of the engagement element 28.

In the embodiment, the sprag type one-way clutch has been described as an example. However, the one-way clutch is not limited to this, and may be a roller-type one-way clutch.

[0065]

As described above, in the present invention, by finding the optimum compositional elements and their contents,
By performing the quenching and tempering treatment or the carbonitriding treatment, it is possible to obtain an engagement member having high hardness, excellent wear resistance and heat resistance, and to improve the durability of the one-way clutch or the clutch built-in pulley. .

[Brief description of the drawings]

FIG. 1 is a schematic view of an accessory driving device using a pulley with a built-in one-way clutch according to the present invention.

FIG. 2 is a longitudinal sectional front view of the pulley with a built-in one-way clutch shown in FIG. 1;

FIG. 3 is a sectional view showing a part of FIG. 2;

FIG. 4 (I) is a schematic diagram of a Savan-type abrasion tester, (II)
Is a front view showing the state of wear of the fixed test piece shown in (I).

FIG. 5 (I) is a longitudinal sectional front view of a conventional pulley with a built-in clutch, and (II) is a longitudinal sectional side view showing a part of (I).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 21 Inner member 21a Cylindrical outer surface 22 Pulley 23 Bearing 25 Clutch outer ring (outer member) 25a Cylindrical inner surface 26 Cage 27 Pocket 28 Engagement element

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C22C 38/50 C22C 38/50 F16H 55/36 F16H 55/36 Z // C22C 38/54 C22C 38/54 F term (reference) 3J031 BA08 BA19 BC02 CA03 4K042 AA18 AA25 BA03 CA02 CA06 CA08 CA10 CA12 CA13 DA01 DA02 DA06

Claims (7)

[Claims] An inner member attached to a rotating shaft, an outer member provided outside the inner member, and a retainer incorporated between the inner member and the outer member. An engagement element is accommodated in a plurality of formed pockets, and the inner member and the outer member are engaged with the outer surface of the inner member and the inner surface of the outer member by a relative rotation of the inner member and the outer member in one direction. The rotational torque is transmitted between the inner member and the outer member by displacing the engaging element to the position, and the transmitting of the rotational torque is interrupted by displacing the engaging element to the disengaging position by the movement of relative rotation in the other direction. In the one-way clutch, at least one of the inner member, the outer member, and the engagement member is formed of a steel material having the following components, and is tempered after a quenching process or a carbonitriding process to obtain a hardened surface. Saga H _R C58
A one-way clutch as described above, wherein the maximum carbide size is 8 μm or less. "The content of alloying elements is% by mass, C is 0.6 or more and 1.3 or less, Si is 0.3 or more and 3.0 or less, Mn is 0.2 or more and 1.5 or less,
P is 0.03 or less, S is 0.03 or less, Cr is 0.3 or more and 5.0 or less, Ni is 0.1 or more and 3.0 or less, Al is 0.050 or less, Ti is 0.003 or less, O is 0.00
A steel material containing not more than 15 and not more than 0.015 N and the balance having Fe and inevitable impurities. " 2. The steel material according to claim 1, further comprising at least one of Mo of 0.05% or more and less than 0.25% and V of 0.05% or more and 1.0 or less in mass%. Item 1. The one-way clutch according to Item 1. 3. The sprag having at both ends a cylindrical outer surface formed on the inner member and arcuate surfaces engageable with the cylindrical inner surface provided on the outer member. Item 1. The one-way clutch according to Item 1 or 2. 4. A built-in clutch pulley in which an outer member of the one-way clutch according to claim 1 is press-fitted into a cylindrical inner surface formed on the pulley. 5. The pulley with a built-in clutch according to claim 4, wherein a pair of bearings for rotatably supporting the inner member and the pulley relative to each other are provided on both sides of the one-way clutch. 6. The pulley with a built-in clutch according to claim 5, wherein the pair of bearings comprises a rolling bearing having a retainer. 7. The pulley with built-in clutch according to claim 6, wherein a retainer of the one-way clutch and a retainer of one of the pair of rolling bearings are integrally formed.