JP2007263216A - One-way clutch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a one-way clutch, in which shortage of lubricating oil on a sliding face is prevented, a usable temperature range is wide, and abnormal noise property, abrasion resistance, and durability are excellent. <P>SOLUTION: The one-way clutch has a clutch casing 1, its closing cover, an outer ring 12 for clutch, and a plurality of roller holding pockets 15 circumferentially disposed on an inner diameter face of the outer ring 12. The outer ring 12 for clutch is sintered metal body, and is formed by impregnating the outer ring 12 with liquid grease having worked penetration of 400 or more. The inner diameter face of the outer ring 12 for clutch has 20% to 35% of a surface opening hole ratio. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a one-way clutch that transmits only one-way torque of an input member to an output member.

One-way clutches are used in a wide range from those having a large torque capacity used for automobiles and electric tools to those having a small torque capacity used for office machines such as copy machines and personal computers, cameras, and the like.
Conventionally, as a one-way clutch, a cylindrical body is provided outside the shaft, and a plurality of cam surfaces are formed on the outer periphery of the shaft to form a wedge-shaped space between the cylindrical inner surface formed on the cylindrical body, A wedge-shaped friction member is incorporated between each cam surface and the cylindrical inner surface, and the friction member is urged toward the narrow part of the wedge-shaped space by an elastic member. There are known those in which the entire arcuate surface is brought into contact with a cylindrical inner surface and a cam surface (see Patent Document 1).
In this one-way clutch, when the shaft rotates in the direction in which the wedge angle becomes smaller, the rollers move in that direction and lock into the wedge-shaped cavity so that the shaft, outer ring and clutch casing are integrated. Rotate. When the shaft rotates in the opposite direction, the rollers are unlocked and the shaft rotates idle.

In conventional one-way clutches as described above, it is often difficult to improve the positional accuracy to match the center of the inscribed circle of the roller with the center of each shaft insertion hole. Appears, which causes a problem of clutch rotation swing. In order to solve this problem, a one-way clutch is known in which the inner ring surface of the outer ring between the roller holding pockets is a radial bearing surface with respect to the shaft to prevent the clutch rotation from swinging (see Patent Document 2).
However, structural support alone is not sufficient in terms of wear resistance and acoustic characteristics, and it is necessary to cope with the slidability between the outer ring and the roller.

  Some one-way clutches have an outer ring impregnated with lubricating oil or the like and the lubricating oil or the like is interposed at the sliding interface in order to properly slide between the outer ring and the roller. As shown in FIG. 4, in an ordinary oil sliding bearing with an inner diameter sliding, as the shaft rotates, the lubricating oil impregnated inside oozes out to the inner diameter surface due to the effect of pumping and heat generation, and performs the lubricating action. . That is, when the shaft rotates, the oil inside the bearing is sucked out, and the oil flows from the upper portion where the hydraulic pressure is low toward the sliding portion that receives the high hydraulic pressure. The oil wedge generated by the oil flow lifts the shaft from the bottom surface of the bearing and functions to prevent contact between metals. Further, the shaft is displaced in the rotational direction by the flow of oil entering, and the hydraulic pressure distribution on the bearing inner diameter surface is as shown in FIG.

However, in the case of a one-way clutch, as shown in FIG. 3 which is an enlarged view of a portion C of FIG. 2 as a cross-sectional view of the one-way clutch, between the outer ring 12 and 17 impregnated with a lubricant, No pumping action occurs because there is no difference in hydraulic pressure around. That is, in FIG. 3, the oil wedge is not formed in the portion a and is not in contact with the roller 17, so there is no change in pressure and there is no element that the lubricant oozes out. Although the pressure difference is generated locally in the vicinity of the roller 17 as in the portion b, the effect is considered to be insignificant as compared with the oil-impregnated bearing. As described above, the one-way clutch has a structure in which the lubricating oil inside the outer ring does not easily leak out, so that the lubricant does not easily leak out.
In addition, when lubricating oil is used as the lubricant, scattering and evaporation are likely to occur, and the oozing state is likely to fluctuate due to changes in ambient temperature. As a result, there is a problem that abnormal noise is generated and wear is easily promoted.
On the other hand, when lubricating grease (miscibility of less than 400) is used as the lubricant, it is less likely to scatter or evaporate compared to the lubricating oil, but it requires a familiar operation after assembly or when grease is filled. There is a demerit such as inconvenient handling due to excess grease overflowing.
JP-A-5-332409 Japanese Patent Laid-Open No. 10-238560

  The present invention has been made to address such problems, and is a one-way clutch that does not have a shortage of lubricating oil on the sliding surface, has a wide usable temperature range, and has excellent noise characteristics, wear resistance, and durability. The purpose is to provide.

The one-way clutch of the present invention is a one-way clutch comprising a clutch casing, a closing lid thereof, an outer ring for clutch, and a plurality of roller holding pockets provided circumferentially on the inner diameter surface of the outer ring, The outer ring for clutch is made of a sintered metal body, and the outer ring is impregnated with liquid grease having a blending degree of 400 or more.
The mixing penetration in the present invention is 60 penetrations at 25 ° C. measured by the method defined in JIS K2220.

The outer ring for clutch is characterized in that the surface opening ratio of the inner diameter surface is 20% to 35%.
In the present invention, the surface aperture ratio refers to the area ratio of the surface aperture (the portion where the pores of the sintered metal body are opened on the outer surface) in the unit area of the inner surface of the outer ring.

The liquid grease is characterized in that a synthetic hydrocarbon oil or polyol ester is used as a base oil and a thickener is contained in an amount of 0.5 to 5% by weight based on the whole grease.
Further, the thickening agent for the liquid grease is a metal soap or a urea compound.

The one-way clutch of the present invention is formed by impregnating the outer ring, which is a sintered metal body, with liquid grease having a miscibility of 400 or more, so that the liquid grease is applied to the inner ring surface of the outer ring by the effect of the thickener. It is easy to adhere and a state in which liquid grease is always present on the inner surface of the outer ring is obtained, and good sliding can be obtained between the roller and the outer ring. In addition, since it is a liquid grease with a blending degree of 400 or more, a familiar operation is not required, and torque fluctuations can be suppressed. In addition, liquid grease is always present on the inner surface of the outer ring regardless of changes in ambient temperature, so that it is possible to prevent abnormal noise and suppress wear.
In addition, since the surface opening ratio of the inner surface of the outer ring is 20% to 35%, in addition to liquid grease held on the inner surface of the outer ring, liquid grease seeps out from the outer ring. Prevention of sound generation and suppression of wear can be expected.

A one-way clutch according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a cross-sectional view of a one-way clutch. FIG. 2 is an enlarged cross-sectional view taken along line BB in FIG. As shown in FIGS. 1 and 2, the one-way clutch includes a clutch casing 1, a closing lid 2, and a clutch unit 3.
The clutch casing 1 is formed of an appropriate resin or the like, and has a cylindrical wall formed with a blocking wall 4 having a required thickness. A shaft insertion hole 5 is provided at the center of the blocking wall 4, and the shaft insertion hole The inner diameter surface of 5 serves as a radial bearing for the shaft 6 inserted therethrough. A storage portion 7 having a diameter larger than that of the shaft insertion hole 5 is provided in the clutch casing 1. The clutch unit 3 is stored in the storage portion 7, and the closing lid 2 is fitted to the open end of the storage portion 7. The closing lid 2 has an engagement rib 8 on its outer diameter surface, and an engagement groove 9 is formed on the inner diameter surface of the open end.
A shaft insertion hole 11 is also provided at the center of the closing lid 2, and the shaft insertion hole 11 is another radial bearing for the shaft 6.

  Further, as shown in FIG. 2, the outer ring 12 constituting the clutch unit 3 is provided with an anti-rotation recess 13 on the outer diameter surface thereof, and an anti-rotation rib 14 on the inner diameter surface of the storage portion 7. Mating. Further, a required number of roller holding pockets 15 are provided on the inner diameter surface of the outer ring 12 at regular intervals in the circumferential direction. The outer ring 12 is made of sintered metal and impregnated with liquid grease having a blending degree of 400 or more.

The bottom of the roller holding pocket 15 is an inclined cam surface 16 inclined in a fixed direction, and a wedge-shaped cavity having a fixed wedge angle between the inclined cam surface 16 and the outer diameter surface of the shaft 6. Is forming. A recess 18 for storing the spring is formed on the end surface of the roller cage pocket 15 opposite to the side where the wedge angle is reduced. The inclined cam surface 16 is also a part of the inner diameter surface of the outer ring 12.
Rollers 17 are housed in the roller holding pockets 15, and leaf springs 19 are housed in the recesses 18, and the spring force of the leaf springs 19 presses the rollers 17 in a direction in which the wedge angle decreases. . Each leaf spring 19 is integrally connected by the annular portion 10, and each leaf spring 19 is inserted into the recess 18 from the side of the closing lid 2. The annular portion 10 is sandwiched between the closing lid 2 and the end surface of the outer ring 12.

When the shaft 6 rotates in the direction in which the wedge angle becomes smaller as indicated by the arrow A in FIG. 2, the roller 17 moves in that direction and bites into the wedge-shaped cavity. The shaft 6, the outer ring 12, and the clutch casing 1 rotate as a unit. At this time, the load acting on the clutch casing 1 is supported by radial bearings in the portions of the blocking wall 4 and the shaft insertion holes 5 and 11 of the closing lid 2. The roller 17 is smoothly moved by the liquid grease held on the inner surface of the outer ring 12 by the liquid grease impregnated in the outer ring 12.
When the shaft 6 rotates in the opposite direction, the roller 17 is unlocked and the shaft 6 rotates idly.

  The outer ring 12 used in the one-way clutch of the present invention is a sintered metal body and has pores formed between the sintered particles inside, and liquid grease is impregnated in the pores. In the manufacturing process of the outer ring 12, first, metal powder such as copper or iron and an additive such as graphite are mixed, and this mixture is filled in a mold and compression-molded into an outer ring shape. The molded product is sintered and sized and then impregnated with liquid grease by vacuum impregnation. After impregnation, the oil is drained so that the liquid grease is thinly and uniformly attached to the inner surface of the outer ring. Depending on the sintered state, a heat treatment for hardening and a barrel treatment for removing scale caused by the heat treatment can be performed between the sizing and the oil impregnation treatment.

In the one-way clutch, the impregnated liquid grease does not generate a pumping action as described above, so that the liquid grease does not easily leak out. Therefore, it is necessary to appropriately set the surface area ratio of the inner diameter surface in order to allow the liquid grease to exude accurately.
The surface opening ratio of the inner surface of the outer ring used in the one-way clutch of the present invention is preferably 20% to 35%. If the surface porosity is less than 20%, the liquid grease impregnated in the sintered metal will not easily ooze out to the outer ring surface, so that only the liquid grease retained on the surface will be lubricated. . Also, if the surface porosity is greater than 35%, the liquid grease impregnated inside the sintered metal tends to scatter and evaporate, and there is not enough liquid grease on the inner ring surface when operating for a long time. Abnormal noise or wear may occur.
The surface open area ratio can be adjusted by the particle diameter of the powder and the density of the green compact. In the present invention, a metal powder having a particle size of 100 mesh or less is used, and the surface open area ratio can be adjusted to the above range by forming the green powder density in the range of 6.4 to 7.2 g / cm ³ . Further, the surface porosity can be finely adjusted by performing sizing, coining, and barrel treatment after sintering.

In the present invention, the base oil used for the liquid grease can be used without limitation as long as it is a commonly used base oil. For example, mineral oil such as naphthenic, paraffinic, liquid paraffin, hydrodewaxed oil, polyglycol oil such as polyalkylene glycol, ether synthetic oil such as alkyldiphenyl ether and polyphenyl ether, diester oil, polyol ester oil, etc. Examples thereof include ester synthetic oils, silicone oils such as polydimethylsiloxane and polyphenylmethylsiloxane, hydrocarbon synthetic oils such as GTL base oil and poly-α-olefin oil, and base oils such as fluorine oil.
When the one-way clutch of the present invention has a resin clutch casing and it is necessary to suppress the aggressiveness of the liquid grease against the resin, a synthetic hydrocarbon oil is required as the base oil, and the heat resistance of the liquid grease is required. In this case, it is preferable to use a polyol ester as the base oil.

The thickener used for the liquid grease in the present invention can be used without particular limitation as long as it is a commonly used thickener. Examples thereof include metal soaps such as lithium soap, lithium complex soap, high-strength soap, calcium complex soap, aluminum soap, and aluminum complex soap, and urea compounds such as diurea compounds and polyurea compounds.
Of these, lithium soap or urea compounds are preferably used because they are relatively inexpensive and can be used in a wide temperature range.

In the present invention, the thickener is blended in such a ratio that the resulting grease has a blending degree of 400 or more. Specifically, the thickener is preferably blended in an amount of 0.5 to 5% by weight based on the entire grease.
A liquid grease having a miscibility of 400 or more has both the fluidity and lubricity, which are the advantages of lubricating oil, and the retainability and non-evaporability, which are the advantages of grease. On the other hand, the lubricating oil has good fluidity and excellent lubricity, but tends to cause scattering and evaporation due to centrifugal force. On the other hand, normal grease (miscibility of less than 400) has a holding force and is difficult to scatter, but has a drawback of poor fluidity and large load.
Since the one-way clutch of the present invention is impregnated with this liquid grease, the grease-like characteristics prevent the grease from scattering and evaporating, and it is always present on the inner surface of the outer ring, and it can be used as a lubricating oil. From such characteristics, good lubricity and appropriate fluidity can be obtained. As a result, a running-in operation or the like is unnecessary and torque fluctuations can be suppressed, and generation of abnormal noise and suppression of wear can be expected over a long period.

  The one-way clutch of the present invention is suitable as a one-way clutch used for office machines and various industrial machines because liquid grease is always present on the inner surface of the outer ring and good sliding is obtained between the rollers and the outer ring. Available to:

It is sectional drawing of the one way clutch which concerns on one Example of this invention. It is a figure which shows the expanded cross section of the AA line of FIG. It is the figure which expanded the B section of FIG. It is a figure which shows the mechanism of a pump action.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Clutch casing 2 Closure lid 3 Clutch unit 4 Closure wall 5 Shaft insertion hole 6 Shaft 7 Storage part 8 Engagement rib 9 Engagement groove 10 Annular part 11 Shaft insertion hole 12 Outer ring 13 Recess 14 Rib 15 Roller holding pocket 16 Inclination cam Surface 17 Roller 18 Recess 19 Leaf spring

Claims (4)

A one-way clutch comprising a clutch casing, its closing lid, an outer ring for clutch, and a plurality of roller holding pockets provided circumferentially on the inner diameter surface of the outer ring,
The one-way clutch characterized in that the outer ring for clutch is made of a sintered metal body, and the outer ring is impregnated with liquid grease having a blending degree of 400 or more.   2. The one-way clutch according to claim 1, wherein the outer ring for a clutch has a surface opening ratio of an inner diameter of 20% to 35%.   3. The liquid grease according to claim 1, wherein the liquid grease contains a synthetic hydrocarbon oil or a polyol ester as a base oil and contains a thickener in an amount of 0.5 to 5% by weight based on the whole grease. One way clutch.   4. The one-way clutch according to claim 1, wherein the thickener of the liquid grease is a metal soap or a urea compound.

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