JP2007327638A - One-way clutch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a one-way clutch equipped both with a high wear resistance in idling and a high friction force stable under engagement so that a sufficient wear resistance of a friction contact surface is secured when the clutch is idling, and when the clutch is in engagement, it is established with as high a friction force as practicable. <P>SOLUTION: The one-way clutch 10 of grease lubrication type is composed of an outer ring 11 fitted by pressure into the inside surface of a pulley 1, an inner ring 12 set inside the outer ring 11, an engaging piece 13 installed between the two rings 11 and 12, a retainer 14 to retain the engaging piece 13, and a resilient member 15 to energize the engaging piece 13 in the direction of engaging, and the friction-engaging surface of the engaging piece 13 is lubricated with a grease. The grease used contains 0.1-20 wt.% alkali metal molybdate in dispersed state, in the form of particulates whose maximum particle size ranges between 0.1-50 μm. Under an extreme pressure condition, the alkali metal molybdate reacts to produce molybdenum oxides on each sliding surface, which exert a wear-suppressing effect. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a one-way clutch that transmits and shuts off rotational torque, and more particularly to a one-way clutch that lubricates a friction engagement surface of an engagement element with grease.

  In general, a mechanical one-way clutch using an engagement element is an engagement element such as a sprag or a roller that engages the inner peripheral surface of the outer ring and the outer peripheral surface of the inner ring to couple the two wheels when the outer ring and the inner ring rotate relative to each other in one direction. The engaging member is urged by an elastic member in a direction to engage with the inner peripheral surface of the outer ring and the outer peripheral surface of the inner ring, and in the biased state, the inner ring and the outer ring are frictionally engaged and rotate integrally, When the engagement is released by the cam, the inner ring and the outer ring idle. Lubricating grease is filled between the outer ring and the inner ring, thereby lubricating the contact portion between the engagement element and the outer ring and the inner ring at the time of idling.

  Such a one-way clutch is incorporated in a rotor of an auxiliary machine such as an air conditioner, an alternator, a water pump, and a cooling fan that is built in a pulley unit and driven via a belt from a crankshaft of an automobile engine, for example. ing.

  When transmitting the main power from the engine etc. to the driven power shaft of the driven auxiliary machine with the equipped one-way clutch, in order to maintain the power shaft on the auxiliary machine side with inertia force as much as possible and increase the power transmission efficiency, For example, the power transmission state and the cut-off state are switched by a one-way clutch in accordance with the rotational difference between the pulley and the rotor, so that the rotor of the auxiliary machine is continuously rotated with as little power as possible. At the time of power transmission, it is necessary to apply high pressure to the friction contact surface by utilizing the wedge effect and engage with a high frictional force. At the time of power interruption, the sliding contact surface at an important point that rotates idly needs to have wear resistance.

  By the way, the wear resistance of the sliding contact surface of the one-way clutch depends greatly on the lubricating grease that is enclosed. It is known to use an ether type grease (Patent Document 1).

  And in order to prevent oil film breakage at the site where the metal contacts with high surface pressure, so-called extreme pressure additive is added to the lubricating grease, but the extreme pressure additive dithiophosphate molybdenum compound or dithiocarbamate molybdenum compound Is used under the condition that the friction coefficient is reduced as much as possible even in the extreme pressure state (Patent Document 2, Patent Document 3).

Japanese Patent Laid-Open No. 11-082688 JP 2002-180076 A JP 2004-256665 A

  However, the one-way clutch in the pulley unit described above has improved wear resistance on the friction contact surface when idling, but when the clutch is engaged, that is, when the friction contact surface is strongly pressurized. Has a problem that it is not engaged with a sufficiently high frictional force due to the presence of the lubricant.

In particular, in a state where the one-way clutch is repeatedly accelerated and decelerated repeatedly, it is required to have both a wear resistance at the time of idling and a stable predetermined frictional force at the time of clutch engagement. It is not easy to configure a one-way clutch so that the conditions to be used are combined.
In addition, these characteristics are easily affected by the level of use of the clutch, and it is difficult to obtain a high coefficient of friction at the time of meshing, especially under low temperature use conditions (for example, about 0 ° C. to −30 ° C.). (For example, about 90 to 110 ° C.), it is difficult to obtain wear resistance during idling.

Accordingly, an object of the present invention is to solve the above-mentioned problems, and when the one-way clutch rotates idly, the friction contact surface has sufficient wear resistance, and when the clutch is engaged, the friction force is high. The one-way clutch can be engaged, and can have both wear resistance during idling and stable high frictional force when coupled.
Furthermore, depending on the use temperature conditions of the one-way clutch, for example, even under low temperature use conditions (for example, about 0 ° C. to −30 ° C.) or high temperature use conditions (for example, about 90 to 110 ° C.) A one-way clutch that can have both wear resistance during idling and stable high frictional force when coupled.

  In order to solve the above problems, in the present invention, in a grease lubrication one-way clutch that lubricates a friction engagement surface of an engagement element of a mechanical one-way clutch with grease, the grease to be lubricated is an alkali metal molybdate salt. Is a grease-lubricated one-way clutch characterized by being a grease containing 0.1 to 20% by weight in a dispersed state.

  That is, the inventors of the present application have found from various test results that the alkali metal salt has remarkable wear resistance among molybdates, and the alkali metal molybdate does not contribute to the low friction coefficient of grease. The present invention has been completed by actively utilizing the characteristics that have been regarded as disadvantageous in the past.

  In the one-way clutch of the present invention, by using a grease containing a predetermined amount of an alkali metal molybdate salt in a dispersed state, the alkali metal molybdate reacts on the sliding surface under extreme pressure conditions, and the molybdenum oxide on the sliding surface. Is generated. This has also been confirmed by XPS analysis, and it is considered that this molybdenum oxide exhibits a wear-inhibiting action.

  Addition of alkali metal molybdate to lubricating grease does not reduce the coefficient of friction, so adding alkali metal molybdate to lubricating grease has both wear resistance at extreme pressure and a high coefficient of friction. Become a one-way clutch.

  In order to provide a one-way clutch with such characteristics, the alkali metal molybdate added to the lubricating grease is preferably contained in a dispersed state in an amount of 0.1 to 20% by weight, and sodium molybdate, potassium molybdate and One or more alkali metal molybdates selected from the group consisting of lithium molybdate are preferred.

The alkali metal molybdate is a fine particle alkali metal molybdate having a maximum particle size of 0.1 to 50 μm, which is a preferable condition in order to invade and react well on the sliding surface under extreme pressure conditions. .
Further, in the above one-way clutch, the alkali metal molybdate is sodium molybdate, the base oil is a mixed oil of ether oil and poly α-olefin oil, the thickener is aromatic diurea, added By using a one-way clutch characterized by containing zinc dithiophosphate and sodium sebacate as agents, the heat resistance of the base oil and thickener eliminates oil film breakage at the contact surface during high-temperature idling, and at low temperatures. At the time of power transmission, a high frictional force is obtained on the frictional contact surface by the selective use of a plurality of additives, and can be reliably engaged.
Further, in the above one-way clutch, sodium molybdate 1.5 to 3% by weight, zinc dithiophosphate 0.5% so that a high coefficient of friction at low temperature and an effect of wear resistance at high temperature are more reliably exhibited. It is preferable to be a one-way clutch characterized by containing ˜1.5 wt% and sodium sebacate 1-3 wt%.

  As one form of the mechanical one-way clutch using the engagement element of the present invention, there are an outer ring, an inner ring rotatable relative to the outer ring, and a circumferential interval between the outer ring and the inner ring. A plurality of engaging members that engage with the inner peripheral surface of the outer ring and the outer peripheral surface of the inner ring to couple the two wheels when the outer ring and the inner ring are relatively rotated in one direction, the cage that holds the engaging elements, It consists of an elastic member that urges the engagement element in the direction of engaging the inner ring surface of the outer ring and the outer ring surface of the inner ring. Lubricating grease filled between the outer ring and the inner ring lubricates the contact part between the engagement element, the outer ring and the inner ring. The one-way clutch can be employed, and the one-way clutch employing the lubricating grease containing a predetermined amount of alkali metal molybdate in a dispersed state can be obtained.

  When the outer ring rotates relative to the inner ring, the engaging element in the above structure engages with each peripheral surface of the inner and outer rings to transmit the rotational torque of the outer ring to the inner ring. At this time, the lubricating grease exhibits a predetermined coefficient of friction and stably exhibits the frictional engagement force between the peripheral surfaces of the engagement element and the inner and outer rings.

  In addition, the engagement element rotates when the outer ring rotates relative to the inner ring in the direction opposite to that during the transmission, or when the rotation speed of the inner ring rotating in the same direction with respect to the outer ring exceeds the rotation speed of the outer ring. The engagement with each peripheral surface is released, and the rotation transmission from the outer ring to the inner ring is cut off.

  In this way, when the one-way clutch rotates idly, the double-row engagement elements rotate relative to the outer ring and the inner ring. Since the engagement element revolves together with the cage while sliding on the inner peripheral surface of the outer ring and the outer peripheral surface of the inner ring, the lubricating grease exhibits predetermined wear resistance, and the engagement element and the inner peripheral surface of the outer ring, the engagement element and the inner ring Abnormal wear due to frictional contact with the outer peripheral surface is prevented.

  In this invention, by adding a predetermined amount of alkali metal molybdate in a dispersed state to the lubricating grease used for the one-way clutch, the frictional contact surface has sufficient wear resistance when idling the one-way clutch. Furthermore, when the clutch is engaged, it is engaged with the required high friction force, that is, there is an advantage that it becomes a one-way clutch that can have both the wear resistance at the time of idling of the clutch and the stable high friction force at the time of engagement. .

The alkali metal molybdate added to the lubricating grease is at least one alkali metal molybdate selected from the group consisting of sodium molybdate, potassium molybdate and lithium molybdate, and has a maximum particle size of 0.1 to 50 μm. By using a fine particle alkali metal molybdate, the above-described effect can be more reliably achieved.
In one-way clutches, sodium molybdate is used as the alkali metal molybdate component of the lubricating grease, and the base oil is a mixed oil of ether oil and poly-α-olefin oil. By adopting diurea and containing zinc dithiophosphate and sodium sebacate as additives, good wear resistance during idling and bonding even at low temperature or high temperature use conditions A one-way clutch that can have both stable and high frictional force. This effect is more reliably achieved by blending the above predetermined components by a predetermined amount.

  According to the present invention, the friction engagement force between each of the peripheral surfaces of the engaging element and the inner and outer rings is stabilized by the one-way clutch having the outer ring inner peripheral surface and the plurality of engaging members that engage with the inner ring outer peripheral surface and couple the two wheels. In addition, there is an advantage that abnormal wear due to frictional contact between the engagement element and the inner peripheral surface of the outer ring and the engagement element and the outer peripheral surface of the inner ring is prevented.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
As shown in FIGS. 1 and 2, a one-way clutch 10 according to the present invention is incorporated into a pulley 1 to form a pulley with a built-in clutch.

  The one-way clutch 10 includes an outer ring 11 press-fitted into the inner diameter surface of the pulley 1, an inner ring 12 incorporated inside the outer ring 11, an engagement element 13 incorporated between the two rings 11, 12, and the engagement element A retainer 14 for holding 13 and an elastic member 15 for biasing the engaging element 13 in the engaging direction.

  The outer ring 11 has a shorter axial length than the inner ring 12, and a cylindrical surface 16 is formed on the inner periphery of the outer ring 11. A cylindrical surface 17 is formed on the outer periphery of the inner ring 12 so as to face the cylindrical surface 16 of the outer ring 11 in the radial direction. Further, on the outer periphery of the inner ring 12, bearing fitting surfaces 18 are formed on both sides of the cylindrical surface 17, and a bearing 19 is supported on each bearing fitting surface 18.

  The bearing 19 is a ball bearing with a single seal. The bearing 19 is assembled so that the seal 20 is located on the outer side, and the pulley 1 and the inner ring 12 are relatively rotatable by the bearing 19. Grease is sealed between the outer ring 11 and the inner ring 12 between the pair of bearings 19.

  The engagement element 13 is made of a sprag. The engagement element 13 is disposed between the cylindrical surface 16 of the outer ring 11 and the cylindrical surface 17 of the inner ring 12 with a gap in the circumferential direction.

  The cage 14 is made of a synthetic resin molded product. As shown in FIG. 2, the retainer 14 is formed with a plurality of pockets 21 for individually accommodating the engaging elements 13 and spring accommodating recesses 22 communicating with the pockets 21. An elastic member 15 made of a spring is incorporated in the frame. The elastic member 15 biases the engaging element 13 in a direction in which the engaging element 13 engages with the cylindrical surface 16 of the outer ring 11 and the cylindrical surface 17 of the inner ring 12.

  Here, when the outer ring 11 together with the pulley 1 rotates relative to the inner ring 12 in the direction of the arrow in FIG. 2, the engaging element 13 engages with each cylindrical surface 16, 17, and applies the rotational torque of the outer ring 11 to the inner ring 12. To communicate. Further, when the outer ring 11 rotates relative to the inner ring 12 in the opposite direction indicated by the arrow or when the outer ring 11 rotates in the direction of the arrow, the rotational speed of the inner ring 12 rotating in the same direction is the outer ring 11. When the rotational speed of the outer ring 11 is exceeded, the engagement with the cylindrical surfaces 16 and 17 is released, and the rotation transmission from the outer ring 11 to the inner ring 12 is cut off. Flange 23 is provided on both sides in the axial direction on the outer peripheral surface of cage 14.

  As shown in FIG. 1, one end of the cage 14 is located in one bearing 19 and holds the ball 19 a of the bearing 19.

  As described above, the retainer 14 of the one-way clutch 10 is held by the retainer 14 of the one-way clutch 10, so that the retainer 14 is rotated during the idling of the one-way clutch 10 in which the outer ring 11 rotates relative to the inner ring 12. Thus, the engaging member 13 rotating together with the retainer 14 can be slid relative to the cylindrical surface 16 of the outer ring 11 and the cylindrical surface 17 of the inner ring 12.

  The pulley with a built-in clutch shown in the embodiment has the above-described structure. In this pulley with a built-in clutch, when the pulley 1 rotates in the direction of the arrow in FIG. 2, the engagement element 13 becomes the cylindrical surface 16 of the outer ring 11 and the cylindrical surface of the inner ring 12. 17, and the rotation of the pulley 1 is transmitted to the inner ring 12. When the rotation speed of the inner ring 12 exceeds the rotation speed of the outer ring 11, the engagement of the engaging elements 13 with respect to the cylindrical surfaces 16 and 17 is released, and the rotation transmission from the outer ring 11 to the inner ring 12 is interrupted.

  For this reason, when the pulley with a built-in clutch as described above is attached to the rotating shaft of the alternator and the belt is passed between the pulley attached to the crankshaft and the pulley on the rotating shaft to drive the alternator, the angular speed of the crankshaft At the time of increase, the one-way clutch 10 is engaged, and the rotation of the crankshaft is transmitted to the rotating shaft of the alternator.

  Further, when the angular velocity of the crankshaft is reduced, the one-way clutch 10 is in an idling state, and the rotation transmission from the crankshaft to the rotating shaft of the alternator is interrupted.

  For this reason, it is possible to prevent slippage between the pulley 1 and the belt applied thereto, and to suppress wear of the belt.

  Here, when the one-way clutch 10 idles, the engaging element 13 rotates relative to the outer ring 11 and the inner ring 12. At this time, the engaging element 13 revolves together with the cage 14 while sliding on the cylindrical surface 16 of the outer ring 11 and the cylindrical surface 17 of the inner ring 12.

The base oil used in the lubricating grease used in the present invention 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 alkyl diphenyl ether and polyphenyl ether, diester oil, polyol ester oil, etc. Ester synthetic oil, silicone oil such as polydimethylsiloxane, polyphenylmethylsiloxane, GTL base oil, hydrocarbon synthetic oil such as poly-α-olefin oil (abbreviated as PAO oil), fluorine oil, etc. These mixed oils are mentioned.
Examples of the ether oil include dialkyl diphenyl ether oil, alkyl triphenyl ether oil, and alkyl tetraphenyl ether oil.

The PAO oil is usually a mixture of an α-olefin or an isomerized α-olefin oligomer or polymer. Specific examples of the α-olefin include 1-octene, 1-nonene, 1-decene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1 -Nonadecene, 1-eicocene, 1-docosene, 1-tetracocene and the like can be mentioned, and usually a mixture thereof is used.
A particularly preferable example is a mixed oil of a polyether oil and a poly α-olefin oil, and the ratio of the mixing may be arbitrary, and more preferably 1 by weight ratio of the polyether oil and the poly α-olefin oil. : 9-5: 5.

  As the thickener used for the base grease in the present invention, a well-known thickener that can be blended with the lubricating grease can be widely used. Examples thereof include a soap such as lithium soap, lithium complex soap, calcium soap, calcium complex soap, aluminum soap, and aluminum complex soap, or a urea-based thickener composed of a urea compound.

  Examples of the urea thickener include, but are not particularly limited to, a diurea compound and a polyurea compound. A diurea compound is obtained by reaction of diisocyanate and a monoamine, for example. Examples of diisocyanates include phenylene diisocyanate, diphenyl diisocyanate, phenyl diisocyanate, diphenylmethane diisocyanate, octadecane diisocyanate, decane diisocyanate, hexane diisocyanate, and monoamines include octylamine, dodecylamine, hexadecylamine, octadecylamine, oleylamine, aniline, p-Toluidine, cyclohexylamine and the like can be mentioned. The polyurea compound can be obtained, for example, by reacting diisocyanate with a monoamine or diamine. Examples of the diisocyanate and monoamine include those used for the production of diurea compounds. Examples of the diamine include ethylenediamine, propanediamine, butanediamine, hexanediamine, octanediamine, phenylenediamine, tolylenediamine, xylenediamine, and the like. Is mentioned.

  Among these, as a thickener applied to this invention, the diurea compound represented by following Chemical formula 1 is mentioned.

Wherein R ₁ and R ₃ are the same or different linear alkyl group having 4 to 24 carbon atoms, alicyclic hydrocarbon group or aromatic hydrocarbon group having 6 to 12 carbon atoms, and R ₂ is carbon (It is an aromatic hydrocarbon group having a number of 6 to 15.)

Here, as a C4-C24 alicyclic hydrocarbon group used for R < ₁ > and R < ₃ >, a cyclohexyl group and a cyclohexyl derivative are mentioned, for example.
Moreover, as a C6-C12 aromatic hydrocarbon group used for R < ₁ > and R < ₃ >, it has the characteristic excellent in thermal stability and oxidation stability, for example, a phenyl group, a toluyl group, a xylyl group, t- Examples thereof include a butylphenyl group and a benzyl group, and a monovalent aromatic hydrocarbon group is particularly suitable. That is, it is particularly preferable to employ aromatic diurea as a thickener in order to give the lubricating grease the required heat resistance.

  The molybdate used in the present invention reacts at the lubrication interface and exhibits characteristics such as wear resistance. It was found by XPS analysis that when molybdate was added to the grease composition, the molybdate reacted on the sliding surface to form molybdenum oxide. This molybdenum oxide is considered to have an effect of suppressing wear.

  If the maximum particle size of the molybdate is too large, it will be difficult to enter the lubrication part, and if it is too small, the molybdate will be buried in the roughness of the sliding part, the reaction will not occur and the expected effect cannot be demonstrated. . Therefore, it is desirable that the maximum particle size of molybdate added to the grease is 0.1 μm to 50 μm. When the particle size is less than the lower limit of 0.1 μm, molybdate is buried in the rolling surface roughness of the bearing. The upper limit of 50 μm is a value confirmed from various experiments, and when it exceeds 50 μm, the wear resistance is poor.

The molybdate used in the present invention is an alkali metal salt, and typical examples thereof include potassium molybdate, sodium molybdate, lithium molybdate and the like.
Since the alkali metal salt of molybdic acid is a solid insoluble in oil, it exists in the grease in a dispersed state in the same manner as a solid lubricant such as molybdenum disulfide. The alkali metal salt of molybdic acid reacts at the lubrication interface of each sliding portion in the rolling bearing to form molybdenum oxide on the metal surface. Although the mechanism by which the wear resistance is exhibited by the alkali metal salt of molybdic acid is not clarified, it is considered that the molybdenum oxide produced as described above has wear resistance.

  In this invention, the blending amount of the alkali metal salt of molybdic acid in the lubricating grease is preferably 0.1 to 20% by weight. This is because if the amount is less than 0.1% by weight, the amount of the alkali metal molybdate becomes too small, so that the expression of wear resistance becomes insufficient. On the other hand, if it exceeds 20% by weight, the effect reaches its peak and the cost becomes disadvantageous. For these reasons, a more preferable blending amount is 0.5 to 10% by weight.

  The lubricating grease used in the present invention can contain known additives as necessary in order to enhance its excellent performance. As this additive, for example, solid lubricants such as molybdenum disulfide and graphite, antioxidants such as amine-based and phenol-based compounds, rust inhibitors such as petroleum sulfonates, dinonylnaphthalene sulfonates, sorbitan esters, sulfurized fats and oils, Sulfur compounds typified by sulfurized olefins, thiophosphates, sulfur-phosphorus compounds typified by thiophosphites, phosphorus compounds typified by tricresyl phosphate, etc., extreme pressure agents, metal sulfonates, metal phosphates Detergents such as organic molybdenum, friction reducers such as organic molybdenum, wax compounds, fatty acid amides, fatty acids, amines, oils such as fats and oils, metal deactivators such as benzotriazole, polymethacrylate, polystyrene, etc. Agents and the like. You may add these individually or in combination of 2 or more types.

  As an example of the combination of the above-described materials so as to function most efficiently, as described above, the alkali metal molybdate is sodium molybdate, and the base oil is a mixed oil of ether oil and poly α-olefin oil. The thickener is an aromatic diurea and contains zinc dithiophosphate and sodium sebacate as additives, and the blending ratio thereof is 1.5 to 3% by weight of sodium molybdate, dithiophosphoric acid The zinc content is preferably 0.5 to 1.5% by weight and sodium sebacate 1 to 3% by weight. And if sorbitan trioleate 0.5-2 weight% is added, rust prevention performance will also be improved.

By blending 1.5 to 3% by weight of sodium molybdate, sodium molybdate is added and decomposes efficiently on the newly formed metal surface exposed by wear, and a molybdenum compound film is formed together with iron oxide to improve wear resistance. be able to.
By blending 0.5 to 1.5% by weight of zinc dithiophosphate, the clutch engages with a high coefficient of friction without almost acting as an extreme pressure agent when contacting the friction surface at a low temperature with a high coefficient of friction. It decomposes at high temperatures and exhibits wear resistance.
Further, by adding 1 to 3% by weight of sodium sebacate, the durability (life) of the lubricating grease at a high temperature is remarkably improved and the wear resistance of the friction surface is improved.

[Examples 1, 3, 5 and Comparative Examples 1-4]
In 2000 g of mineral oil (kinematic viscosity at 100 ° C. of 13.5 mm ² / sec), 60.6 g of diphenylmethane-4,4′-diisocyanate, 31.3 g of octylamine and 66.2 g of stearylamine were reacted. The resulting urea compound was uniformly dispersed to obtain a grease. Additives were added to this base grease A at the blending ratios shown in Table 1, and the resulting compound was subjected to JIS consistency No. 1 using a three-stage roll mill. A lubricating grease was obtained by adjusting to 1 grade.

[Examples 2, 4 and 6]
Production by reacting 158.2 g of diphenylmethane-4,4′-diisocyanate, 81.3 g of octylamine and 58.9 g of aniline in 2000 g of mineral oil (kinematic viscosity at 100 ° C. of 13.5 mm ² / sec) The resulting urea compound was uniformly dispersed to obtain a grease. Additives were added to this base grease B in the formulation shown in Table 1, and the resulting compound was subjected to JIS consistency no. Lubricating grease was obtained by adjusting to 1 grade.

  Among the additives 1) to 6) comprising the molybdenum compound in Table 1, sodium molybdate was manufactured by Taiyo Kogyo Co., Ltd .: Morisoh, and other additives were reagents manufactured by Wako Pure Chemical Industries.

  The obtained lubricating grease was examined for wear resistance by using a reciprocating (SRV) friction and wear test machine assuming the use state of the one-way clutch under the following conditions, and further manufactured by NTN Corporation having the structure shown in FIG. A pulley with a built-in directional clutch was enclosed between the outer ring 11 and the inner ring 12 and the following clutch durability test was conducted. The results are summarized in Table 1.

<SRV reciprocating friction and wear test>
A wear test was conducted under the following conditions using an SRV reciprocating friction wear tester, and the wear resistance performance of various grease compositions was compared.
・ Load 800N ・ Amplitude 1mm ・ Frequency 20Hz ・ Test time 5h
-Ball SUJ2φ10 steel ball-Disc SCM material After the wear test under these conditions, the wear width of the disc sliding part was measured, and this was evaluated as wear resistance.

<Clutch durability test>
Using a rapid acceleration / deceleration test machine, the test clutch was a NTN one-way clutch built-in pulley (see Figs. 1 and 2), and the rotational speed was 0 to 20000 rpm under the conditions of a radial load of 1400 N and a test atmosphere of 110 ° C. The deceleration / stop process up to this was repeated as one cycle, and the presence or absence of durability for 500 hours was examined.

  In each of the examples, in addition to the stability of the friction coefficient, the clutch function (locking and good idling state) was ensured even after the end of the required durability time of 500 hours. About the comparative example which became the driving | running failure in less than 500 hours, the damage state which abnormally wears or pops out in less than durable time was seen.

[Example 7]
In 2000 g of a mixed oil (2: 8 [weight ratio]) of a polyether oil and a polyalphaolefin oil, 269.4 g of diphenylmethane-4,4′-diisocyanate and 288.3 g of p-toluidine are reacted. The resulting aromatic diurea compound was uniformly dispersed to obtain a base grease. Additives were added to this base grease at a blending ratio of 1.5% by weight of sodium molybdate, 0.5% by weight of zinc dithiophosphate, 1% by weight of sodium sebacate, and 0.5% by weight of sorbitan trioleate. The JIS consistency No. is measured using a three-stage roll mill. A lubricating grease was obtained by adjusting to 1 grade.

[Example 8]
In 2000 g of a mixed oil (5: 5 [weight ratio]) of a polyether oil and a polyalphaolefin oil, 269.4 g of diphenylmethane-4,4′-diisocyanate and 288.3 g of p-toluidine are reacted. The resulting aromatic diurea compound was uniformly dispersed to obtain a base grease. To this base grease, an additive was added at a blending ratio of 3% by weight of sodium molybdate, 1.5% by weight of zinc dithiophosphate, 3% by weight of sodium sebacate, and 2% by weight of sorbitan trioleate. No. JIS consistency No. A lubricating grease was obtained by adjusting to 1 grade.

  In order to evaluate the obtained lubricating greases of Examples 7 and 8, the NTN-made one-way clutch pulley with the structure shown in FIG. 1 was sealed between the outer ring 11 and the inner ring 12, and the above-mentioned clutch durability test was performed under the same conditions. It was done in. In addition, one cycle of the deceleration / stop process (locking and idling) from the rotational speed 0 to 20000 rpm is as follows: acceleration 1.2 seconds, constant speed 9.0 seconds, deceleration 1.0 seconds, stop 9.0 seconds It was.

  In this clutch durability test, it was evaluated that both Examples 7 and 8 had a durability time of 500 hours or more. In addition, a meshing test of the test clutch was performed at −30 ° C., and it was confirmed that the clutch operated normally.

[Comparative Example 5]
A base grease was obtained by uniformly dispersing an aliphatic diurea compound in 2000 g of an ether-based synthetic oil. To this base grease, 2% by weight of an amine-based antioxidant, 0.5% by weight of a naphthenic acid inhibitor and 0.5% by weight of a succinic acid derivative were added. A lubricating grease was obtained by adjusting to 1 grade.

  The obtained lubricating grease was subjected to a clutch durability test under exactly the same conditions as in Example 8, but the durability time was less than 1/10 of that in Example 8, which was about 30 hours.

[Comparative Example 6]
A base grease was obtained by uniformly dispersing an alicyclic diurea and an aliphatic diurea compound in 2000 g of an ester synthetic oil. To this base grease, 2% by weight of an amine-based antioxidant, 0.5% by weight of a naphthenate inhibitor and 0.5% by weight of zinc dithiophosphate (Zn-DTP) are added, and the resulting compound is mixed with a three-stage roll mill. JIS consistency No. A lubricating grease was obtained by adjusting to 1 grade.

  The obtained lubricating grease was subjected to a clutch durability test under exactly the same conditions as in Example 8. However, the durability was about 1/10 of that in Example 8, which was about 50 hours.

Longitudinal front view of the embodiment with the one-way clutch incorporated in the pulley Sectional view along the line II-II in FIG.

Explanation of symbols

1 pulley 10 one-way clutch 11 outer ring 12 inner ring 13 engagement element 14 cage 15 elastic member

Claims (6)

In the one-way clutch that lubricates the friction engagement surface of the mechanical one-way clutch with grease,
The one-way clutch characterized in that the grease to be lubricated is a grease containing 0.1 to 20% by weight of an alkali metal molybdate salt in a dispersed state.   The one-way clutch according to claim 1, wherein the alkali metal molybdate is at least one alkali metal molybdate selected from the group consisting of sodium molybdate, potassium molybdate, and lithium molybdate.   The one-way clutch according to claim 1 or 2, wherein the alkali metal molybdate is a particulate alkali metal molybdate having a maximum particle size of 0.1 to 50 µm.   3. The one-way clutch according to claim 2, wherein the alkali metal molybdate is sodium molybdate, the base oil is a mixed oil of ether oil and polyalphaolefin oil, and the thickener is an aromatic diurea. A one-way clutch characterized by containing zinc dithiophosphate and sodium sebacate as additives.   The one-way clutch according to claim 4, characterized by containing 1.5 to 3% by weight of sodium molybdate, 0.5 to 1.5% by weight of zinc dithiophosphate, and 1 to 3% by weight of sodium sebacate. One way clutch to do.   A mechanical one-way clutch using an engagement element is arranged with an outer ring, an inner ring rotatable relative to the outer ring, and a circumferential interval between the outer ring and the inner ring. A plurality of engagement elements that engage with the inner peripheral surface of the outer ring and the outer peripheral surface of the inner ring to couple the two wheels when rotated relative to each other, a retainer that holds the engagement elements, and the inner engagement surface of the outer ring. And a one-way clutch that lubricates the contact portion of the engagement element, the outer ring and the inner ring with lubricating grease filled between the outer ring and the inner ring. The one-way clutch according to any one of claims 1 to 5.

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