JP2009227896A - Torque limiter, and lubricating oil for torque limiter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent occurrence of stick-slip between a torque transmission member and the frictional surface of an inner member, and to reduce the initial drop level of transmitted torque. <P>SOLUTION: A lubricating oil for torque limiter, which is to be fed onto the outer diameter surface of a cylindrical inner member as an input member 2 tightened with coil springs 4, is provided. This lubricating oil, whose base oil consists of a poly-α-olefin oil, has a kinematic viscosity of 200-500 mm<SP>2</SP>/s at 40°C. By using this lubricating oil, occurrence of stick-slip between the outer diameter surface as the frictional surface of an inner member and coil springs 4 as a torque transmission member is prevented, and the initial drop level of transmitted torque is reduced. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a torque limiter that transmits torque by a frictional force between a friction surface provided on a cylindrical or columnar inner member and a torque transmission member, and a lubricating oil for torque limiter.

  A torque limiter used in a paper feeder of an office machine has a torque transmission member in which at least one of an input member and an output member is a cylindrical or columnar inner member and is interposed between the input member and the output member Is pressed against the friction surface provided on the inner member, torque is transmitted from the input member to the output member by the friction force between the friction surface of the inner member and the torque transmission member, and the torque limiter is applied to the friction surface of the inner member. A torque limiter is used in which when the lubricating oil is supplied and a load exceeding a predetermined level is applied to the output member, the torque transmitting member slips with the friction surface of the inner member, causing the input member to idle. (For example, refer to Patent Documents 1 and 2).

Conventionally, mineral oils and synthetic oils having a kinematic viscosity at 40 ° C. of 100 to 200 mm ² / s are generally used for lubricating oil for torque limiter supplied to the friction surface of the inner member. Some members are made of a sintered metal member, and an inner member made of the sintered member is impregnated with lubricating oil. Further, for a torque limiter used under high temperature and high humidity, a lubricating oil in which an emulsifier is blended with a base oil composed of a saturated synthetic hydrocarbon oil having a kinematic viscosity at 40 ° C. of 500 to 1200 mm ² / s is used. There is also one that prevents a decrease in lubricity due to water droplets being mixed in (see, for example, Patent Document 3).

Japanese Utility Model Publication No. 5-8062 JP-A-8-270675 Japanese Patent Laid-Open No. 2006-2018

The above-mentioned lubricating oil for torque limiter having a kinematic viscosity of 100 to 200 mm ² / s that is generally used for supplying the inner member to the friction surface is likely to cause an oil film breakage during low-speed rotation. There is a problem that stick slip occurs between the friction surface and the torque transmission member. When such a stick-slip occurs, the transmission torque changes in a sawtooth shape as shown in FIG. 6, and the smooth rotation of the output member is hindered, and an annoying noise is generated.

  In addition, when the torque limiter lubricating oil is mineral oil, in addition to the friction coefficient being lowered due to the influence of sulfur contained as impurities, the impurities may chemically attack the resin parts constituting the torque limiter. It is difficult to maintain the transmission torque stably for a long time. There is also a risk that the lubricating oil leaks from the torque limiter and chemically attacks resin parts such as a rubber roller mounted on the outside.

As described in Patent Document 3, the one using a high viscosity oil having a base oil kinematic viscosity of 500 to 1200 mm ² / s has a large viscosity drop due to a temperature increase in the initial operation, as shown in FIG. There is a problem that the initial reduction amount ΔT of the transmission torque becomes large at the beginning of operation. Since the torque limiter is designed with a stable transmission torque with a stable transmission torque, if the initial decrease ΔT of the transmission torque increases, not only the torque transmission at the initial stage of operation becomes unstable but also an excessive amount at the initial stage of the operation. Torque is transmitted to the output member, which may shorten the durability life.

  Therefore, an object of the present invention is to prevent the occurrence of stick-slip between the friction surface of the inner member and the torque transmission member, and to reduce the initial reduction amount of the transmission torque.

In order to solve the above problems, the lubricating oil for torque limiter according to the present invention has at least one of the input member and the output member as a cylindrical or columnar inner member interposed between the input member and the output member. The torque transmission member is pressed against the friction surface provided on the inner member, and torque is transmitted from the input member to the output member by the friction force between the friction surface of the inner member and the torque transmission member. Torque that causes the input member to idle when the torque transmission member slips with the friction surface of the inner member when a predetermined load or more is applied to the output member by supplying lubricating oil to the surface. In the lubricating oil for torque limiter supplied to the friction surface of the limiter, the base oil of the lubricating oil is one or two selected from hydrides of poly-α-olefin and ethylene-α-olefin copolymer A saturated synthetic hydrocarbon oil in which the above was combined was adopted, and a configuration in which the kinematic viscosity of the lubricating oil at 40 ° C. was 200 to 500 mm ² / s was adopted.

That is, the lubricating base oil is a saturated synthetic hydrocarbon oil in which one or two or more selected from poly-α-olefin and ethylene-α-olefin copolymer hydrides are combined, and lubrication at 40 ° C. By setting the kinematic viscosity of the oil to 200 to 500 mm ² / s, preferably 300 to 400 mm ² / s, it is possible to prevent stick slip from occurring between the friction surface of the inner member and the torque transmitting member and to transmit the oil. Reduced the initial drop in torque.

The reason why the kinematic viscosity at 40 ° C. of the lubricating oil is set to 200 mm ² / s or more is that when the kinematic viscosity is less than 200 mm ² / s, the oil film may be cut between the friction surface of the inner member and the torque transmission member. Because there is. The reason why the kinematic viscosity at 40 ° C. is set to 500 mm ² / s or less is that when the kinematic viscosity exceeds 500 mm ² / s, the initial reduction amount of the transmission torque increases.

Examples of the poly-α-olefin used in the base oil include oligomers having about 3 to 20 carbon atoms such as butene-1, isobutene-1, α-octene, and decene-1, and ethylene-α-olefin copolymer The coalescence is a copolymer of these and ethylene. These hydrides are saturated synthetic hydrocarbon oils that are liquid at room temperature and preferably have a kinematic viscosity at 100 ° C. of about 40 to 100 mm ² / s.

  In addition, a saturated synthetic hydrocarbon oil base oil in which one or more of these poly-α-olefins and ethylene-α-olefin copolymers are combined has excellent resin resistance. Since there is no attack and the polarity is low, the adsorption energy to the metal surface is also low, and the friction coefficient on the friction surface can be stably maintained.

  In the torque limiter of the present invention, at least one of the input member and the output member is a cylindrical or columnar inner member, and a torque transmission member interposed between the input member and the output member is provided on the inner member. The frictional force between the frictional surface of the inner member and the torque transmission member is used to transmit torque from the input member to the output member, and lubricating oil is supplied to the frictional surface of the inner member, In the torque limiter, wherein the torque transmission member slips on the friction surface of the inner member when the load more than a predetermined value acts on the output member, and the input member rotates idly, the inner member and the torque By adopting a structure in which at least one of the transmission members is formed of a metal sintered member and this sintered member is impregnated with the above-described lubricating oil for torque limiter, oil shortage on the friction surface of the inner member is prevented. Prevention And, thereby prevent the occurrence of stick-slip between the friction surface and the torque transmitting member of the inner member, and to be able to reduce the initial amount of decrease in the transmitted torque.

The lubricating oil for torque limiter of the present invention is a saturated synthetic carbonization in which a base oil of a lubricating oil is combined with one or more selected from hydrides of poly-α-olefin and ethylene-α-olefin copolymer. Since it is hydrogen oil and the kinematic viscosity of the lubricating oil at 40 ° C. is 200 to 500 mm ² / s, preferably 300 to 400 mm ² / s, the stick slip between the friction surface of the inner member and the torque transmission member is reduced. Generation | occurrence | production can be prevented and the initial fall amount of transmission torque can be decreased. Further, since the torque limiter lubricating oil is excellent in resin resistance, there is no possibility of chemical attack of the resin parts constituting the torque limiter or the resin parts mounted on the outside.

  In the torque limiter according to the present invention, at least one of the inner member and the torque transmission member is formed of a metal sintered member, and the sintered member is impregnated with the above-described lubricating oil for torque limiter. It is possible to prevent oil shortage on the friction surface of the member, to prevent the occurrence of stick-slip between the friction surface of the inner member and the torque transmission member, and to reduce the initial reduction amount of the transmission torque.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a first embodiment. The torque limiter 1 is a cylindrical inner member in which an input member 2 is fitted and fixed to an input shaft 21, and an output member 3 is a cylindrical member that is rotatably fitted to the input member 2. A coil spring 4 serving as a torque transmission member is wound around an outer diameter surface serving as a friction surface of the input member 2. The cylindrical output member 3 is closed at one end by an end wall 3 a and the other end is closed by a separate resin lid 3 b, and inside the outer diameter surface of the input member 2 and the coil spring 4. A torque limiter lubricating oil for lubricating the gap is enclosed. The input member 2 is formed of a metal sintered member, and the input member 2 is impregnated with a lubricating oil for torque limiter. This lubricating oil is a poly-α-olefin oil (a saturated synthetic hydrocarbon oil in which the base oil is a hydride of a poly-α-olefin), and has a kinematic viscosity at 40 ° C. of 200 to 500 mm ² / s. .

  The coil spring 4 includes a small-diameter coil portion 4 a fastened to the outer diameter surface of the input member 2 and a large-diameter coil portion 4 b that is lifted from the outer diameter surface of the input member 2, and both ends are end walls of the output member 3. 3a and the lid 3b. When the input member 2 rotates in the direction opposite to the coil winding direction when viewed from the lid 3b side, the coil spring 4 increases the tightening force and transmits torque to the output member 3 by the frictional force with the outer diameter surface of the input member 2. To do. When a load exceeding a predetermined value is applied to the output member 3, the coil spring 4 slips from the outer diameter surface of the input member 2 with the supplied torque limiter lubricating oil, causing the input member 2 to idle.

As an example, a torque limiter was prepared in which the kinematic viscosity at 40 ° C. of the poly-α-olefin oil as the torque limiter lubricating oil supplied to the outer diameter surface of the input member was 200 to 500 mm ² / s ( Examples 1-6). As a comparative example, the kinematic viscosity at 40 ° C. for poly--α- olefin oil as a lubricating oil for the torque limiter, respectively ^{100mm 2 / s, 150mm 2 /} s, were also prepared the torque limiter was 600 mm ² / s (comparative Examples 1-3). The rated torque of each torque limiter was set to 35 mN · m.

  For each of the torque limiters of the above-described embodiment and the comparative example, using the transmission torque measuring device shown in FIG. 2, the presence or absence of stick-slip in the low-speed rotation test and the initial reduction amount ΔT of the transmission torque in the high-speed rotation test. The size of was investigated. In this transmission torque measuring device, the input shaft 21 to which the torque limiter 1 is attached is driven to rotate by a belt 23 by switching the motors 22a and 22b for low speed rotation and high speed rotation. A load cell 26 for measuring a transmission torque is attached to an output shaft 25 connected to 1 through a coupling 24. Although not shown, the output of the load cell 26 is output to a recorder through an amplifier.

  In the low-speed rotation test, the rotational speed of the input shaft 21 is set to 10 rpm, and an oscilloscope is used as a recorder to determine whether or not stick slip occurs depending on the presence or absence of the output waveform of the sawtooth transmission torque as shown in FIG. Judged. In the high-speed rotation test, the rotation speed of the input shaft 21 was set to 300 rpm, and the initial decrease amount ΔT in the output of the transmission torque as shown in FIG. 7 was measured using a pen recorder as a recorder. Note that the input torque from the input shaft 21 was set to 35 mN · m, which is equal to the rated torque, in any test.

Table 1 shows the results of the low-speed rotation test and the high-speed rotation test. In Comparative Examples 1 and ^{2 where} the kinematic viscosity of the lubricating oil for torque limiter was lower than 200 mm ² / s, the initial decrease ΔT in the transmitted torque was small at 2 mN · m, but significant stick slip occurred. did. Further, in Comparative Example 3 in which the kinematic viscosity of the lubricating oil for torque limiter was higher than 500 mm ² / s, stick slip did not occur, but the initial reduction amount ΔT of the transmission torque was as large as 3 mN · m. . On the other hand, in each of the examples in which the kinematic viscosity of the lubricating oil for torque limiter is 200 to 500 mm ² / s, no stick slip occurs, and the initial reduction amount ΔT of the transmission torque is within an allowable range. It was less than 2 mN · m. In Examples 1 and ^{2 where} the kinematic viscosities of the lubricating oil for the torque limiter are 200 mm ² / s and 250 mm ² / s, a slight sawtooth wave is included in part of the output of the transmission torque in the low-speed rotation test. Was recognized.

FIG. 3 shows a second embodiment. As in the first embodiment, the torque limiter 1 includes a cylindrical member in which the input member 2 is a cylindrical inner member, and the output member 3 is rotatably fitted to the input member 2. Then, a coil spring 4 as a torque transmission member is wound around an outer diameter surface serving as a friction surface of the input member 2, and both ends are locked to the end wall 3 a and the lid 3 b of the output member 3. This embodiment is different in that the coil spring 4 has a single diameter and is entirely clamped to the outer diameter surface of the input member 2. The other parts are the same as those of the first embodiment, and the output member 3 has 40 ° C. as a torque limiter lubricating oil that lubricates between the outer diameter surface of the input member 2 and the coil spring 4. A poly-α-olefin oil having a kinematic viscosity at 200 to 500 mm ² / s is enclosed. The input member 2 is formed of a metal sintered member, and the input member 2 is impregnated with a lubricating oil for torque limiter.

FIG. 4 shows a third embodiment. The torque limiter 1 is a cylindrical inner member in which an input member 2 and an output member 3 are coaxially abutted, and a coil spring 4 serving as a torque transmission member on the outer diameter surface of the input member 2 and the output member 3. Is wound. A portion of the input member 2 and the output member 3 around which the coil spring 4 is wound is covered with a protective cover 5, and the kinematic viscosity at 40 ° C. is 200 in the protective cover 5 as in the first embodiment. A poly-α-olefin oil of ˜500 mm ² / s is enclosed as a lubricating oil for torque limiter.

  The coil spring 4 is fastened to the outer diameter surfaces of the input member 2 and the output member 3, and the outer diameter of the input member 2 is formed slightly larger than the outer diameter of the output member 3. The input member 2 side is stronger than the output member 3 side. In this embodiment, when the input member 2 rotates in the winding advance direction of the coil spring 4, torque is applied to the output member 3 by the frictional force between the input member 2 and the outer diameter surface of the output member 3 due to the tightening force of the coil spring 4. When a load of a predetermined level or more is transmitted to the output member 3, the coil spring 4 slips due to the torque limiter lubricating oil supplied on the output member 3 side where the tightening force of the coil spring 4 is weak, and the input member 2 is idling. To do.

FIG. 5 shows a fourth embodiment. In this torque limiter 1, the input member 2 is a cylindrical inner member having a flange portion 2a, and the torque transmitting member is a friction plate 6 fitted on the input member 2, and the friction plate 6 is used as the input member. 2 is pressed against the flange portion 2a by a coil spring 7 fitted on the outer periphery 2, and torque is transmitted to an output member (not shown) connected to the friction plate 6 by the frictional force between the flange portion 2a and the friction plate 6. It has become. In this embodiment, the input member 2 and the friction plate 6 are formed of a metal sintered member, and these sintered members are impregnated with a torque limiter lubricating oil. The lubricating oil for torque limiter is an ethylene-α-olefin oil (a base synthetic oil is a saturated synthetic hydrocarbon oil made of a hydrogenated ethylene-α-olefin copolymer) and has a kinematic viscosity at 40 ° C. of 200 to 500 mm ^2. / S. Note that only one of the input member 2 and the friction plate 6 may be used as a sintered member, and the lubricating oil for torque limiter may be impregnated.

  In the first, second, and fourth embodiments described above, the input member is a cylindrical inner member, but these inner members may be output members.

A longitudinal sectional view showing a torque limiter of a first embodiment The front view which shows the transmission torque measuring apparatus used for the test of an Example A longitudinal sectional view showing a torque limiter of a second embodiment Cutaway front view showing the torque limiter of the third embodiment Longitudinal sectional view showing a torque limiter of a fourth embodiment Graph showing an example of the output waveform of sawtooth transmission torque Graph showing the initial decrease in transmission torque

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Torque limiter 2 Input member 2a Flange part 3 Output member 3a End wall 3b Cover 4 Coil spring 4a Small diameter coil part 4b Large diameter coil part 5 Protective cover 6 Friction plate 7 Coil spring 21 Input shafts 22a and 22b Motor 23 Belt 24 Coupling 25 Output shaft 26 Load cell

Claims (2)

At least one of the input member and the output member is a cylindrical or columnar inner member, and a torque transmission member interposed between the input member and the output member is pressed against the friction surface provided on the inner member. Torque is transmitted from the input member to the output member by the frictional force between the friction surface of the member and the torque transmission member, lubricating oil is supplied to the friction surface of the inner member, and a load exceeding a predetermined value acts on the output member. The torque transmission member slips on the friction surface of the inner member, and the torque limiter lubricating oil supplied to the friction surface of the torque limiter is configured so that the input member idles. A saturated synthetic hydrocarbon oil in which one or more selected from poly-α-olefins and hydrides of ethylene-α-olefin copolymers are combined, and said base oil at 40 ° C. A lubricating oil for torque limiters, characterized in that the kinematic viscosity of the lubricating oil is 200 to 500 mm ² / s.   At least one of the input member and the output member is a cylindrical or columnar inner member, and a torque transmission member interposed between the input member and the output member is pressed against the friction surface provided on the inner member. Torque is transmitted from the input member to the output member by the frictional force between the friction surface of the member and the torque transmission member, lubricating oil is supplied to the friction surface of the inner member, and a load greater than a predetermined value acts on the output member. In the torque limiter in which the torque transmission member slips on the friction surface of the inner member and the input member rotates idly, at least one of the inner member and the torque transmission member is made of metal. A torque limiter formed of a binding member and impregnated with the lubricating oil for torque limiter according to claim 1.

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