JP2009047232A - Torque limiter and paper coordinating mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a torque limiter capable of preventing thrust force from being induced and lubricants from leaking while accelerating heat liberation without hindering compactification of the torque limiter. <P>SOLUTION: The torque limiter is composed of an inner wheel 11, an outer wheel 12 fitted relatively and rotatably in the inner wheel 11 and a coil spring 13 depressed with elasticity in an extended diameter direction to the inter diameter face of the outer wheel 12, and in the torque limiter in which both ends of the coil spring 13 are engaged with the inner wheel 11, the coil springs 13a, 13b whose numbers are identical but winding directions are different as the coil spring 13 are arranged and constituted in contact in the axis direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a torque limiter and a paper separation mechanism for an office machine using the torque limiter, and in particular, promotes heat dissipation and reduces induced thrust force.

  A friction type torque limiter using a coil spring has been conventionally known as a torque limiter used in office paper separation mechanisms (Patent Document 1). This type of torque limiter has a configuration in which an inner ring and an outer ring are fitted so as to be rotatable relative to each other, and hooks at both ends of a coil spring that are bound to an inner diameter surface of the inner ring by elasticity in a diameter reducing direction are engaged with the outer ring. (For example, refer to FIG. 8 of Patent Document 1). This torque limiter generates a predetermined torque by friction generated between the inner ring and the coil spring.

  Further, as a friction type torque limiter used for the same application, there is also known one in which a coil spring is pressed against an inner diameter surface of an outer ring by elasticity in a diameter expanding direction (Patent Document 2). In addition to the coil spring pressed against the inner diameter surface of the outer ring, the torque limiter disclosed in Patent Document 2 includes a coil spring whose winding direction is opposite to that of the coil spring in a storage cylinder provided on the outer diameter surface of the inner ring. It is stored and pressed against its inner surface. Both coil springs are continued by a bend.

  When the torque limiter disclosed in Patent Document 2 rotates in a certain direction, one of the coil springs expands in diameter to generate a required torque, but the other coil spring contracts in diameter and locks. It becomes. Further, when the rotation directions are opposite, the coil spring that generates torque and the coil spring that is locked are interchanged. In this torque limiter, torque is generated by one of the coil springs according to the rotation direction, and both the coil springs do not generate torque at the same time.

In the torque limiter using the coil spring as described above, there is a tendency that a lubricant such as grease filled inside is pushed out in one direction by the screw action accompanying the rotation of the coil spring and leaks to the outside. In order to solve this problem, it is also known that an air reservoir is provided outside both ends of the coil spring, and the leakage of the lubricant is suppressed by the action of the air (Patent Document 3).
JP 2006-10060 A JP-A-7-229524 JP-A-10-78044

  As in the torque limiter disclosed in the above-mentioned Patent Document 1, a type that generates a predetermined torque by friction between the coil spring and the inner ring has a heat generating portion relatively inside the torque limiter. It is difficult to be performed and heat tends to stay. The retention of heat has a problem that causes abnormal noise and torque fluctuation due to early deterioration of the lubricant. There is also a problem that the lubricant is likely to leak due to the screw action of the coil spring.

  As described in Patent Document 2, the problem of the heat retention is that the coil spring is pressed against the inner diameter surface of the outer ring so that the heat generation part due to friction is relatively outside, and heat is radiated from the outer diameter of the outer ring. One of the means is to promote this.

  However, in any of the above cases, in a state where a predetermined torque is generated, the winding direction of the coil spring is constant. Force is induced. For this reason, there is a problem that the coil spring is pressed against one of the closed portions of the torque limiter, causing a fluctuation in torque value or a factor that hinders smooth rotation.

  Furthermore, in any case, there is a problem that the lubricant is pushed out by the screw action due to the rotation of the coil spring, and in order to suppress this, the means for providing the air reservoir as described in Patent Document 3 described above is a torque limiter. There is a problem that hinders radial compaction.

  Accordingly, an object of the present invention is to provide a torque limiter that can promote heat dissipation and prevent induction of thrust force and leakage of a lubricant without hindering the reduction in the radial direction of the torque limiter. .

  In order to solve the above problems, a torque limiter according to the present invention includes an inner ring 11, an outer ring 12 fitted to the inner ring 11 so as to be relatively rotatable, and an inner diameter surface of the outer ring 12, as shown in FIG. And a coil spring 13 which is pressed with elasticity in the diameter-expanding direction, and in a torque limiter in which both end portions of the coil spring 13 are engaged with the inner ring 11, the coil spring 13 a has a different winding direction. , 13b are arranged in contact with the same number of axes.

  The torque limiter having the above-described configuration has a predetermined gap between the coil springs 13a and 13b and the inner diameter surface of the outer ring 12 when a force in the diameter reducing direction acts on the coil springs 13a and 13b by the relative rotation of the inner ring 11 and the outer ring 12. Torque is generated.

  The heat accompanying the generation of torque is generated on the inner surface of the outer ring 12 and is radiated to the outside from the outer surface of the outer ring 12. Further, since the thrust forces induced in both the coil springs 13a and 13b are opposite in direction, they cancel each other and the coil springs 13a and 13b are prevented from moving to one closing side. Further, the direction of the lubricant moved by the screw action is also opposite and cancels each other, so that leakage of the lubricant is suppressed.

Since the present invention is as described above, the following effects can be obtained.
(1) Since the heat generation part accompanying the generation of torque is located on the outer ring inner diameter surface relatively close to the outside and can be radiated from the outer surface of the outer ring, it is possible to prevent heat from staying inside the torque limiter. it can. Furthermore, heat dissipation can be further promoted by providing cooling fins on the outer ring.
(2) The induced thrust force is canceled out by a combination of coil springs having opposite winding directions, so that a stable torque value can be obtained. Further, since the screw action is canceled out, leakage of the lubricant is prevented. Further, the torque limiter is not affected in the radial direction.

  Embodiments of a torque limiter according to the present invention will be described below with reference to the accompanying drawings.

  The torque limiter of the first embodiment shown in FIG. 1 to FIG. 4 is fitted with an inner ring 11, an outer ring 12 that is rotatably fitted to the inner ring 11, and an inner diameter surface of the outer ring 12 with elasticity in the diameter increasing direction. Coil spring 13.

  The inner ring 11 is integrally provided with a disk-shaped inner ring side blocking portion 15 at one end of the cylindrical portion 14. The tip of the cylindrical portion 14 is formed thin, and the remaining portion is formed relatively thick. In the thick portion, as shown in FIGS. 2 and 4, axial engagement grooves 16, 16 are formed at two centrally symmetric locations.

  Further, a snap fit piece 17 is provided on the extension of the engagement grooves 16 and 16 in the thin portion of the cylindrical portion 14. The snap-fit piece 17 is partially cut off by two parallel slits 18 (see FIG. 4), and is formed to have elasticity in the radial direction. A check claw 19 is provided on the outer surface of the tip.

  The inner ring side blocking portion 15 is provided with a step portion 21 having a small diameter on the cylindrical portion 14 side, and one end portion of the outer ring 12 is fitted to the step portion 21. Further, a radial fixing pin insertion groove 22 is provided on the end surface on the large diameter side of the inner ring side blocking portion 15 (see FIG. 4).

  The outer ring 12 has a cylindrical shape, and one end thereof is rotatably fitted to the step portion 21 of the inner ring side blocking portion 15 as described above. Further, two engagement convex portions 23 (see FIG. 4) protruding in the axial direction are provided on the other end surface of the outer ring 12. The outer ring 12 is fitted to the inner ring 11 with a coil spring 13 mounted on the inner diameter surface thereof.

  An annular outer ring-side blocking member 24 is fitted to the engagement convex portion 23 side of the outer ring 12. The outer ring side blocking member 24 is provided with an engagement concave portion 25 corresponding to the engagement convex portion 23 on the inner end surface thereof (see FIG. 4), and the outer ring 12 and the outer ring side blocking member 24 are rotated in the rotation direction by fitting both. Integrated. An inner diameter surface of the outer ring side blocking member 24 is rotatably fitted to a distal end outer diameter surface of the cylindrical portion 14 of the inner ring 11.

  Since the snap fit piece 17 is provided at the tip of the cylindrical portion 14 of the inner ring 11 as described above, the outer ring side blocking member 24 has the check pawl 19 portion on the inner diameter side by its inner diameter surface. The snap-fit piece 17 returns to its original state due to its elasticity when it is inserted while being elastically deformed and exceeds the check claw 19, and is prevented from coming off by the check claw 19.

  A counterbore 26 that receives the check claw 19 is provided on the outer end surface of the outer ring side blocking member 24. Further, radial engagement grooves 27 are provided at two symmetrical positions on the outer diameter surface.

  A spring accommodating portion 38 surrounded by the outer diameter surface of the inner ring 11, the inner diameter surface of the outer ring 12, the inner ring side blocking portion 15 and the outer ring side blocking member 24 is formed.

  The coil spring 13 is composed of two right-handed coil springs 13a and left-handed coil springs 13b that have the same number of turns, sizes, and the like but differ only in the winding direction. In either case, the hooks 28 and 29 at both ends are bent inward. When both hooks 28 and 29 are viewed on the basis of one hook 28, the other hook 29 is formed at the tip of the portion that is lacking by the required number of arcs with respect to a predetermined integer number of turns. It is a type (referred to herein as an underwinding die). The coil springs 13a and 13b of this type have a property of elastically reducing the diameter when an external force is applied in a direction in which the hooks 28 and 29 are relatively pulled.

  On the other hand, as shown in FIG. 5, when viewed on the basis of one hook 28, the other end is wound on the tip of the portion wound by an extra portion corresponding to the required arc number for a predetermined integer number of turns. In some cases, a type in which the hook 29 is formed (referred to herein as overwinding) is used. The coil springs 13a and 13b of this type have a property of elastically reducing the diameter when an external force is applied in a direction in which the hooks 28 and 29 are relatively separated from each other.

  As shown in FIG. 3, the under-winding coil springs 13a and 13b are arranged so that the hooks 28 and 28 of both the coil springs 13a and 13b are in axial contact with each other. The coil springs 13 a and 13 b are both pressed against the inner diameter surface of the outer ring 12 with elasticity in the diameter increasing direction, the hooks 28 and 28 are engaged with one engagement wall 31 of the engagement groove 16, and the other hook 29. 29 are engaged with the other engaging wall 32. When the inner ring 11 rotates relative to the outer ring 12 (see the arrow in FIG. 2), the coil springs 13a and 13b receive a force in the direction in which the hooks 28 and 29 are drawn regardless of the direction of rotation. Undergoes a diameter reducing action.

  When the above-described overwinding mold is used as the coil springs 13a and 13b, the cylindrical portion 14 of the inner ring 11 is thinly formed as a whole, and as shown in FIG. Is provided. The hooks 28 and 29 of the coil springs 13a and 13b are engaged with engagement walls 34 and 35 formed on both sides of the engagement projection 33, respectively. Also in this case, when the inner ring 11 rotates relative to the outer ring 12, a force is applied in the direction in which the hooks 28 and 29 are pulled apart in any rotation direction, and the coil springs 13a and 13b have a diameter reducing action. receive.

  In the figure, 36 is a rotating shaft and 37 is a fixed pin. By passing the fixing pin 37 through the fixing pin insertion groove 22, the inner ring 11 is integrated with the rotating shaft 36. A load, for example, a reverse roller 45 of a paper separating mechanism is fitted and integrated with the outer ring side blocking member 24.

  The torque limiter according to the first embodiment is configured as described above, and the operation thereof will be described next.

  When the rotating shaft 36 and the inner ring 11 engaged therewith rotate in either the left or right direction and the outer ring 12 stops or reversely rotates with respect to the inner ring 11, the engaging groove of the inner ring 11 is Since one of the 16 engaging walls 31 or 32 exerts a force in a direction to draw the hooks 28 and 29 relatively, it exerts a diameter reducing action on the coil springs 13a and 13b. As a result, a predetermined torque (set torque) is generated on the inner diameter surface of the outer ring 12.

  Heat generated by friction with the coil springs 13 a and 13 b on the inner diameter surface of the outer ring 12 is radiated to the outside from the outer diameter surface of the outer ring 12. When the cooling fin 20 (see the chain line in FIGS. 1 and 2) is provided on the outer diameter surface of the outer ring 12, the heat dissipation action is further promoted. Moreover, if the cooling hole 30 (refer to the chain line in FIG. 1) is provided in both or one of the inner ring side blocking portion 15 and the outer ring side blocking member 24, heat dissipation of the accumulated heat inside the spring housing portion 38 is promoted.

  Further, a thrust force is induced by the helical portions of the coil springs 13 a and 13 b rotating with respect to the inner diameter surface of the outer ring 12. If the winding directions of the coil springs 13a and 13b are the same, both thrust forces are added, and both the coil springs 13a and 13b are moved to the inner ring side closing portion 15 or the outer ring side closing member 24 side, and the added thrust is added. The force is pressed against the inner ring side blocking portion 15 or the outer ring side blocking member 24, which causes torque fluctuations.

  However, in the case of this invention, since the winding directions of the coil springs 13a and 13b are opposite, the directions of both thrust forces S are opposite. As a result, when the directions are inward of each other (see the white arrow in FIG. 3), they cancel each other out and the influence of the thrust force can be eliminated. Further, in the case of outwardly facing each other, the magnitude of the thrust force pressed against the inner ring side blocking portion 15 or the outer ring side blocking member 24 is halved.

  The above action is the same when an overwinding mold (see FIG. 5) is used as the coil springs 13a and 13b.

  When the number of coil springs 13 is an even number of 4 or more, half of the coil springs 13 are opposite in the winding direction.

  In the periphery of the coil springs 13a and 13b, a lubricant such as grease is usually sealed. The coil springs 13a and 13b rotate against the lubricant and are pushed in a certain direction at the spiral portion, so-called. Screw action occurs. However, in the case of the present invention, since the winding directions of the coil springs 13a and 13b are opposite as described above, the screw action is canceled and leakage of the lubricant to the outside is suppressed.

  Next, a paper separating mechanism using the torque limiter 41 of the first embodiment will be described with reference to FIGS.

  In these figures, 42 is a paper stock, 43 is a pickup roller, 44 is a paper feed roller, and 45 is a reverse roller. The torque limiter 41 is fitted to the axis of the reverse roller 45, and the rotating shaft 36 is integrally passed through the torque limiter 41. The paper feed roller 44 is pressed against the reverse roller 45 so as to generate a constant nip pressure. The pickup roller 43 and the paper feed roller 44 are rotated in the paper 46 feeding direction (clockwise). The rotary shaft 36 is rotated clockwise below the paper 46 (see the arrow in the figure).

  Now, as shown in FIG. 6, if one sheet 46 is fed out, torque is transmitted from the sheet feed roller 44 to the reverse roller 45 through the sheet 46. Since the torque is larger than the set torque of the torque limiter 41, the reverse roller 45 rotates counterclockwise together with the outer ring 12 and feeds the paper 46. At this time, the inner ring 11 and the coil spring 13 rotate clockwise together with the rotating shaft 36.

  As shown in FIG. 7, when the paper 46 is double fed, slip occurs between the papers 46, so that the torque transmitted to the reverse roller 45 is smaller than the set torque of the torque limiter 41 than the case of one sheet. Become. As a result, the torque limiter 41 and the reverse roller 45 are integrally rotated in the rotation direction (clockwise) of the rotary shaft 36, and the sheet 46 in contact therewith is pushed back to prevent double feeding.

Sectional drawing of the torque limiter of Example 1 Sectional view of the _X 1 -X ₁ line in FIG 1 Sectional view of the _X 2 -X ₂ line in FIG. 1 Exploded perspective view of Example 1 Partial sectional view of a partial modification of the first embodiment Schematic side view of the paper separating mechanism of Example 2 Schematic side view at the time of double feeding in the case of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Inner ring 12 Outer ring 13, 13a, 13b Coil spring 14 Cylindrical part 15 Inner ring side obstruction | occlusion part 16 Engaging groove 17 Snap fitting piece 18 Slit 19 Checking claw 20 Cooling fin 21 Step part 22 Fixed pin insertion groove 23 Engaging convex part 24 Outer ring side closing member 25 Engaging recess 26 Countersink portion 27 Engaging groove 28 Hook 28 Hook 30 Cooling hole 31 Engaging wall 32 Engaging wall 33 Engaging projection 34 Engaging wall 35 Engaging wall 36 Rotating shaft 37 Fixing pin 38 Spring storage part 41 Torque limiter
42 Paper stock 43 Pickup roller 44 Paper feed roller 45 Reverse roller 46 Paper

Claims (7)

  An inner ring (11), an outer ring (12) fitted to the inner ring (11) so as to be capable of relative rotation, and a coil spring (13) pressed against the inner diameter surface of the outer ring (12) with elasticity in the expanding direction. In the torque limiter in which both ends of the coil spring (13) are engaged with the inner ring (11), the same number of coil springs (13a) and (13b) having different winding directions are used as the coil spring (13). A torque limiter arranged in contact with an axial direction.   The torque limiter according to claim 1, wherein a cooling fin (20) is provided on an outer diameter surface of the outer ring (12).   A cooling hole (30) leading to the outside is formed in the axially closed portion of the storage portion of the coil spring (13) formed between the outer diameter surface of the inner ring (11) and the inner diameter surface of the outer ring (12). The torque limiter according to claim 1, wherein the torque limiter is provided.   Hooks (28) and (29) bent at the inner diameter side are provided at both ends of the coil spring (13), and the hooks (28) and (29) are engaged with the outer diameter surface of the inner ring (11). A groove (16) is formed in the axial direction, and the hooks (28), (29) are engaged with engagement walls (31), (32) formed on both wall surfaces of the engagement groove (16). The torque limiter according to any one of claims 1 to 3, wherein   The inner ring (11) is provided with an inner ring side blocking portion (15) at one end thereof, and a snap fit piece (17) that is elastically deformable in the radial direction at the other end, and the snap fit piece (17) is provided. An outer ring side blocking member (24) is rotatably fitted to the outer diameter surface of the other end of the inner ring (11), and one end of the outer ring (12) is relatively rotatable with respect to the inner ring side blocking part (15). The torque limiter according to any one of claims 1 to 4, wherein the torque limiter is fitted to the outer ring side closing member (24).   The coil spring (13) is composed of two coil springs (13a) and (13b) opposite in the winding direction, and the coil springs (13a) and (13b) are arranged in the axial direction, and one end portions thereof are mutually connected. 6. The torque limiter according to claim 1, wherein the torque limiter is abutted in the axial direction.   The inner ring (11) of the torque limiter (41) according to any one of claims 1 to 6 is attached to a rotating shaft (36) driven in a paper feeding direction and a counter-rotating direction, and the outer ring of the torque limiter (41). (12) A paper separating mechanism which is fitted to a reverse roller (45) so as to be integrally rotatable, and a paper feeding roller (44) is pressed against the reverse roller (45) with a required nip pressure.

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