JP4133904B2 - Torque limiter - Google Patents

Description

The present invention relates to an improvement in a magnet type torque limiter in which a cylindrical permanent magnet is fixed to an outer surface of a rotating member or an inner surface of a rotating cylindrical member.

  The torque limiter is generally used for a mechanism such as a printer such as an OA device, a paper feeding, conveying, and discharging portion of a copying machine. Most of the torque limiters are contact type that is caused by mechanical friction because of low cost, but the price is high, but the non-contact type has advantages such as semi-permanent life and maintenance free. Magnetic torque limiters have also been used for certain devices for some time.

Various applications have been filed and improved for the magnet type torque limiter. In such a torque limiter, a cylindrical magnet is used as a permanent magnet. However, the thickness of the cylindrical magnet is limited in terms of downsizing and cost, and therefore the cylindrical magnet has a certain degree of mechanical strength. There is a problem that it is broken when subjected to an impact or external force. For this reason, it is disclosed that an adhesive is used to fix the cylindrical permanent magnet to the outer surface of the inner rotating member or the inner surface of the rotating cylindrical body located outside (for example, Patent Document 1). reference). In addition, it is disclosed that an adhesive may be used (for example, see Patent Documents 2 to 4). If an adhesive is used, it is possible to bond without giving mechanical stress between the cylindrical permanent magnet and the outer surface of the rotating shaft or the rotating cylindrical body.
Japanese Patent Laid-Open No. 10-306832 JP 2001-178109 A JP 2001-218448 A JP 2003-269485 A

  However, when using an adhesive, apply the adhesive to the outer surface of the rotating shaft located inside the cylindrical permanent magnet, or the outer surface of the cylindrical permanent magnet located inside the rotating cylindrical body, Work to insert the rotating shaft into the cylindrical permanent magnet or insert the permanent magnet into the rotating cylindrical body must be performed, and work must be done so that there is no leakage of adhesive. bad. Even if it does in this way, it may leak depending on the quantity of applied adhesives, and there is also a problem that adhesives deteriorate and adhesive strength falls.

The present invention aims to solve the conventional problems as described above, and to fix the cylindrical permanent magnet to the outer surface of the inner rotating shaft or the inner surface of the rotating cylindrical body located outside. It uses press-fitting without using an adhesive or the like, and further provides a structure that does not crack or crack during press-fitting.

In order to solve the above-mentioned problems, the first invention is a cylindrical magnetic member, a cylindrical permanent magnet disposed with a minute gap in the cylindrical magnetic member, and fixed in the cylindrical permanent magnet. In the torque limiter comprising an inner ring member, the cylindrical permanent magnet has a protrusion or a groove extending in the width direction on the inner surface thereof, and the inner ring member has a groove or a protrusion extending in the width direction on the outer surface thereof. A portion of the cylindrical permanent magnet or the inner ring member near the base of the protrusion and a portion near the entrance of the groove of the inner ring member or the cylindrical permanent magnet are pressed into contact with each other, and the cylindrical shape Compared to the inclination of the contact portion of the permanent magnet or the portion of the inner ring member close to the root of the protrusion or the cylindrical permanent magnet from the groove portion side, the cylindrical permanent magnet Or before The inclination of the contact portion of the inner ring member or the cylindrical permanent magnet in the vicinity of the entrance of the groove from the projection or groove side of the inner ring member is greater in the rotational direction than in the radial direction. Thus, a torque limiter having a steep slope is provided.

A second invention is a housing member having a cylindrical inner surface, a cylindrical permanent magnet fixed to the cylindrical inner surface of the housing member, and a cylinder disposed with a minute gap inside the cylindrical permanent magnet. In the torque limiter including a cylindrical magnetic member and an inner ring member fixed in the cylindrical magnetic member, the cylindrical permanent magnet has a protrusion or a groove extending in the width direction on the outer surface thereof, and the housing member A portion of the cylindrical permanent magnet or the housing member that is close to the base of the projection, and the groove portion of the housing member or the cylindrical permanent magnet. In the vicinity of the entrance of each of the cylindrical permanent magnets, the cylindrical permanent magnets or the cylindrical permanent magnets from the groove part side or the front of the cylindrical permanent magnets or the housing member The housing member or the cylindrical permanent magnet from the projection or groove portion side of the cylindrical permanent magnet or the housing member, as compared with the inclination of the contact portion of the housing member near the base of the projection The torque limiter is characterized in that the inclination of the abutting portion in the vicinity of the entrance of the groove portion is steep so that a larger pressing force is applied in the rotational direction than in the radial direction. .

A third invention provides a torque limiter according to the first invention or the second invention , wherein one or more cylindrical permanent magnets are arranged side by side in accordance with a required torque. .

According to the first and second inventions, since the cylindrical permanent magnet is fixed by press-fitting, it is possible to provide a torque limiter with good workability and high reliability. In addition, since the pressure applied to the protrusion and the groove is larger in the rotational direction than in the radial direction, the risk of the cylindrical permanent magnet being cracked or broken can be reduced.

According to the third aspect , the cylindrical permanent magnet can be standardized, and a torque limiter that exhibits a desired torque can be obtained by juxtaposing the cylindrical permanent magnets in accordance with the required magnetic force.

[Embodiment 1]
A one-way torque hinge 100 according to a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a perspective view showing components before assembly of the one-way torque hinge 100, and FIG. 2 is a side view showing a partial cross section of the one-way torque hinge 100. 3 is a cross-sectional view of the one-way torque hinge 100 taken along the cutting line XY of FIG. 2, FIG. 4 is a front view of the rotating shaft, and FIG. 5 is a groove of the rotating shaft and a cylindrical permanent magnet. It is drawing for demonstrating the relationship with this processus | protrusion.

  The one-way torque hinge 100 includes a housing member 1, a cylindrical magnetic member 2, a cylindrical permanent magnet 3, an inner ring member 4, and a shield member 5 that are arranged coaxially.

  A housing member 1 made of a resin material or the like has a cylindrical inner surface 1A, and a cylindrical magnetic member 2 made of, for example, an iron-based magnetic material is press-fitted into the inner surface 1A and fixed firmly. The housing member 1 may have a cylindrical shape as shown in the figure or a structure that also serves as a part of a device such as a printer. The housing member 1 has a large-diameter portion 1B into which the shield member 5 is press-fitted at one end, and the shield member 5 is press-fitted into the large-diameter portion 1B so that one end thereof is closed.

  The cylindrical permanent magnet 3 is made of a neodymium bonded magnet that is easy to mold with high productivity, low cost, and high magnetic force, but may be made of other magnetic materials such as ferrite or samarium. The cylindrical permanent magnet 3 has at least two or more protrusions on its inner surface. In this embodiment, there are three protrusions 3a, 3b, 3c at intervals of approximately 120 degrees. The protrusions 3a, 3b, and 3c extend continuously or intermittently along the central axis Z indicated by the alternate long and short dash line in FIG. 2, and radiate by press-fitting the rotation stopper and the inner ring member 4 to be described below. And reducing the mechanical stress in the direction.

  The inner ring member 4 in the first embodiment is an inner ring, a shaft member, or a combination thereof, and functions as a rotating member. The inner ring member 4 is preferably made of a synthetic resin, such as a polyacetal resin material, which is excellent in mechanical strength and has elasticity compared to a metal, but may be made of a metal material. Three grooves 4a, 4b, 4c are provided on the outer surface of the inner ring member 4 at positions corresponding to the three protrusions 3a, 3b, 3c of the cylindrical permanent magnet 3. When the inner ring member 4 is press-fitted into the cylindrical permanent magnet 3, a mechanical force is generated between the three projections 3a, 3b, and 3c of the cylindrical permanent magnet 3 and the three grooves 4a, 4b, and 4c. It is preferable to have such a structure.

  The inner ring member 4 has a large-diameter portion 4X at one end, and the large-diameter portion 4X has a locking portion 4X1 for locking the inner ring member 4 to a shaft (not shown). After the assembly is completed, the locking portion 4X1 prevents the inner ring member 4 from shifting in the axial direction. The inner ring member 4 has a central hole 4Y into which a shaft (not shown) is inserted, and the central hole 4Y is provided with a detent portion 4Z for the shaft as shown in FIG.

  An inner ring member 4 is inserted into the central hole of the shield member 5 and also serves to hold the cylindrical permanent magnet 3 in the center. That is, the outer surface of the cylindrical permanent magnet 3 is not in contact with the inner surface of the cylindrical magnetic member 2, and the shield member 5 is maintained so as to maintain a slight gap W between the inner surface of the cylindrical magnetic member 2. The cylindrical permanent magnet 3 is supported on the inner center of the cylindrical magnetic member 2.

  Then, in a state where the shield member 5 is press-fitted into the large-diameter portion 1B of the housing member 1, a torque greater than the torque value due to the magnetic force generated between the cylindrical permanent magnet 3 and the cylindrical magnetic member 2 is applied from the outside. Then, sliding friction occurs between the inner peripheral surface of the shield member 5 and the outer peripheral surface of the inner ring member 4, and the inner ring member 4 rotates. In order to reduce the sliding friction, it is preferable to apply a lubricant such as grease to the sliding portion or to form a dry lubricant.

  Next, the three protrusions 3a, 3b, and 3c of the cylindrical permanent magnet 3 and the three grooves 4a, 4b, and 4c of the inner ring member 4 which are important structures of the present invention will be described in detail with reference to FIG. Describe. Since the protrusions 3a, 3b, and 3c have the same structure, and the grooves 4a, 4b, and 4c have the same structure, only the protrusion 3a of the cylindrical permanent magnet 3 and the groove 4a of the inner ring member 4 are shown. FIG. 5A is a partially enlarged view of the protrusion 3a of the cylindrical permanent magnet 3 and the groove 4a of the inner ring member 4, and FIG. 5B is a further enlarged view of the protrusion 3a and the groove. It is drawing for demonstrating the inclination angle with 4a.

  In FIG. 3, it appears that the cylindrical outer surface of the inner ring member 4 is press-fitted so as to contact the entire cylindrical inner surface of the cylindrical permanent magnet 3, but the cylindrical outer surface of the inner ring member 4 is preferably cylindrical. Only the projections 3a, 3b, 3c of the cylindrical permanent magnet 3 and the three grooves 4a, 4b, 4c of the inner ring member 4 are in contact with each other, and the other surfaces are hardly in contact with each other, or the other surfaces are in light contact with each other. is there.

  As shown in FIG. 5, both the protrusion 3a and the groove 4a are arcuate. Preferably, the protrusion 3a and the groove 4a abut on the portion P near the root of the protrusion 3a and the vicinity of the entrance Q of the groove 4a. As shown in FIG. 5B, the angle formed between the tangent lines m and n of the portion P near the base of the projecting portion 3a that abuts and the near-entrance portion Q of the groove portion 4a and the horizontal direction is tangent to the projecting portion 3a. The angle m is Q1, the angle of the tangent n of the groove 4a is Q2, and the angle Q2 is larger than the angle Q1. That is, the inclination of the portion Q near the entrance of the groove 4a must be steep compared to the portion P near the base of the protrusion 3a.

  Thus, if the protrusion 3a and the groove 4a abut on the portion P near the base of the protrusion 3a and the vicinity of the entrance Q of the groove 4a, a pressure is applied to the abutted portion during press-fitting. Since the direction is substantially perpendicular to the tangent line n of the groove 4a, most of the applied pressure is the rotational direction, and the applied pressure in the radial direction is sufficiently small. FIG. 5B shows only one of the places where the protrusion 3a and the groove 4a abut, but the protrusion 3a and the groove 4a similarly abut at the other place. When considered in vector terms, the applied pressure in the rotational direction is canceled out. Although the radial pressing force is almost doubled, as described above, the radial pressing force is not a problem in this structure because the radial pressing force is sufficiently small.

  The same applies to the operation of the torque limiter. The mechanical force applied by the operating torque is caused by the projections 3a, 3b and 3c of the permanent magnet 3 and the three grooves 4a of the inner ring member 4, 4b and 4c are applied to the contact points P and Q. However, since most of the mechanical force is the rotational force and the radial force is small, the cylindrical permanent magnet 3 is broken. There is no danger. This structure makes it possible to press-fit cylindrical permanent magnets that are easily broken.

[Embodiment 2]
A torque limiter 200 according to a second embodiment of the present invention will be described with reference to FIG. FIG. 2 is a view showing a cross section of a torque limiter 200 similar to FIG. The same symbols as those used in FIGS. 1 to 3 indicate members having the same names.

  In this embodiment, the cylindrical housing member 1 is a rotating body, and the cylindrical permanent magnet 3 is fixed to the inner surface of the housing member 1. The cylindrical magnetic member 2 is fixed to the outer surface of the inner ring member 4 and is disposed inside the cylindrical permanent magnet 3. A minute gap W exists between the cylindrical outer surface of the cylindrical magnetic member 2 and the inner surface of the cylindrical permanent magnet 3. The cylindrical magnetic member 2 and the inner ring member 4 are on the fixed side.

Three projections 3a, 3b, 3c as described above are formed on the cylindrical outer surface of the cylindrical permanent magnet 3 at intervals of approximately 120 degrees. The cylindrical inner surface of the housing member 1, they protrusions 3a, 3b, in a position corresponding to 3c, comprises protrusions 3 a, 3b, groove portions 1a accept 3c, 1b, and 1c. The relationship between the protrusions 3a, 3b, and 3c and the grooves 1a, 1b, and 1c is the same as the relationship between the protrusions 3a, 3b, and 3c of the torque limiter 100 and the grooves 4a, 4b, and 4c of the inner ring member 4, and a cylindrical shape. The vicinity of the inlets of the grooves 1a, 1b, and 1c of the housing member 1 abuts on the vicinity of the roots of the protrusions 3a, 3b, and 3c of the permanent magnet 3. Therefore, the vector of the mechanical force applied between the protrusions 3a, 3b, and 3c and the grooves 1a, 1b, and 1c is mostly in the rotational direction, and the radial direction is sufficiently small. Therefore, the cylindrical permanent magnet 3 Will not crack or crack.

  In any of the embodiments described above, both the protrusion and the groove are arcuate, but the protrusion may be triangular or trapezoidal and narrow toward the tip, and the inlet portion of the groove covers the inclined portion of the protrusion. It may be a triangular shape with a steep slope or a rectangular shape.

  In the above embodiments, preferred examples have been described. However, most of the mechanical force applied between the permanent magnet 3 and the inner ring member 4 or between the housing member 1 and the permanent magnet 3 is caused by the protrusions. It may be applied to the portion P close to the root and the vicinity of the entrance Q of the groove, and the remaining force may be distributed and applied to other portions.

  Furthermore, the number of protrusions and grooves may be two, or four or more. From the viewpoint of mechanical strength, it is preferable that the cylindrical permanent magnet is provided with a protrusion and the inner ring member or housing member is provided with a groove, but the permanent magnet is provided with a groove and the inner ring member or housing member is provided with a protrusion. May be. Or you may provide a projection part and a groove part in both as needed.

  Furthermore, the cylindrical permanent magnet 3 may be one in which a plurality of narrow cylindrical permanent magnets are juxtaposed. In order to standardize cylindrical permanent magnets, a large number of ring-shaped cylindrical permanent magnets having a small length may be prepared, and a necessary number of cylindrical permanent magnets may be juxtaposed according to the required magnetic force. .

  Here, the term “cylindrical” includes a ring having a short length, regardless of the length in the axial direction.

It is a perspective view which shows each member before the assembly of the torque limiter 100 of Embodiment 1 which concerns on invention. It is a side view formed by cutting a part of the torque limiter 100 shown in FIG. It is a figure which shows the cross section cut | disconnected by the cutting line XY of FIG. It is the figure which looked at the inner ring member used for the torque limiter 100 shown in FIG. 1 from the front. It is a figure for demonstrating the press-fit structure of the cylindrical permanent magnet in the torque limiter which concerns on Embodiment 1 of this invention. It is a perspective view which shows each member before the assembly in the torque limiter 200 of Embodiment 2 which concerns on invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Housing member 1A ... Cylindrical inner surface of housing member 1B ... Large diameter part of housing member 1a, 1b, 1c ... Groove part 2 ... Cylindrical magnetic member 3 ... Cylindrical permanent Magnets 3a, 3b, 3c ... projections 4 ... inner ring members 4a, 4b, 4c ... grooves 5 ... shield members

Claims (3)

In a torque limiter comprising a cylindrical magnetic member, a cylindrical permanent magnet arranged with a minute gap in the cylindrical magnetic member, and an inner ring member fixed in the cylindrical permanent magnet,
The cylindrical permanent magnet has a protrusion or a groove extending in the width direction on the inner surface thereof,
The inner ring member has a groove or a protrusion that extends in the width direction on the outer surface thereof,
A portion near the base of the projection of the cylindrical permanent magnet or the inner ring member and a portion near the entrance of the groove portion of the inner ring member or the cylindrical permanent magnet are pressed into contact with each other,
Compared to the inclination of the abutting portion of the cylindrical permanent magnet or the inner ring member close to the base of the projection of the cylindrical permanent magnet or the inner ring member from the projection or groove portion side, the cylinder The inclination of the contact portion of the inner ring member or the cylindrical permanent magnet in the vicinity of the entrance of the groove portion from the projection or groove portion side of the inner permanent magnet or the inner ring member is in the rotational direction compared to the radial direction. A torque limiter characterized by a steep slope so that a large pressure is applied . A housing member having a cylindrical inner surface, a cylindrical permanent magnet fixed to the cylindrical inner surface of the housing member, a cylindrical magnetic member disposed with a minute gap inside the cylindrical permanent magnet, In a torque limiter comprising an inner ring member fixed in a cylindrical magnetic member,
The cylindrical permanent magnet has a protrusion or a groove extending in the width direction on the outer surface thereof,
The housing member has a groove or a protrusion extending in the width direction on the cylindrical inner surface,
The inner ring member has a groove or a protrusion that extends in the width direction on the outer surface thereof,
A portion near the base of the projection of the cylindrical permanent magnet or the housing member and a portion near the entrance of the groove portion of the housing member or the cylindrical permanent magnet are pressed into contact with each other,
Compared to the inclination of the abutting portion of the cylindrical permanent magnet or the portion close to the base of the projection of the housing member from the projection or groove portion side of the housing member, the cylinder The inclination of the abutting portion in the vicinity of the entrance of the groove portion of the housing member or the cylindrical permanent magnet from the protruding portion or groove portion side of the cylindrical permanent magnet or the housing member is in the rotational direction compared to the radial direction. A torque limiter characterized by a steep slope so that a large pressure is applied . In claim 1 or claim 2 ,
One or more cylindrical permanent magnets are arranged side by side in accordance with a required torque.

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