JP2004308767A - Torque limiter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a torque limiter capable of reducing the manufacturing cost and preventing the cracking of a permanent magnet in assembling. <P>SOLUTION: An internal rotating body 10 is assembled in an external rotating body 11, one of the rotating bodies is made out of a resin, the permanent magnet 14 is fitted to a peripheral face of the resin rotating body, the other rotating body is provided with a semihard magnetic member 16 positioned in opposition to the permanent magnet 14, a plurality of projecting parts 13 are formed on one of the rotating body and the permanent magnet 14 on a contact face of the resin rotating body and the permanent magnet 14, and tips of the projecting parts 13 are pressure-contacted with the resin rotating body or the permanent magnet, when the permanent magnet 14 and the resin rotating body are fitted. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a torque limiter using a magnetic force.
[0002]
[Prior art]
As a torque limiter using magnetic force, for example, a torque limiter shown in FIG. 21 is conventionally known (Patent Document 1).
In this conventional torque limiter, a first rotating body 2 is fixed to a shaft 1 and the first rotating body 2 is incorporated in a second rotating body 3.
The first rotator 2 and the second rotator 3 are arranged coaxially and are relatively rotatable.
[0003]
A cylindrical permanent magnet 4 is fixed to the outer periphery of the first rotating body 2, and a cylindrical semi-hard magnetic body is fixed to the inner periphery of the second rotating body 3 opposed to the permanent magnet 4. 5 is fixed. A predetermined clearance 6 is provided between the permanent magnet 4 and the semi-hard magnetic body 5.
Note that reference numeral 7 in the drawing denotes a lid member, which prevents the first rotator 2 from falling out of the second rotator 3.
Reference numeral 8 in the figure denotes a rubber roller to which the second rotating body 3 and the shaft 1 are fixed.
[0004]
In the conventional torque limiter as described above, the relative rotation between the first rotating body 2 and the second rotating body 3 is restricted by the magnetic force between the permanent magnet 4 and the semi-hard magnetic body 5. However, for example, when the rotation torque input to the first rotating body 2 becomes equal to or more than the torque regulated by the magnetic force, the first rotating body 2 and the second rotating body 3 overcome the magnetic force and rotate relatively. That is, the torque limiter transmits the rotation of the first rotating body 2 to the second rotating body 3 when the input rotating torque is small, but when the input rotating torque exceeds a predetermined magnitude, the first torque limiter transmits the first rotating body 2 to the second rotating body 3. The rotating body 2 and the second rotating body 3 rotate relative to each other so that an excessive load does not act on the second rotating body 3.
[0005]
Incidentally, the first rotating body 2 is made of resin such as plastic, and the permanent magnet 4 is fixed to the outer periphery thereof with an adhesive. As a means for fixing the permanent magnet 4 to the outer periphery of the first rotating body 2, a simple and inexpensive press-fitting method is conceivable, but in this conventional example, a fixing means called an adhesive is used without using the press-fitting method. ing. The reason why the adhesive is specifically used will be described below.
[0006]
As described above, the torque limiter satisfies the condition in which the first rotating body 2 and the second rotating body 3 rotate integrally or relatively, so that a certain amount of magnetic force is required. It becomes. In order to obtain a large magnetic force, a permanent magnet having a strong magnetic force is used, but the permanent magnet 4 is generally made of a hard and brittle material. Therefore, when the first rotating body 2 is pressed into the permanent magnet 4, the permanent magnet 4 is broken by a large force acting from the first rotating body 2 side. Therefore, in the above conventional example, the permanent magnet 4 is fixed to the first rotating body 2 with an adhesive.
[0007]
[Patent Document 1]
JP-A-7-007919 (page 2, FIG. 1)
[0008]
[Problems to be solved by the invention]
As described above, the permanent magnet 4 is conventionally bonded to the first rotating body 2, but according to the fixing method using this adhesive, there are the following problems.
The first problem is that in order to bond the permanent magnet 4 to the first rotating body 2, it is necessary to keep the fitting accuracy of these two members high, and the manufacturing cost increases accordingly. . That is, the set torque of the torque limiter is determined by the attractive force between the permanent magnet 4 and the semi-hard magnetic material 5, and the attractive force depends on the clearance 6 between the permanent magnet 4 and the semi-hard magnetic material 5. are doing. For this reason, if the fitting accuracy between the first rotating body 2 and the permanent magnet 4 is deteriorated, the clearance 6 between the permanent magnet 2 and the semi-hard magnetic body 4 varies. If the clearance 6 varies as described above, the attractive force also varies, so that a predetermined set torque cannot be obtained.
[0009]
In order to avoid such inconvenience, it is necessary to keep the fitting accuracy between the first rotating body 2 and the permanent magnet 4 high, but the manufacturing cost is accordingly increased as described above.
In addition, since a resin such as a plastic has a large deformation amount at the time of molding, when the first rotating body 2 is made of a resin, a predetermined dimensional accuracy may not be obtained. In such a case, it is conceivable that the first rotating body 2 is made of metal. However, if the first rotating body 2 is made of metal in this way, the material cost increases, and as a result, the manufacturing cost increases. That is, even if the material of the first rotating body 2 is changed, there is a problem that an increase in manufacturing cost is unavoidable.
[0010]
The second problem is that it is difficult to spread the adhesive evenly between the first rotating body 2 and the permanent magnet 4 while maintaining high fitting accuracy in the manufacturing process. Since it is difficult to spread the adhesive evenly, there has been a problem that the assembling accuracy of all products cannot be maintained high.
The third problem is that it takes a certain amount of time for the adhesive to dry completely, which further increases the manufacturing cost.
An object of the present invention is to provide a torque limiter that can solve the above-mentioned problems and that does not break the permanent magnet during assembly.
[0011]
[Means for Solving the Problems]
The first invention incorporates the inner rotating body into the outer rotating body, makes one of the rotating bodies made of resin, fits a permanent magnet on the peripheral surface of the resin rotating body, and attaches one of the other rotating bodies to the other rotating body. A semi-hard magnetic body facing the permanent magnet is provided, and a plurality of convex portions are provided on one of the rotating body and the permanent magnet on a contact surface between the resin rotating body and the permanent magnet. When the rotating body is fitted, the tip of the convex portion comes into pressure contact with either the rotating body made of resin or the permanent magnet.
When the convex portion is provided on the resin rotating body, the pressure contact refers to plastically deforming the distal end of the convex portion or shaving the distal end of the convex portion. In this case, it means that a part of the resinous rotator is plastically deformed by the convex portion, or a part of the resinous rotator is shaved.
[0012]
In a second aspect based on the first aspect, the plurality of projections provided on the rotating body or the permanent magnet include three or more protrusions formed at equal intervals in a circumferential direction of the rotating body or the permanent magnet, and This projection is characterized in that the projection is gradually narrowed from the base to the tip.
[0013]
According to a third invention, in the first or second invention, the projection has a constant length in the axial direction.
[0014]
A fourth invention is characterized in that, in the first to third inventions, a guide surface is provided on an insertion-side end surface of the resin rotary body or the permanent magnet.
[0015]
A fifth invention is characterized in that, in the first to fourth inventions, a rotation regulating mechanism for regulating relative rotation between the resin rotating body and the permanent magnet is provided.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
1 to 11 show a first embodiment of the present invention.
As shown in FIG. 1, a cylindrical inner rotating body 10 is incorporated in an outer rotating body 11. As shown in FIG. 1 as viewed from the side II (FIG. 2) and FIG. 1 as viewed from the side III (FIG. 3), the two rotating bodies 10 and 11 are coaxially arranged. Relative rotation is enabled.
The inner rotating body 10 is made of resin such as plastic, and has a regulating piece 12 on its outer periphery as shown in FIG. Further, as shown in a plan view (FIG. 5) of FIG. 4 as viewed from the direction V, a plurality of projections 13 are formed on the outer periphery of the inner rotating body 10. The plurality of protrusions 13 have a fixed length in the axial direction, and, as shown in a side view (FIG. 6) of FIG. 4 viewed from the VI direction, are balanced at equal intervals in the circumferential direction of the inner rotating body 10. Well placed. Further, as shown in a partially enlarged view of FIG. 7, these projections 13 are gradually narrowed from the base 13a to the tip 13b, and the angle of the tip is about 60 degrees.
[0017]
As shown in FIG. 1, a cylindrical permanent magnet 14 is fixed to the outer periphery of the inner rotating body 10 as described above. The permanent magnet 14 is fixed to the inner rotating body 10 without using an adhesive, and a specific fixing method will be described later.
Further, the permanent magnet 14 is formed with a regulating recess 15 which is open at the left end in the figure. The restricting piece 12 provided on the inner rotating body 10 fits into the restricting recess 15. Thus, the relative rotation between the inner rotating body 10 and the permanent magnet 14 is completely restricted by the restriction piece 12 being fitted into the restriction recess 15. The rotation restricting mechanism of the present invention is constituted by the restriction piece 12 and the restriction recess 15.
[0018]
On the other hand, as shown in FIG. 1, an annular semi-hard magnetic body 16 is fixed to the inner periphery of the outer rotating body 11. The semi-hard magnetic body 16 is opposed to the permanent magnet 14, and a predetermined clearance C is maintained between the inner periphery of the semi-hard magnetic body 16 and the outer periphery of the permanent magnet 14.
Further, as shown in FIG. 9, the outer rotating body 11 to which the semi-hard magnetic body 16 is fixed has an annular recess 17 formed on the right side in the figure. Then, as shown in FIG. 1, in a state where the lid member 18 is incorporated in the right inner periphery of the outer rotating body 11, an annular convex portion 19 formed on the outer periphery of the lid member 18 is fitted into the annular concave portion 17. . By attaching the lid member 18 to the outer rotating body 11 in this manner, the inner rotating body 10 is prevented from falling out of the outer rotating body 11.
[0019]
In the torque limiter as described above, the relative rotation between the inner rotating body 10 and the outer rotating body 11 is regulated by the magnetic force attracting the permanent magnet 14 and the semi-hard magnetic body 16 to each other. When the rotation torque input to the rotation body 10 or the outside rotation body 11 becomes equal to or more than the regulation torque by the magnetic force, the inside rotation body 10 and the outside rotation body 11 overcome the magnetic force and rotate relatively. That is, if the input rotational torque is small, the rotation of the inner rotary body 10 or the outer rotary body 11 is transmitted to the outer rotary body 11 or the inner rotary body 10, but the input rotary torque exceeds a predetermined magnitude. Then, the inner rotating body 10 and the outer rotating body 11 rotate relative to each other so that an excessive load does not act on the outer rotating body 11 or the inner rotating body 10.
[0020]
Next, a method of fixing the permanent magnet 14 to the inner rotating body 10 will be described.
The inner diameter of the permanent magnet 14 is smaller than the outer diameter of the inner rotating body 10 up to the tip of the projection 13. Therefore, when the inner rotating body 10 is inserted into the permanent magnet 14 from the left side in FIG. 8 in the direction of the arrow, the tips 13 b of the plurality of protrusions 13 provided on the inner rotating body 10 are pressed against the inner surface of the permanent magnet 14. . At this time, since the plurality of projections 13 are made of the same resin as the inner rotating body 10, the tip 13 b is plastically deformed or cut by the inner surface of the permanent magnet 14 which is harder. Then, the permanent magnets 14 are firmly fixed to the inner rotating body 10 at the plurality of projections 13.
[0021]
That is, in the first embodiment, the permanent magnet 14 does not entirely contact the peripheral surface of the inner rotating body 10 but partially contacts the peripheral surface. The projections 13 that partially contact with each other are plastically deformed or scraped during the assembling work, so that the force acting on the permanent magnets 14 from the inner rotating body 10 side is not so large. Therefore, even if the inner rotating body 10 is inserted into the permanent magnet 14, there is no inconvenience that the permanent magnet 14 is broken.
[0022]
Further, the height of the projection 13 is set such that the tip 13b of the projection 13 contacts the inner surface of the permanent magnet 14 in any situation in consideration of the tolerance of the inner rotating body 10 and the tolerance of the permanent magnet 14. Is set to That is, as shown in FIG. 10, the gap between the outer surface 10a of the inner rotating body 10 and the inner surface 14a of the permanent magnet 14 is maximized because a maximum tolerance occurs in the direction in which the outer diameter of the inner rotating body 10 decreases. In the case where the maximum tolerance occurs in the direction in which the inner diameter of the permanent magnet 14 increases, the height H of the projection 13 is set to a size corresponding to the maximum gap L generated at this time.
In this way, even if the gap between the inner rotating body 10 and the permanent magnet 14 is increased due to the tolerance, the tip 13b of the projection 13 can be brought into contact with the inner surface 14a of the permanent magnet 14. Therefore, the permanent magnet 14 can be fixed to the inner rotating body 10 via the plurality of protrusions 13.
[0023]
On the other hand, as shown in FIG. 11, when the maximum tolerance occurs in the direction in which the outer diameter of the inner rotating body 10 increases and the maximum tolerance occurs in the direction in which the inner diameter of the permanent magnet 14 decreases, There is almost no gap between the outer surface 10a and the inner surface 14a of the permanent magnet 14. In such a case, when the inner rotating body 10 is inserted into the permanent magnet 14, the portion of the projection 13 is almost cut off from the portion of the base 13a. The permanent magnet 14 can be firmly fixed.
As described above, the plastic deformation of the tip of the projection 13 and the shaving of the projection are referred to as pressure contact of the present invention. By making the pressure contact in this manner, the permanent magnet 14 is attached to the inner rotating body 10. Since they can be fixed, there is no need to use an adhesive to fix them. Since no adhesive is used, the conventional three problems can be solved.
[0024]
In the first embodiment, the guide surface 20 is provided on the insertion-side end surface 14b of the permanent magnet 14, as shown in FIG. 8, in order to easily insert the inner rotating body 10 into the permanent magnet 14. The guide surface 20 is formed so as to widen toward the insertion-side end surface 14b. The guide surface 20 has an edge 10c of the insertion-side end surface 10b (see FIG. 5) of the inner rotating body 10 and an end of the protrusion 13. When the portion 13c comes into contact, the inner rotating body 10 moves to the center along the guide surface 20, so that its axis and the axis of the permanent magnet 14 coincide.
In the first embodiment, the guide surface 20 is formed on the permanent magnet 14 side. However, as in the second embodiment shown in FIG. 12, the guide surface 21 is formed on the insertion end face 10b side of the inner rotating body 10. May be formed.
[0025]
The protrusions 13 provided on the inner rotating body 10 are arranged at equal intervals in the circumferential direction with good balance as shown in FIG. Therefore, when the inner rotating body 10 is inserted into the permanent magnet 14, the inner rotating body 10 moves to the center of the permanent magnet 14 in a well-balanced manner, whereby the axis of the inner rotating body 10 and the axis of the permanent magnet 14 are moved. Are more likely to match.
In the first embodiment, the protrusions 13 are provided at six positions at equal intervals in the circumferential direction. However, the number of these protrusions 13 may be three or more as long as they are at equal intervals in the circumferential direction.
In the first embodiment, the projections 13 are arranged at regular intervals in the circumferential direction. However, the positions of the projections 13 do not necessarily have to be arranged at regular intervals in the circumferential direction. For example, as in the third embodiment shown in FIG. 13, four projections 13 may be provided at line-symmetric positions. Even if the protrusions 13 are provided at the line-symmetric positions in this manner, since each protrusion 13 contacts the inner surface 14a of the permanent magnet 14 with good balance, the axis of the inner rotating body 10 efficiently matches the axis of the permanent magnet. Can be done.
[0026]
Furthermore, in the first embodiment, as shown in FIG. 5, the protrusion 13 has a predetermined length in the axial direction. When the permanent magnet 14 is assembled, the inclination of the permanent magnet 14 with respect to the axis is regulated by the projection 13. If the permanent magnet 14 is inclined with respect to the axis, the clearance C between the permanent magnet 14 and the semi-hard magnetic body 16 varies, and the set torque also changes. , The stable set torque can be obtained.
In addition, the projections 13 formed in the axial direction can be easily formed by forming them in the axial direction when the inner rotating body 10 is formed, so that the manufacturing cost can be reduced accordingly. .
[0027]
However, in the present invention, the projection 13 does not necessarily have to have a predetermined length in the axial direction. For example, in the fourth embodiment shown in FIGS. 14 and 15, a pair of projections 22 formed in the circumferential direction are installed at two locations at a predetermined interval in the axial direction. The projections 22 are also gradually tapered from the base to the tip.
According to the fourth embodiment as well, since the inner rotating body 10 partially contacts the permanent magnet 14, it is possible to prevent the permanent magnet 14 from being damaged during assembly. Moreover, when the permanent magnet 14 is assembled to the inner rotating body 10, the inclination of the permanent magnet 14 with respect to the axis can also be restricted.
[0028]
In the first to fourth embodiments, the protrusions 13 and 22 each have a predetermined length. However, as in the fifth embodiment shown in FIG. A plurality of triangular pyramid projections 23 may be provided on the peripheral surface of the inner rotating body 10. Also in this case, since the inner rotating body 10 comes into partial contact with the permanent magnet 14, it is possible to prevent the permanent magnet 14 from being damaged at the time of assembling, and to restrict the inclination of the permanent magnet 14. Can be.
The projections 13, 22, and 23 shown in the first to fifth embodiments correspond to the projections of the present invention. Any shape can be used as long as it comes into pressure contact.
[0029]
Further, in the first to fifth embodiments, the regulating piece 12 is provided on the inner rotating body 10 and the regulating recess 15 is provided on the permanent magnet 14 side. However, in the sixth embodiment shown in FIGS. As described above, the mounting positions of the restriction piece 12 and the restriction recess 15 may be reversed. That is, as shown in FIGS. 17 and 18, the first rotating body 10 is provided with the flange portion 24 and the flange portion 24 is formed with the regulating concave portions 25, 25. Further, as shown in FIGS. 19 and 20, the permanent magnet 14 is provided with regulating pieces 26, 26. The relative rotation between the inner rotating body 10 and the permanent magnet 14 is regulated by inserting the regulating pieces 26, 26 into the regulating recesses 25, 25.
[0030]
In the above embodiment, the relative rotation between the inner rotating body 10 and the permanent magnet 14 is regulated by the rotation regulating mechanism including the regulating pieces 12 and 26 and the regulating recesses 15 and 25, but the projection 13 is brought into pressure contact. Thus, the relative rotation between the inner rotating body 10 and the permanent magnet 14 can be restricted. In such a case, the rotation restricting mechanism is unnecessary. Therefore, in the present invention, the rotation restricting mechanism is not an essential component.
[0031]
By the way, in the first to sixth embodiments, the protrusion is provided on the inner rotating body 10. However, a plurality of protrusions are formed on the permanent magnet 14 side, and these protrusions are made to bite into the inner rotating body 10. Good. In this case, the fact that a part of the inner rotating body 10 is plastically deformed by the projection or a part of the inner rotating body 10 is shaved by the projection corresponds to the pressure contact of the present invention.
Further, the semi-hard magnetic body 16 may be fixed to the inner rotating body 10 and the permanent magnet 14 may be fixed to the outer rotating body 11. In this case, the outer rotating body 11 may be made of resin, and a protrusion may be provided on the inner surface or the outer surface of the permanent magnet 14.
Even in the case of the above-described configuration, it is possible to prevent a large force from acting on the permanent magnet 14 as in the above embodiments, and thus it is possible to prevent the problem that the permanent magnet 14 is damaged during assembly.
[0032]
【The invention's effect】
According to the first aspect, the resin rotating body and the permanent magnet are configured to be partially in contact with each other via the resin protrusion, so that a large force does not act on the permanent magnet during assembly. Therefore, the permanent magnet can be fixed to the resin rotary body without damaging the permanent magnet. In addition, since no adhesive is used, the inconvenience of using an adhesive can be eliminated.
[0033]
According to the second aspect, since the protrusions are formed at equal intervals in the circumferential direction, the axes of the resin rotating body and the permanent magnet can be matched at the time of assembly. In addition, by gradually narrowing the tip of the convex portion, the portion that comes into contact with the pressure is easily plastically deformed and cut, so that it is possible to prevent a large force from acting on the permanent magnet via the convex portion.
According to the third aspect, since the projection has the predetermined length in the axial direction, it is possible to prevent the permanent magnet from being inclined in the axial direction when the permanent magnet is assembled to the resin rotary body. .
[0034]
According to the fourth aspect, since the guide surface is provided on the end face on the insertion side of the resin rotary body or the permanent magnet, when the resin rotary body is inserted into the permanent magnet, it is easy to align the axes of the two.
According to the fifth aspect, since the rotation restricting mechanism for restricting the rotation of the resin rotator and the permanent magnet is provided, the relative rotation between the two can be surely restricted.
[Brief description of the drawings]
FIG. 1 is an overall sectional view showing a first embodiment.
FIG. 2 is a plan view of the whole of FIG. 1 as viewed from a direction II.
FIG. 3 is a plan view of the entirety of FIG. 1 as viewed from a direction III.
FIG. 4 is a sectional view of the inner rotating body 10;
FIG. 5 is a plan view of the inner rotating body 10 of FIG. 4 when viewed from a V direction.
FIG. 6 is a plan view of the inner rotating body 10 of FIG. 4 as viewed from a direction VI.
7 is a partially enlarged view of a protrusion 13 in FIG.
FIG. 8 is a cross-sectional view of the permanent magnet 14.
FIG. 9 is a sectional view of the outer rotating body 11;
FIG. 10 is a perspective view showing an assembled state of the inner rotating body 10 and the permanent magnet 14.
11 is a perspective view showing an assembled state of the inner rotating body 10 and the permanent magnet 14. FIG.
FIG. 12 is a sectional view showing an inner rotating body 10 according to a second embodiment.
FIG. 13 is a side view showing the inner rotating body 10 of the third embodiment.
FIG. 14 is a side view showing the inner rotating body 10 of the fourth embodiment.
FIG. 15 is a plan view showing an inner rotating body 10 of a fourth embodiment.
FIG. 16 is a plan view showing an inner rotating body 10 according to a fifth embodiment.
FIG. 17 is a sectional view showing an inner rotating body 10 according to a sixth embodiment.
FIG. 18 is a side view showing the inner rotating body 10 of the sixth embodiment.
FIG. 19 is a sectional view showing a permanent magnet 14 according to a sixth embodiment.
FIG. 20 is a side view showing a permanent magnet 14 according to a sixth embodiment.
FIG. 21 is an overall sectional view of a conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 Outer rotating body 10 Inner rotating body 14 Permanent magnet 16 Semi-hard magnetic body 13, 22, 23 Protrusion 13b corresponding to projection of this invention Tip 10b, 14b of projection corresponding to the tip of projection of this invention Insertion end face 20, 21 Guide surfaces 12, 26 Restriction pieces 15, 25 constituting rotation restriction mechanism of the present invention Restriction recesses forming rotation restriction mechanism of the present invention

Claims (5)

While incorporating the inner rotating body into the outer rotating body, one of the rotating bodies is made of resin, and a permanent magnet is fitted on the peripheral surface of the resin rotating body, and the other rotating body is opposed to the permanent magnet. A semi-hard magnetic body is provided, and a plurality of convex portions are provided on one of the rotating body and the permanent magnet on the contact surface between the resin rotating body and the permanent magnet, and the permanent magnet and the resin rotating body are fitted. A torque limiter characterized in that, when combined, the tip of the convex portion comes into pressure contact with either the resin rotary body or the permanent magnet. The plurality of protrusions provided on the rotating body or the permanent magnet include three or more projections formed at equal intervals in the circumferential direction of the rotating body or the permanent magnet, and the projections gradually increase from the base to the tip. 2. The torque limiter according to claim 1, wherein the torque limiter is made thinner. 3. The torque limiter according to claim 1, wherein the protrusion has a constant length in the axial direction. The torque limiter according to any one of claims 1 to 3, wherein a guide surface is provided on an end surface on the insertion side of the resin rotating body or the permanent magnet. The torque limiter according to any one of claims 1 to 4, further comprising a rotation restricting mechanism that restricts relative rotation between the resin rotator and the permanent magnet.

Images