JPH0460221A - Thrust bearing setting structure in magnetic clutch - Google Patents

Abstract

PURPOSE:To prolong the extent of service life as a thrust bearing by forming a cylindrical part in one side of both ends of the inner tube of a rotor and the central shaft part of a stator, and a small diametral part being fitted in this cylindrical part in the other part, respectively, and keeping off any radial extension of a circular seat set up as a thrust bearing. CONSTITUTION:A cylindrical part 10a is formed in the end of an inner tube 10, and a small diametral part 4a being fitted in this cylindrical part 10 is formed in the end of a stator central shaft part 4. A gap X between an inner surface to the cylindrical part 10a and an outer surface to this small diametral part 4a is formed to be smaller than thickness (t) of a circular seat 14 or a thrust bearing, and a peripheral edge of this circular seat 14 is made so as not to get into the gap X. In addition, wall thickness of the cylindrical part 10a is thickened and its depth is deepened, and an area of a fitting surface between the cylindrical part 10a and the small diametral part 4a and each sectional area of these elements 4a, 10a are all formed into such that there is sufficient room for passing a magnetic flux to be produced by a magnet coil, through which it is unnecessary to set a bearing surface, where the circular seat 14 exists, down to a magnetic passage, thus the circular seat 14 is thickened and, what is more, thrust load can be made smaller as well.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a thrust bearing mounting structure in an electromagnetic clutch in which a circular seat is disposed as a thrust bearing between an inner tube of a rotor and a central shaft portion of a stator.

[Prior Art] Fig. 3 shows a conventional electromagnetic clutch. A stator 2 made of a magnetic material and fixed to a fixed part 1 has a cylindrical part 3 and a central shaft part 4, and an electromagnetic coil 5 is provided on the inner surface of the cylindrical part 3. The rotor 6 includes an outer tube 8 made of a magnetic material to which an input gear 7 is fixed on the outer periphery, and an inner tube 10 made of a magnetic material rotatably fitted to a fixed center penetrating shaft 9 made of a non-magnetic material passing through the clutch axis. , and a connecting portion 11 made of a non-magnetic material that connects the inner tube 10 and the outer tube 8. A small constant clearance is formed between the outer peripheral surface of the cylindrical portion 3 of the stator 2 and the inner peripheral surface of the outer tube 8 of the rotor 6. Further, an armature 12 is rotatably attached to the central penetrating shaft 9 so as to be able to come into contact with and separate from the rotor 6, and to which the rotation of the rotor 6 is transmitted, and an output gear 13 that engages with this armature 12 in the rotational direction. is rotatably attached to the central penetrating shaft 9. Further, as shown in an enlarged view in FIG. 4, a circular sheet 14 made of, for example, a Teflon sheet is disposed between the lower end surface of the inner tube 10 and the upper end surface of the stator central shaft portion 4 as a thrust bearing. Teflon sheets are used because they are suitable for thrust bearings because they have high strength and low frictional resistance. When the electromagnetic coil 5 is energized, a magnetic circuit as shown by the arrow is formed. In order to reduce the magnetic resistance of this magnetic circuit, it is desirable that the circular sheet 14 be as thin as possible; for example, the thickness t = 0. A material with a diameter of about .1 mm is used.

[Problems to be Solved by the Invention] Since the Teflon sheet is ductile, when a thrust load is applied to it, the circular sheet 14 stretches in the radial direction.
The peripheral edge of the bearing protrudes out of the surface as shown in FIG. Then.

As the thickness t becomes thinner, the protruding portion impedes smooth rotation and becomes unusable as a thrust bearing1.
For example, a Teflon circular sheet that is 0.1 mm thick at the beginning of use becomes 0.08 mm to 0.0 mm thick after 300 hours of use.
It becomes thinner to about 0.05mm.

The present invention has been made to solve the above-mentioned conventional drawbacks, and an object of the present invention is to provide a thrust bearing mounting structure that can extend the life of a circular sheet-shaped thrust bearing.

[Means for Solving the Problems] The invention according to claim 1 which solves the above problems includes disposing a circular seat as a thrust bearing between the end face of the inner tube of the rotor and the end face of the central shaft portion of the stator facing thereto. The thrust bearing in the electromagnetic clutch has a mounting structure, and has a thin cylindrical part formed at one end of the inner tube or the end of the stator central shaft part, and a small diameter part that fits into the cylindrical part at the other end, The invention of claim IR2 is characterized in that the gap X between the inner surface of the cylindrical portion and the outer surface of the small diameter portion is formed to be smaller than the thickness t of the circular sheet that is a thrust bearing. A thick and deep cylindrical part is formed at one end of the part, and a small diameter part that fits into the cylindrical part is formed at the other end,
The area of the fitting surface between the cylindrical part and the small diameter part is approximately equal to or larger than the cross-sectional area of the inner tube, and the cross-sectional area of the small diameter part and the cross-sectional area of the cylindrical part are both such that an electromagnetic coil is generated. A thrust bearing in an electromagnetic clutch characterized by having a sufficient area for passing magnetic flux has a mounting structure, and the area of the fitting surface between the cylindrical part and the small diameter part is approximately equal to or larger than the cross-sectional area of the inner tube. , and the thrust bearing in the electromagnetic clutch is a mounting structure, wherein both the cross-sectional area of the small diameter portion and the cross-sectional area of the cylindrical portion have a sufficient area to pass the magnetic flux generated by the electromagnetic coil.

[Function] In the thrust bearing of claim 1, in the mounting structure, when a thrust load is applied to the circular seat, the circular seat tends to extend in the radial direction, but the gap X between the inner surface of the cylindrical portion and the outer surface of the small diameter portion is Since it is smaller than the thickness t of the circular sheet,
The peripheral edge of the circular sheet does not enter into this gap, so that the peripheral edge of the circular sheet is reliably restrained by the inner surface of the cylindrical part and is prevented from extending in the radial direction. In this way, the circular sheet is confined within a constant volume, does not become thinner, and is prevented from shortening its lifespan.

In the thrust bearing of claim 2, in the mounting structure, the magnetic flux generated by the electromagnetic coil passes through the small diameter part in the axial direction, passes through the fitting surface between the small diameter part and the cylindrical part in the approximately radial direction, and passes through the cylindrical part in the axial direction. Pass in the direction. Then, the cross-sectional area of the small diameter part, the cross-sectional area of the cylindrical part, and the area of the fitting surface between the small diameter part and the cylindrical part are:
Since both have a sufficient area to pass the magnetic flux generated by the electromagnetic coil, bearings with circular seats can pass the necessary magnetic flux without using the surface as a magnetic path.

Therefore, the circular sheet does not need to have low magnetic resistance and can be thickened and have a long life.

[Example code] FIG. 1 shows an embodiment of the invention according to claim 1.

In the following embodiments, the structure of the electromagnetic clutch itself is the same as the structure explained in FIG. 3 except for the thrust bearing, and a repeated explanation will be omitted.

In FIG. 1, the reference numeral 10 is an inner tube of the rotor 6, and the reference numeral 4 is a central shaft portion of the stator 2, which is a central penetrating shaft.

In this embodiment, a one-thick cylindrical portion 10a is formed at the end of the inner tube 10, a small diameter portion 4a that fits into the cylindrical portion 10 is formed at the end of the stay center shaft portion 4, and the Gap X between the inner surface of the cylindrical portion 10a and the outer surface of the small diameter portion 4a
is formed to be smaller than the thickness t of the circular sheet 14 which is a thrust bearing using a Teflon sheet. in this case,
Since the magnetic flux generated by the electromagnetic coil 5 passes through the circular sheet 14, the circular sheet 14 needs to be thin in order to reduce the magnetic resistance of the magnetic circuit. In the illustrated example, the thickness t of the circular sheet 14 is approximately 0.1 mm, and the gap 7x is 0.
．． It is approximately 0.02rnrn-0.05mm.

In the above-described thrust bearing, in the mounting structure, when a thrust load is applied to the circular seat 14, the circular seat 14 tends to extend in the radial direction, but the gap X between the inner surface of the cylindrical portion 10a and the outer surface of the small diameter portion 4a is circular. Since the thickness t of the sheet 14 is smaller than the thickness t of the sheet 14, the peripheral edge of the circular sheet 14 does not enter into this gap, and therefore the peripheral edge of the circular sheet 14 is reliably constrained by the inner surface of the cylindrical portion Oa and radially This prevents it from elongating.

In this way, the circular sheet 14 is confined within a constant volume, does not become thinner, and is prevented from shortening its lifespan.

FIG. 2 shows an embodiment of the invention according to claim 2.

Similar to the case of FIG. 1, a cylindrical portion] and Oa are formed at the end of the inner tube 10, and a small diameter portion 4a that fits into the cylindrical portion 10 is formed at the end of the stator central shaft portion 4. However, in the present invention, the thickness of the cylindrical portion Oa is increased, and the depth 11 is increased. Furthermore, the cylindrical part 10
The area S of the fitting surface between the small diameter portion 4a and the small diameter portion 4a is approximately equal to or larger than the cross sectional area s2 of the inner tube 1o, and the cross sectional area S3 of the small diameter portion 4a and the cylindrical portion], Oa
The cross-sectional area S.

In either case, the area should be large enough to pass the magnetic flux generated by the electromagnetic coil 5. If the diameter of the inner tube 10 is D, the diameter of the small diameter portion 4a of the stator central shaft portion 4 is d, and the shaft passing through the center of the clutch axis is made of a non-magnetic material and its diameter is m, each of the above-mentioned areas S l, S2.
S 3. S- is represented by the following formula.

S −π dx S 2-yr (D 2 m')/4S s
= π(d 2m 2) y'4S, -π (D2
d2)z'4 Note that in this embodiment, the cylindrical portion 1 is
The gap X between the inner surface of 0a and the outer surface of small diameter portion 4a is 0,
The thickness of the circular sheet 14 is about 0.02 mm to 0.05 mm, which is smaller than the thickness t=0.1 mrn.

In addition, the cylindrical portion 1.0 a (7
1) The gear lug n between the tip surface and the shaft part 4 (inside the stator) is:
n = 0, about 5 mm. In the embodiment, this gap n is not considered to be part of the magnetic circuit through which magnetic flux passes. If this gap n is made narrower, the magnetic flux can pass through, but in this case, there is a risk that the circular sheets will come into contact with each other when they are worn out, so the gap is made large enough to allow for a sufficient margin.

In the mounting structure of the above thrust bearing, the magnetic flux generated by the electromagnetic coil 5 is transferred to the small diameter portion 4 as shown by the arrow.
a in the axial direction, passes through the fitting surface A where the small diameter portion 4a and the cylindrical portion 10a have a gap X of 0.02 mm to 0.05 mm, and passes through the cylindrical portion 10a in the axial direction. In this case, the area S1 of the fitting surface A between the small diameter portion 4a and the cylindrical portion 10a is equal to or larger than the cross-sectional area S2 of the inner tube 10, and
Cross section MS of small diameter portion 4a and cross section S of cylindrical portion 10a
, have a sufficient area to pass the magnetic flux generated by the electromagnetic coil 5, so the bearing with the circular seat 14 can pass the necessary magnetic flux without using the surface as a magnetic path. Therefore, the circular sheet 14 is no longer required to have low magnetic resistance, and for example, the thickness t can be reduced to 0.1 mm.
By increasing the thickness, the lifespan can be extended.

Furthermore, the magnetic attraction force between the inner tube 10 and the stator central shaft portion 4 is caused by the gap n between the distal end surface of the cylindrical portion 10a.
is made large, so it acts on the end face of the small diameter portion 4a (i.e., the surface of a bearing with a circular seat), but the area of this end face (
-The area of the small diameter portion 4a) is narrower than the area (-π(D2-d2)) in the case of the conventional structure in which the inner tube of the same diameter and the stator center shaft are simply opposed, so the electromagnetic The magnetic flux generated by the coil 5 causes the inner tube 1 to
0 and the stator center shaft portion 4 becomes smaller, the thrust load acting on the thrust bearing becomes smaller, and the life of the circular seat 14 becomes longer.

Note that, contrary to each of the above embodiments, the inner tube 10
A small diameter portion instead of a cylindrical portion may be formed on the side, and a cylindrical portion instead of a small diameter portion may be formed on the stator central shaft side 4.

[Effects of the Invention] Since the present invention is configured as described above, it has the following effects.

According to the mounting structure of the thrust bearing according to claim 1, the gap between the inner surface of the cylindrical portion and the outer surface of the small diameter portion is smaller than the thickness t of the circular sheet that is the thrust bearing.
This prevents the circular sheet from extending in the radial direction and becoming thinner, extending the life of the thrust bearing.

According to the mounting structure of the thrust bearing of claim 2, since the bearing with the circular sheet has a structure in which the surface does not have a magnetic circuit, the thickness of the circular sheet can be increased, thereby extending the life of the thrust bearing. can do.

Furthermore, the magnetic attraction force acting between the inner tube and the stator central shaft portion is reduced, and the thrust load acting on the thrust bearing is reduced, so the life of the thrust bearing is extended in this respect as well.

[Brief explanation of drawings]

FIG. 1 is a sectional view of the mounting structure of a thrust bearing showing an embodiment of the invention of claim 1, FIG. 2 is a sectional view of the mounting structure of a thrust bearing showing an embodiment of the invention of claim 2, and FIG. The figure is a sectional view of an electromagnetic clutch having a conventional thrust bearing mounting structure, and FIGS. 4 and 5 are diagrams illustrating problems with the conventional thrust bearing mounting structure. 2... Stator, 4... Stator center shaft portion, 4a.
・Small diameter part, 5... Electromagnetic coil, 6... Roller, 9.
・Center penetrating shaft, 10... Inner tube, 10a・
...Cylindrical part, 14...Circular seat (thrust bearing)
.

Claims (2)

[Claims] (1) A thrust shaft mounting structure in an electromagnetic clutch in which a circular seat is disposed as a thrust bearing between an end face of an inner tube of a rotor and an end face of a central shaft portion of a stator opposing thereto, wherein the end face of the inner tube Alternatively, a thin cylindrical part is formed at one end of the stator central shaft part, and a small diameter part that fits into the cylindrical part is formed at the other end, and the gap x between the inner surface of the cylindrical part and the outer surface of the small diameter part is filled with a thrust bearing. A thrust shaft mounting structure for an electromagnetic clutch, characterized in that the structure is formed to be smaller than the thickness t of a certain circular sheet. (2) A thrust shaft mounting structure in an electromagnetic clutch in which a circular seat is arranged as a thrust bearing between an end face of an inner tube of a rotor and an end face of a center shaft portion of a stator opposing thereto, the end face of the inner tube Alternatively, a thick and deep cylindrical portion is formed at one end of the stator center shaft portion, and a small diameter portion that fits into the cylindrical portion is formed at the other end, and the area of the fitting surface between the cylindrical portion and the small diameter portion is the inner tube. The electromagnetic coil is substantially equal to or larger than the cross-sectional area of the electromagnetic coil, and the cross-sectional area of the small diameter portion and the cross-sectional area of the cylindrical portion are both sufficient to pass the magnetic flux generated by the electromagnetic coil. Thrust shaft mounting structure in clutch.