JP2005143190A - Eddy current type reduction gear - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To optimize the profile of a wind hole, being provided in the side board of a drum type eddy current reduction gear where the cylindrical section of a rotor and the side board for supporting the rotor have an integral structure, from the view point of durability. <P>SOLUTION: In the drum type eddy current reduction gear for decelerating rotation of a cylindrical rotor 1, coupled with a rotary shaft 7 by a side board 1c provided with a plurality of wind holes 1ca in the circumferential direction, by the magnetic field from the permanent magnet 3 of a stator 2 provided on the inner circumferential surface side of the rotor 1, a first linear section 11 is provided at least on one side face part in the circumferential direction of the side board 1c at least at one wind hole 1ca and the first linear section 11 is made continuous to the inner and outer circumferential parts of the wind hole 1ca, respectively, through a curve part 12. Consequently, fatigue crack occurring around the wind hole after long term use can be suppressed effectively resulting in an eddy current reduction gear exhibiting excellent durability. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an eddy current type reduction gear mounted on a large vehicle such as a truck or a bus for assisting a main brake.

  In recent years, the functions required of eddy current type reduction gears have been diversified, and even when used for a long period of time, a device with excellent durability capable of securing a stable braking force is desired, while cost reduction of the device is desired. Therefore, there is a need for a device having a simplified structure while ensuring durability.

Among these, the present applicant has proposed a technique in which the cylindrical portion of the rotor and the side plate that supports the rotor are integrated with each other with regard to the simplification of the structure of the drum-type eddy current reduction device having the cylindrical rotor.
Japanese Patent Laid-Open No. 11-308852

  By the way, regardless of whether the magnet is an electromagnet or a permanent magnet, the magnetic force generally decreases when the temperature becomes high, and the braking force of the eddy current reduction device decreases. For example, a circular air hole is provided in the side plate, By urging the air convection, the magnets arranged at the portion surrounded by the cylindrical portion and the side plate are cooled. In addition, this air hole is useful for improving the fuel efficiency when the vehicle travels (when braking of the eddy current reduction device is turned off) due to the weight reduction of the rotor.

  An object of the present invention is to optimize the shape of air holes and the like provided in a side plate of a drum-type eddy current speed reducer in which a cylindrical portion of the rotor and a side plate supporting the rotor are integrated, from the viewpoint of improving durability. It was made as.

  The present invention decelerates the rotation of a cylindrical rotor connected to a rotating shaft by a side plate having a plurality of air holes in the circumferential direction by a magnetic field from a stator magnet provided on the inner peripheral surface side of the rotor. In the drum-type eddy current type speed reducer, at least one side surface portion in the circumferential direction of the side plate in at least one of the air holes is provided with a first straight portion, and the first straight portion and the inner and outer peripheral portions of the air holes are provided. The most important feature is that they are connected through curved portions.

  In the eddy current type speed reducer according to the present invention, a first straight portion is provided on at least one side surface in the circumferential direction of the side plate in at least one air hole, and the first straight portion and the inner and outer peripheral portions of the air hole are curved. Therefore, the fatigue cracks around the air holes that are likely to occur when used for a long period of time can be effectively suppressed, and the durability is excellent. Providing a plurality of air holes in the circumferential direction of the side plate is effective not only for reducing the weight of the rotor, but also for lowering the temperature of the permanent magnet, that is, thermal expansion of the cylindrical portion of the rotor.

  When braking of the eddy current type reduction gear is turned on, the cylindrical portion of the rotor expands due to Joule heat, and the diameter increases. At this time, in the eddy current type speed reducer in which the cylindrical portion of the rotor and the side plate supporting the rotor are integrated, the outer peripheral side of the side plate is coupled to the cylindrical portion, so that the diameter of the cylindrical portion increases. While a load is applied, the inner peripheral portion of the side plate is fixed to a support member that is coupled to the rotation shaft, so that deformation is restrained, and stress and strain in the radial direction and the circumferential direction are generated in the side plate.

  When this air hole is circular, both side surfaces of the support portion formed between adjacent air holes are arcs, and as shown in FIG. 7, the width of the support portion 1cb is the central portion in the radial direction of the side plate 1c. Is the narrowest, and the width becomes wider toward the inner and outer peripheral sides.

  When such a circular air hole is provided, if the cylindrical part is thermally expanded during braking, stress and strain are concentrated on the cross section where the width of the support part is the narrowest, and severe use that causes repeated braking ON / OFF It was found by simulation that fatigue cracks may occur in the cross-section where the width of the support portion is the narrowest under the conditions.

  Furthermore, when circumferential stress / strain is repeatedly applied to the side plate, the circular air holes concentrate stress / strain on the inner and outer side surfaces of the air hole, and depending on the conditions of use, this part may also be affected. Simulations also show that fatigue cracks can occur. Thus, in general, the fatigue crack generation life becomes shorter as large stress / strain is repeatedly applied.

  As a result of conducting various studies and theoretical analysis from such a viewpoint, the present inventors have found that the side surface of the support portion, that is, the linear portion on at least one side surface portion in the circumferential direction of the side plate in the air hole. It has been found that the concentration of stress and strain can be alleviated because there is no portion where the width of the support portion is locally narrowed when it is provided. This is because stress and strain concentrate at the center in the radial direction of the support when the air hole is circular, but when a straight part is provided, stress and strain are dispersed without concentrating and suppressing the occurrence of fatigue cracks. This is because it is considered possible.

  In this way, in the eddy current type speed reducer in which the cylindrical portion and the side plate of the rotor are integrated, it has been confirmed that the optimization of the shape of the air hole is important in order to improve the durability of the rotor. Completed the invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a cross-sectional view of the upper half of an apparatus showing an example of the eddy current type speed reducer of the present invention using a permanent magnet as a magnet.
The eddy current type speed reducer includes a rotor 1 and a stator 2, and the stator 2 includes a support ring 4 including a permanent magnet 3 and a pole piece 5 formed of a ferromagnetic material, and is a fixed part of a vehicle. It is fixed to the rear case of the transmission.

And the said permanent magnet 3 is arrange | positioned in a line at equal intervals so that the magnetic pole of the magnetic pole surface of the adjacent permanent magnet 3 may become mutually opposite, for example in the circumferential direction of the support ring 4. FIG.
Further, the support ring 4 is provided so as to be rotatable in the circumferential direction by a half arrangement pitch of the permanent magnets 3, and the pole piece 5 and the permanent magnets fixed to the case 6 at the same arrangement pitch as the permanent magnets 3. When the magnetic pole surface of 3 is in a position where it faces directly, the braking force acts on the rotor 1 (braking ON state) as will be described later, and the magnetic pole surface of the permanent magnet 3 is in an intermediate position (one pole piece) of the adjacent pole piece 5 If the position 5 crosses two adjacent permanent magnets 3), the braking force does not act on the rotor 1 (braking OFF state). Note that the rotation of the support ring 4 for switching the brake is performed by, for example, an air cylinder.

  On the other hand, the rotor 1 transmits to the rotating shaft 7 of the vehicle the cylindrical portion 1a, the fin 1b for cooling the cylindrical portion 1a, and the braking force generated in the cylindrical portion 1a while supporting the cylindrical portion 1a. It is comprised integrally with the side plate 1c.

  In the brake-on state, the cylindrical portion 1a of the rotor 1 rotates across the magnetic flux generated from the permanent magnet 3, so that an eddy current is generated near the inner peripheral surface of the cylindrical portion 1a. As a result, a braking force is generated in the rotor 1.

  On the other hand, in the brake OFF state, a magnetic short circuit is formed by the two adjacent permanent magnets 3, the one pole piece 5 facing the two permanent magnets 3, and the support ring 4, and therefore the cylindrical portion 1 a of the rotor 1. Magnetic flux hardly works, and almost no braking force is generated.

FIG. 2 is a view showing the upper half of the rotor 1 of the eddy current type speed reducer shown in FIG.
As shown in FIG. 2A, the side plate 1c that supports the cylindrical portion 1a of the rotor 1 is provided with a plurality of air holes 1ca in the circumferential direction. Hereinafter, the portion between the adjacent air holes 1ca and 1ca is referred to as a support portion 1cb. In the example shown in FIG. 2A, the air holes 1ca are provided at equal intervals in the circumferential direction. However, the air holes 1ca are not necessarily provided at equal intervals in the circumferential direction. good.

  In the eddy current type speed reducer according to the present invention, among the air holes 1ca formed in the side plate 1c, at least one air hole 1ca in the circumferential direction of the side plate 1c, for example, on both side surfaces, as shown in FIG. As shown, the first straight portion 11 is provided to form a straight portion in the support portion 1cb, and the air holes are provided via the curved portions 12 provided on the inner and outer peripheral sides of the first straight portion 11. The inner and outer peripheries of 1ca are continuous, and the inner and outer peripheries of adjacent support portions 1cb are smoothly connected. Hereinafter, the coupling portions in the inner and outer peripheral portions of the adjacent support portions 1cb are referred to as an inner circumferential side coupling portion 1cd and an outer circumferential side coupling portion 1ce.

  Thus, by forming linear portions on both sides of the support portion 1cb by the first straight portion 11 of the air hole 1ca, the width of the support portion 1cb in the circumferential direction of the side plate 1c, that is, the adjacent air holes 1ca. The distance between the side surfaces (hereinafter referred to as “the width of the support portion 1cb”) is not locally reduced, and stress / strain can be prevented from being concentrated locally in the support portion 1cb.

  At this time, if the width of the support portion 1cb is surrounded by an arc as shown in FIG. 7, the stress / strain is not concentrated locally, but the width of the support portion 1cb is the narrowest portion. Stress and strain will be concentrated. However, if the first straight portion 11 of the adjacent air hole 1ca is formed so that the width of the support portion 1cb increases or decreases at a constant rate with respect to the radial direction as shown in FIG. 3, it occurs in the support portion 1cb. The concentration of stress and strain can be reduced more effectively.

  In the eddy current type speed reducer according to the present invention shown in FIG. 3 (a), the inner and outer peripheral portions of the air hole 1ca are formed in an arc shape, but as shown in FIG. 3 (b), the air hole 1 ca may be provided with the second linear portion 13 on the inner peripheral side portion and the outer peripheral side portion. And when the 2nd linear part 13 is provided in an inner peripheral side part and an outer peripheral side part in this way, it is desirable to make these both 2nd linear parts 13 parallel.

  Thus, when the second linear portions 13 on the inner and outer peripheries are made parallel, the width of the inner peripheral side coupling portion 1cd and the outer peripheral side coupling portion 1ce (the length in the radial direction of the side plate 1c) becomes constant as compared with the case of the arc shape. Further, it is possible to more effectively prevent stress and strain from being concentrated locally on the inner peripheral side coupling portion and the outer peripheral side coupling portion.

  By the way, if the 2nd straight line part 13 is provided in the inner peripheral side part of the air hole 1ca, the center part of the 2nd straight line part 13 will be closest to the rotation center of the rotor 1, and in this center part, it will be closest to the fixed part 1cc. Therefore, the degree to which deformation is constrained by the fixing portion 1cc increases.

  Moreover, when the 2nd straight part 13 is provided in the outer peripheral side part of the air hole 1ca, the center part of the 2nd straight part 13 is furthest away from the cylindrical part 1a of the rotor 1, and both ends of the 2nd straight part 13 are the cylindrical parts 1a. To be closest. As a result, when the cylindrical portion 1a expands due to thermal expansion during braking, a large stress / strain acts on both end portions of the second straight portion 13 where the distance between the outer peripheral coupling portion 1ce and the cylindrical portion 1a is short. Become.

  On the other hand, as shown in FIG. 3 (c), instead of the second linear portion 13, the inner peripheral side portion and the outer peripheral side portion are arc portions 14 centered on the rotation center of the rotor 1. In this case, the widths of the inner peripheral side coupling portion 1cd and the outer peripheral side coupling portion 1ce can be kept constant, and the above-described problem does not occur.

  In addition, in the above-described eddy current type speed reducer according to the present invention, it is desirable that the side plate 1c be bent to the opposite side of the cylindrical portion 1a of the rotor 1 as shown in FIG. This is because if the side plate 1c is curved, the deformation of the cylindrical portion 1a (the deformation in the radial direction of the side plate 1c in the case of FIG. 4) can be absorbed by the elastic deformation of the curved portion, so that inelastic strain hardly occurs in the side plate 1c. . Furthermore, since the deformation of the cylindrical portion 1a is facilitated, inelastic strain is hardly generated in the cylindrical portion 1a, and fatigue cracks are not easily generated even when used repeatedly for a long period of time.

  As shown in FIG. 4, the center O in the radial direction of the side plate 1c (the center in the radial direction of the air hole 1ca) of the support portion 1cb formed between the adjacent air holes 1ca is the bolt 8 of the side plate 1ca. The air hole 1ca is arranged so as to be located on the outer peripheral side from the center part of the distance between the fixed part 1cc and the inner peripheral surface of the cylindrical part 1a (W in FIG. 4), and the air hole 1ca is shown in FIG. As described above, it is preferable that at least a part of the air hole 1ca preferably overlaps the case 6 of the stator 2 so as to face the side surface 2a of the stator 2.

This is because when the support portion 1cb (air hole 1ca) is provided on the inner peripheral surface side from the central portion of the distance W, (1) the degree of deformation around the support portion 1cb is restricted by the fixing portion 1cc, Stress / strain generated on the inner peripheral side surface of the air hole 1ca is increased,
(2) Even if the shape of the support portion 1cb (the air hole 1ca) is the same, since the circumferential interval between the support portions 1cb is reduced, the area of the air hole 1ca is reduced, the cooling effect of the stator 2 and This is because the effect of reducing the weight of the rotor is reduced.

  Further, if the temperature of the permanent magnet 3 rises excessively, the permanent magnet 3 is demagnetized and the braking force is lowered, so it is necessary to suppress the temperature rise. Since the stator 2 holding the permanent magnet 3 is provided close to the inner surface of the cylindrical portion 1a, the side surface of the stator 2 (the side surface facing the side plate 1c) is necessarily opposed to the outer peripheral side of the side plate 1c. Become. Therefore, in order to efficiently cool the stator 2 and the permanent magnet 3 with the wind flowing into the stator 2 side through the air holes 1ca, the air holes 1ca are provided on the outer peripheral side, and the side surfaces of the air holes 1ca and the stator 2 face each other. It is desirable that the wind flowing from the air hole 1ca hits the stator 2 efficiently.

In order to confirm the effect of the eddy current type speed reducer according to the present invention, the relationship between the shape of the support portion (air hole) and the inelastic strain generated in the side plate was evaluated by finite element method analysis (FEM analysis). The evaluated rotor shapes are shown in Tables 1 and 2 below.

  As shown in Table 1 and Table 2, the shapes of the cylindrical portion, fins, and side plates of the rotor were the same in all examples, and only the shape of the support portion (air hole) was changed. Here, as shown in FIG. 6, the width of the cylindrical portion 1a is the length of the cylindrical portion 1a in the direction parallel to the rotation shaft 7, and the amount of bending of the side plate 1c is the cylinder on the side to which the side plate 1c is coupled. Maximum value of the distance between the end surface of the portion 1a and the center of the side plate 1c (the distance between the end surface of the circumferential portion and the center portion of the side plate at the most protruding portion opposite to the cylindrical portion 1a), and W is the side plate by bolt This is the distance between the fixed portion 1cc of 1c and the inner surface of the cylindrical portion 1a.

As shown in FIG. 2, the inner peripheral surface of the side plate 1 c was fixed with four bolts 8. Further, the fin 1b has a rectangular cross-sectional shape and is provided so as to form an angle of 45 ° with the rotation direction of the rotor 1.
As shown in FIG. 5, the shape of the support portion 1cb (air hole 1ca) is such that the curvature radius R1, R2 of the curved portion 12 (the radius of curvature on the inner circumference side is R1 and the radius of curvature on the outer circumference side is R2), It is defined by the center O of the support portion 1cb which is an intermediate position between the widths L2 and L1 of the support portion at an intermediate position between the rotor radial lengths L1 and L1 of the portion 1cb and an intermediate position between L2. The center position of the support portion 1cb in Table 2 refers to the distance between the center of the rotor 1 (axial center of the rotating shaft 7) and the center O of the support portion 1cb.

  In addition, the linear part formed in the side surface of the support part 1cb (air hole 1ca) is made to correspond to the radiation extended from the rotation center of the rotor 1, and the inner and outer peripheral parts of the air hole 1c are shown in FIG. As shown, it was formed in an arc shape centered on the rotation center of the rotor 1.

  Nos. 1 to 5 are provided with air holes so that the center O of the support part is located at the center of the distance W between the fixed part by the bolt and the inner surface of the cylindrical part. The air holes were provided so that the center O of the support portion was positioned on the outer peripheral side from the center portion of the distance W.

  In the FEM analysis, the material of the rotor is made of molybdenum heat-resistant steel disclosed in JP-A-8-49041, and braking ON and braking OFF are repeated so that the maximum temperature on the inner surface of the cylindrical portion is 650 ° C. and the minimum temperature is 100 ° C. The inelastic strain range generated in the side plate when a thermal cycle was applied was evaluated. Here, the inelastic strain range is a fluctuation range of the inelastic strain.

  Table 3 below shows the evaluation results of the inelastic strain range generated in the side plate. In Table 3 below, the value of the portion where the generated inelastic strain range is the maximum is shown, but numbers 1 to 7 all had the largest inelastic strain range around the air hole.

The comparative example of No. 1 is a side plate provided with a circular air hole. Since the air hole is circular, there is no straight portion on the side surface of the support portion.
The comparative example of No. 2 does not provide a curved portion at the inner and outer peripheral portions of the first straight portion of the air hole. Even if the straight portion is provided on the side surface of the air hole, the generated inelastic strain range is large in the rectangular air hole in which the inner peripheral side portion and the outer peripheral side portion are not continuous via the curved portion.

  In the present invention examples Nos. 3 and 4, the first straight portion is provided on the side surface portion of the air hole so that the straight portion is formed on the side surface of the support portion. In addition to being continuous through the curvilinear portion, the inner and outer peripheral portions of the air hole are each provided with an arc portion centered on the rotation center of the rotor, so that the generated inelastic strain range is more than that of the above comparative examples (numbers 1 and 2). small.

  In the present invention example No. 5, the first straight portion is provided on the side surface portion of the air hole so that the straight portion is formed on the side surface of the support portion, and the first straight portion and the inner and outer peripheral portions of the air hole are respectively curved portions. However, the inner and outer peripheral portions of the air hole are not provided with an arc portion or a second straight portion. This shape also has a smaller inelastic strain range than that of the present invention examples of Nos. 3 and 4, but is smaller than the comparative example (Nos. 1 and 2).

  In the present invention examples Nos. 6 and 7, the first straight part is provided on the side surface of the air hole so that the straight part is formed on the side surface of the support part, and the first straight part and the inner and outer peripheral parts of the air hole are respectively provided. Continuing through the curved part, providing an arc part centering on the rotation center of the rotor at the inner and outer peripheral parts of the air hole, and the center of the support part being positioned on the outer peripheral side from the central part of the distance W Side plate.

  In the present invention examples of Nos. 6 and 7, the inelastic strain range generated is obviously smaller than that of the comparative examples (Nos. 1 and 2), but the center of the support portion is further provided at the center of the distance W. It is smaller than the examples 3 to 5 of the present invention. In particular, the example 6 of the present invention has substantially the same air hole shape as the example 4 of the present invention, but the example 6 of the present invention in which the support portion is arranged on the outer peripheral side has a smaller inelastic strain range.

  In general, the smaller the inelastic strain range, the longer the life of fatigue cracks, so the examples of the invention of No. 3 to No. 7 have a longer life of fatigue cracks than the comparative examples of Nos. 1 and 2, and have excellent durability. It was confirmed that

  The embodiment of the present invention is not limited to those shown in FIGS. 1 to 4, and the first straight portion 11 may be provided only on one side surface of the air hole 1 ca facing the inner side or the outer side of the air hole 1 ca. The second straight line portion 13 and the circular arc portion 14 are provided on the inner peripheral side portion and the outer peripheral side portion of the air hole 1ca. Things can be used. Further, the side plate 1c may not be formed in a curved shape.

  Further, in FIG. 1, a single-row magnet type eddy current reduction device is arranged in which a row of permanent magnet groups is arranged in the circumferential direction and the permanent magnet group is rotated in the circumferential direction to switch braking ON / OFF. As shown in the figure, a double-row magnet system in which two rows of permanent magnet groups are arranged in the circumferential direction and only one row is rotated in the circumferential direction to switch braking ON / OFF, or the permanent magnet is turned in the axial direction of the rotation axis. It is also possible to switch the braking ON / OFF by reciprocally moving. Furthermore, the magnet group may use an electromagnet.

  In the present invention, any manufacturing method may be adopted as long as the rotor finally has the shape of the present invention. However, if the rotor is manufactured by a casting method, a side plate provided with a cylindrical portion, fins, and air holes. Can be molded at a time and is inexpensive, so it is desirable to manufacture by casting.

  As described above, since the eddy current reduction device of the present invention is excellent in durability, the eddy current of a vehicle that travels in an area having a difference in elevation or a vehicle that travels from an urban area to a remote area by traveling on a highway. Suitable for current type speed reducer.

It is sectional drawing of the upper half of the apparatus which showed an example of the eddy current type deceleration device of this invention. It is the figure which showed the upper half of the rotor 1 of the eddy current type reduction gear shown in FIG. 1, (a) is a front view, (b) is the center longitudinal cross-sectional view of (a). (A)-(c) is the figure which showed the example of the air hole provided in the rotor of the eddy current type reduction gear of this invention. It is the figure which showed an example of the rotor of the eddy current type deceleration device of this invention, and is a figure of the rotor which curved the side plate. It is a figure for demonstrating the parameter for defining the shape of an air hole and a support part. It is a figure explaining the parameter for defining the shape of the cylindrical part and side plate of a rotor. It is a figure explaining the problem in case the air hole provided in the side plate is circular.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rotor 1a Cylindrical part 1b Side plate 1ca Air hole 1cb Support part 1cc Fixed part 2 Stator 3 Permanent magnet 11 1st linear part 12 Curved part 13 2nd linear part 14 Arc part

Claims (9)

A drum-type vortex that decelerates the rotation of a cylindrical rotor connected to a rotating shaft by a side plate provided with a plurality of air holes in the circumferential direction by a magnetic field from a stator magnet provided on the inner peripheral surface side of the rotor An electric current reducer,
A first straight portion is provided on at least one side surface in the circumferential direction of the side plate in at least one of the air holes, and the first straight portion and the inner and outer peripheral portions of the air hole are respectively connected via a curved portion. An eddy current type speed reducer characterized by   The first straight portion of the adjacent air holes is made parallel so that the circumferential width of the side plate of the support portion formed between the adjacent air holes is constant. Eddy current speed reducer.   3. The eddy current reduction device according to claim 1, wherein a second straight portion is provided on at least one of an inner peripheral side portion and an outer peripheral side portion of the air hole.   3. The eddy current reduction device according to claim 1, wherein a second straight portion is provided on an inner peripheral side portion and an outer peripheral side portion of the air hole, and the second straight portions are parallel to each other.   3. The eddy current reduction device according to claim 1, wherein at least one of the inner peripheral side portion and the outer peripheral side portion of the air hole is an arc portion centered on the rotation center of the rotor. .   A second straight portion is provided on either the inner peripheral side or the outer peripheral side of the air hole, and the other outer peripheral side or inner peripheral side is an arc portion centered on the rotation center of the rotor. The eddy current type speed reducer according to claim 1 or 2.   The eddy current reduction device according to any one of claims 1 to 6, wherein the side plate is curved to the opposite side to the cylindrical portion of the rotor.   The center of the side plate in the radial direction of the support portion formed between the adjacent air holes is located on the outer peripheral side from the center line position of the distance between the fixed portion of the side plate and the inner peripheral surface of the cylindrical portion of the rotor. The eddy current type speed reducer according to any one of claims 1 to 7, wherein   The eddy current type reduction device according to any one of claims 1 to 8, wherein at least a part of the air hole is provided at a position facing a side surface of the stator.

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