JPH07101648B2 - Resin magnet assembly - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnet assembly used as a component of a sensor used to detect the number of rotations and the rotation speed of various equipment, and more particularly to a magnet assembly.
Provides a magnet assembly that enables long-distance detection in rotation sensors for automobiles, etc., which require durability against vibration, heat or strength compared to when used in static and normal temperature environments such as equipment A To do.

[0002]

2. Description of the Related Art In recent years, a sensor for detecting the magnetism of a permanent magnet is used in a speed detecting device for an automobile or the like, by a method of detecting a speed by rotation of a mechanical cable or a method of detecting a rotation speed by a gear. Is being replaced by an electronic detection device that uses In this electronic detection device, a sintered ferrite magnet, a ferrite magnet resin molded product, or a sintered Sm-Co magnet is used as a magnet assembly that enables long-distance detection.
A magnet is given. However, when a sintered ferrite magnet is used, it is difficult to detect a long distance because the magnetic flux density is low as well as cracking and chipping of the magnet. Further, when a ferrite magnet resin molded body is used, the problem of cracking and chipping of the magnet can be solved, but long-distance detection is difficult because of the low magnetic flux density.

In order to enable this long-distance detection, a magnet assembly using a sintered Sm-Co magnet having a high magnetic flux density is often used. For example, as shown in FIG. 7, one using a magnetic sensor S and a sintered magnet assembly 80 rotating at high speed is known. The sintered magnet assembly 80 includes a cylindrical sintered Sm-Co magnet 81, a casing 82, and a flange portion.
It comprises a shank 84 having 83.

However, the sintered magnet assembly 80 has a low product yield due to cracking and chipping of the sintered Sm-Co magnet in the manufacturing process, poor dimensional accuracy, and a large number of parts, and assemblability. There was a defect such as bad. For example, in the production of the cylindrical sintered Sm-Co magnet 81, the problem of cracking or chipping similarly occurs during machining into a predetermined size after sintering or during the process. Further, the sintered magnet assembly 80 requires the casing 82 to prevent the sintered magnet from cracking or chipping when it is used as a rotating component. The casing 82 and the sintered Sm—Co magnet 81 are joined together. It is caulked or fixed with an adhesive. Sintered Sm-Co magnet for caulking
There is a problem in strength because 81 is cracked or peeled off in case of adhesion. Further, in order to prevent the two parts composed of the sintered Sm-Co magnet 81 and the casing 82 from peeling off from the end surface of the flange portion 83 when the sintered magnet assembly rotates at high speed, the sintered Sm-Co magnet 81 and In order to fix the two parts, which are fixed to the casing 82, to the end surface of the flange portion 83 with an adhesive, it is necessary to perform a step of applying anti-slip processing to the end surface of the flange portion 83 to which the adhesive is applied. On the other hand, sintered Sm-Co magnet
Since the casing 82 is arranged on the outer diameter of 81, the sintered Sm-C
o When the distance between the surface of the magnet and the magnetic sensor S increases, the detectable magnetic flux density decreases.

[Problems to be Solved by the Invention]

An object of the present invention is to provide a magnet assembly which enables long-distance detection, prevents a decrease in manufacturing yield due to cracking or chipping of the magnet in the manufacturing process, has a small number of parts, and is easy to assemble. To do.

[0006]

As a permanent magnet powder of a resin magnet assembly according to the present invention, a cylindrical resin magnet containing a rare earth permanent magnet powder and a thermoplastic resin as main components, and a shaft member on the inner peripheral portion thereof. In the integrally molded resin magnet assembly having, the shaft member is composed of a core portion, a flange portion and a shaft portion, and the core portion is made of a metal material having a yoke function.

That is, the cylindrical resin magnet of the present invention includes
Rare earth-based permanent magnet powder such as Sm-Co-based and Nd-Fe-B-based is used. Further, as the thermoplastic resin, nylon, polypropylene or the like is used. A composition containing a rare earth-based permanent magnet powder and a thermoplastic resin as main components is injection-molded to a shaft member that has been previously inserted into a mold to form a cylindrical resin magnet and to be integrated with the shaft member. Mold. Then, the cylindrical resin magnet is radially magnetized so as to have multiple polarities.

A metal material having a yoke function, such as S10C or soft magnetic stainless steel, is used for the core of the shaft member used in the present invention. Here, the yoke function means an amplification function of increasing the magnetic flux density on the surface of the magnet by increasing the permeance coefficient of the magnet. When these metal materials having a yoke function are used for the shaft member core, the cylindrical resin magnet that is in contact with the shaft member core having the yoke function should be bonded in such a manner that the inner circumference of the cylindrical resin magnet has no gap. is necessary.

Further, according to the present invention, when the flange portion constituting the shaft member is made of a metal material having a yoke function similarly to the core portion having a yoke function, the thickness T of the flange portion and the cylindrical resin magnet. T / W, which is the ratio to the width W, is 0
It features a range of 0.30.

Further, the present invention is characterized in that the shaft member has a taper of 1 or 2 or more particularly in the shape of the outer periphery of the core portion. When it has a flange portion, it has a taper of 1, and the direction thereof extends from the intersection line of the flange portion in contact with the end face of the core portion in the outer peripheral direction of the core portion. In the case of not having a flange portion, it is characterized by comprising two continuous chevron shapes and having two taper types of open type or closed type with respect to the center line of the core portion. Also,
In the case of not having a flange portion, a corrugated taper of 3 or more may be used. The peaks of the continuous chevron may have an arc. Even if it does not have a flange part, it is 2 to 3
The above taper may be used. As the shape of the outer circumference of the core portion, a key groove may be provided over a part or the entire circumference of the outer circumference, or a flange may be provided instead of the key groove.

[0011]

FUNCTION AND EFFECT As in the present invention, the composition containing the rare earth-based permanent magnet powder and the thermoplastic resin as the main components is injected into the shaft member having the core function which is inserted into the mold and also has the yoke function. By performing the forming and integrally forming, the problem of cracking and chipping does not occur because the sintered magnet is not used, and the manufacturing yield is improved. Moreover, the number of parts is reduced to one point of the integrally molded parts of the cylindrical resin magnet, and the assembling property is greatly improved.

Further, since the core portion disposed on the inner peripheral portion of the cylindrical resin magnet has a yoke function, the magnetic flux density on the outer peripheral surface of the cylindrical resin magnet is amplified,
It enables long-distance detection. That is, by adding the yoke function to the core portion, the magnetic flux density that can be detected by the magnetic sensor is improved even when the distance from the outer peripheral surface of the cylindrical resin magnet is large. When disposing the core portion having the yoke function on the inner peripheral portion of the cylindrical resin magnet, the inner peripheral surface of the cylindrical resin magnet and the outer peripheral surface of the core portion having the yoke function are not completely intimately contacted with each other to form a gap. With the above, since the yoke function is drastically reduced, the magnetic flux density on the outer peripheral surface of the cylindrical resin magnet is not amplified, and therefore the magnetic flux density detectable by the magnetic sensor is not improved.

Further, from this action, when the distance between the outer peripheral surface of the cylindrical resin magnet and the magnetic sensor is small, the thickness of the cylindrical resin magnet can be reduced, and expensive rare earth-based permanent magnet powder can be obtained. It is possible to obtain the effect of reducing the use of.

Further, in the present invention, when the flange portion constituting the shaft member is made of a metal material having a yoke function similarly to the core portion having a yoke function, one magnetic flux directed from the cylindrical resin magnet to the magnetic sensor. Is attracted toward the flange portion, so that the magnetic flux density reaching the magnetic sensor tends to decrease. Therefore, in order to reduce the attracted magnetic flux, the T / W value, which is the ratio of the thickness T of the flange portion to the width W of the cylindrical resin magnet, is set to 0.3.
By setting it to 0 or less, the magnetic flux density that can be detected by the magnetic sensor is secured. When the T / W value is 0, the flange may not be provided or a non-magnetic metal material may be used.

Further, since one or more tapers, keyways or flanges are provided on the outer periphery of the core portion of the present invention, in addition to the physical connection between the cylindrical resin magnet and the core portion, the mechanical structure is provided. Since the cylindrical resin magnet and the shaft member are more firmly coupled to each other, the cylindrical resin magnet may fall out of the shaft material under vibration or heat of the resin magnet assembly or during high-speed rotation. ,
It is possible to prevent idling.

Further, since the cylindrical resin magnet can be prevented from slipping out of the shaft material or idling, the flange portion can be omitted in the construction of the shaft material. This facilitates the processing step of the shaft material, and increases the magnetic flux density that can be detected by the magnetic sensor because the T / W value becomes 0.

[0017]

EXAMPLES Next, examples of the present invention will be described. Example 1 will be described below with reference to FIGS. 1, 2 and 6. As shown in FIG. 1, a shaft member was manufactured by cutting from S10C having a yoke function in the core 12. The target molding dimension of the cylindrical resin magnet 12 has an outer diameter of 8.00.
mm, inner diameter 4.00 mm, and cylindrical resin magnet 12
Had a thickness of 2.00 mm and a width W of 6.00 mm. The core portion 12 forming the shaft member has a cylindrical resin magnet 11
The outer diameter of the joint surface with the inner diameter of is 4.0mm, the width is 6.0mm
And The flange portion 13 has an outer diameter of 8.00 mm and the thickness T is 1.50 mm, and the shaft portion 14 has an outer diameter of 3.00.
mm and length 25 mm.

Then, by weight ratio, rare earth permanent magnet powder (trade name: MQ1, General Motors Corporation, USA) is used.
Pellets (commercial name RNI-125) made of 88 wt% to 92 wt% and the remainder made of thermoplastic resin and additives.
5, manufactured by Mate Co., Ltd.) was used to mold the shaft member at an injection temperature of 270 ° C. and an injection pressure of 1500 kgf / cm ² to obtain a molded product having a density of 5.1 g / cm ³ .

No cracks occurred during injection molding after molding 500 pieces, and there was no gap in the joint surface between the outer circumference 12a of the core portion and the inner circumference 11b of the cylindrical resin magnet, and a complete integral molding was obtained. . Further, even when the shaft 14 of the shaft was assembled in the rotation tester and the rotation test was performed at 1000 to 3000 rpm, the problem of the idle rotation of the cylindrical resin magnet 11 or the dropping and chipping did not occur.

Further, in FIG. 2, instead of the shaft member having the flange portion shown in FIG. 1, a shape member of the shaft member having the same size and having no flange portion, that is, from the core portion 22 and the shaft portion 24, A resin magnet 21 was injection-molded under the same conditions on the outer periphery of the core portion of the shaft member made of ash. No cracks were observed during the injection molding when examined by molding 300 pieces, and the rotation test was conducted, and the result was the same as that of the molded body of the shaft member having the flange portion.

A molded body using the shaft member having the flange portion shown in FIG. 1 was subjected to radial magnetization of 8 poles to investigate the effect of the yoke function, and the result is shown in FIG. The radial magnetizing condition for the molded body is a magnetizing voltage of 1000 to 1500.
It was magnetized at V and a magnetizing current of 10,000 to 20,000A. Using the resin magnet assembly 10 thus obtained, the peak value on one side of the magnetic flux density was measured for a distance from the outer peripheral surface 11a of the cylindrical resin magnet to the magnetic sensor S of 1.0 to 6.0 mm. In addition, 1 resin resin assembly 10 was used for measurement.
The rotation was performed at 800 rpm.

As a comparative example, a resin magnet assembly having no yoke function is made of JIS steel SUS304, and a shaft member machined to the same size as the resin magnet assembly 10 of the present invention is used. A cylindrical resin magnet was injection-molded under the same conditions as in the above-mentioned manufacturing, and was then radially magnetized into 8 poles for measurement.

As a conventional example, the resin assembly 80 shown in FIG. 8 was used. The outer diameter of the sintered Sm-Co magnet 81 is 5.8.
The casing 82 was a metal Al pipe having an inner diameter of 6.00 mm and an outer diameter of 8.00 mm cut into a length of 6.00 mm. The sizes of the flange portion and the shaft portion were the same as those of the flange portion and the shaft portion used in the resin magnet assembly 10 of the present invention.
This magnet assembly 70 was subjected to measurement.

In FIG. 6, the distance from the outer peripheral surface 11a of the cylindrical resin magnet to the magnetic sensor S is 1.0 on the horizontal axis.
.About.6.0 mm was taken, and the vertical axis represents the magnetic flux density (G; Gauss) detected by the magnetic sensor S. From this, it can be seen that the magnetic flux density tends to decrease as the distance increases. However, in the case of the resin magnet assembly 10 of the present invention having the yoke function in the core, as compared with the comparative example in which the core does not have the yoke function, it is improved at all distances and a high magnetic flux density is obtained. There is. Therefore, it is possible to detect a long distance by adding a yoke function. Further, by adding a yoke function, almost the same performance as a magnet assembly using a conventional sintered Sm-Co magnet was obtained.

Next, as Example 2, the result of an experiment conducted on the influence of the T / W value, which is the ratio of the thickness T of the flange portion having the yoke function to the width W of the cylindrical resin magnet, is shown in FIG.
In Example 1, the width W of the cylindrical resin magnet of the resin magnet assembly 10 was kept constant at 6.00 mm, and the thickness T of the flange portion of the shaft member was changed from 0.6 to 6.0 mm to obtain T / The effect of W value was investigated. The T / W value of 0 means
The case without a flange was investigated. The measurement was performed in the same manner as in Example 1, and the distance from the outer peripheral surface of the cylindrical resin magnet to the magnetic sensor was 3.0 mm.

It can be seen from FIG. 7 that the maximum magnetic flux density is obtained when the T / W value is 0, but the magnetic flux density tends to gradually decrease as the T / W value increases. When the T / W value exceeds 0.3, an inflection point appears in the decrease in the magnetic flux density, and then becomes a substantially constant value.

Further, the width W of the cylindrical resin magnet is 4.00.
~ 12. The same tendency as in FIG. 7 was obtained when the thickness T of the flange portion was changed to 0.5 to 6.0 mm while the thickness T was changed to 0.5 mm.

From these results, it was found that a shaft member having a yoke function was used, and that the thickness T of the flange portion of the shaft member and the width W of the cylindrical resin magnet were 0.
It has been clarified that it is necessary to set it to 3 or less in long-distance detection.

Next, regarding an embodiment of the resin magnet molded body in which the shape of the core portion of the shaft member is changed, FIG. 3 shows Embodiment 3 having a core portion having a taper of 1, and a core portion having a taper of 2. 4 is shown in FIG. 4, and Example 5 having a key groove around the outer circumference of the core is shown in FIG. In Example 3, in processing the shaft member, the flange portion
The core portion 32 having an angle α (2 degrees in the present embodiment) in the outer peripheral direction of the core portion from the intersection line of the flange portion that contacts the core end surface on the 33 side.
Was manufactured by cutting. The outer diameter of the flange side is 4.00 mm, the other surface is 4.42 mm, and the width is 6.0.
It was set to 0 mm. The sizes of the flange portion 33 and the shaft portion 34 were the same as those in the first embodiment. The cylindrical resin magnet 31 of the molded body obtained by injection molding using this shaft member has a large inner diameter of 4.02 mm on the surface in contact with the flange portion 33 and 4.42 mm on the other surface. Therefore, the structure in which the cylindrical resin magnet 31 is hard to come off from the shaft member core portion 32 is obtained.

In the fourth embodiment, when the shaft member is machined, the outer shape of the core portion is composed of two continuous chevron shapes, and the angles γ and β (each 2 degrees in this embodiment) with respect to the center line of the core portion. A core portion 41 having two tapers, which is open, is manufactured by cutting. The outer diameter of the upper and lower end surfaces of the core portion 42 is 4.00 mm, and the minimum diameter of the center of the core portion is 3.
The width was 79 mm and the width was 6.00 mm. The shaft member did not have a flange portion, and the size of the shaft portion 44 was the same as that in the first embodiment. The cylindrical resin magnet 41 of the molded body obtained by injection molding using this shaft member has a dimension of 4.01 mm in contact with the upper and lower end surfaces of the shaft portion 42, and a dimension of 4.21 mm in contact with the center of the shaft portion 42. A structure was obtained in which the cylindrical resin magnet 41 was hard to come off from the shaft member core portion 42 because it became large.

In the fifth embodiment, when the shaft member is processed, the key groove 55 is formed on the outer periphery of the core portion 52 by cutting.
That is, from the outer diameter 4.00 mm and the width 6.00 mm to the core
A keyway 55 having a rounded shape with a width of 1.50 mm and a depth of 0.30 mm at the center of 52 is formed. The shaft member does not have a flange portion, and the shaft portion 54 has the same size as that of the first embodiment. A cylindrical resin magnet 51 of a molded body obtained by injection molding using this shaft member has a convex portion with an inner diameter of 4.60 mm with respect to an inner diameter of 4.00 mm of the cylindrical resin magnet 51, so that the cylindrical resin magnet A structure was obtained in which the magnet 51 was difficult to come off from the shaft member core portion 52.

Even if a resin magnet assembly having one or more such taper or key grooves is assembled in a rotation tester and a high speed rotation test of 6000 to 12000 rpm is performed, the resin magnets 31, 41, or 51 of the cylindrical resin magnets 31, 41, or 51 are idle. The problem of dropout did not occur. Further, even in the combined test of the heat cycle test of -20 to 120 ° C and the high speed rotation test, there was no problem of idling or dropping of the cylindrical resin magnet 31, 41 or 51.

Regarding the shape of the shaft member of the resin magnet assembly, not only the shape of the core shown in the embodiment of the present invention, but also a shape of a non-cylindrical shape to obtain a mechanical structural connection. It includes.

[0025]

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a resin magnet assembly having a flange portion according to the first embodiment.

FIG. 2 is a cross-sectional view of a resin magnet assembly without a flange portion according to the first embodiment.

FIG. 3 is a sectional view of a resin magnet assembly according to a third embodiment.

FIG. 4 is a sectional view of a resin magnet assembly according to a fourth embodiment.

FIG. 5 is a sectional view of a resin magnet assembly according to a fifth embodiment.

FIG. 6 is an effect obtained by adding a yoke function.

FIG. 7 shows the influence of the ratio T / W of the thickness T of the flange portion to the width W of the cylindrical resin magnet on the magnetic detection force.

FIG. 8 is a sectional view of a conventional resin magnet assembly.

[Explanation of symbols]

10. ． ． Resin magnet assembly according to Example 1 11. ． ． Cylindrical resin magnet 11a. ． ． Outer circumference of cylindrical resin magnet 11b. ． ． Inner circumference of cylindrical resin magnet 12. ． ． Core part of shaft member 12a. ． ． Outer circumference of core of shaft member 13. ． ． Flange portion of shaft member 14. ． ． Shaft member shaft portion S. ． ． Magnetic sensor 20. ． ． 20. Resin magnet assembly having no flange portion in Example 1 21. ． ． Cylindrical resin magnet 22. ． ． Core part of shaft member 24. ． ． Shaft member shaft portion 30. ． ． Resin magnet assembly according to example 3 31. ． ． Cylindrical resin magnet 32. ． ． Core part of shaft member 33. ． ． Flange portion of shaft member 34. ． ． Shaft member shaft α. ． ． Angle of taper formed by core 40. ． ． Resin magnet assembly according to example 4 41. ． ． Cylindrical resin magnet 42. ． ． Core part of shaft member 44. ． ． Shaft member shaft γ. ． ． Angle of 1 taper made by the core β. ． ． Other taper angles formed by the core 50. ． ． Resin magnet assembly according to example 5 51. ． ． Cylindrical resin magnet 52. ． ． Core part of shaft member 53. ． ． Flange portion of shaft member 54. ． ． Shaft member shaft

Claims (3)

[Claims] 1. An integrally-molded resin magnet assembly having a cylindrical resin magnet containing a rare earth-based permanent magnet powder and a thermoplastic resin as main components, and a shaft member on an inner peripheral portion thereof, wherein the shaft member is a core portion, A resin magnet assembly, comprising a flange portion and a shaft portion, and the core portion made of a metal material having a yoke function. 2. The ratio T / W between the thickness T of the flange portion having a yoke function and the width W of the cylindrical resin magnet in the shaft member is 0 to 0.30.
The resin magnet assembly described in. 3. The resin magnet according to claim 1, wherein the core portion has a non-cylindrical shape at the joining surface between the outer periphery of the core portion of the shaft member and the inner periphery of the cylindrical resin magnet. Assembly.