JP2007068270A - Component for motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a component for a motor excellent in heat and impact resistances. <P>SOLUTION: A shaft 50 as the component for the motor has a yoke 10, a neodymium magnet 20, and an adhesive layer 30 for attaching and fixing them. An outer circumference 11a as an adhesive face between the yoke 10 and the adhesive layer 30 is formed with irregularity by a zinc calcium phosphate processed coating 12. A surface roughness Sm (an average interval of the irregularity) is 0.5-6 μm on the outer circumference 11a. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a motor component, and more particularly to a motor component in which a rare earth magnet is bonded and fixed to a yoke used for a rotor or a stator.

  For example, in a rotor or a stator of a motor, an adhesion structure in which a neodymium magnet is adhered and fixed to an iron yoke is known. In such an adhesive structure, when there is a thermal change in which high and low temperatures are repeatedly applied (hereinafter referred to as thermal shock), the difference in coefficient of linear expansion between the iron yoke and the neodymium magnet causes the yoke to change. Shear stress acts on the adhesive interface between the magnet and the neodymium magnet, and peeling is likely to occur between the yoke and the neodymium magnet.

  As a technique for solving such a problem, there is a technique disclosed in Patent Document 1 below. In this technique, a groove filled with an adhesive having a predetermined thickness is formed in the longitudinal center of the yoke, and a plate-like neodymium magnet having a longer longitudinal length than the groove is connected to both ends of the neodymium magnet in the longitudinal direction. Are arranged so as to protrude from both ends in the longitudinal direction of the groove. According to such a configuration, since both ends of the neodymium magnet are not bonded to the yoke and are free ends, the shear stress resulting from the difference in linear expansion when a thermal change occurs can be reduced. it can.

Another technique is disclosed in Patent Document 2 below. In this technique, in the adhesive structure as in Patent Document 1, the adhesive strength between the yoke and the neodymium magnet decreases further toward the both ends in the longitudinal direction of the neodymium magnet. According to such a configuration, the shear stress caused by the difference in linear expansion coefficient between the yoke and the neodymium magnet can be further reduced.
JP 2004-187411 A JP 2005-057835 A

  However, according to the technique disclosed in Patent Document 1, the shear stress acting between the neodymium magnet and the yoke can be reduced, but stress concentration still occurs at the bonding interface. Therefore, peeling between the yoke and the neodymium magnet cannot be sufficiently suppressed. In addition, since the adhesion area is relatively small, there is also a problem that the adhesion strength of the rare earth magnet is lowered and peeling is likely to occur.

  In the technique disclosed in Patent Document 2, the same problem as that of Patent Document 1 occurs. Furthermore, in the technique of Patent Document 2, as a means for gradually reducing the adhesive strength toward both ends in the longitudinal direction, the width (or thickness) in the direction perpendicular to the longitudinal direction at both ends in the longitudinal direction of the adhesive layer is gradually increased. A groove filled with an adhesive is formed in the yoke so as to be small, and complicated machining of the yoke is required. Therefore, there is a problem that the cost is increased.

  This invention is made | formed in view of the said present condition, and makes it a subject to provide the components for motors excellent in the thermal shock resistance. More specifically, it is an object of the present invention to provide a motor component that hardly causes separation between the yoke and the rare-earth magnet even when used in an environment where the temperature changes rapidly.

  In order to solve the above-described problems, a first technical means of the present invention includes a yoke used for a rotor or a stator and a material disposed on the surface of the yoke and having a different linear expansion coefficient. In a motor component comprising: a rare earth magnet; and an adhesive layer that is disposed between the yoke and the rare earth magnet and adheres and fixes the yoke and the rare earth magnet. An adhesive surface of the yoke with the adhesive layer The surface roughness of this is a motor component characterized in that Sm (average interval of irregularities) is 0.5 to 6 micrometers. The surface roughness Sm (average interval of irregularities) is defined in JIS: B0601-1994. More specifically, assuming that the adhesion surface of the yoke is a roughness curve, the average value of the lengths of the average lines corresponding to one peak and one valley adjacent to the peak among the average lines of the roughness curve. Sm.

  By setting the surface roughness Sm of the adhesive surface of the yoke to the adhesive layer to 0.5 to 6 micrometers, among the irregularities formed on the adhesive surface of the yoke, a peak portion (convex portion) Is formed every 0.5 to 6 micrometers. Further, when the yoke and the adhesive layer are bonded, the adhesive layer is mainly bonded to the convex portion. Here, according to the present invention, since the surface roughness Sm of the bonding surface of the yoke is set to 0.5 to 6 micrometers as described above, the interval between the convex portions is set to be relatively small. With such a configuration, it is possible to reduce the shear stress acting on each bonding surface when there is a temperature change.

  In addition, as an upper limit of the surface roughness Sm, 5 micrometers, 4 micrometers, and 3 micrometers can further be illustrated. Moreover, as a minimum of surface roughness Sm, 0.7 micrometer, 1 micrometer, and 2 micrometers can further be illustrated. When the surface roughness Sm exceeds the upper limit, shear stress tends to act on the bonded surface of the yoke due to temperature change, and the peel strength between the yoke and the rare earth magnet after thermal shock cannot be sufficiently maintained. . On the other hand, it is not preferable to make the surface roughness Sm smaller than the lower limit value because the production efficiency is lowered or the cost of the product is increased in the production process of the motor component of the present invention.

  It is considered that the shear stress acting at the time of temperature change can be reduced by the configuration of the present invention for the following reason. First, since the width | variety of each convex part will become large when the space | interval of each convex part is large, the range which a shear stress acts in each convex part becomes wide. For this reason, it is considered that a large shear stress acts on one convex portion. On the other hand, if the interval between the convex portions is small, the width of each convex portion is also small, and the range in which shear stress acts on each convex portion is also narrowed. Therefore, it is considered that the shear stress acting on one convex portion can be reduced.

  Moreover, it can also be considered that the shear stress acting upon temperature change can be reduced by the configuration of the present invention for the following reason. First, since Sm, which is the average interval between the irregularities, is set to be relatively small, the interval between the convex portions is also set to be small. Since the interval between the convex portions is set to be small, the amount of change in the interval between the convex portions when the yoke expands / shrinks due to a temperature change is also small. It is considered that the working shear stress is also reduced.

  Here, when the members are bonded and fixed, it is common to improve the bonding strength by the anchor effect by positively increasing the roughness of the surface of the members. However, in the present invention, attention is paid to the average interval Sm of unevenness in the surface roughness, and this average interval Sm is deliberately set to 0.5 to 6 μm unlike the general technical common sense as described above. The feature is that it is set as small as meters. Thus, the present invention has a configuration that cannot be easily conceived by those skilled in the art.

  Furthermore, in the motor component according to the present invention, it is preferable that a phosphate-treated film is formed as a base of the adhesive layer on the adhesive surface of the yoke with the adhesive layer. As the phosphating film, it is preferable to adopt a film formed by depositing granular crystals on the bonding surface of the yoke with the bonding layer by phosphating. Furthermore, in this case, the phosphate treatment coating may be a zinc calcium phosphate treatment coating. The zinc-calcium phosphate-treated film is formed by depositing granular crystals composed of a compound containing at least Zn and Ca (Zn—Ca-based compound) on the adhesion surface of the yoke. This granular crystal contributes to relatively reducing the surface roughness Sm of the bonded surface of the yoke. Furthermore, by controlling the size of the granular crystals, the surface roughness Sm on the bonded surface of the yoke can be adjusted to 0.5 to 6 micrometers.

  As described above, the surface roughness Sm on the bonded surface of the yoke can be made relatively small by forming the zinc calcium phosphate-treated film as the base of the bonded layer on the bonded surface of the yoke. It can also be understood as the following second technical means. That is, the second technical means of the present invention made to solve the problems of the present invention are a yoke used for a rotor or a stator and a surface of the yoke, and the yoke has a linear expansion coefficient. In a motor component having a different rare earth magnet, and an adhesive layer that is disposed between the yoke and the rare earth magnet, and that bonds and fixes the yoke and the rare earth magnet, an adhesive surface of the yoke with the adhesive layer And a zinc calcium phosphate-treated film as a base of the adhesive layer.

  According to the second technical means as described above, as described above, the surface roughness Sm on the bonded surface of the yoke can be made relatively small. Therefore, the shear stress acting on the bonded surface of the yoke can be reduced when the temperature changes. In this case, in order to further reduce the shear stress acting on the bonded surface of the yoke, the surface roughness Sm of the yoke outer peripheral surface is adjusted to a desired range by controlling the size of the granular crystal of the zinc calcium phosphate-treated film. It is preferable to do.

  In the first and second technical means described above, as means for controlling the size of the granular crystals, before forming the zinc calcium phosphate-treated film on the surface of the yoke, the adhesive surface with the adhesive layer of the yoke A method for performing the surface adjustment treatment can be exemplified. Examples of the surface adjustment process include a process of attaching the above-described substance serving as the nucleus of the granular crystal to the adhesive surface of the yoke with the adhesive layer. According to this surface adjustment treatment, the size of the granular crystals formed on the adhesion surface of the yoke can be adjusted by the zinc calcium phosphate treatment by adjusting the distribution density of the substance attached to the adhesion surface of the yoke. it can. In other words, when the distribution density of the substance adhering to the yoke is large, the interval between the distributed substances is narrowed, and as a result, the granular crystals growing with the substance as a nucleus interfere with each other, and as a result, the growth of the granular crystals is limited. Therefore, the size of the granular crystal can be made relatively small. As a result, the surface roughness Sm of the bonded surface of the yoke can be set to a relatively small value. On the other hand, when the distribution density of the substance adhering to the yoke is small, the interval between the substances to be distributed becomes wide, so that the granular crystals that grow using the substance as a nucleus are unlikely to interfere with each other, and the growth of the granular crystals is difficult to be restricted. Therefore, the size of the granular crystal becomes relatively large. For this reason, the surface roughness Sm of the bonded surface of the yoke becomes relatively large.

  As a means for attaching the substance that becomes the nucleus of the granular crystal to the adhesion surface of the yoke, a method of attaching titanic acid colloid to the adhesion surface with the adhesion layer of the yoke can be exemplified, more specifically, titanic acid. A method of immersing the yoke in the colloidal solution can be exemplified. In this case, the distribution density of the titanate colloid attached to the yoke can be adjusted by adjusting the concentration of the titanate colloid. In order to realize the motor component of the present invention, the concentration of the titanate colloidal solution is adjusted to 2 to 4 g / liter, more preferably 3 g / liter. If the concentration of the colloidal titanate solution is too low, the size of the granular crystals deposited on the bonded surface of the yoke tends to increase, and the surface roughness Sm tends to increase. On the other hand, if the concentration of the titanate colloidal solution is too high, the effect of adjusting the distribution density of on-grain crystals precipitated on the bonded surface of the yoke is saturated, which is not economical.

  As described above, the surface roughness Sm on the bonded surface of the yoke can be relatively easily adjusted to 0.5 to 6 micrometers by forming the phosphate treatment coating on the bonded surface of the yoke. In addition, since the phosphate treatment film has excellent corrosion resistance, the corrosion resistance of the yoke can be obtained by forming a phosphate treatment film in a region other than the bonded surface of the yoke or a region not covered with the rare earth magnet of the yoke. Can be improved. In this case, from the viewpoint of productivity, the entire surface of the yoke before bonding the rare earth magnet is preferably subjected to phosphating.

  The phosphate-treated film is a process generally used for plastic working or rust prevention, but the treated film is formed as a base of the adhesive layer, and other members are bonded and fixed via the adhesive layer. It is not adopted for the purpose. The configuration of the present invention has a technical idea of adopting a phosphate-treated film as a base (primer) for an adhesive layer when the yoke and the rare earth magnet are bonded and fixed via the adhesive layer. This configuration cannot be easily conceived by those skilled in the art.

  In the first technical means of the present invention, as a method for adjusting the surface roughness Sm on the bonded surface of the yoke, a method other than the method for forming the phosphate-treated film on the bonded surface of the yoke is adopted. You can also

In the rare earth magnet for motors of the present invention, the rare earth magnet has a coefficient of linear expansion in the easy axis direction of 0.6 × 10 ^{−6 to} 60 × 10 ⁻⁶ k ⁻¹ and is perpendicular to the easy axis of magnetization. linear expansion coefficient of the direction is the ^{-0.01 × 10 -6 ~-10 ×} 10 -6 k -1, the yoke, the linear expansion coefficient of ^{0.1 × 10 -5 ~50 × 10 -5} k - ¹ can be assumed. As described above, when the linear expansion coefficient of the rare earth magnet and the linear expansion coefficient of the yoke are greatly different, a problem that separation occurs between the yoke and the rare earth magnet is likely to occur. Can be resolved. In particular, the yoke is formed in a cylindrical shape so that the radial direction of the yoke and the easy magnetization axis direction of the rare earth magnet coincide with each other, and the axial direction of the yoke and the perpendicular direction of the easy magnetization axis of the rare earth magnet coincide with each other. In addition, when the rare earth magnet is bonded to the yoke, the difference in linear expansion coefficient between the yoke and the rare earth magnet becomes extremely large in the axial direction of the yoke. In such a case, peeling between the yoke and the rare earth magnet due to thermal shock is more likely to occur, but this problem can be solved by the configuration of the present invention.

  As described above, as an example of a combination of a yoke and a rare earth magnet having significantly different linear expansion coefficients, the yoke is made of an iron-based metal, and the rare earth magnet is a neodymium magnet. it can. Since neodymium magnets have good magnetic properties, they can be suitably employed as magnets for motor parts. Further, since iron-based metal is easy to process, it can be suitably used as a yoke for motor parts. According to the configuration of the present invention, even if the motor component is configured with such a large difference in linear expansion coefficient, the separation between the yoke and the magnet at the time of thermal shock can be suppressed, so that the performance is improved. In addition, both cost reduction and reliability improvement (improvement of thermal shock resistance) can be achieved.

  Furthermore, in the motor component of the present invention, the adhesive layer may have a room temperature elastic modulus of 500 to 2000 MPa. Here, the room temperature elastic modulus means an elastic modulus at 23 ° C. Thus, by adopting an adhesive layer having a relatively high elastic modulus, the yoke and the rare earth magnet can be firmly bonded and fixed. In addition, when the yoke and the rare earth magnet are bonded by the adhesive layer having a relatively high elastic modulus, the adhesive layer is not easily deformed even if the yoke and the rare earth magnet are deformed due to a temperature change, and thus the adhesive layer works on each bonding surface. Shear stress tends to increase. Therefore, when a thermal shock is applied, the yoke and the rare earth magnet are likely to be separated. However, as described above, by adjusting the surface roughness Sm of the adhesion surface with the adhesion layer of the yoke to 0.5 to 6 micrometers as the feature of the present invention, the shear stress acting on the adhesion surface of the yoke as described above. And the separation between the yoke and the rare earth magnet can be suppressed. Therefore, it is possible to simultaneously realize an improvement in the bonding strength between the yoke and the rare earth magnet and an improvement in the thermal shock resistance (inhibition of peeling between the yoke and the rare earth magnet due to thermal shock). Furthermore, in this case, the elastic modulus at −40 ° C. (low temperature) of the adhesive layer may be 1000 to 10,000 MPa, and the elastic modulus at 120 ° C. (high temperature) may be 100 MPa or less. Thus, by adopting an adhesive layer having a relatively high elastic modulus at low temperatures (−40 ° C.) and high temperatures (120 ° C.), the adhesive strength at low temperatures and high temperatures can be sufficiently maintained. Furthermore, since the elastic modulus at a low temperature and a high temperature is set to be relatively high, when the temperature changes to a low temperature and a high temperature, the shear stress acting on each bonding surface tends to increase due to the temperature change, but in the present invention Since the surface roughness Sm on the bonding surface of the yoke is adjusted to 0.5 to 6 micrometers, the shear stress on the bonding surface with the bonding layer of the yoke can be reduced. That is, it is possible to reduce the shear stress acting on each bonding surface when the temperature changes while maintaining the bonding strength between the yoke and the rare earth magnet at a low temperature and a high temperature to a certain level. Therefore, a more reliable motor component can be provided.

  The adhesive layer may be composed of an epoxy adhesive. The epoxy adhesive is an example of an adhesive that can form the above-described adhesive layer having a relatively high elastic modulus. Epoxy adhesive is a commonly used adhesive, but when the difference in coefficient of linear expansion between the yoke and the rare earth magnet is large, the yoke is made of an iron-based metal, and the rare earth magnet is a neodymium magnet. In the case where it is constituted by, its use was avoided. This is because the elastic modulus (elastic modulus at normal temperature, low temperature, and high temperature) of the epoxy adhesive is relatively high, and the shear stress acting between the yoke and the rare earth magnet cannot be sufficiently absorbed during thermal shock. This is because. However, the epoxy adhesive has a feature that when the yoke and the rare earth magnet are bonded, the yoke and the rare earth magnet can be firmly bonded due to the high elastic modulus. Therefore, in the present invention, by setting the surface roughness Sm on the bonded surface of the yoke to a relatively small value of 0.5 to 6 micrometers, the weak point when using the epoxy adhesive is improved. Only the advantages of epoxy adhesives can be utilized. That is, as in the configuration of the present invention, the yoke whose surface roughness Sm on the bonding surface of the yoke is set to a relatively small value of 0.5 to 6 micrometers and the epoxy adhesive having a relatively high elastic modulus. By combining with the constituted adhesive layer, it is possible to realize a motor component having excellent thermal shock resistance while sufficiently maintaining the adhesive strength between the yoke and the rare earth magnet at room temperature, low temperature and high temperature.

  Furthermore, the adhesive layer is preferably applied to the entire surface of the yoke that faces the rare earth magnet. According to such a configuration, since the yoke and the rare earth magnet are bonded to each other over the entire surface facing each other via the adhesive layer, the bonding strength between the yoke and the rare earth magnet can be improved. In this case, by setting the surface roughness Sm on the bonded surface of the yoke to a relatively small value of 0.5 to 6 micrometers, thermal shock is applied even if the yoke and the rare earth magnet are bonded to each other on the entire surface facing each other. Can prevent the yoke and the rare earth magnet from being separated.

  According to the motor component of the present invention as described above, it is possible to further reduce the stress generated at the bonding interface between the yoke and the rare earth magnet when a temperature change occurs (during thermal shock). Therefore, it is possible to provide a motor component having excellent thermal shock resistance. More specifically, it is possible to provide a motor component in which the yoke and the rare-earth magnet are less likely to be peeled even when used in an environment where the temperature changes rapidly.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing an example of a motor component of the present invention. The motor component in FIG. 1 is a shaft (rotor) 50 in which a rare earth magnet 20 is fixed to a yoke 10. The yoke 10 has a cylindrical cylindrical portion 11, and a rare earth magnet 20 is bonded and fixed to the outer peripheral surface (bonding surface) 11 a of the cylindrical portion 11. The rare earth magnet 20 is formed in a rectangular plate shape, and is bonded to the yoke 10 so that the longitudinal direction coincides with the axis O direction of the yoke 10 and the short side direction coincides with the circumferential direction of the cylindrical portion 11 of the yoke 10. Yes. More specifically, the rare-earth magnet 20 is formed so that the cross-sectional shape when cut along the short-side direction has an arc shape, and the curvature thereof is on the outer peripheral surface 11 a of the cylindrical portion 11 of the yoke 11. It is almost equivalent to the curvature. That is, both are arranged so that the curved surface of the outer peripheral surface 11a of the cylindrical portion 11 and the curved surface of the surface of the rare earth magnet 20 facing the cylindrical portion 11 coincide. A plurality of rare earth magnets 20 are arranged at equal intervals along the circumferential direction of the yoke 20. The rare earth magnet 20 and the yoke 10 are bonded and fixed by applying an adhesive to the entire surface of the rare earth magnet 20 facing the yoke 10.

The rare earth magnet 20 is a neodymium magnet 20. Moreover, the yoke 10 is comprised with the iron-type metal, and is specifically comprised with the steel material (S45). The neodymium magnet 20 has a linear expansion coefficient in the easy axis direction of 0.6 × 10 ^{−6 to} 60 × 10 ⁻⁶ k ⁻¹ and a linear expansion coefficient in the direction perpendicular to the easy axis of −0.01 ×. 10 ⁻⁶ to ⁻¹⁰ × 10 ⁻⁶ k ⁻¹ . Further, the yoke 10 has a linear expansion coefficient of 0.1 × 10 ⁻⁵ to 50 × 10 ⁻⁵ k ⁻¹ . Further, the yoke 10 is arranged such that the easy axis direction of the neodymium magnet 20 coincides with the radial direction of the yoke 10, and the perpendicular direction of the easy axis of the neodymium magnet 20 coincides with the axis O direction of the yoke 10. And a neodymium magnet are bonded and fixed. Therefore, the neodymium magnet 20 is bonded and fixed to the yoke 10 while being magnetized in the radial direction of the yoke 10.

  FIG. 2 is a cross-sectional view schematically showing an adhesion state between the yoke 10 and the neodymium magnet 20 of the shaft 50 of FIG. As shown in FIG. 2, relatively dense irregularities (convex portions 11 b and concave portions 11 c) are formed on the outer peripheral surface 11 a of the cylindrical portion 11 of the yoke 10. And surface roughness Sm in this outer peripheral surface 11a is 0.5-6 micrometers. That is, on the outer peripheral surface 11a, one convex portion is formed every 0.5 to 6 micrometers on average. An adhesive layer 30 is formed on the outer peripheral surface 11 a of the yoke 10 on which the unevenness is formed, and the yoke 10 and the neodymium magnet 20 are bonded and fixed via the adhesive layer 30.

  The adhesive layer 30 is specifically composed of an epoxy adhesive, and the room temperature elastic modulus is 500 to 2000 MPa. Moreover, the elasticity modulus in -40 degreeC of this epoxy-type adhesive agent is 1000-10000 MPa, and the elasticity modulus in 120 degreeC (high temperature) is 100 Mpa or less. As described above, by using an epoxy adhesive having a relatively high elastic modulus for the adhesive layer 30, the adhesive strength between the yoke 10 and the neodymium magnet 20 can be further improved.

  In the bonded state of the yoke 10 and the neodymium magnet 20 as shown in FIG. 2, since the unevenness is formed on the outer peripheral surface 11 a of the yoke 10, the protrusion 11 b and the adhesive layer 30 are concentrated in the unevenness. Will be joined. Here, when the temperature of the environment in which the shaft 50 is arranged changes, there is a difference in the linear expansion coefficient between the yoke 10 and the neodymium magnet 20, and an epoxy adhesive (adhesive layer 30) having a relatively high elastic modulus. ), A shear stress acts on the convex portion 11b of the yoke 10. However, since the interval between the convex portions 11b is set to be relatively small as described above, the width of each convex portion 11b is also set to be relatively small. For this reason, the range in which shear stress acts on each convex portion 11b is also narrowed. For this reason, it is considered that the shear stress acting on one protrusion 11b can be reduced. On the other hand, since the interval between the convex portions 11b is set small, even if the yoke 10 expands / contracts when the temperature changes, the interval between the convex portions 11b does not change greatly. It is considered that the shear stress acting on 11b is reduced. From another point of view, by setting the surface roughness Sm on the outer peripheral surface 11a of the yoke 10 to be small, the number of convex portions per reference length increases, and the shear stress acting on the entire outer peripheral surface 11a increases. As a result of being distributed to the convex portions 11b, it is considered that the shear stress acting on each convex portion 11b is reduced.

  On the other hand, FIG. 3 schematically shows an adhesion state between the yoke 10 and the neodymium magnet 20 when the surface roughness Sm on the outer peripheral surface 11a of the yoke 10 is relatively large. As shown in FIG. 3, when the surface roughness Sm of the outer peripheral surface 11a is relatively large, the width of each convex portion 11b is increased, so that the range in which shear stress acts on each convex portion 11b is widened. As a result, a larger shearing stress acts on one convex portion 11b, and a thermal shock is applied, so that the yoke 10 and the neodymium magnet 20 are easily separated.

  A phosphating film 12 is formed on the outer peripheral surface 11a of the yoke 10 to which the adhesive layer 30 is bonded. More specifically, the phosphate treatment coating 12 is a zinc calcium phosphate treatment coating 12. The zinc calcium phosphate-treated coating 12 forms a convex portion 11 b and a concave portion 11 c on the outer peripheral surface 11 a of the yoke 11. More specifically, the zinc phosphate calcium-treated film 12 is mainly formed of a Zn—Ca based compound, and granular crystals made of the Zn—Ca based compound are precipitated on the outer peripheral surface 11 a of the yoke 10. The convex part 11b and the recessed part 11c are formed.

FIG. 4 shows an example of a process for forming the phosphate treatment coating 12 on the outer peripheral surface 11 a of the yoke 10. First, in the alkaline degreasing step (S1), the yoke 10 is immersed in a liquid agent, and the outer peripheral surface 11a of the yoke 10 is degreased. Subsequently, in the water washing step (S2), the yoke 10 is immersed in tap water, and the liquid agent on the outer peripheral surface 11a of the yoke 10 is washed. After the cleaning, in the pickling step (S3), the yoke 10 is immersed in a hydrochloric acid bath to remove rust and the like formed on the outer peripheral surface 11a of the yoke 10. The concentration of the hydrochloric acid bath can be exemplified by about 13%. Thereafter, in the water washing step (S4), the yoke 10 is immersed in tap water to wash the hydrochloric acid on the outer peripheral surface 11a of the yoke 10. This water washing step (S4) can be performed in a plurality of, for example, two steps. A surface adjustment process (S5) is performed after a water washing process (S4). This surface conditioning treatment (S5) is performed by immersing the yoke 10 in the colloidal titanate solution. An example of the concentration of the titanate colloid in the titanate colloid solution is about 3 g / liter. By this surface adjustment process (S5), the colloid titanate is distributed on the outer peripheral surface 11a of the yoke 10. Then, the yoke 10 (the yoke 10 with the titanate colloid attached to the outer peripheral surface 11a) after the surface adjustment treatment (S5) is immersed in a phosphate treatment bath in the phosphate treatment (S6). As a phosphating bath, zinc calcium phosphate containing zinc ions (Zn ²⁺ ), phosphoric acid (H ₂ PO ₄ ), nitric acid (HNO ₃ ), nickel ions (Ni ⁺ ), calcium ions (Ca ²⁺ ) It is a treatment bath. As a result, granular crystals composed of a Zn—Ca-based phosphate compound (for example, Zn ₂ Ca (PO ₄ ) ₂ .4H ₂ O: scholzeite) are deposited on the outer peripheral surface 11a of the yoke 10, and zinc calcium phosphate is precipitated. A treatment coating 12 is formed. Then, the water washing process (S7) by a tap water and the hot water washing process (S8) by a 70 degreeC tap water are performed in order, and the process of forming the zinc-calcium-phosphate processing film 12 is completed.

  Hereinafter, the surface adjustment treatment (S5) and the phosphate treatment (S6) will be described in more detail with reference to FIG. First, in the surface conditioning process (S5), when the yoke 10 is immersed in the titanate colloid solution, the titanate colloid 13 adheres to the outer peripheral surface 11a of the yoke 10 with a predetermined distribution density as shown in FIG. . By immersing the yoke 10 in this state in the zinc calcium phosphate treatment bath in the phosphate treatment (S6), as shown in FIG. The granular crystal 12a comprised by this grows. That is, the titanate colloid 13 is a substance that becomes the nucleus of the granular crystal 12a. Then, when the granular crystal 12a further grows, as shown in FIG. 5C, the granular crystals 12a that grow with the titanate colloids 13 adjacent to each other interfere with each other, and the growth of the granular crystals 12a is restricted. . Thus, the granular crystal 12a precipitates on the outer peripheral surface 11a of the yoke 10, so that the zinc calcium phosphate-treated film 12 is formed on the outer peripheral surface 11a of the yoke 10. With such a zinc calcium phosphate-treated coating 12, convex portions 11b and concave portions 11c are formed on the outer peripheral surface 11a of the yoke 10.

  At this time, it can be understood from the explanation of FIG. 5 that the interval between the convex portions 11a and the surface roughness Sm of the outer peripheral surface 11a depend on the distribution density of the titanate colloid 13 distributed on the outer peripheral surface 11a of the yoke 10. . The distribution density of the titanate colloid 13 can be adjusted by adjusting the concentration of the titanate colloid solution in the surface adjustment treatment (S5). Therefore, the surface roughness Sm on the outer peripheral surface 11a of the yoke 10 can be adjusted to a range of 0.5 to 6 micrometers by adjusting the concentration of the titanate colloid solution to a predetermined concentration. Specifically, in order to adjust the surface roughness Sm on the outer peripheral surface 11a of the yoke 10 to a range of 0.5 to 6 micrometers, it is preferable to adjust the concentration of the titanate colloid solution to a range of 2 to 4. .

  In order to adjust the surface roughness Sm on the outer peripheral surface 11a of the yoke 10, in the phosphate treatment (S6), the concentration and temperature of the zinc calcium phosphate treatment bath in which the yoke 10 is immersed, or the immersion time in the bath It can also be performed by adjusting the above.

  According to the shaft (motor part) 50 of the present embodiment as described above, the surface roughness Sm on the outer peripheral surface 11a of the yoke 10 is 0.5 to 6 micrometers. Even if the neodymium magnet 20 is bonded and fixed via the wire, the shear stress acting on the bonding surface of the yoke 10 to the bonding layer 30 due to the temperature change can be reduced. Therefore, the thermal shock resistance of the shaft 50 can be improved, and as a result, a highly reliable shaft 50 that is unlikely to peel off between the yoke 10 and the neodymium magnet 20 even when used in an environment where the temperature changes rapidly can be realized.

  Further, since the phosphate treatment coating 12a, particularly the zinc calcium phosphate treatment coating 12a is formed on the outer peripheral surface 11a of the yoke 10, the surface roughness Sm on the outer peripheral surface 11a of the yoke 10 can be set to be relatively small. As a result, the shear stress acting on the bonding interface between the yoke 10 and the bonding layer 30 can be reduced when the temperature changes. Therefore, the shaft 50 of this embodiment is excellent in thermal shock resistance.

  In addition, since an epoxy adhesive having a high elastic modulus is adopted for the adhesive layer 30, the shaft 50 having good thermal shock resistance while maintaining the adhesive strength between the yoke 10 and the neodymium magnet 20 at a high level is provided. be able to. In this embodiment, an epoxy adhesive is used as the adhesive layer 30, but an adhesive other than the epoxy adhesive can be used as the adhesive layer.

  In the present embodiment, the shaft (rotor) 50 has been described as an example of the motor component. However, the motor component of the present invention can also be employed in the stator.

  In order to confirm the effect of the present invention, the following experiment was conducted. First, a steel material (S45) was formed by machining to produce a cylindrical yoke 10 as shown in FIG. Then, a phosphate treatment coating was formed on the outer peripheral surface of the yoke 10 by a process as shown in FIG. Here, a plurality of samples were prepared by changing the step of forming the phosphate treatment.

  Example 1 First, in the pickling step (S3) of FIG. 4, a hydrochloric acid bath having a concentration of 13% was used, and the yoke 10 was immersed in this hydrochloric acid bath for 8 minutes. In the surface conditioning treatment (S5), Prepan Z manufactured by Parker Rising Co., Ltd. was used as the titanate colloid solution. The concentration of the titanate colloidal solution was 3 g / liter. And FT-7 by Parker Rising Co., Ltd. was used for the phosphate treatment (S6) as a zinc calcium phosphate treatment bath. The concentration of the treatment bath was 32 pt and the temperature was 70 ° C. The yoke 10 was immersed in this treatment bath for 8 minutes to form a zinc calcium phosphate treatment film on the outer peripheral surface of the yoke 10.

  (Example 2) Except not performing the pickling process (S3) of FIG. 4, it processed similarly to the process of Example 1, and formed the zinc calcium phosphate process film in the outer peripheral surface of the yoke 10. FIG.

  (Comparative Example) In the phosphate treatment (S6) of FIG. 4, PB-181X manufactured by Parker Rising Co., Ltd. was used as the zinc phosphate treatment bath. The concentration of the treatment bath was 32 pt and the temperature was 70 ° C. The yoke 10 was immersed in this treatment bath for 8 minutes to form a zinc phosphate treatment film on the outer peripheral surface of the yoke 10.

  On the outer peripheral surfaces of the respective yokes manufactured as described above, the surface roughness Sm (average interval of unevenness) was measured by the method defined in JIS: B0601-1994. The measurement results are shown in Table 1. The surface roughness of each sample was the average when the surface roughness was measured twice at different positions.

Furthermore, the outer peripheral surfaces of the yokes according to Example 1 and the comparative example after the phosphate treatment were observed with an SEM (scanning electron microscope). FIG. 6 shows an observation image according to Example 1, and FIG. 7 shows an observation image according to a comparative example. As shown in FIG. 6, it was observed that granular crystals were deposited on the surface of the yoke according to Example 1. This granular crystal is presumed to be composed of a Zn—Ca-based phosphate compound (scholzite). On the other hand, it was observed that elongated leaf-like crystals were deposited on the surface of the yoke according to the comparative example. This crystal is composed of a Zn phosphate compound (mainly Zn ₃ (PO ₄ ) ₂ .4H ₂ O: Hopeite) because the treatment bath is a zinc phosphate treatment bath and is a leaf-like crystal. It is speculated that it has been.

Subsequently, a neodymium magnet having an arc shape in cross section is bonded to the outer peripheral surfaces of the plurality of yokes as described above using an epoxy adhesive (manufactured by Sumitomo 3M: DP190G), and shafts used for brushless motors are respectively provided. Produced. And the peeling strength of a neodymium magnet and a yoke was measured with respect to the shaft produced in this way using a dedicated jig. Specifically, when the claw member is engaged with the axial end portion of the rare earth magnet and a load is applied to the axial end portion of the rare earth magnet through the engaging member, the rare earth magnet and the yoke are separated. The value obtained by dividing the load by the adhesion area between the rare earth magnet and the yoke was defined as the peel strength. Furthermore, after performing a thermal shock test on each shaft, the peel strength between the neodymium magnet and the yoke was measured by the same method. Peel strength is measured by a thermal shock test. Specifically, the temperature is lowered to −40 ° C. and held in that state for 1 hour, and then the temperature is raised to 120 ° C. and held in that state for 1 hour. This cycle was performed by repeating 100 cycles. The measurement temperature of the peel strength was 23 ° C., respectively. The obtained results are shown in Table 1 together with the measurement results of the surface roughness Sm of the yoke. The peel strength was measured three times under each condition, and the average of the obtained peel strengths was determined as the average peel strength. Further, FIG. 8 shows the relationship between the surface roughness Sm on the outer peripheral surface of the yoke and the peel strength after the thermal shock test.

  From Table 1, it can be seen that in Examples 1 and 2, the surface roughness Sm on the outer peripheral surface of the yoke 10 is in the range of 0.5 to 6 micrometers. On the other hand, the surface roughness Sm on the outer peripheral surface of the yoke according to the comparative example was much larger than 6 micrometers. Thus, the surface roughness Sm depends on the method of phosphating, and as can be seen from FIGS. 5 and 6, the surface roughness Sm is higher in the zinc calcium phosphate-treated film on which granular crystals are deposited. It turns out that it is advantageous in reducing.

  Moreover, in Example 1 and Example 2, although the peel strength after a thermal shock test has fallen from the initial state, it turns out that it is maintained at a sufficiently high level. On the other hand, in the comparative example, although the peel strength in the initial state is higher than that in Example 1, the peel strength after the thermal shock test is greatly reduced from the initial state, and sufficient peel strength is maintained after the thermal shock test. You can see that it has not been done. Further, as shown in Table 1, the smaller the surface roughness Sm on the outer peripheral surface of the yoke, the higher the peel strength after the thermal shock test is maintained. That is, it can be seen that setting the surface roughness Sm of the outer peripheral surface of the yoke smaller is effective in improving the thermal shock resistance. In the comparative example, the variation in peel strength measured after the thermal shock test is large, but in the example, the variation in peel strength measured after the thermal shock test is small. That is, it can be seen that the shaft of the example is superior in reliability compared to the comparative example.

  Here, for example, various motor parts used in automobiles are required to satisfy 10 MPa or more as peel strength after a thermal shock test. As shown in FIG. 8, by setting the surface roughness Sm on the outer peripheral surface of the yoke to 6 micrometers or less, the peel strength between the yoke and the rare earth magnet after the thermal shock test can be made 10 MPa or more.

  The motor component of the present invention can be used as a rotor or stator of a motor used in an automobile, for example, a brushless motor used in an electric stabilizer or a brushless motor used in an electric power steering apparatus.

The perspective view which shows one Embodiment of the components for motors of this invention. The schematic diagram which shows the adhesion state of the yoke of the motor components shown in FIG. 1, and a rare earth magnet. The schematic diagram which shows the adhesion state of the yoke and rare earth magnet of the motor components different from this invention. The figure explaining a phosphate treatment process. The schematic diagram explaining a surface adjustment process and a phosphate process. The electron microscope observation image of the yoke outer surface concerning Example 1. FIG. The electron microscope observation image of the yoke outer surface concerning a comparative example. The figure which shows the relationship between the surface roughness Sm of a yoke outer peripheral surface, and the peeling strength after a thermal shock test.

Explanation of symbols

10 Yoke 11 Cylindrical part 11a Outer peripheral surface (adhesion surface)
11b Convex part 11c Concave part 12 Zinc calcium phosphate treatment film (phosphate treatment film)
12a Granular crystal 20 Neodymium magnet (rare earth magnet)
30 Adhesive layer 50 Shaft (motor parts)

Claims (8)

A yoke used for a rotor or a stator, a rare earth magnet disposed on the surface of the yoke and having a linear expansion coefficient different from that of the yoke, and disposed between the yoke and the rare earth magnet, the yoke and the rare earth magnet In a motor component having an adhesive layer that adheres and fixes
The motor component according to claim 1, wherein the surface roughness of the surface of the yoke bonded to the adhesive layer is Sm (average unevenness) of 0.5 to 6 micrometers.   The motor component according to claim 1, wherein a phosphate-treated film is formed as a base of the adhesive layer on the adhesive surface of the yoke.   The motor component according to claim 2, wherein the phosphate treatment coating is a zinc calcium phosphate treatment coating. A yoke used for a rotor or a stator, a rare earth magnet disposed on the surface of the yoke and having a linear expansion coefficient different from that of the yoke, and disposed between the yoke and the rare earth magnet, the yoke and the rare earth magnet In a motor component having an adhesive layer that adheres and fixes
A motor component, wherein a zinc calcium phosphate-treated film is formed as a base of the adhesive layer on an adhesive surface of the yoke with the adhesive layer.   5. The motor component according to claim 1, wherein the yoke is made of an iron-based metal, and the rare earth magnet is a neodymium magnet. 6.   The motor component according to claim 1, wherein the adhesive layer has a room temperature elastic modulus of 500 to 2000 MPa.   The motor component according to claim 1, wherein the adhesive layer is made of an epoxy adhesive.   The motor component according to any one of claims 1 to 7, wherein the adhesive layer is applied to an entire surface of the yoke that faces the rare earth magnet.

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