JP2009225504A - Manufacturing method of divided stator core - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a divided stator core which is suppressed in the deterioration of its magnetic characteristic caused by a pressing force acting at shrink-fit processing without causing an increase of manufacturing cost. <P>SOLUTION: The manufacturing method of the divided stator core is composed of: a first process for thermally expanding a cylindrical body 20 by preparing an annular sidewall 21 having an internal hollow diameter having a magnitude larger than a diameter of a core body 100 composed of divided cores 10 and having an internal hollow height lower than the height of the core body 100, flanges 22 protruding toward the inside of the radial direction at both ends of the annular sidewall 21, and the cylindrical body 20; a second process for forming the circular ring-shaped core body 100 in the cylindrical body 20 while being thermally expanded; and a third process for fastening the core body 100 by imparting a pressing force in the height direction to the core body 100 by using the flanges 22 by shrinking the cylindrical body 20. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a stator core of an electric motor, and more particularly to a method for manufacturing a split stator core formed by fastening a split core from its outer periphery.

  A stator core constituting an electric motor is manufactured by punching a magnetic steel sheet or the like in a shape having a plurality of teeth protruding radially inward from an annular yoke, and laminating such steel sheets to a predetermined height. Is common. In the case of such a manufacturing method, a substantially annular steel plate portion defined by the tips of a plurality of teeth is used for rotor manufacture without discarding the steel plate after being punched into a substantially annular shape.

  By the way, since the fluctuation of the magnetic flux density in the rotor is extremely small compared to the stator, the material steel plate used for rotor manufacture does not necessarily have to have the magnetic characteristics required for the material steel plate used for stator manufacture. Absent. However, according to the stator core manufacturing method described above, from the viewpoint of reducing the amount of material disposal, it is necessary to use a relatively expensive material such as an electromagnetic steel plate similar to the stator, and as a result, Manufacturing costs were unnecessarily increased.

  As a technology to reduce the amount of steel sheet disposal and efficiently manufacture the stator and rotor from different steel sheets, manufacturing a stator core by joining a plurality of divided stators in the circumferential direction as a technology to reduce the amount of steel sheet disposal. Technology has been developed and is generally known. According to this manufacturing method, for example, a split piece for a split stator can be punched out as much as possible from an electromagnetic steel plate, so that the steel plate portion remaining after punching is used for the rotor in order to avoid disposal of the steel plate. There is no need to do it. That is, a relatively expensive steel plate such as an electromagnetic steel plate is applied for stator production, and a steel plate made of a soft magnetic material that is cheaper than the electromagnetic steel plate can be used as a steel plate for rotor production.

  Another advantage of manufacturing the stator from the split core is an improvement in the yield of the entire stator manufacturing including the coil forming. This is because the divided core pieces are laminated to produce the divided core, and the stator is produced by connecting the divided cores in the circumferential direction after forming the coil around the teeth of each divided core. It is possible to save manufacturing labor when post-processing the coil in a relatively narrow gap (slot) of the manufactured stator core, and to significantly improve the manufacturing time.

  By the way, in the method of forming the stator core from the split cores, it is essential to firmly connect the split cores. In order to connect or constrain such divided cores, a stator is conventionally manufactured by shrink fitting a stator core assembled in an annular shape inside a cylindrical body (case). This shrink fitting is performed by applying a compressive force in the radial direction from the outer periphery of the split core, so that the compressive stress in the in-plane direction acts on the split core (the steel plate constituting the split core), and the magnetic domain in the steel plate. The direction of the magnetic field is disturbed and the movement of the domain wall is hindered, which has been a factor that hinders the magnetic flow in the steel plate. Therefore, how to suppress an increase in iron loss due to the stress acting at the time of shrink fitting has been a major issue.

  To solve the above-described problem, Patent Document 1 discloses a magnet motor in which a core material is provided with a through hole for stress relaxation. According to this motor, although stress at the time of shrink fitting can be effectively relieved, by providing a through-hole in the core material, the strength reduction and magnetic characteristics of the stator core and the like are hindered, and further, the magnetic resistance in the magnetic path It is easy to understand that the rotational performance of the motor is reduced by providing a large gap.

  Therefore, an electric motor disclosed in Patent Document 2 has been proposed as a technique for solving the above-described problems of the magnet motor disclosed in Patent Document 1. In this electric motor, a stepped portion is provided inside the side wall of the case, a stator core (stator) is placed on the stepped portion, and the upper end of the stator is pressed by a flat plate fixed to the case by a bolt, whereby the stator is placed in the case. It is to be fixed.

JP 2002-136003 A JP-A-2005-304106

  According to the electric motor disclosed in Patent Document 2, the stress acting on the stator due to the pressing force can be reduced, and since the stator does not have a stress relief through hole, the rotational performance of the electric motor is not reduced. . However, such as forming a step for mounting the stator inside the case, or bolting the case to the case via a flat plate after mounting the stator, it takes a lot of manufacturing work and the number of parts is large. Soaring is undeniable.

  The present invention has been made in view of the above-described problems, and relates to a method of manufacturing a split stator core by fastening a split core assembled in the circumferential direction.In a simple manufacturing method, particularly a simple fastening method, And it aims at providing the manufacturing method of a division | segmentation stator core in which the iron loss of a core material is not increased by the pressing force which acts at the time of fastening.

  In order to achieve the above object, a method of manufacturing a split stator core according to the present invention manufactures a split stator core of an electric motor by fastening an annular core body formed by assembling the split core in the circumferential direction with a cylindrical body from the outer periphery. An annular side wall having an inner air diameter larger than the diameter of the core body and having an inner air height less than the height of the core body, and radial directions at both ends of the annular side wall A cylindrical body having a flange projecting inward is prepared, a first step of thermally expanding the cylindrical body, and forming the annular core body inside the cylindrical body in a thermally expanded posture And a third step of contracting the cylindrical body and applying a pressing force in the height direction to the core body by the flange to tighten the core body.

  The present invention manufactures a divided stator core by assembling a plurality of divided cores in the circumferential direction in the circumferential direction to form an annular core body in plan view and shrink-fitting the outer peripheral portion with a cylindrical body (case). It relates to a manufacturing method.

  Each divided core is a steel sheet laminate made of, for example, electromagnetic steel sheets, and includes an arc-shaped yoke and a plurality of teeth or a single tooth that protrude from the yoke toward the center of the arc and are spaced apart from each other. It is configured by stacking the divided pieces at a predetermined height. The soft magnetic metal powder may be molded from a powder magnetic core formed by pressure-molding in a similar shape in a mold, but according to the manufacturing method of the present invention, a split core is formed from a steel sheet laminate. A particularly large effect is exerted on the core body.

  Each divided core is accommodated as needed in a thermally expanded cylindrical body, and is assembled in the circumferential direction in the cylindrical body to form an annular core body.

  Here, the cylindrical body surrounding the core body has an inner air diameter larger than the diameter of the core body, an annular side wall having an inner air height less than the height of the core body, and both ends of the annular side wall And a flange protruding radially inward are, for example, integrally molded members.

  When the cylindrical body is thermally expanded, the cylindrical body expands in the height direction and the radial direction, and after the annular core body is assembled in this state, the cylindrical body naturally or artificially When the core body is cooled and contracted, a pressing force is applied to the core body and shrink fitting is performed.

  Since the inner air diameter of the cylindrical body is larger than the diameter of the core body, when this cylindrical body contracts, the pressing force (compression force) from the cylindrical body to the in-plane direction acts on the core body (the steel plate that constitutes the core body). do not do. On the other hand, since the inner height of the cylinder (the distance between the flanges at both ends) is lower than the height of the core, when the cylinder contracts, the pressing force in the height direction from both flanges to the core (Compressive force) acts.

  According to the present inventors, the compressive stress acts in the in-plane direction on the steel sheet constituting the core body, thereby reducing the magnetic properties of the steel sheet, while the compressive stress acts on the steel sheet in the vertical direction. In addition, it is specified that almost no deterioration of the magnetic properties of the steel sheet is observed.

  According to the manufacturing method of the present invention described above, when the annular core body composed of the divided cores is shrink-fitted in the cylindrical body, the processing is performed only by applying a pressing force only in the height direction of the core body. The core body can be firmly shrink-fitted, and the deterioration of the magnetic properties of the core body that has occurred during the conventional shrink-fitting process can be effectively suppressed.

  In another embodiment of the method for manufacturing a split stator core according to the present invention, a protrusion is provided at one end of the core body or the flange, and a groove is provided at a position corresponding to the other protrusion. In addition, at least when the cylindrical body contracts, the projection is fitted into the concave groove. In addition to the form provided at both ends of the core body, the protrusions or concave grooves formed on the core body may be provided only at one of the upper and lower ends. A concave groove or a projection is provided on the flange.

  For example, a set of concave grooves is provided at both ends of each split core constituting the core body, and the concave grooves are formed at positions corresponding to the concave grooves on the inner side surface (surface on the core body side) of the flange constituting the cylindrical body. By providing the engaging protrusions, it is possible to engage the corresponding recessed grooves and protrusions when positioning the split core in the thermally expanded cylindrical body, and to improve the processing efficiency. .

  In addition, the engagement between the groove and the protrusion can eliminate the risk of relative displacement between the core body and the cylindrical body when the motor is driven after the shrink fitting process, for example. Assembly of a simple core body and cylindrical body can be realized.

  The motor including the stator having the divided stator core manufactured by the manufacturing method of the present invention described above is intended for all types of motors of the inner rotor type, for example, a synchronous reluctance motor, an induction motor, a brushless motor, It includes general motors such as IPM motors.

  In this electric motor, since the magnetic characteristics of the split core constituting the stator core that is a constituent member thereof is not deteriorated during the shrink fitting process, an increase in iron loss is suppressed, and the rotational performance and torque performance are excellent. Become. In addition, the stator core is composed of split cores to improve the manufacturing yield, reduce the amount of steel plate material discarded, reduce the manufacturing cost resulting from it, and provide sufficient connection strength between the core body and the cylindrical body. It is possible to improve the durability by ensuring.

  As can be understood from the above description, according to the split stator core manufacturing method of the present invention, by adjusting the size of the core body composed of the cylindrical body for shrink fitting and the plurality of split cores, A split stator core is manufactured by the same method, and a split stator core whose magnetic characteristics are not deteriorated by a pressing force acting during shrink fitting can be manufactured without increasing the manufacturing cost.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing an electric motor composed of a stator and a rotor manufactured by the manufacturing method of the present invention, and FIG. 2 is an exploded vertical section of one embodiment of a split core and one embodiment of a cylindrical body. FIG. FIG. 3 is a longitudinal sectional view showing a state in which a core body composed of divided cores is assembled in a cylindrical body in a posture in which the cylindrical body is thermally expanded. FIG. 4 is a continuation of FIG. It is a longitudinal cross-sectional view which shows the stator core of a state.

  FIG. 1 is a diagram schematically showing an electric motor composed of a divided stator core and a rotor manufactured by the manufacturing method of the present invention. In this electric motor, the divided cores 10,... Divided into a plurality in the circumferential direction are assembled in the cylindrical body 20 to form an annular core body 100, and the cylindrical body 20 is shrink-fitted to obtain the core body 100. A cylindrical body 20 is integrally formed to form a stator core, and a cylindrical rotor 30 is disposed inside the stator core to form an inner rotor type electric motor. In the illustrated example, the illustration of coils formed on the outer periphery of each tooth is omitted.

  Each of the split cores 10 is formed of a magnetic steel sheet cut into a shape including an arc-shaped yoke and one tooth projecting radially from the yoke at a predetermined height and integrally formed by welding or the like. Is.

  Next, a method for manufacturing a stator core will be outlined based on FIGS.

  A predetermined number of split cores 10 according to the number of magnetic poles are manufactured by the method described above, and a cylindrical body 20 made of a suitable non-conductive material such as aluminum or an alloy thereof is prepared.

  The cylindrical body 20 is formed by integrally forming an annular side wall 21 and a pair of ring-shaped flanges 22, 22 projecting radially at both ends thereof, and the divided cores 10,. The annular core body 100 is assembled inside the cylindrical body 20 by being sequentially inserted.

  Here, the inner air height of the cylindrical body 20 is h1, the inner air diameter is φ1, the height of the split core 10 (core body 100) is h2, and the relationship of h1 <h2 is set.

  When inserting the split core 10 into the cylindrical body 20, first, the cylindrical body 20 is thermally expanded in a high temperature atmosphere, and the overall dimensions are expanded in the radial direction and the height direction as shown in FIG. X1 direction and Y1 direction).

  In the cylindrical body 20 in a thermally expanded posture, the respective split cores 10... Having coils (not shown) formed on the outer periphery of the teeth are sequentially inserted and assembled in the circumferential direction to form the annular core body 100.

  Here, the height of the formed core body 100 is h2 like the divided core 10, and its diameter is φ2.

  The diameter of the annular core body 100: φ2 is set smaller than the inner air diameter: φ1 of the cylindrical body 20 at normal temperature (or contraction) shown in FIG. 2 (φ2 <φ1).

  After the core body 100 is formed in the cylindrical body 20, the cylindrical body 20 is naturally cooled or artificially cooled by a fan or the like, so that the thermally expanded cylindrical body 20 contracts as shown in FIG. (X2 direction and Y2 direction) The core body 100 is shrink-fitted by the cylindrical body 20.

  In this shrink-fitting posture, the height of the core body 100 is higher than the inner air height of the cylindrical body 20, and the diameter is set smaller than the inner air diameter of the cylindrical body 20. A pressing force P in the height direction acts from the flanges 22 of the body 20. On the other hand, a gap G is formed between the side surface of the core body 100 and the inner surface of the annular side wall 21, and the pressing force from the annular side wall 21 does not act in the radial direction of the core body 100.

  It should be noted that the core body 100 and the inner diameter of the annular side wall 21 at the normal temperature may be the same (φ1 = φ2 and no gap G is formed), and even in this case, the core body 100 is contracted from the contracted cylindrical body 20. The pressing force does not act in the radial direction.

  Since the pressing force does not act in the radial direction (in-plane direction) on each electromagnetic steel sheet constituting the core body after the shrink-fitting treatment, the pressing force acts in the in-plane direction during the conventional shrink-fitting treatment. The problem that the magnetic properties of the steel sheet have deteriorated and the iron loss has increased is effectively eliminated.

  Moreover, since the core body 100 and the cylindrical body 20 are firmly shrink-fitted with a pressing force P in the height direction, the integrity (connection strength) of the core body 100 and the cylindrical body 20 constituting the split stator core is Fully secured.

  FIG. 5 shows another embodiment of the split core and cylindrical body used. For example, a set of concave grooves 11 is formed at both ends of each divided core 10A forming the core body, and each concave groove 11 on the inner side surface (surface on the core body side) of the flange 22 constituting the cylindrical body 20A. Are provided at the positions corresponding to the groove 11.

  When positioning the divided cores 10A,... In the thermally expanded cylindrical body 20A, the assembling efficiency of the divided cores 10 can be improved by engaging the corresponding concave grooves 11 and the protrusions 24. . In addition, the hole length of this concave groove 11 may be very short, and the magnetic characteristic of the core body 100 may not be inhibited by forming the concave groove 11.

  In the split stator core in which the core body and the cylindrical body 20A are integrated with the pressing force only in the height direction by shrinking and shrink-fitting the cylindrical body 20A in a posture in which the concave groove 11 and the protrusion 24 are engaged. The occurrence of misalignment between the core body and the cylindrical body 20A can be suppressed, and a split stator core with higher connection strength can be obtained.

  The above-described method for manufacturing a split stator core according to the present invention is a simple configuration that only adjusts the dimensions of both the core body and the cylindrical body, and the conventional shrink-fit processing and the method thereof are not changed. A split stator core having excellent magnetic properties can be manufactured without increasing the cost.

  The electric motor having the above-described split stator core is prevented from increasing the iron loss due to the shrink-fitting process, and the rotational performance and torque performance are improved because the magnetic properties of the magnetic steel sheets constituting the electric motor are not hindered. It becomes possible. Such a high-performance electric motor has recently been expanded in production, and is particularly suitable for application to an electric vehicle, a hybrid vehicle, and the like in which improvement in the performance of the driving motor is an urgent issue.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. They are also included in the present invention.

The perspective view which showed the electric motor which consists of a stator and a rotor manufactured by the manufacturing method of this invention. It is the longitudinal cross-sectional view which decomposed | disassembled one Embodiment of the split core, and one Embodiment of a cylindrical body. It is a longitudinal cross-sectional view which shows the state which assembled | attached the core body which consists of a split core in the cylindrical body of the attitude | position which thermally expanded the cylindrical body. FIG. 4 is a longitudinal sectional view showing the stator core in a state in which the cylindrical body is contracted and shrink-fitted following FIG. 3. It is the longitudinal cross-sectional view which decomposed | disassembled other embodiment of a split core, and other embodiment of a cylindrical body.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10,10A ... Split core, 11 ... Groove, 20 ... Cylindrical body, 21 ... Annular side wall, 22 ... Flange, 23 ... Center opening, 24 ... Protrusion, 30 ... Rotor, 100 ... Core body

Claims (2)

A method of manufacturing a split stator core of an electric motor by tightening an annular core body formed by assembling the split core in the circumferential direction with a cylindrical body from the outer periphery,
An annular side wall having an inner air diameter larger than the diameter of the core body and having an inner air height less than the height of the core body, and a flange protruding radially inward at both ends of the annular side wall And a first step of thermally expanding the cylindrical body,
A second step of forming the annular core body inside the cylindrical body in a thermally expanded posture;
And a third step of tightening the core body by contracting the cylindrical body and applying a pressing force in the height direction to the core body by the flange.   A protrusion is provided at one end of the core body or the flange, and a groove is provided at a position corresponding to the other protrusion. At least when the cylindrical body contracts, the protrusion is formed in the groove. The manufacturing method of the division | segmentation stator core of Claim 1 fitted.

Images