JPH04150748A - Permanent magnet motor - Google Patents

Abstract

PURPOSE:To suppress vibration of rotor due to eddy current loss or shifted center of gravity by making an opening through a nonmagnetic metal cover such that the width of the opening decreases gradually in the inserting direction of a permanent magnet and the opening vanishes at a position separated by a predetermined distance from the end face opposite to the inserting side. CONSTITUTION:An opening 15 is made through a nonmagnetic metal cover 10 to be press fitted with a permanent magnet 9 such that the width L between two sides 15c, 15d of the opening 15 decreases gradually in the inserting direction A of the permanent magnet 9 and vanishes at a position separated by a predetermined distance M. Since a space, causing shift of the center of gravity between the permanent magnet 9 and the metal cover 10, is eliminated vibration of a rotor 6 can be suppressed. Furthermore, the permanent magnet 9 is prevented from being caught by the metal cover 10 at the time of insertion although a sufficiently wide opening 15 is provided in order to suppress eddy current loss.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a permanent magnet motor having a rotor having a non-magnetic metal cover on the outer peripheral surface of the permanent magnet.

(Prior Art) Conventionally, a permanent magnet rotor provided with a non-magnetic metal cover on the outer peripheral surface of the permanent magnet in order to increase the strength of the permanent magnet motor is known from Japanese Patent Publication No. 63-26623. In order to minimize eddy current loss, this permanent magnet motor has a configuration in which the metal cover is provided with slits in a direction perpendicular to the axial direction of the rotor method and along the circumferential direction of the cover. Was.

(Problem to be Solved by the Invention) However, in this permanent magnet motor, since the permanent magnet and the metal cover are connected using adhesive,
The adhesive may protrude from the slits or edges of the metal cover, or the adhesive may harden unevenly in the space between the metal cover and the permanent magnet, causing the center of gravity to be uneven and impacting the rotor. This had the problem of vibration.

The present invention has been made in consideration of the above circumstances, and its purpose is to provide a permanent magnet motor in which eddy current loss is suppressed as much as possible and vibration of the rotor due to eccentric center of gravity is suppressed as much as possible.

[Structure of the Invention] (Means for Solving the Problem) In order to solve the above object, the present invention provides a rotor having a permanent magnet and a non-magnetic metal cover fitted around the outer periphery of the permanent magnet, and a rotating and a stator that generates a magnetic field, the opening provided in the non-magnetic metal cover has an opening width that gradually decreases in the circumferential direction with respect to the direction in which the permanent magnet is inserted. It is characterized in that it is configured to disappear at a position having a predetermined distance from the end face on the opposite side to the insertion side.

(Function) Since the permanent magnet is press-fitted into the non-magnetic metal cover, there is no space between the permanent magnet and the metal cover that would cause an eccentric center of gravity, thereby suppressing vibration of the rotor as much as possible. , despite having an opening that makes it difficult to cause eddy current loss due to eddy currents.
It is also possible to prevent the permanent magnet from getting caught on the metal cover when inserting the permanent magnet into the metal cover, which deteriorates assembly efficiency.

(Example) An embodiment of the present invention will be described below with reference to the drawings.

First, in FIG. 2 showing the overall structure, numeral 1 denotes a stator made of laminated plates and having 24 teeth, which is sandwiched between an upper frame 2 and a lower frame 3 from both vertical directions and fixed with rivets 4. A coil 5 is wound around the teeth. Reference numeral 6 denotes a rotor having a rotating shaft 7 at the center, and this rotor 6 includes a yoke 8 made of a laminated plate and a thickness of each central portion provided on the outer periphery of the yoke 8 compared to the end portion in the circumferential direction. It is constructed of four slightly thick permanent magnets 9 and a metal cover 10 made of a non-magnetic material such as aluminum provided around the outer periphery of the permanent magnets 9, and is disposed inside the stator 1. Reference numeral 11 denotes a Hall element disposed facing the inner circumferential surface of the permanent magnet 9, and this Hall element 11
The coils 5 are sequentially energized based on signals from 3 and 3.
It constitutes a phase permanent magnet motor.

Next, the metal cover 10 provided on the outermost periphery of the rotor 6 will be described in detail. This metal cover 10 has an upper end 1
The permanent magnet 9 has four bent portions 13 at positions facing the central portion of the permanent magnet 9, and has a cylindrical shape with a lower end portion 14 open.

Reference numeral 15 indicates four substantially diamond-shaped openings provided on the circumferential surface of the metal cover 10, and the circumferential and axial centers of the openings 15 are arranged to approximately coincide with the center of the permanent magnet 9. ing. In addition, when press-fitting the permanent magnet 9 into the metal cover 10 from its lower end 14 in the direction of arrow entry, the insertion side 2
As the sides 15a and 15b go in the direction of arrow A, they widen to almost the center of the metal cover 10 in the axial direction, and then the opening width, which is the distance between the two sides 15c and 15d of the opening 15, is as shown by the arrow. It gradually becomes narrower in proportion as it goes in the A direction, and its converging portion 15e converges at a position a predetermined distance M away from the upper end portion 12, which is an end surface.

Next, to explain the operation of the above structure, after pasting the permanent magnet 9 on the outer periphery of the yoke 8, the permanent magnet 9
is press-fitted into the metal cover 10 from the lower end 14 side. In this case, the metal cover 10 is slightly deformed depending on the shape of the permanent magnet 9. When the tip of the permanent magnet 9 comes to a position facing the two sides 15a and 15b of the opening 15, the metal cover 10 further deforms, and the permanent magnet 9 moves to the opening 1.
5 slightly protrudes toward the outer wall.

When the press-fitting is further progressed, the permanent magnet 9 has two sides 15c,
It comes to a position opposite to 15d. Here, the two sides are 15c,
15d gradually narrows in the insertion direction A (therefore, the permanent magnet 9 does not get caught on the two sides 15c, 15d and the press-fit progresses to the convergence part 15e. Also, in this convergence part 15, the circumferential direction Since there is almost no flat part compared to the circumferential distance H of the center of the opening 15, the permanent magnet 9 is not caught in the converging part 15e, and the permanent magnet 9 is press-fitted up to the bent part 13. As a result, the permanent magnet 9 and the metal cover 10 are in a fitted state.Furthermore, by bending the entire circumference of the lower end portion 14 inward, the permanent magnet 9 and the metal cover 10 are joined together. It is further strengthened.

According to the above embodiment, the opening 15 provided in the non-magnetic metal cover 10 into which the permanent magnet 9 is press-fitted is arranged in the circumferential direction with respect to the direction A in which the permanent magnet 9 is inserted.
Since the opening width between the sides 15c and 156 is configured to gradually decrease and disappear at a position having a predetermined distance M, an eccentric center of gravity is not generated between the permanent magnet 9 and the metal cover 10. By eliminating the space, vibrations of the rotor 6 can be suppressed as much as possible, and even though the permanent magnet 9 has enough openings 15 to make it difficult to cause eddy current loss due to eddy current. the metal cover 10
It is also possible to prevent the permanent magnet 9 from getting caught on the metal cover 10 when the permanent magnet 9 is inserted into the metal cover 10, which deteriorates the ease of assembly.

Further, since the opening 15 has a predetermined distance between the upper end 12 and the lower end 14, the presence of the opening 15 prevents the strength of the metal cover 10 from weakening as much as possible. be able to.

Note that the present invention is not limited to the embodiments described above, and when press-fitting the permanent magnet into the metal cover, it is also possible to strengthen the bond by inserting an adhesive between the permanent magnet and the metal cover, and furthermore, it is possible to strengthen the bonding between the permanent magnet and the metal cover. If the distance between the two sides of the opening toward the end gradually decreases, the side on the insertion side is perpendicular to the axial direction,
In the end, even if the opening is triangular, the features of the present invention can be sufficiently achieved, and various modifications are possible.

[Effects of the Invention] According to the present invention, there is provided a rotor that grows a permanent magnet and a non-magnetic metal cover fitted around the outer periphery of the permanent magnet, and a stator that generates a rotating magnetic field. The opening provided in the magnetic metal cover has an opening width that gradually decreases in the circumferential direction with respect to the direction in which the permanent magnet is inserted, and has a predetermined distance from the end face on the opposite side to the insertion side. Since the permanent magnet is press-fitted into the non-magnetic metal cover, there is no space between the permanent magnet and the metal cover that would cause an eccentric center of gravity, which causes the rotor to vibrate. Despite having an opening that prevents eddy current loss from occurring due to eddy currents, the permanent magnet gets caught in the metal cover when inserted into the metal cover. This also makes it possible to avoid poor assembly performance.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, in which Fig. 1 is a side view of the metal cover, Fig. 2 is a cross-sectional view of the entire metal cover, Fig. 3 is a top view of the metal cover, and Fig. 4 is a partially cutaway view of the rotor. FIG. 5 is a side view of the rotor, and FIG. 5 is a top view of the rotor. In the drawing, 1 is a stator, 6 is a rotor, 9 is a permanent magnet, 1
0 is a non-magnetic metal cover, 15 is an opening, 12 is an end surface (upper end), and L is the opening width. Agent Patent Attorney Nori Ken Chika Yudo Uji Hiroki Figure Figure Figure Figure Figure

Claims (1)

[Claims] 1. A rotor that has a permanent magnet and a non-magnetic metal cover fitted around the outer periphery of the permanent magnet, and a stator that generates a rotating magnetic field, and the permanent magnet is inserted into the non-magnetic metal cover. What is claimed is: 1. A permanent magnet motor having an opening whose width in a circumferential direction gradually decreases and disappears at a position a predetermined distance from an end face.