JP3438920B2 - Cantilever cage induction motor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotor of a cantilever-supporting rotor structure motor used for, for example, a compressor, and more particularly to reducing the suction force on the rotor non-supporting side. The present invention relates to a cantilever type cage induction motor having a rotor skew structure that enables stable starting and rotation.

[0002]

2. Description of the Related Art Conventionally, for a hermetic compressor such as a rotary compressor or a reciprocating compressor,
Generally, a motor having a cantilevered support (single bearing) rotor structure is used. A motor having a cantilevered support rotor structure (hereinafter abbreviated as a motor) has a structure as shown in FIG. FIG. 2 is a schematic view of a partial cross section as seen from the side with the outer case of the motor removed. Reference numeral 1 is a cross section of the stator.
The rotary shaft 3 of the rotor 2 is rotatably supported by a bearing 4a provided at the center of the shaft support 4 inside the shaft. Status 1
In the figure, 1a is a stator core and 1b is a stator coil. Further, 2 is a rotor, and 2a is a rotor core provided with a rotor slot 2b in which a conductor is embedded. An end of a conductor (not shown) embedded in the rotor slot 2b is short-circuited by a supporting side end ring 2c and a non-supporting side end ring 2d. The rotor core 2a is usually laminated so as to form the rotor slot 2b in a skew (oblique) as shown in the drawing. Although only one rotor slot is shown in FIG. 2, a predetermined number of rotor slots are provided around the rotor at equal intervals. In a motor having such a structure, If the number of rotor slots is 20 and the number of rotor slots is 26, the skew is generally formed at a stator slot pitch of 1.0 to 1.3.

[0003]

In the motor of the conventional rotor structure described above, the magnetic attraction characteristic generated in the rotor corresponding to the eccentricity of the rotor is as shown in FIG. It has characteristics. In FIG. 4, the horizontal axis represents the eccentricity of the rotor, and the vertical axis represents the magnetic attraction force generated in the skew of the rotor. By the way, in the cantilever support rotor structure motor, the eccentricity of the rotor is smaller as it is closer to the shaft support portion 3 and is larger as it is farther from the shaft support portion 4 as shown in FIG. Become. Incidentally, FIG. 3 is a diagram in which the stator 1 having the motor structure shown in FIG. 2 is removed, and the same reference numerals are used for corresponding portions. That is, as shown in FIG. 3, the eccentric amount of the portion a near the shaft supporting portion 4 of the rotor 2 is small, and the eccentric amount of the portion b of the rotor 2 far from the shaft supporting portion 4 is large, a and b. The eccentricity amount of the middle portion c is between the a portion and the b portion.

Therefore, as shown in FIG. 4, the magnetic attraction force at the point a is small, and the magnetic attraction force increases in the order of c and b. Further, when the rotor eccentricity is constant, the magnetic attraction force at the start of the motor is as shown in FIG. 5 corresponding to the size of the skew, and therefore the magnetic attraction force corresponding to the magnetic attraction force is also obtained. The quantity is also shown as in FIG. In FIG. 5, the horizontal axis shows the amount of rotor skew (ratio to the stator slot pitch), and the vertical axis shows the changing tendency of the magnetic attraction force and the magnetic attraction amount. Therefore, at the time of starting the motor, the magnetic attraction force causes the air gap on the non-support side of the rotor to change and become large, and the magnetic attraction force further increases, which may cause a start failure. There was a problem. For this reason, in an ordinary double-bearing motor, in order to prevent the attraction force in the axial direction, skews are provided in slots symmetrically from the magnetic center of the rotor toward both sides. Without the skew of the rotor,
Alternatively, although proposals have been made to change the lengths of the rotor and the stator, for a cantilever-supported rotor structure motor, a means for preventing the influence of the magnetic attraction force in the vicinity of the unsupported portion is used. There was no

Further, assembling a cantilever support rotor structure motor as a motor for a hermetic compressor so as to obtain a uniform air gap is troublesome, and depending on the state of the air gear, the non-contact side. There is also a problem that it is difficult to apply the torque necessary to start the compressor due to the contact between the rotor and the stator due to the suction force generated at the rotor.

The present invention solves the above problems (problems),
It is an object of the present invention to provide a cantilever type cage induction motor that maintains the same motor characteristics as before and reduces the magnetic attraction force on the non-rotor side to enable stable starting and rotation. .

[0007]

In order to solve the above problems, in a rotor of a cantilever type cage induction motor (hereinafter abbreviated as a motor) according to the present invention, a rotor skew (hereinafter (Abbreviated as skew) is changed in the axial direction of the rotor according to a predetermined linear shape, and the skew on the non-support side is made smaller than that on the support side. The predetermined shape of this changing skew is a polygonal line that bends at at least one place, or at least 2
It is desirable to form a curve composed of more than one kind of curvature or a composite shape of the above-mentioned broken line and curve. Further, it is desirable to set the average value of the varying skew amount to a value of 0.7 to 1.6 of the stator slot pitch.

[0008]

Since the rotor according to the present invention has the above-mentioned structure, the magnetic attraction force characteristic required for the rotor shaft can be obtained by the change of the skew. By making the skew of the non-support side smaller than that of the support side, the magnetic attraction force on the non-support side becomes smaller. That is, the magnetic attraction force is made uniform along the rotor axis by appropriately setting the skew along the rotor axis in accordance with the characteristics described above with reference to FIGS. The magnetic attraction force on the side can be reduced.
By forming the changing shape along the axis of the skew into a bent line that bends at least at one or more points, or a curved line composed of at least two types of curvatures, or a combined shape of the bent line and the curved line, The change characteristic shape of the magnetic attraction force generated at each position on the axis and the magnetic attraction force along the axis can be made to have an appropriate characteristic. Further, by setting the average value of the skew amount to a value of 0.7 to 1.6 of the stator slot pitch, a motor characteristic equivalent to that of the conventional motor can be obtained.

[0009]

Embodiment 1 Embodiment 1 of the present invention is shown in FIGS. 1 (A) and 1 (B).
Explained by. 1 (A) and 1 (B) show the rotor 2 in the motor structure shown in FIG. 2 in an extracted manner, and the same functions as those in FIG. 2 use the same reference numerals. .

Example 1 Next, Example 1 will be described with reference to FIG. In FIG. 1A, 2A is a rotor having a skew structure according to the present invention. In the rotor 2A, 2Aa is a rotor core in which a slot 2Ab in which a conductor is embedded is provided and laminated, and an end of a conductor (not shown) embedded in the slot 2Ab is a support side end ring 2Ac.
Is short-circuited by the non-support side end ring 2Ad. In FIG. 1 (A), only one of the slots provided at a predetermined pitch around the rotor 2A corresponding to the required characteristics of this motor is represented on the basis of the number of stator slots. Shows. The slot 2Ab is formed by dividing the surface of the rotor 2A from the supporting side to the non-supporting side ab, bc, c.
The polygonal line has a polygonal line in which each of d is connected by a straight line, that is, a polygonal line in which points b and c are refraction points. In FIG. 1 (A),
The skew of the polygonal line section is formed in the order of section ab, section bc, and section cd from the supporting side to the non-supporting side of the switch 2A. The above is an example of a skew having a polygonal line shape, and the case where there are two bending points has been exemplified. However, the number of folding lines and the interval between the bending points and The amount of skew and the amount of skew may be arbitrarily set. For the average value of the skew amount, refer to the characteristics shown in FIG. 4 and FIG. 5, and as the set value corresponding to the structure of this motor and the required characteristics, for example,
It can be said that a desirable value is a range of 0.7 to 1.6 of the tuslot pitch.

Second Embodiment Next, a second embodiment of the present invention will be described with reference to FIG.
This will be described with reference to (B). In FIG. 1B, 2B is a skew structure rotor according to the present invention. Rotor 2
In B, 2Ba is a slot 2Bb in which a conductor is embedded.
A rotor core in which a slot 2Bb is provided.
The end portion of the conductor (not shown) embedded in is short-circuited by the support-side end ring 2Bc and the non-support-side end ring 2Bd. Although only one slot is shown in FIG. 1 (B), only one slot provided at a predetermined pitch around the rotor 2B is shown as a representative as in FIG. 1 (A). Is. The slot 2Bb keeps the skew of the rotor 2B while sequentially changing the entire length L of the surface of the rotor 2B with a predetermined curvature.
It is formed so that it becomes a continuous curve so that it becomes smaller in order from the supporting side to the non-supporting side. The above-mentioned change in curvature and the center of curvature thereof may be arbitrarily set according to the structure and characteristics of this motor. Similar to the first embodiment, the average value of the amount of skew can be set by referring to the characteristics shown in FIGS. It can be said that a value in the range of 0.7 to 1.6 is desirable.

Third Embodiment: Next, a third embodiment will be described with reference to FIGS. 1 (A) and 1 (B). The first embodiment described above is an example in which the slot 2Ab is formed in a polygonal line shape, and the second embodiment is an example in which the slot 2Bb is formed in a curved shape. Corresponding to the structure and characteristics of the motor, the polygonal line shown in the first embodiment and the curved shape based on the change in curvature shown in the second embodiment are appropriately combined and made continuous from the supporting side to the non-supporting side of the rotor. Toward this, a continuous linear shape is formed to reduce the skew amount.
That is, the slot shape is a shape obtained by appropriately combining the polygonal line shape shown in FIG. 1 (A) and the curved shape shown in FIG. 1 (B). Also in the case of this embodiment, as the average value of the amount of skew, as in the case of Embodiments 1 and 2, refer to the characteristics shown in FIG. 4 and FIG. If set, the value in the range of 0.7 to 1.6 of the stator slot pitch can be said to be a desirable value.

The above description shows the basic method and configuration for realizing the technical idea of the present invention, and corresponds to the concrete shape of the cantilever type cage induction motor and the conditions such as its required characteristics. Then, various modifications may be made to make an appropriate configuration. For example, as a matter of course, the average value of the skew amount may be set to an appropriate value other than 0.7 to 1.6 of the starter slot pitch described above. Also, the tendency of changes in skew is
Instead of successively reducing the size from the supporting side to the non-supporting side of the rotor as shown in FIGS. 1 (A) and 1 (B), other appropriate changed shapes may be formed. .

[0014]

Since the present invention is formed as described above, it has the following excellent effects. The magnetic attraction force is made uniform along the rotor axis according to the condition of the skew change characteristic.
Further, the magnetic attraction force on the non-supporting side can be reduced. The magnetic attraction force generated at each position of the rotor shaft can be adjusted to an appropriate value by selecting the skew change characteristic. Since the suction force generated on the unsupported side of the rotor shaft can be reduced or eliminated, the starting torque can be reduced and stable starting can be achieved. Since the suction force generated on the unsupported side of the rotor shaft can be reduced or eliminated, the required assembly accuracy at the time of assembly with the drive target mechanism such as the compressor can be reduced and the productivity can be improved. it can. Since the suction force generated on the rotor shaft can be set appropriately by selecting the skew change characteristic, stable rotation characteristics can be obtained and other characteristics can be improved. By changing the shape of the skew along the rotor axis into a polygonal line that bends at at least one place or a curve formed by at least two or more types of curvatures or a combined shape of the polygonal line and the curved line, It is possible to make the magnetic attraction force generated in the device have appropriate characteristics and values. By setting the average value of the skew amount to a value of 0.7 to 1.6 of the stator slot pitch, a motor characteristic equivalent to that of the conventional motor can be obtained.

[Brief description of drawings]

FIG. 1 illustrates a skew shaped slot according to the present invention.
1A is a schematic structural diagram of a rotor for explaining a skew shape in a cantilever type cage induction motor provided on the rotor, and FIG. 1A is a schematic structural diagram of the skew shape rotor of the first embodiment. 2B is a schematic structural diagram of the skew-shaped rotor of the second embodiment.

FIG. 2 is a side view showing a schematic structure of a conventional cantilever support rotor structure motor equipped with a skew-shaped rotor.

FIG. 3 is a side view of a rotor for explaining a problem of a rotor suction force in a motor having a cantilever support rotor structure.

FIG. 4 shows a rotor of a cantilever support rotor structure motor,
FIG. 6 is a magnetic attraction characteristic diagram showing a magnetic attraction force generated in the rotor corresponding to the amount of eccentricity of the rotor.

FIG. 5 is a magnetic attraction characteristic diagram showing a tendency of a magnetic attraction force and a magnetic attraction amount corresponding to a rotor skew amount.

[Explanation of symbols]

2A, 2B: Rotor 2Aa, 2Ba: Rotor core 2Ab, 2Bb: Rotor slot (slot) 2Ac, 2Ad, 2Bc, 2Bd: End ring

Front page continuation (58) Fields surveyed (Int.Cl. ⁷ , DB name) H02K 17/16

Claims (3)

(57) [Claims] 1. A basket type induction motor having a structure in which a basket type rotor is supported in a cantilever manner, wherein a rotor skew formed on the rotor has a predetermined linear shape along a rotation axis of the rotor. The cantilever type cage induction motor is characterized in that the linear shape is such that the rotor support side has a larger rotor skew than the rotor non-support side. 2. The changing rotor skew according to claim 1.
The predetermined linear shape is a polygonal line bent at least at one or more points, a curved line formed by at least two kinds of curvatures, or a cantilever type cage induction motor formed by a combination of the polygonal line and the curved line. 3. A cantilever type cage induction motor, wherein the average value of the varying rotor skew according to claim 1 or 2 is set to a value of 0.7 to 1.6 of the stator slot pitch. .