JPH0379945B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the improvement of a two-pole single-phase induction motor, particularly in compressors for refrigerators, etc., which have recently been required to be smaller in size and have lower noise. Concerning the stator of a polar single-phase induction motor.

Generally, the stator of a two-pole single-phase induction motor used in refrigerators, etc. consists of a stator core, and main and auxiliary windings wound in 24 slots provided in the stator core. has been done. The main winding (wire diameter is φ0.90) is inserted into two slots arranged concentrically.
The poles were inserted in portions, each pole having five series of windings inserted into opposing slots in an order in which the number of turns decreased substantially from the center to the circumference of the stator bore. Note that although no winding is inserted between the slots on the outermost circumference, since auxiliary windings are inserted, there are no empty slots.

By gradually reducing the number of turns of the main winding and inserting it, the height of the coil end can be flattened, and the magnetic force of each pole is reduced from the center of the hole to the circumference, reducing harmonics. It was possible to obtain a magnetic force distribution advantageous for generation.

The auxiliary winding has an electrical angle of 90 with each coil of the main winding.
It is wound in the slot at the wrong position. After inserting the main winding and the auxiliary winding, the stator is completed by pressing and shaping the coil ends of these windings so that they expand outward over the entire circumference.

Here, the first pole side (A pole side) and the second pole side (B pole side) of the main winding are
The ratio of the effective number of turns of each pole is set to 1:1 so that the magnetomotive force on the pole side is the same.

However, when an electric motor with such a structure is built into a compressor, the coil ends are shaped to have a uniform height dimension, so it is especially difficult to install compression elements such as cylinders and pistons on the coil end on one pole side. Such a reciprocating compressor has a problem in that the height is equal to the height of the coil end plus the size of the compression element, making the compressor large.

Therefore, first, a series of coils from the center of the second pole side (B pole side) of the main winding is folded back to the first pole side (A pole side), and a height difference is formed at the coil end.
An attempt was made to lower the height of the compressor by placing a compression element at the coil end on the lower stage side. With this configuration, the compression element is located in the lower part of the coil end, which makes it possible to reduce the height of the compressor. However, if only a series of coils were bent, the lower coil The end was not low enough.

Next, in order to further lower the coil end on the low stage side, as shown in Figures 1 and 2, the two coils closest to the center on the 2nd pole side (B pole side) of the main winding are moved to the 1st pole side ( I tried one that was folded back to the A pole side. In FIG. 1, 5 is a stator, and main windings 9' (wire diameter φ0.90) on the A-pole side and the B-pole side are inserted into 24 slots provided in the stator core. FIG. 2 is an explanatory diagram showing the arrangement of the main winding 9' of the stator 5 shown in FIG. 1. 1 to 24 represent slot numbers, and the 24th slot is followed by the 1st slot. It is something that connects. In order to equalize the magnetomotive force on the A-pole side and the B-pole side, each main winding was composed of five windings with the same number of effective turns. That is,
On the A pole side of the main winding, the first coil has 51 turns wound around the 1st slot and the 12th slot, and the second coil has 51 turns wound around the 2nd slot and the 11th slot. It is a turn-wound coil, and the third coil is connected to the third slot.
The 10th slot is a coil wound with 36 turns, and the 4th coil is a coil wound with 34 turns in the 4th slot and the 9th slot.
The continuous coil is a coil wound with 20 turns in the 5th slot and the 8th slot. Similarly B
On the pole side, the first coil is a coil wound with 51 turns in the 13th slot and the 24th slot, and the second coil is a coil wound with 51 turns in the 14th slot and the 23rd slot. and
The third coil is a coil wound with 36 turns in the 15th slot and the 22nd slot, and the fourth coil is a coil wound with 34 turns in the 16th slot and the 21st slot. The fifth coil is a coil wound with 20 turns in the 17th slot and the 20th slot.

The effective number of turns A constituting each pole of such a two-pole single-phase induction motor is determined by the product of the characteristic constant (found by Fourier expansion) between the slots into which the coils are inserted and the actual number of turns, and is the value shown in the formula below. become.

A=0.991α ₁ +0.924α ₂ +0.793α ₃ +0.609α ₄ +
0.383α ₅ (However, α ₁ is the number of turns of the first coil, α ₂ is the number of turns of the second coil, and α ₃ to α ₅ are similarly 3
It is clear from this equation that the characteristic constant between the slots decreases from the center side of the stator toward the circumferential stations. Even if the number of turns of the coil is increased, the effective number of turns cannot be expected to increase accordingly. Also,
If the distribution of the magnetomotive force of the poles due to the coils of each series is made smaller from the center side of the stator toward the circumferential series, it is possible to reduce the generation of harmonics during Fourier expansion. Furthermore, when the coil end is expanded, the smaller the number of turns of the coil in the circumferential series, the more the coil end can be shaped to be flat. In consideration of the above points, the number of turns of the coil in each pole series was configured to decrease from the center side to the circumferential side of the stator.

After winding 5 coils on each of the A and B poles in this way, fold the first and second coils 9'c on the B pole side back to the A pole to shape the coil ends. do. (Situation shown in Figure 2) The height of the coil end on the A pole side is the height of coil 9'a and coil 9'c overlapped, and the height of the coil end on the B pole side is coil 9'b. , and a difference in height is created. Compression elements such as cylinders and pistons were arranged at a lower part of the coil end on the B pole side, reducing the height dimension and making the compressor more compact. The auxiliary winding is wound in a slot electrically 90 degrees apart from the main winding.

In the above-mentioned winding, the main winding 9' is connected to the A-pole side main winding 9'a and the B-pole side main windings 9'b and 9'c, respectively, in order to improve the motor characteristics. It is constructed in five series so that the effective windings are equal, but among the main windings 9'b and 9'c on the B pole side, the first and second main windings 9' Since c is tilted toward the A pole side, the coil circumference becomes longer as a result, copper loss increases by this length, and the output torque of the motor decreases. Generally, the amount of decrease in output torque due to this increase in copper loss decreases in proportion to the copper loss, and 1
Since the continuous and second coil ends are folded back toward the A pole side, it was confirmed that as the coil circumference increases, the output torque decreases by about 3%. Furthermore, this 1st and 2nd series
By folding back the continuous coils, the leakage reactance at the coil end on the A pole side increased in proportion to the natural logarithm, and the output torque further decreased by about 4%. That is, it was confirmed that the output was reduced by about 7% by folding back the two coils.

Furthermore, in this case, a second harmonic appears in the torque characteristics of the electric motor, causing a problem that the torque decreases at a specific rotation speed.

As described above, in the conventional technology, when there is only one coil end that is folded back from the B pole side to the A pole side, the coil end cannot be lowered sufficiently and the original purpose cannot be achieved, and the two coil ends are folded back. In this case, there was a problem in that the characteristics of the motor deteriorated.

In view of these problems, the present invention provides a two-pole, single-phase induction motor in which the coil end on the B pole side can be lowered while suppressing deterioration of motor characteristics.

The configuration of the present invention consists of a compression element, a frame to which the compression element is attached, a rotation shaft for driving the compression element that is cantilevered by the frame, and 24 slots arranged at equal intervals on a concentric circle. In an electric motor that has a stator core, main windings that are wound around these slots in two poles, and auxiliary windings that are wound around the slots at an electrical angle of 90 degrees from these main windings, compression The four sets of coils of the main winding on the side facing the element are inserted into four sets of windings in opposite slots in an order in which the number of turns decreases substantially from the center side to the circumferential side of the stator hole. The coils of the other main winding are inserted into opposing slots in a substantially decreasing order from the center to the circumferential side of the stator hole. Along with forming
The effective number of turns of the four windings is set to be less than 10% of the effective number of turns of the five windings.

Embodiments of the present invention will be described below based on the drawings. FIG. 3 is a sectional view of the compressor. In this figure, reference numeral 1 denotes a hermetic electric compressor which is formed by housing a compression element 3 in the upper part of a substantially spherical hermetic container 2 and a motor 4 in the lower part thereof. The electric motor 4 includes a stator 5 and a rotor 6, and the rotor 6 rotates around a rotating shaft 8. Reference numeral 7 denotes a frame that supports the compression element 3 and supports the rotating shaft 8 in a cantilevered manner by a bearing portion 7a. The compression element 3 is driven by the rotation of the rotating shaft 8.

FIG. 4 is a top view of the electric motor 4 shown in FIG. 3. (With the compression element removed, 1 on the B pole side
This is the state before the consecutive coils are folded back. ) In this figure, 9 is the main winding, 9a is the main winding on the A pole side, 9b is the main winding on the B pole side, 9c is a series of coils in the main winding that is later turned back to the A pole side, 11 is an auxiliary winding, which is inserted into the slot at a position electrically angularly shifted by 90 degrees from the main winding 9.

The main winding 9 and the auxiliary winding 11 each have a wire diameter of φ0.85 and are inserted into slots 1 to 24, respectively.

The main winding 9 is divided into two poles: the A pole side (pole including the 1st slot to the 12th slot) and the B pole side (pole including the 13th slot to the 24th slot). There is. The main windings on the A pole side are opposite 1
The coil inserted between the 1st slot and the 12th slot, and the 2nd slot facing each other.
The coil inserted between the 11th slot and
A coil inserted between the 3rd slot and the 10th slot facing each other, a coil inserted between the 4th slot and the 9th slot facing each other, and a coil inserted between the 5th slot and the 8th slot facing each other. The main winding on the B pole side is inserted between the opposing 13th slot and the 24th slot. The coil inserted between the 14th and 23rd slots facing each other, the coil inserted between the 15th slot and 22nd slot facing each other, and the coil inserted between the 15th and 22nd slots facing each other. towards
The four coils are arranged in four series, including the coil inserted between the 16th slot and the 21st slot.

The main windings 9a on the A pole side are the 1st and 12th, the 2nd and 11th, the 3rd and 10th, the 4th and 9th,
The number of turns (hereinafter abbreviated as T) of the main winding 9a inserted into each of the 5th and 8th slots is 50T,
It is essentially gradually decreasing as 54T, 37T, 33T, and 28T. (In this example, there is a slot in which the auxiliary winding is not inserted, so the number of turns of the main winding (second coil) inserted in this slot is increased to the extent that it does not interfere with coil end shaping.
We are trying to improve. ) When the number of slots is 24, the value of the effective number of turns A that takes into account the magnetomotive force of the stator core is determined by the product of the actual number of turns and the inherent constant determined by the position of the slots, and is the value shown in the following formula.

A=0.991α ₁ +0.924α ₂ +0.793α ₃ +0.609α ₄ +
0.383α ₅ = 159.6 (However, α ₁ = 50, α ₂ = 54, α ₃ = 37, α ₄ = 33, α ₅
=28) Here, if a coil is inserted between the 6th slot and the 7th slot, the constant for obtaining the effective number of turns will be extremely small (0.13 from Fourier expansion), so the actual value of the coil will be Even if the number of turns is increased, a substantially effective rotating magnetic field cannot be obtained even though the number of turns is increased. Therefore, no coil is inserted in this embodiment. Incidentally, since the auxiliary windings are inserted into the sixth and seventh slots, there are no empty slots.

In addition, the main winding 9b on the B pole side configured in four series,
9c sequentially changes the number of turns of the main windings 9b and 9c inserted into the 13th and 24th slots, the 14th and 23rd slots, the 15th and 22nd slots, and the 16th and 21st slots to 50T,
54T, 37T, and 33T, and like the main winding 9a on the A pole side, the number of turns of the second coil is increased to increase the efficiency of the motor. In addition, the value of the effective number of turns B is
The value is shown in the formula below.

B=0.991α ₁ +0.924α ₂ +0.793α ₃ +0.609α ₄ =
148.9 (However, α ₁ = 50, α ₂ = 54, α ₃ = 37, α ₄ = 33,) When the main winding is configured with 5 stations on the A pole side and 4 stations on the B pole side as described above. Since the actual number of turns on the B pole side is reduced, the coil end on the B pole side can be shaped low. This decrease in the circumferential length of the winding on the A pole side corresponded to the circumferential length required for folding back two series as shown in the prior art. Therefore, the coil end can be lowered in the same way as when the two main windings on the B pole side are folded back.

Furthermore, the first coil of the main winding on the B pole side is
By folding back toward the pole side (see the main winding arrangement diagram in FIG. 5), the coil end of the main winding on the B pole side can be made lower. In order to fold back the first coil 9c to the A pole side, it is necessary to lengthen the coil circumference and raise the coil end, which increases weight loss and reduces the output torque of the motor by approximately 1.0. It was %. After this, the first coil 9c
By folding back toward the A pole side, the leakage reactance at the coil end increases. The decrease in output torque at this time was about 0.0 to 0.5%. Originally, the reactance at the coil end does not become an effective magnetic flux output from the stator core, but is treated as leakage reactance. That is, the effective magnetic flux of the motor is obtained from the windings inserted into the slots of the stator core. Therefore, originally, the output torque of the motor can be determined only from the effective number of turns, regardless of the shape of the coil end, but as mentioned above, there is an increase in copper loss, and the main winding on the A pole side when the coil end is folded back. The output torque of the motor decreases due to a decrease in reactance due to the influence of the wire. This decrease in output torque is approximately 1.0 to 1.5% and can be considered to be substantially within the measurement error range.

Therefore, if one series of coils of the main winding on the B pole side is folded back to the A pole side, the decrease in the output torque of the motor due to folding back this one series of coils will be suppressed to within the error range. be. Therefore, the output torque characteristics of the motor when the main windings on the A pole side are 5 series and the main windings on the B pole side are 4 series, regardless of whether one series of coils is folded or not, are the same for each pole. It can be treated as something that changes depending on the effective number of turns.

Here, the ratio of the effective number of turns between the 1st pole side and the 2nd pole side of the main winding of the motor is basically preferably 1:1 in terms of the characteristics of the motor, but the present invention is designed to prevent the characteristics of the motor from deteriorating as much as possible. The goal is to promote downsizing of the compressor by shaping the upper coil ends at different levels and placing the compression element (including the motor case) on the lower coil end.
Therefore, in the present invention, in order to increase the effective number of turns of the main winding on the B pole side to the same number as the effective number of turns of the main winding on the A pole side, it is necessary to increase the actual number of turns of the main winding on the B pole side. This is not done because the coil end will be high.

Figure 6 shows the experimental results showing the relationship between the transient torque and the number of revolutions when the main winding is arranged with the number of turns shown in Figure 5 and one series of coils is folded back. (torque until normal operation is achieved). As shown in Figure 6, the reduction rate of the effective number of turns B of the four main windings 9b and 9c with respect to the effective number of turns A of the five main windings 9a (the effective number of turns B on the B pole side relative to the effective number of turns A on the A pole side) 7% (≒6.7%=
(159.6−148.9)/159.6), the transient torque decreases and the second harmonic (1
There are almost no occurrences of these factors, and there is no effect on the motor characteristics. Note that in the figure, the torque characteristics due to the main winding and the auxiliary winding indicate the torque characteristics of only the main winding. In addition, the change in the load torque of the compressor is located between the torque curves of and.

In other words, in the above experimental measurement values, as explained in the formula for the effective number of turns, even if the coil between the 17th slot and the 20th slot on the B pole side is removed, there is almost no deterioration in the torque characteristics of the motor. The results were obtained. Therefore, it is possible to lower the coil end of this main winding by removing the coil between the 17th slot and the 20th slot and reducing the amount of coil in the main winding on the B pole side. By arranging the compression element 3 on the coil end side, it is possible to downsize the compressor without degrading the characteristics of the compressor.

In addition, as shown in Figure 7, the reduction rate of the effective number of turns of the 4 main windings relative to the effective number of turns of the 5 main windings is 10%.
In this case, a transient torque higher than the normal load torque can be obtained, but second harmonics appear and may not be allowable when the load torque is large. In other words, this level is considered to be the limit for compressors used in general refrigerators and the like.

Furthermore, as shown in Figure 8, the reduction rate of the effective number of turns of the 4 main windings relative to the effective number of turns of the 5 main windings is calculated.
When it is set to 15%, the second harmonic appears greatly,
The load torque exceeds the excessive torque, leading to a situation where the engine cannot be started or the engine stops even after starting.

From the above, the 5th part of the four main windings 9b and 9c
When the coil end of the four main windings 9b is lowered by changing the reduction rate of the effective number of turns for the main windings 9a of the series, the range in which the characteristics of the motor can be tolerated is such that the second harmonic does not appear to a large extent. The effective number of turns of the four main windings 9b and 9c is set to 5 within a range where transient torque greater than the load torque can be secured, that is, within a range where the reduction rate of the effective number of turns is approximately 10% or less (about 7% is most preferable). It has been confirmed through experiments that it is necessary to make it smaller than that of the main winding 9a of the series.

Next, connect the 16th slot of the main winding 9b on the B pole side.
Let's consider the case where you remove the coil inserted between the 21st slot and try to lower the coil end of the main winding on the B pole side.

In this case, the effective number of turns on the A pole side remains the same as 159.6, but the effective number of turns on the B pole side decreases to 0.991α ₁ +0.924α ₂ +0.793α ₃ =128.8. This reduction rate in the effective number of turns is approximately 19%, which is greater than the 15% reduction rate shown in FIG. Therefore, similarly to the above, there is a high possibility that the electric motor used in the compressor etc. will cause startup failure, making it unsuitable for practical use.

Also, the number of coils in the main winding on the B pole side is reduced compared to the number of coils in the main winding on the A pole side, such as 6 main windings on the A pole side and 3 main windings on the B pole side. If the ratio is increased, the reduction rate of the effective number of turns on the B pole side increases as described above, making it unsuitable for practical use.

In addition, according to this embodiment, in order to prevent torque down, it is possible to make the main winding line thin (conventional - φ0.90, this embodiment - φ0.85), and the main winding coil End volume (coil cross-sectional area x
By reducing the number of turns), the upper coil end of the main winding 9c can be easily folded back, and costs can be reduced.

As a result, the upper coil ends of the remaining four main windings 9b can be shaped lower without impairing the characteristics of the motor 4, which is effective for downsizing the compressor.
We can provide an extremely single-layer induction motor.

As described above, the motor of the present invention is a cantilevered two-pole single-phase induction motor with four main windings on one pole and five main windings on the other pole. Therefore, the coil amount of the main winding on the 4-side main winding is smaller than the coil amount of the main winding on the 5-side main winding, and the coil end of the main winding on the 4-side side can be lowered. By arranging the compression element there, the length of the compressor incorporating this electric motor in the direction of the rotation axis can be shortened.

In particular, even if the coils are wound in an irregular manner, such as by removing the coils on the far side from the center of the stator core and placing the coil ends on a step, torque reduction will not occur.

Therefore, the upper coil end can be shaped into a stepped shape without degrading the performance of the motor, and the compression element can be arranged on the lower stage side to promote downsizing of the compressor.

[Brief explanation of drawings]

Figure 1 is a front view of a conventional electric motor, and Figure 2 is a front view of a conventional electric motor.
An explanatory diagram showing the arrangement of the main windings of the motor shown in the figure,
3 is a longitudinal sectional view of a hermetic electric compressor showing an embodiment of the present invention, FIG. 4 is a plan view of the electric motor shown in FIG. 3, and FIG. 5 is a main body of the electric motor shown in FIG. 4. Explanatory diagrams showing the arrangement of the windings, and FIGS. 6, 7, and 8 are torque-rotational speed characteristic diagrams of the electric motor showing experimental results. 4...Electric motor, 5...Stator, 9, 10...Main winding, 11...Auxiliary winding.

Claims (1)

[Claims] 1. A compression element, a frame to which this compression element is attached, a rotating shaft for driving the compression element that is cantilevered by this frame, and a stator core in which 24 slots are arranged concentrically at equal intervals; In an electric motor that has a main winding that is wound around these slots in two poles, and an auxiliary winding that is wound around the slot at an electrical angle of 90 degrees from these main windings, the side facing the compression element is The four sets of coils of the main winding of the stator are formed into four sets of windings inserted into opposing slots in an order in which the number of turns substantially gradually decreases from the center side to the circumferential side of the stator hole, and 5 sets of main winding coils,
The windings are formed into five windings inserted into opposing slots in an order in which the number of turns substantially gradually decreases from the center side to the circumferential side of the stator hole, and the effective windings of the four windings are formed into five windings. A two-pole, single-phase induction motor, characterized in that the number of turns is set to be reduced within 10% of the effective number of turns.