JP6115937B2 - Compressor motor and control method thereof - Google Patents

Compressor motor and control method thereof Download PDF

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JP6115937B2
JP6115937B2 JP2013020059A JP2013020059A JP6115937B2 JP 6115937 B2 JP6115937 B2 JP 6115937B2 JP 2013020059 A JP2013020059 A JP 2013020059A JP 2013020059 A JP2013020059 A JP 2013020059A JP 6115937 B2 JP6115937 B2 JP 6115937B2
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motor
air pressure
stator
compressor
permanent magnet
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JP2014155233A (en
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裕一 相澤
裕一 相澤
乙顔 司守
司守 乙顔
吉弘 土屋
吉弘 土屋
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株式会社甲府明電舎
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  The present invention relates to a compressor motor for driving a gas (air) compressor and a control method therefor, and particularly to a portable air compressor that has been required to be lightweight, inexpensive, quiet and energy-saving. It is suitable for application.

Air compressors used in civil engineering and construction work are desired to be compact and lightweight portable because of their handling and workability. Various portable air compressors have been devised and put into practical use. It has been.
Naturally, lighter, more powerful, cheaper, etc. are required, and recently, it has become desirable to be able to operate silently and save energy according to the use situation.

  In this type of air compressor, a piston-cylinder part (air compression part) that sucks and compresses air, a crank mechanism part that reciprocates the piston, a motor part that applies rotational force to the crank mechanism part, and a piston-cylinder A cover that covers the motor, the crank mechanism, the motor, and the like, a pressure accumulation tank that stores the compressed air, and a controller that drives the motor.

Moreover, the control part mounted in the air compressor detects a tank pressure (air pressure in the pressure accumulating tank) and controls the motor to stop when the pressure reaches an upper limit value. When the tank pressure is reduced to the lower limit value using the compressed air, the control unit restarts the motor and supplies the compressed air to the pressure accumulation tank.
As described above, the motor mounted on the air compressor is repeatedly operated from start to stop to restart.

  In recent years, when multiple air tools (nailing machine, etc.) are used in parallel at the same time, or when you want to use the same power supply for lighting or other power tools, such as at night, or in the surroundings There is an increasing demand for switching the operating state of the air compressor according to the usage situation, for example, when it is desired to reduce the noise as much as possible in consideration of the environment.

  As an example of an air compressor configured to generate high-pressure compressed air with a large air supply amount, a first air compression mechanism including a pair of piston-cylinder mechanisms, a similar second air compression mechanism, The mainstream is a horizontally opposed two-stage air compressor in which are opposed to each other.

JP2011-208648 JP2009-24602 JP-A-2005-120928 Japanese Patent No. 3599832 JP 62-110468 A JP 2006-94604 A

Both of the motor structures described in FIG. 7 of Patent Document 1 and FIG. 8 of Patent Document 2 are of the add-on type, and are provided with a stator on the outside and a rotor on the inside. In Patent Document 3, an axial magnetic flux type (plane facing type) motor is shown as the motor structure shown in FIG. 1, and the weight is reduced by using a non-ferrous material.
Further, no specific explanation has been made about the axial length of the magnet and the axial length of the stator core, whether they are of the add-on type or the plane-opposed type.

  Since the rotor of such an internal rotation type or planar opposed type motor has a small inertia of the rotating part, the effect of absorbing the vibration generated by the reciprocating motion of the piston is poor. For this reason, an inertia weight is added in addition to the motor rotor. This hinders weight reduction and cost reduction.

  In Patent Document 2, efforts are made to maintain the durability and reliability of the machine by attenuating the vibration of the compressor by using a flexible pipe or a buffer material in particular, but this hinders weight reduction and cost reduction.

  Patent document 4 is a pioneering invention in the industry that has the patent right in our company (the present applicant). However, the inertia of the rotor is increased by using the motor as an outer rotation structure, and the inertia weight effect necessary for the compression mechanism is obtained. It is an enhanced one. However, the ratio between the axial length of the magnet and the axial length of the stator core, and the ratio between the outer diameter of the stator core and the axial length of the core are not described.

  As an internal-compression type motor using an air compressor found on the market, a 6-pole 9-coil motor using a rare earth magnet is often seen. Due to the recent surge in rare earth materials, it is strongly desired to save rare earths in terms of cost and stable supply. Patent Document 5 describes that the ratio of the number of poles P and the number of slots S (the number of coils) of the motor is 0.67 <P / S <1.33 so that the winding coefficient can be increased and the motor can be reduced in size. Except for our company, the air compressor motors seen in the market are 6P9S and 12P9S motors, P / S = 0.6666 or 1.3333, 0.67 <P / S <1. It is not included in the range of 33.

In Patent Document 1, the silent operation is enabled by a method of switching between the silent mode and the normal mode according to the use situation.

  Patent Document 6 discloses a permanent magnet type motor that is devised for magnet orientation.

  In view of the above prior art, the present invention enhances the effect of absorbing vibrations caused by the reciprocating motion of the piston, is light and small, achieves both low cost and rare earth savings, and further has three modes according to the usage situation. By adopting a control method that can select the operation mode, it is possible to reduce the frequency of starting and stopping, reduce the load on the machine, and contribute to the silent operation and energy saving effect and its control It aims to provide a method.

The invention according to claim 1 of the present invention for solving the above problem is provided in a gas compressor having a compression mechanism for compressing gas and a pressure accumulating tank for storing the compressed gas compressed by the compression mechanism, and the compression In the motor that drives the mechanism,
A stator having a stator core and a motor winding wound around the stator core, and being arranged concentrically with a gap with respect to the motor shaft;
A rotor yoke fixed to the motor shaft and having an outer diameter larger than the outer diameter of the stator, and a ferrite permanent magnet disposed on the rotor yoke and facing the outer peripheral portion of the stator with a gap therebetween And a rotor having
When the outer diameter dimension of the stator core is DA, the core length of the stator core is LG, DA / LG> 10, and when the axial length of the permanent magnet is LM, LM / LG > Ri 1.4 der,
The motor windings are concentrated windings, where P is the number of poles and S is the number of slots, and the range is 0.67 <P / S <1.33 .

Further, in the invention according to claim 2 of the present invention, the rotor is formed by shaping a soft steel plate into a cup shape by drawing and forming a disk-shaped bottom surface portion and a cylindrical portion formed at the periphery of the bottom surface portion. A rotor yoke having
It is composed of a ferrite-based permanent magnet fixedly arranged on the inner peripheral side of the cylindrical portion,
The bottom surface portion is provided with an air hole for allowing cooling air to pass therethrough.

Further, the invention according to claim 3 of the present invention is characterized in that a fan blade integrally formed with the rotor yoke and made of the same material as the soft iron steel plate is provided on the surface on the stator side of the bottom surface portion. .

The invention according to claim 4 of the present invention is characterized in that a fan blade made of a lightweight material is fixed to a surface on the side opposite to the stator of the bottom surface portion.

In the invention according to claim 5 of the present invention, when the magnetic orientation of the permanent magnet is viewed from the front, the magnetic orientation center where the magnetic orientation converges is closer to the permanent magnet than the rotation center of the rotor yoke. It is characterized by that.

The invention according to claim 6 of the present invention is characterized in that the magnetic orientation of the permanent magnet is converged at a portion of the stator core when viewed in a side view.

The invention according to claim 7 of the present invention is a method for controlling a motor for a compressor as described above,
Regarding the air pressure P in the pressure accumulating tank, air pressures P1, P2, P3, and P4 satisfying a relationship of P1 <P2 <P3 <P4 <Pmax when the maximum air pressure is Pmax are set in advance, and the rotation of the motor Regarding the speed N, the rotational speeds N1, N2, and N3 satisfying the relationship of N1 <N2 <N3 <Nmax when the maximum speed is Nmax are preset, and the three modes of the powerful mode, the normal mode, and the silent / energy saving mode are set. The mode can be selected and switched. When the powerful mode is selected, the following control (1) is performed. When the normal mode is selected, the control (2) is performed. When the silent / energy saving mode is selected, the control (3) is performed. Control is performed.
(1) In the powerful mode, when the motor is started so that the rotation speed of the motor becomes Nmax and the air pressure reaches P4, the rotation speed is reduced to N3. Thereafter, when the air pressure decreases to P3, the rotational speed is increased to Nmax. When the air pressure reaches Pmax on the way, the motor is stopped. Thereafter, when the air pressure drops to P3, the motor is restarted so that the rotational speed of the motor becomes Nmax.
(2) In the normal mode, when the motor is started so that the rotation speed of the motor becomes Nmax and the air pressure reaches P3, the rotation speed is reduced to N2. Thereafter, when the air pressure decreases to P2, the rotational speed is increased to Nmax. When the pressure reaches Pmax on the way, the motor is stopped. Thereafter, when the air pressure drops to P2, the motor is restarted so that the rotational speed of the motor becomes Nmax.
(3) In the silent / energy saving mode, the motor is started so that the rotational speed of the motor becomes N2, and when the air pressure reaches P2, the rotational speed is reduced to N1. Thereafter, when the air pressure drops to P1, the rotational speed is increased to N2. When the pressure reaches Pmax on the way, the motor is stopped. Thereafter, when the air pressure decreases to P1, the motor is restarted so that the rotational speed of the motor becomes N2.

  The invention according to claim 1 uses a ferrite permanent magnet as the abduction motor, and the ratio of the axial length (LM) of the magnet to the axial length (LG) of the stator core LM / LG> 1.4 and an extremely flat structure in which the ratio of the stator core outer diameter (DA) to LG is DA / LG> 10, which increases the inertia of the motor rotor and reduces the size of the stator. Light weight is realized by saving rare earth. While the structure of Patent Document 4 is evolved and developed to maintain the inertia largely, the motor unit is further reduced in weight and cost.

In the invention according to claim 1, when the number of poles of the motor is P and the number of slots is S, the ratio of P and S is in the range of 0.67 <P / S <1.33. Compared with a 6-pole 9-coil motor, which is often seen in, the winding coefficient can be increased, which can contribute to further miniaturization and weight reduction.

The inventions according to claims 2 , 3, and 4 relate to the cooling of the motor, and since the stator coil portion is dominant in the heat generating portion of the motor, the flatness of the stator of the motor is increased and the coil is A coil hole is effectively cooled by providing an air hole in the bottom surface of a very close rotor and providing a fan blade in the air hole.
Claim 2 is an invention of providing an air hole, and claim 3 shows a method of providing a fan blade with the same material as the rotor for the purpose of cost reduction. This method tends to cause difficulty in weight reduction and cooling effect. Therefore it is the fan blade by weight member such as plastic by the claims 4 to the outside of the rotor to the rotor that devised to increase the weight and the cooling effect by integrally fixing.

In the inventions according to claims 5 and 6 , the torque of the motor can be increased by devising the magnetic orientation.

The invention according to claim 7 is a mode in which a plurality of air tools are used in parallel at the same time, but a normal mode in which one air tool which is considered to be frequently used is used, and a small amount of air is used. In some cases, the three operation modes can be used properly as a silent / energy-saving mode. Since this is an abduction type motor with a large inertial effect, if the frequency of start / stop is high, the energy loss at start-up is large, and the power supply voltage is low when restarting with a high tank pressure May take a long time to start. In addition, there is a problem that other devices connected to the same power source tend to be affected.

According to the first aspect of the present invention, the axial length of the iron core is extremely shortened (the flatness is increased), and the axial length of the magnet is further increased so that the stator core can be removed. Magnetic flux from a certain magnet can also be collected and used in the iron core. Since it is an inexpensive ferrite magnet, even if the length of the magnet in the magnetization direction (in this case, corresponding to the thickness in the radial direction) is increased, there is little effect on the cost. Naturally, the gap is larger for the magnet in the range outside the iron core, but since the length in the magnetization direction is large, the decrease in the permeance coefficient is small and the decrease in the magnetic flux density is small. Here, the permeance coefficient is a coefficient that influences the magnetic flux density at the operating point of the magnet. As shown in FIG. 5, when the length in the magnetization direction is lm and the gap length is lg, the permeance coefficient ∝lm / lg The larger this value, the higher the magnetic flux density at the operating point of the magnet. Therefore, even if the gap length lg is large, the permeance coefficient can be increased if the length lm in the magnetization direction of the magnet is large. This greatly increases the inertia of the rotor and contributes to the weight reduction and cost reduction of the stator.
This is a special technique that is possible because it is an inexpensive magnet material, and is suitable for a portable air compressor that wants to reduce the weight of the motor part (especially the stator) while increasing the inertia.

According to the invention according to claim 1, by taking the 0.67 <P / S <1.33, since large take the winding factor, particularly the stator of the motor size and weight, the effect that can be less costly is there.

According to the inventions related to claims 2 , 3, and 4 , cooling air is generated to intensively cool the stator coil, which is the main heat source of the motor, to enhance the cooling effect, and to achieve both light weight and low cost. Can be made. According to the second aspect of the present invention , air holes are provided in the vicinity of the stator coil on the bottom surface portion of the rotor, and particularly the coil can be intensively cooled. According to the third aspect of the present invention , the fan blade is formed of the same material as the rotor material on the bottom coil portion of the rotor. According to the fourth aspect of the present invention , since the fan blade made of a lightweight material such as plastic is provided on the anti-stator side of the bottom surface of the rotor, the cost is slightly increased, but the effect of reducing the weight and improving the cooling effect is high. By increasing the cooling effect in this way, it is possible to achieve both reduction in the size, weight and cost of the stator. By using together with claim 1 , it becomes more suitable as a motor for an air compressor.

In the inventions according to the fifth and sixth aspects, by devising the magnetic orientation, it is possible to increase the torque of the motor, and thus it is possible to reduce the size and cost of the motor and the air compressor.

Here, the reason why it is advantageous as an air compressor to increase the inertia of the rotor of the motor will be described.
A piston, which is an air compression mechanism, reciprocates by a crank mechanism. Due to this reciprocation, the compression mechanism section generates considerably large vibrations. This vibration not only becomes a noise source, but also adversely affects the durability reliability of all parts mounted on the machine. In Patent Document 2, in order to attenuate this vibration and fix it to the tank, flexible pipes and cushioning materials are frequently used. Therefore, when the inertia of the motor rotor is increased, a gyro effect is generated, and the effect of absorbing vibration itself is enhanced. Therefore, in a machine that involves a reciprocating motion of mass, it is advantageous in terms of damping surface that the inertia of the rotating part is large.

Furthermore, in machines with large fluctuations in the required torque during one rotation of the motor (including air compressors), the effect of overcoming the momentary large torque by inertia can be given, reducing the burden on the motor drive circuit It will be possible.
Therefore, in the air compressor, it is preferable that the inertia of the rotating part is large.

However, the large inertia of the rotor is inconvenient from the viewpoint of energy saving because the energy loss consumed at the time of start-up will be large if it is used with a high frequency of start / stop. Therefore, according to the invention according to claim 7 , three kinds of operation modes can be selected according to the use situation, and the frequency of starting and stopping can be reduced.

  When a plurality of air tools are used in parallel at the same time (it is assumed that this case is rare in practice), the power mode is set to the maximum pressure and the maximum rotation speed. Naturally, in this case, it will be used at the maximum capacity of the compressor, and it is neither silent nor energy saving. When the load on the machine is large and the environmental temperature is high, the machine may be stopped by heating protection.

  In the next normal mode (assuming that this case is practically many), the tank pressure and rotation speed are reduced compared to the powerful mode, assuming one person working (using one air tool) Yes. Even if you are alone, there are individual differences and situational differences, so it is not bad to use in powerful mode, but you can reduce the burden on the machine and reduce the probability of stopping with overheat protection. When the environmental temperature is high, it can be operated for a longer time.

  The next energy-saving / silent mode is to select a method with lower tank pressure and rotation speed. It is especially effective when you want to use one air tool and reduce the compressor capacity, and you want to save energy and operate silently. This mode is particularly effective when it is desired to turn on the power supply for power tools and other power tools.

By selecting and using the three types of modes in this way, the frequency of starting and stopping the motor is reduced, so that the energy saving effect is increased even with a motor having a large inertia.
The three types of modes are considered not to be expected to be used for mode switching so frequently, and even if too many modes can be selected, it becomes rather troublesome.

The front view which shows the air compressor carrying the motor which concerns on this invention. The top view which shows the air compressor carrying the motor which concerns on this invention. The side view which shows the motor which concerns on this invention partially fractured | ruptures. The front view which shows the motor which concerns on this invention. Explanatory drawing which shows the magnetism collection effect. Explanatory drawing which shows the magnetized state of a permanent magnet by front view. Explanatory drawing which shows the magnetization state of a permanent magnet by a side view. Explanatory drawing which shows the magnetized state of a permanent magnet by front view. Explanatory drawing which shows the magnetization state of a permanent magnet by a side view. The circuit diagram which shows the control circuit which controls a motor.

  Hereinafter, a motor for a compressor and a control method thereof according to the present invention will be described in detail based on examples.

〔Example〕
A portable air compressor 1 equipped with a motor according to the present invention will be described with reference to FIG. 1 which is a front view and FIG. 2 which is a plan view.

  The air compressor 1 includes a support structure unit 2 including a compression mechanism 3, a pressure accumulating tank 4, a handle 5, a motor 100, a control unit 200, and the like.

The motor shaft 101 of the motor 100 is connected to a crankshaft (not shown) of the compression mechanism 3, and when the motor 100 rotates, the compression mechanism 3 is driven, and the driven compression mechanism 3 compresses air. The compressed air compressed is sent to the accumulator tank 4 through a pipe (not shown) and stored. The compressed air stored in the pressure accumulation tank 4 is supplied to an air tool (eg, a nailing machine) via a hose (not shown).
A cooling fan 31 is attached to the compression mechanism 3.

Next, FIG. 3 which is a side view showing the detailed structure of the motor 100 with the upper half cut away, FIG. 4 which is a front view, and a diagram showing an extracted portion of a stator core and a permanent magnet to show a magnetic flux collecting effect. This will be described with reference to FIG. In FIG. 5, dotted lines indicate magnetic flux lines.
This motor 100 is an outer rotation type motor (outer rotor type motor), and is a permanent magnet type motor in which an inner peripheral side stator 110 is fixedly supported, and an outer peripheral side rotor 120 rotates.

The stator 110 is configured by winding a motor winding 113, which is an armature winding, around a stator core 111 via a bobbin 112. When a current is passed through the motor winding 113 via the electric wire 114, a rotating magnetic field is generated around the stator 110.
The stator 110 is mounted around the motor shaft 101 in a concentric state with a gap.

  As shown in FIG. 3, a mounting hole 115 is formed in the inner peripheral side portion of the stator core 111. The stator 110 is fixedly supported by bolting the fixing hole 21 through the mounting hole 115 to the fixing portion 21 fixed to the support structure portion 2.

  The winding method of the motor winding 113 is concentrated winding, where P is the number of poles and S is the number of slots, and the range is 0.67 <P / S <1.33.

  The rotor 120 includes a rotor yoke 121 having a central portion fixed to the motor shaft 101 and a plurality of permanent magnets 122 arranged side by side on the rotor yoke 121 in the circumferential direction.

  The rotor yoke 121 is formed by shaping a soft steel plate into a cup shape by drawing, and has a disk-shaped bottom surface portion 121a and a cylindrical portion 121b formed along the periphery of the bottom surface portion 121 and orthogonal to the bottom surface portion 121. doing. The bottom surface portion 121a faces the stator 110 with a gap, and the cylindrical portion 121b faces the outer periphery of the stator 110 with a gap.

  A permanent magnet 122 is fixedly disposed on the inner peripheral side of the cylindrical portion 121 b of the rotor yoke 121. The permanent magnet 122 is a ferrite permanent magnet, and faces the outer peripheral portion of the stator 110 with a gap.

A plurality of air holes 123 are formed in the bottom surface portion 121a of the rotor yoke 121 to allow cooling air to pass.
Further, a fan blade 124 is formed on the surface of the bottom surface 121 a of the rotor yoke 121 that faces the stator 110. The fan blade 124 is formed integrally with the rotor yoke 121 by subjecting a soft steel plate to be the rotor yoke 121 to a stamping or bending method.

  Instead of integrally forming the fan blade 124, the bottom surface portion 121a of the rotor yoke 121 is made of a light material such as plastic, aluminum alloy, magnesium alloy on the surface opposite to the surface facing the stator 110. Fan blades can be fixedly installed.

Here, a fixing structure for fixing the rotor yoke 121 to the motor shaft 101 will be described. As shown in FIG. 3, an intermediate boss 131 is attached to the end of the motor shaft 101. The intermediate boss 131 is constrained from rotating with respect to the motor shaft 101 by the key 132, and is fastened in the axial center direction from the shaft end by the washer 133 and the bolt 134, and is fixed to the end of the motor shaft 101.
Then, the bolt 135 is fastened to the intermediate boss 131 through the bottom surface 121 a of the rotor yoke 121, so that the rotor yoke 121 is fixed to the motor shaft 101 via the intermediate boss 131.

  The control unit 200 controls the rotational speed of the motor 100, and details of the control method will be described later.

The dimensional ratio of each part of the motor 100 having the above-described configuration is as follows.
That is, when the outer diameter dimension of the stator core 111 is DA, the core length of the stator core 111 is LG, DA / LG> 10, and when the axial length of the permanent magnet 122 is LM, LM / LG> 1.4.
Because of such a dimensional ratio, the motor 100 has an extremely flat structure, and the inertia of the rotor 120 of the motor 100 is increased, and the stator 110 can be reduced in size and weight with a rare earth saving. Can do. For this reason, it is possible to achieve a further reduction in weight and cost of the motor 100 while maintaining a large inertia.

  Further, by setting the ratio P / S of the number of motor poles P to the number of slots S in the range of 0.67 <P / S <1.33, compared with a 6 pole 9 coil motor often found in the conventional market. Since the winding coefficient can be increased, the size and weight can be further reduced.

  Further, since the heat generating portion of the motor 100 is dominated by the motor winding 113 portion of the stator 110, the flatness of the stator 110 of the motor 100 is increased and the bottom surface of the rotor 120 is very close to the motor winding 113. By providing the air hole 123 in the part 121a and providing the fan blade 124 in the vicinity of the air hole 123, the part (coil part) of the motor winding 113 can be effectively cooled.

Here, the magnetic orientation (magnetization direction) of the permanent magnet 122 will be described with reference to FIGS. 6A, 6B, 6C, and 6D.
6A and 6C show the permanent magnet 122 by being cut off on a plane orthogonal to the shaft 101, and the state shown in FIGS. 6A and 6C will be described as “front view”.
FIGS. 6B and D show the permanent magnet 122 by breaking along a plane along the shaft 101 (parallel to the shaft 101). The state shown in FIGS. 6B and 6D is defined as “side view”. I will explain.
In FIGS. 6A, 6B, 6C, and 6D, the magnetic flux is indicated by a dotted line.

  As described above, a plurality of permanent magnets 122 are fixedly arranged on the inner peripheral side of the cylindrical portion 121 b of the rotor yoke 121, and one magnetic pole is formed by one permanent magnet 122.

  As the magnetic orientation (magnetization direction) of the permanent magnet 122, the following (A) to (C) can be adopted.

(A) As shown in FIG. 6A, when viewed from the front, the magnetic orientation 122a of each part of the permanent magnet 122 is concentrated on the rotation center (magnetic orientation center 122b) of the rotor yoke 121, and shown in FIG. 6B. As described above, each permanent magnet 122 is magnetized so that the magnetic orientation 122a of each part of the permanent magnet 122 is parallel when viewed from the side.

(B) As shown in FIG. 6C, when viewed from the front, the magnetic orientation center 122c of the magnetic orientation 122a of each part of the permanent magnet 122 is positioned closer to the permanent magnet 122 than the rotational center of the rotor yoke 121; As shown in FIG. 6B, each permanent magnet 122 is magnetized so that the magnetic orientation 122a of each part of the permanent magnet 122 is parallel when viewed in a side view.

(C) As shown in FIG. 6C, when viewed from the front, the magnetic orientation center 122c of the magnetic orientation 122a of each part of the permanent magnet 122 is located closer to the permanent magnet 122 than the rotational center of the rotor yoke 121; As shown in FIG. 6D, each permanent magnet 122 is arranged such that the magnetic orientation 122a of each part of the permanent magnet 122 is focused on the portion of the stator core 111 (magnetic orientation center 122c) even when viewed in a side view. Magnetized.

  The motor 100 of the present embodiment has an extremely flat structure in which the dimension of the stator core 111 is extremely short compared to the dimension of the permanent magnet 122, but the above-described (A), (B), (C) By adopting such a magnetic orientation 122a, the magnetic flux generated from the permanent magnet 122 can enter the stator core 111 more efficiently, contributing to torque increase and motor efficiency improvement.

  If the magnetic orientation 122a as described in (b) and (c) is adopted, the torque of the motor 100 can be increased as compared with the magnetic orientation 122a as described in (a) above. The air compressor 1 can be reduced in size and cost.

Next, a control method of the motor 100 by the control unit 200 will be described with reference to FIG. 7 which is a control circuit diagram.
The pressure accumulation tank 4 is provided with a pressure sensor 41 that detects the air pressure in the pressure accumulation tank 4. The pressure sensor 41 sends a pressure signal P indicating the detected air pressure to the control unit 200.
The motor 100 is provided with a speed sensor 102 that detects the rotational speed of the motor 100. The speed sensor 102 sends a speed signal N indicating the detected rotation speed to the control unit 200.

The control unit 200 is provided with a mode changeover switch 201, and the mode changeover switch 201 can selectively switch among three operation “modes (powerful mode, normal mode, silent / energy saving mode)”.
Further, the control unit 200 has air pressures P1, P2, P3, and P4 that satisfy the relationship of P1 <P2 <P3 <P4 <Pmax when the maximum air pressure is Pmax with respect to the air pressure P in the pressure accumulating tank 4. With respect to the rotational speed N of the motor 100, rotational speeds N1, N2, and N3 that satisfy a relationship of N1 <N2 <N3 <Nmax when the maximum speed is Nmax are preset.
The control unit 200 performs the following operation control according to each operation mode when any one of the three operation modes is selected by the mode changeover switch 201 in accordance with the use situation. .

(1) In the powerful mode, when the motor 100 is started so that the rotational speed of the motor 100 becomes Nmax and the air pressure reaches P4, the rotational speed is reduced to N3.
Thereafter, when the air pressure decreases to P3, the rotational speed is increased to Nmax. If the air pressure reaches Pmax on the way, the motor 100 is stopped. Thereafter, when the air pressure decreases to P3, the motor 100 is restarted so that the rotation speed of the motor 100 becomes Nmax.
(2) In the normal mode, when the motor 100 is started so that the rotational speed of the motor 100 becomes Nmax and the air pressure reaches P3, the rotational speed is reduced to N2.
Thereafter, when the air pressure decreases to P2, the rotational speed is increased to Nmax. If the pressure reaches Pmax on the way, the motor 100 is stopped. Thereafter, when the air pressure decreases to P2, the motor 100 is restarted so that the rotation speed of the motor 100 becomes Nmax.
(3) In the silent / energy saving mode, the motor 100 is started so that the rotational speed of the motor 100 becomes N2, and when the air pressure reaches P2, the rotational speed is reduced to N1.
Thereafter, when the air pressure drops to P1, the rotational speed is increased to N2. If the pressure reaches Pmax on the way, the motor 100 is stopped. Thereafter, when the air pressure decreases to P1, the motor 100 is restarted so that the rotational speed of the motor 100 becomes N2.

  By selecting and using the three types of modes in this way, the frequency of starting and stopping the motor 100 is reduced, so that the energy saving effect can be enhanced even with the motor 100 having a large inertia.

  The motor for a compressor of the present invention can be used not only as a compressor that compresses air but also as a motor that drives a compressor that compresses various gases.

DESCRIPTION OF SYMBOLS 1 Air compressor 2 Support structure part 21 Fixed part 3 Compression equipment 4 Accumulation tank 5 Handle 31 Cooling fan 41 Pressure sensor 100 Motor 101 Motor shaft 102 Speed sensor 110 Stator 111 Stator iron core 112 Bobbin 113 Motor winding 114 Electric wire 115 Attachment Hole 116 Bolt 120 Rotor 121 Rotor yoke 121a Bottom portion 121b Cylindrical portion 122 Permanent magnet 122a Magnetic orientation 122b, 122c Magnetic orientation center 123 Air hole 124 Fan blade 131 Intermediate boss 132 Key 133 Washer 134 Bolt 135 Bolt 200 Control section 201 Mode change switch

Claims (7)

  1. In a motor for driving the compression mechanism, provided in a gas compressor having a compression mechanism for compressing gas and a pressure accumulating tank for storing compressed gas compressed by the compression mechanism,
    The motor is
    A stator having a stator core and a motor winding wound around the stator core, and being arranged concentrically with a gap with respect to the motor shaft;
    A rotor yoke fixed to the motor shaft and having an outer diameter larger than the outer diameter of the stator, and a ferrite permanent magnet disposed on the rotor yoke and facing the outer peripheral portion of the stator with a gap therebetween And a rotor having
    When the outer diameter dimension of the stator core is DA, the core length of the stator core is LG, DA / LG> 10, and when the axial length of the permanent magnet is LM, LM / LG > Ri 1.4 der,
    The motor winding is a concentrated winding, wherein the number of poles is P and the number of slots is S, the range is 0.67 <P / S <1.33. .
  2. The rotor is
    A rotor yoke having a disk-shaped bottom surface portion and a cylindrical portion formed on the periphery of the bottom surface portion by shaping a soft iron steel plate into a cup shape by drawing,
    It is composed of a ferrite-based permanent magnet fixedly arranged on the inner peripheral side of the cylindrical portion,
    The motor for a compressor according to claim 1, wherein an air hole for passing cooling air is provided in the bottom surface portion.
  3. The motor for a compressor according to claim 2 , wherein a fan blade integrally formed with the rotor yoke and made of the same material as that of the soft iron steel plate is provided on a surface of the bottom surface portion on the stator side.
  4. The motor for a compressor according to claim 2 , wherein a fan blade made of a lightweight material is fixed to a surface on the side opposite to the stator of the bottom surface portion.
  5. The magnetic orientation of the permanent magnet is
    When viewed in a front view, magnetic orientation around said magnetic orientation is focused is, in any one of claims 1 to 4, characterized in that also the rotation center of said rotor yoke in said permanent magnet-side The motor for the compressor as described.
  6. The magnetic orientation of the permanent magnet is
    The motor for a compressor according to any one of claims 1 to 4 , wherein the magnetic orientation is converged at a portion of the stator core when viewed in a side view.
  7. A method for controlling a motor for a compressor according to any one of claims 1 to 6,
    Regarding the air pressure P in the pressure accumulating tank, air pressures P1, P2, P3, and P4 satisfying a relationship of P1 <P2 <P3 <P4 <Pmax when the maximum air pressure is Pmax are set in advance, and the rotation of the motor Regarding the speed N, the rotational speeds N1, N2, and N3 satisfying the relationship of N1 <N2 <N3 <Nmax when the maximum speed is Nmax are preset, and the three modes of the powerful mode, the normal mode, and the silent / energy saving mode are set. The mode can be selected and switched. When the powerful mode is selected, the following control (1) is performed. When the normal mode is selected, the control (2) is performed. When the silent / energy saving mode is selected, the control (3) is performed. A method of controlling a motor for a compressor, characterized by performing control.
    (1) In the powerful mode, when the motor is started so that the rotation speed of the motor becomes Nmax and the air pressure reaches P4, the rotation speed is reduced to N3. Thereafter, when the air pressure decreases to P3, the rotational speed is increased to Nmax. When the air pressure reaches Pmax on the way, the motor is stopped. Thereafter, when the air pressure drops to P3, the motor is restarted so that the rotational speed of the motor becomes Nmax.
    (2) In the normal mode, when the motor is started so that the rotation speed of the motor becomes Nmax and the air pressure reaches P3, the rotation speed is reduced to N2. Thereafter, when the air pressure decreases to P2, the rotational speed is increased to Nmax. When the pressure reaches Pmax on the way, the motor is stopped. Thereafter, when the air pressure drops to P2, the motor is restarted so that the rotational speed of the motor becomes Nmax.
    (3) In the silent / energy saving mode, the motor is started so that the rotational speed of the motor becomes N2, and when the air pressure reaches P2, the rotational speed is reduced to N1. Thereafter, when the air pressure drops to P1, the rotational speed is increased to N2. When the pressure reaches Pmax on the way, the motor is stopped. Thereafter, when the air pressure decreases to P1, the motor is restarted so that the rotational speed of the motor becomes N2.
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