JP3068354B2 - Scroll compressor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scroll compressor.

[0002]

2. Description of the Related Art FIG. 3 is a vertical sectional view of a conventional scroll compressor, and FIG. 4 is an electric circuit diagram of an electric motor provided in the compressor. In FIG. 3, a scroll-type compression mechanism C is provided in an upper part of the inside of a closed housing 8, and an electric motor M is provided in a lower part thereof, and these are connected to each other via a rotating shaft 5. As the electric motor M, a DC brushless motor including a rotor Ma having a permanent magnet and a stator Mb having a three-phase connected armature winding Mc shown in FIG. 4 is used.
By switching the excitation current supplied from the power supply to the armature winding Mc through the conduction switching means 101, a rotating magnetic field is generated, whereby the rotor Ma of FIG. It has become.

In FIG. 3, a scroll type compression mechanism C permits a fixed scroll 1, an orbiting scroll 2 and a revolving orbiting motion of the orbiting scroll 2 but prevents a rotation thereof such as an Oldham link, a frame 6, and a rotation. It comprises an upper bearing 71 and a lower bearing 72 which support the shaft 5. The fixed scroll 1 has an end plate 11 and a spiral wrap 12 erected on the inner surface thereof.
A discharge port 13 is provided at the center of the. The orbiting scroll 2 includes an end plate 21 and a spiral wrap 22 erected on the inner surface of the end plate 21. A drive bush 54 is rotatable via a slewing bearing 73 in a boss 23 erected on the outer surface of the end plate 21. An eccentric pin 53 projecting from the upper end of the rotary shaft 5 is slidably fitted in a hole 55 formed in the drive bush 54. Since the fixed scroll 1 and the orbiting scroll 2 are eccentric with each other by a predetermined distance and are meshed with each other at an angle shifted by 180 degrees, a plurality of closed spaces 24 are formed.

When the electric motor M is driven, the orbiting scroll 2 is driven by a revolving orbiting mechanism including a rotating shaft 5, an eccentric pin 53, a drive bush 54, a boss 23, and the like. While being blocked, it revolves around a circular orbit having the radius of revolution. Then, the gas is supplied to the suction pipe 82.
Through the passage 85.
And is sucked into the closed space 24 through the suction passage 15. Then, as the volume of the closed space 24 decreases due to the revolving orbiting motion of the orbiting scroll 2, the compressed space reaches the central portion while being compressed, pushes and opens the discharge valve 17 from the discharge port 13, enters the discharge cavity 14, and from there. Discharge pipe 83
Is discharged to the outside.

[0005]

In the conventional scroll type compressor described above, when the operating speed is low, the pressure difference ΔP between the discharge side pressure and the suction side pressure is small, so that the compression mechanism C is mechanically driven. A fluctuation in load torque occurs during rotation. As a result, during one mechanical rotation of the compression mechanism C, the rotation speed of the electric motor M fluctuates and the vibration increases, and the piping and equipment of the refrigeration system in which the compressor is incorporated are damaged, and problems such as noise generation occur. there were. The variation pattern of the load torque with respect to the rotation position of the rotor Ma is determined by the shapes of the fixed scroll 1 and the orbiting scroll 2, and for example, becomes a variation pattern as shown in FIG. 5, and this is repeated periodically.

An object of the present invention is to solve such disadvantages of the prior art, to provide a scroll type compressor in which fluctuations in the number of revolutions are reduced and vibrations are suppressed.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has a permanent magnet as an electric motor for driving a compression mechanism housed in a sealed housing via a rotating shaft. DC with two or more rotors
In a scroll type compressor using a brushless motor, an average rotation speed detecting means for detecting an average rotation speed of the electric motor in one mechanical rotation, and a driving frequency (electrical period) for driving the electric motor. It is provided with rotation speed detecting means for detecting the rotation speed of the motor, and compares the average rotation speed during one mechanical rotation with the rotation speed of each electric cycle to predict a rotation speed change due to periodic load fluctuation. The present invention relates to a scroll-type compressor, which is provided with control means for performing rotational speed control.

[0008]

The scroll compressor according to the present invention has the above-described structure, and therefore has the following effects. That is, the number of rotations II per electrical cycle detected by the number of rotations detecting means and the average number of rotations I in one mechanical rotation detected by the average number of rotations detecting means.
If the rotation speed II> the average rotation speed I, the load is determined to be smaller than the average load, and if the rotation speed II <the average rotation speed I, the load is determined to be larger than the average load and stored. Here, since the load fluctuation pattern of the compressor is determined by the mechanical position and is periodically repeated, by storing the load fluctuation pattern,
The magnitude of the next load can be predicted. And
When it is predicted that the next load will be small based on the stored load fluctuation pattern, the voltage applied to the electric motor is controlled to decrease by a predetermined value to suppress an increase in the rotation speed due to the decrease in load. Similarly, when it is predicted that the load is large, control is performed to increase the applied voltage by a predetermined value. With such control, fluctuations in the rotational speed can be reduced.

[0009]

FIG. 1 is an electric circuit diagram of an electric motor provided in a scroll compressor according to one embodiment of the present invention. The structure of the compressor other than the electric circuit is the same as that shown in FIG. The electric motor M includes a rotor Ma
In addition, a brushless DC motor having permanent magnets and having two or more pole pairs, in this embodiment, two pole pairs is used, and three phases of the armature winding Mc of FIG. That is, the exciting currents to be supplied to the U-phase, V-phase, and W-phase are sequentially switched via the conduction switching means 101.

In FIG. 1, reference numeral 106 denotes an average rotation number detecting means for detecting the rotation number I of the rotor Ma in one mechanical rotation of the compression mechanism C, and an exciting current is applied to the armature winding Mc via the current switching means 101. The energization time is measured twice in the U phase, V phase and W phase, and the average rotation speed I is detected from the measurement time.

Reference numeral 107 denotes a rotation speed detecting means for detecting a rotation speed II of the rotor Ma for each electric cycle (a driving frequency for driving the electric motor Ma). The time during which the current flows through the U phase, V phase and W phase is measured, and the rotational speed II is detected from the measured time. Here, the rotation number detecting means 107 detects the same number of rotations as the number of pole pairs per mechanical rotation of the compression mechanism C.

FIG. 2 is a diagram showing the relationship between the load torque fluctuation characteristics and the control method in the above embodiment. Since the rotor Ma of this embodiment has two pole pairs, as shown in the figure, two rotation speeds II ₁ , II of an electric odd period and an electric even period are provided.
₂ are each detected.

Reference numeral 108 in FIG. 1 denotes a controller which controls the rotation speed of the rotor Ma by inputting signals from the average rotation speed detection means 106 and the rotation speed detection means 107 to increase or decrease the voltage applied to the armature winding Mc. It is supposed to. The parts other than the parts described above are the same as in the related art.

The compressor having the above-described configuration is used to control the rotational speed A corresponding to the operating value of the refrigeration system incorporating the compressor.
When the controller 8 is driven based on the average rotation speed I, the controller 8 detects the average rotation speed I in one mechanical rotation detected by the average rotation speed detection unit 106, and the rotation in each electrical cycle detected by the rotation speed detection unit 107. The number II, that is, in this example, the rotational speeds II ₁ and II ₂ of the electric odd period and the electric even period are input, respectively. Here, the values of the rotational speeds are compared, and the rotational speed II> the average rotational speed I Then the load is less than the average load,
On the other hand, if the rotation speed II <the average rotation speed I, the load is determined to be larger than the average load, and this load variation pattern is stored.

Here, since the load fluctuation pattern of the compressor is determined by the mechanical position and is repeated periodically, it is possible to predict the magnitude of the next load by storing the load fluctuation pattern as described above. it can. Then, based on the load variation pattern stored here, the controller 108 predicts that the next load will be small, that is, during a high electrical odd period of the rotation speed II ₁ as shown in FIG.
The voltage applied to the armature winding Mc is controlled to decrease by a predetermined value corresponding to the deviation from the average rotation speed I, and the rotation speed of the rotor Ma is reduced to the average rotation speed I.

[0016] When it is predicted that comes next load is large contrast, i.e., the low electrical even-period of the rotation speed II ₂ as shown in FIG. 2, predetermined corresponding to the deviation between the average rotational speed I Is controlled to increase the applied voltage to the armature winding Mc by the value of
The rotation speed of the rotor Ma is increased to the average rotation speed I.

Further, when there is a difference between the command rotation speed A and the average rotation speed I, the controller 108 increases or decreases the voltage applied to the armature winding Mc according to the difference between the two. , The average rotation speed I is corrected to match the command rotation speed A.

In this manner, the rotational speed is controlled to be reduced during an electric odd period in which the load torque during one mechanical rotation is small and the rotational speed of the rotor Ma is high, and the load torque is large and the rotational speed is reduced. Since the rotation speed is controlled to increase during an electrical even period that is a high region, fluctuations in the rotation speed during one mechanical rotation can be reduced, and vibrations caused by fluctuations in the rotation speed can be suppressed.

In the above description, the average rotation speed detecting means 1
In a reference numeral 06, the average rotation speed I is detected by measuring the energization time of the exciting current, and the average value is obtained from the rotation speed II for each electrical cycle detected by the rotation speed detection means 107 and the average rotation speed is calculated. I. In this case, the rotation speed detecting means 107 and the average rotation speed detecting means 106 can be partially shared, so that the cost for detection can be reduced.

As described above in detail, in the present embodiment, the periodic load fluctuation pattern of the compressor is predicted by comparing the rotation speed of each electrical cycle with the average rotation speed of one mechanical rotation. Based on this load variation pattern, in a region where the load is small and exceeds the rotational speed average rotational speed, the voltage applied to the electric motor is controlled so as to decrease the rotational speed. Is controlled to increase the applied voltage to the electric motor to increase the rotation speed in a region where the rotation speed is smaller than the average rotation speed, so that the fluctuation of the rotation speed can be reduced. Vibration can be suppressed.

[0021]

According to the scroll compressor of the present invention, an average rotation speed detecting means for detecting an average rotation speed of the electric motor in one mechanical rotation, and a drive frequency (one electric cycle) for driving the electric motor. A rotation speed detecting means for detecting the rotation speed of the motor in the motor, and comparing the average rotation speed during one mechanical rotation with the rotation speed for each electric cycle, and detecting the rotation speed change due to periodic load fluctuation. Since the control means for predicting and controlling the rotation speed is provided, the fluctuation of the rotation speed can be reduced, and the vibration caused by the fluctuation of the rotation speed can be suppressed. As a result, it is possible to prevent damage to pipes and equipment and noise.

[Brief description of the drawings]

FIG. 1 is an electric circuit diagram of an electric motor of a scroll compressor according to one embodiment of the present invention.

FIG. 2 is a diagram showing the relationship between load torque fluctuation characteristics and a control method in the embodiment.

FIG. 3 is a vertical sectional view of a conventional scroll compressor.

FIG. 4 is an electric circuit diagram of an electric motor of the compressor.

FIG. 5 is a view showing a fluctuation characteristic of a load torque in the compressor.

[Explanation of symbols]

 C Compression mechanism M DC brushless motor Ma Rotor Mb Stator Mc Armature winding 5 Rotating shaft 8 Sealed housing 101 Energization switching means 106 Average rotation speed detection means 107 Rotation speed detection means 108 Controller

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F04C 18/02 311 F04C 29/00 F04C 29/10

Claims (1)

(57) [Claims] 1. A scroll compressor using a DC brushless motor having a permanent magnet and a rotor having two or more pole pairs as an electric motor for driving a compression mechanism housed in a closed housing via a rotary shaft. Means for detecting the average number of rotations of the electric motor in one mechanical rotation, and means for detecting the number of rotations of the motor at a drive frequency (one electrical cycle) for driving the electric motor. Control means for comparing the average rotation speed during one mechanical rotation with the rotation speed for each electric cycle, and predicting the rotation speed change due to periodic load fluctuation to perform the rotation speed control. A scroll compressor.