JPH062691A - Clean pump - Google Patents

Abstract

PURPOSE:To provide a clean pump by which electric current consumption of a control type bearing can be reduced and necessary driving force can be obtained and radial directional rigidity becomes large. CONSTITUTION:A magnetic coupling is composed of a permanent magnet 9 installed in a rotor 8 and a permanent magnet 4 installed in an impeller 3, and a complex electromagnet 20 is arranged on the opposite side of the rotor 8 so as to be opposed to a soft iron member 6 of the impeller 3. In the complex electromagnet 20, a permanent magnet 21 is arranged in one core, and two coils 22 and 23 are wound round the other core, and zero power control is carried out on these coils 22 and 23 by means of a control circuit according to output of position sensors S1-S4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a clean pump, and more particularly, it is applied to semiconductor manufacturing technology and medical equipment, and holds an impeller (impeller) itself at a predetermined position in a casing by a magnetic action from the outside of the casing. And a clean pump that rotates.

[0002]

2. Description of the Related Art A centrifugal pump rotates an impeller,
It imparts rotational motion to a fluid to increase its pressure and is widely used in the industry.

FIG. 6 is disclosed by the inventor of the present application in Japanese Patent Laid-Open No. 22998/1993.
It is a longitudinal cross-sectional view of the clean pump proposed in No. 7. Figure 6
Referring to, an impeller 3 is provided in the casing 2 of the pump 1. The casing 2 is made of a non-magnetic material,
The impeller 3 includes a non-magnetic member 5 having a permanent magnet 4 that constitutes an uncontrolled magnetic bearing, and a soft iron member 6 corresponding to the rotor of the controlled magnetic bearing. The permanent magnet 4 is divided in the circumferential direction of the impeller 3, and adjacent portions thereof are magnetized in opposite directions. A rotor 8 pivotally supported by a shaft 7 is provided outside the casing 2 so as to face the side of the impeller 3 having the permanent magnet 4. The rotor 8 is driven by a motor (not shown) to rotate. Rotor 8
Is provided with the same number of permanent magnets 9 as the impeller side so as to face the permanent magnets 4 of the impeller 3 and to exert an attractive force. On the other hand, the permanent magnets 4 in the casing 2 are arranged so as to face the side of the impeller 3 having the soft iron member 6.
An electromagnet 10 is attached that acts to overcome the attractive force of 9 and hold the impeller 3 in the center of the casing 2.

In the clean pump constructed as described above, the permanent magnet 9 embedded in the rotor 8 supports the drive of the impeller 3 and the radial direction, and is interposed between the permanent magnet 9 and the permanent magnet 5 provided in the impeller 3. Generates an axial suction force. A current is applied to the coil of the electromagnet 10 so as to balance with the attraction force, and the impeller 3 floats. Then, when the rotor 8 rotates, the permanent magnets 4 and 9 form a magnetic coupling, the impeller 3 rotates, and the liquid is sent from a discharge port (not shown). The impeller 3 is separated from the rotor 8 by the casing 2 and is not contaminated by the electromagnet 10. Therefore, the fluid discharged from the pump 1 maintains a clean state.

[0005]

By the way, the permanent magnet 5
If the attractive force of the magnetic coupling between and is small, the current flowing through the coil of the electromagnet 19 is small, the heat generation here is also small, and the power consumption is also small. However, if the attraction force is reduced, the driving force by the magnetic coupling and the radial rigidity are also reduced, which is not practical. In order to increase the required driving force and the rigidity in the radial direction, it is necessary to pass a current equal to or higher than a certain value through the coil of the electromagnet 10, resulting in large heat generation and power consumption.

Therefore, a main object of the present invention is to provide a clean pump which can reduce the current consumption of the control type bearing, obtain a necessary driving force, and increase the radial rigidity. is there.

[0007]

The invention according to claim 1 is a non-controllable radial magnetic bearing having a rotation transmitting function by a permanent magnet, and an active magnetic bearing for controlling two degrees of freedom around a rotation axis direction and a center of gravity. In a clean pump in which a disk-shaped impeller provided in a pump casing is magnetically supported by and driven to rotate, an active magnetic bearing is composed of a composite electromagnet having a permanent magnet in a part of its main part. , Is configured to be controlled by zero power.

The invention according to claim 2 is further provided with limit means for limiting the range of zero power operation so that the impeller can rotate without contact in the pump casing.

According to a third aspect of the present invention, in the composite electromagnet of the first aspect of the invention, two coils for increasing and decreasing the attractive force due to the magnetomotive force of the permanent magnet are wound around the core.

[0010]

The clean pump according to the present invention is composed of a composite electromagnet having a permanent magnet in a part of the yoke of the active magnetic bearing, and by controlling the composite electromagnet with zero power, a necessary driving force is obtained to obtain a radius. Direction rigidity is increased,
Moreover, the current consumption can be reduced.

[0011]

FIG. 1 is a sectional view of an embodiment of the present invention,
2 is a diagram showing coordinates for explaining a balanced state of the impeller shown in FIG. 1, FIG. 3 is a diagram showing a core of the electromagnet shown in FIG. 1, and FIG. 4 is a line IV- of FIG. It is sectional drawing which follows IV.

First, referring to FIG. 1, a clean pump 1
Is constructed in the same manner as in FIG. 6 except for the electromagnet 20. The electromagnet 20 is provided with a permanent magnet 21 on a part of one side yoke of a core formed of a ferromagnetic material and having a U-shaped cross section. Coils 22 and 23 are wound around the core on the other side, and when a current flows through one coil 22, the magnetomotive force of the composite electromagnet including the permanent magnet 21 is increased, and when power flows through the other coil 23, a magnetomotive force is generated. Is wired so that

The composite electromagnet 20 is designed so that the resultant force of attracting the impeller 3 when the coil current is not flowing is approximately equal to the force of the coupling portion attracting the impeller, and the distance is maintained. Is dripping Each electromagnet 2
Between 0, as shown in FIG. 4, the position sensors S1 to S4 are
Are placed. These position sensors S1 to S4 detect the gap between the composite electromagnet 20 and the soft iron member 6, and the detection output is given to the control unit shown in FIG. 5, which will be described later, and z, θ _x and θ _y shown in FIG. Controlled, impeller 3 with casing 2
Held in the center of.

FIG. 5 is a block diagram showing a control system according to an embodiment of the present invention. Next, referring to FIG. 5, the zero power control in the embodiment of the present invention will be described. The four position sensors S1, S2, S3 shown in FIG.
As for the output of S4, (S1 + S2 + S3 + S4) becomes the feedback input of the z-axis control, and (s1 + s2)-(s3
+ S4) is θ _x , (S1 + S4) − (S2 + S3) is θ
It becomes a feedback input for _y and control is performed for each control axis.

Here, the case of the z axis will be described as an example. Set the z-axis feedback input to (S1 + S2 +
S3 + S4), if the loop I shown in FIG. 5 is not present, the position setting signal Rz and the feedback input are comparatively amplified, and the PID control adjusts the phase and the gain.
The voltage v ₁ is output. The voltage v ₁ is input to the A circuit and the B circuit. The A circuit is a circuit that outputs only a positive signal of the voltage v ₁ , and the B circuit is a circuit that outputs only a negative signal. That is, when the deviation is large with respect to the set value, the output of the A circuit is converted into a force with K ₆ , which acts in the direction of increasing the electromagnetic force of the composite electromagnet 20, exerting a force on the mass M of the impeller 3, Move 3 on the other hand,
In the case of a negative deviation with respect to the set value, the output of the B circuit is generated, and it becomes a force in the direction of weakening the electromagnetic force of the permanent magnet 21 at K ₆ , and the impeller 3 acts in the direction away from the composite electromagnet 20. When the voltage v ₁ is close to 0, the C circuit provides a bias amount for eliminating the dead zone of electromagnetic force. That is,
When v ₁ = 0, the two coils 22 shown in FIG.
A current of the same value flows through 23, but the attractive force of the composite electromagnet 20 does not change from the value of only the permanent magnet 21. Note that M is the force of only the permanent magnet when the current is 0.

Next, when the loop I is connected, the voltage v ₁ is integrated, amplified by K ₅ , and added to the set value. That is, by updating the initial set value, shortening the distance between the composite electromagnet 20 and the impeller 3, and balancing the attractive force of only the permanent magnet 21, a so-called zero power control operation is performed. Since the position change of the impeller 3 for zero power is limited to the inside of the pump casing, the impeller 3 and the case come into contact with each other for a large movement. For this reason, K ₅ includes a limit circuit to avoid this contact. The time constant of the integrator I is selected to be larger than the time constant of the integrator I in the PID controller. Further, changing the set position for zero power can also be performed by performing addition shown by a dotted line. Naturally, when the impeller 3 is in the center of the casing 2, the attractive force of the coupling magnet for rotation and the total attractive force of the composite electromagnet 20 must be adjusted to be approximately equal when the current is zero. . Furthermore, for rotation the coupling may be by a rotating magnetic field.

[0017]

As described above, according to the present invention, a permanent magnet is provided in a part of the yoke of the active magnetic bearing to form a composite electromagnet, and the composite electromagnet is controlled at zero power. A required driving force can be obtained, rigidity in the radial direction can be increased, and current consumption can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention.

FIG. 2 is a diagram showing coordinate axes for explaining a balanced state of the impeller shown in FIG.

3 is a diagram showing a core of the electromagnet shown in FIG.

4 is a cross-sectional view taken along the line IV-IV in FIG.

FIG. 5 is a block diagram showing a control system of an embodiment of the present invention.

FIG. 6 is a vertical sectional view of a clean pump proposed by the inventor of the present application in Japanese Patent Laid-Open No. 3-229987.

[Explanation of symbols]

 2 Casing 3 Impeller 4,9 Permanent magnet 6 Soft iron part 8 Rotor 20 Composite electromagnet 21 Permanent magnet 22,23 Coil PID PID controller I Integrator

Claims (3)

[Claims] 1. A disk-shaped member provided in a pump casing by a non-controllable radial magnetic bearing having a rotation transmitting function of a permanent magnet and an active magnetic bearing controlling two degrees of freedom around a rotation axis direction and a center of gravity. In the clean pump in which the impeller is magnetically supported and rotationally driven, the active magnetic bearing is constituted by a composite electromagnet having a permanent magnet in a part of its yoke, and is controlled in zero power. , Clean pump. 2. The clean pump according to claim 1, further comprising limit means for limiting a range of the zero power operation so that the impeller can rotate without contact in the pump casing. 3. The clean pump according to claim 1, wherein the composite electromagnet has two coils wound around a core for increasing and decreasing the attractive force due to the magnetomotive force of the permanent magnet.