JPH0734236Y2 - Rotating machines such as turbo pumps equipped with magnetic bearings - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention has a rotor yoke (yoke) fixed to a magnetic bearing, that is, a rotary shaft, and a minute gap is provided from the rotor yoke.
An electromagnet stator yoke having an exciting coil for generating a magnetomotive force is fixed to the casing, and a displacement sensor for measuring the relative displacement between the rotor yoke and the electromagnet stator yoke is provided. Based on the output signal from the displacement sensor, In addition, the present invention relates to a turbo rotating machine such as a turbo pump or a compressor, which is provided with a magnetic bearing in which a magnetic attraction force is exerted between the rotor yoke and the electromagnet stator yoke to perform a bearing action.

[Conventional technology]

Conventionally, the motor pump provided with the magnetic bearing as described above,
As shown in FIG. 2, a rotor shaft 3 to which an impeller 2 is attached by a shaft end nut 1 includes a touch-down bearing 4 formed of a ball bearing that functions as a thrust and radial emergency bearing, and an opposite side formed of a stator and a rotor. Thrust side (lower side in the figure) radial magnetic bearing 5, thrust side radial touchdown bearing (ball bearing) 6, thrust side (upper side in the figure) radial magnetic bearing 7 consisting of a stator and rotor, and disk (rotating disc) 8a. And a stator 9 supported by a thrust magnetic bearing 8 composed of two opposing exciting coils 8b.
And is driven by an electric motor including the rotor 10. In the figure, 11 is an anti-thrust side radial sensor,
12 is the thrust side radial sensor, 13 is the thrust sensor,
14 is the suction casing of the pump, 15 is the discharge casing,
16 is a balance disc, 17 is a balance sheet, and 18 is an intermediate chamber.

During pump operation, the axial thrust unbalance due to the pump discharge pressure acting on the side plate (shroud) and the main plate of the impeller 2 is caused by the axial gap (fixed throttle part) on the outer circumference of the liner ring 2a on the main plate side of the impeller 2. ), The pressure of the fluid flowing into the intermediate chamber 18 passes through the balance disk 16 facing each other as the shaft 3 moves.
And the balance sheet 17 is changed in accordance with the displacement of the clearance (variable throttle portion) in the radial direction to balance (balance), and the residual axial thrust is provided in the rotor shaft (pump shaft) 3 by the thrust sensor. By means of 13, the displacement behavior of the rotor shaft 3 is detected and supported by controlling the exciting current of the exciting coil 8b of the thrust magnetic bearing 8.

On the other hand, regarding the displacement due to the radial load, the displacement behavior of the rotor shaft 3 is detected by the non-contact type radial sensors 11 and 12, and this is input to a negative feedback circuit (not shown) to supply the exciting currents of the load electromagnets 5 and 7. The rotor shaft 3 is levitationally supported by controlling, and the pump impeller 2 and the rotor shaft 3 are held at proper positions in the radial direction.

As described above, since the magnetic bearing can support the rotating body in a non-contact manner, it is convenient to use this in a turbomachine such as a pump or a compressor. In recent years, such a turbomachine has begun to appear. The rotor of a turbomachine has a larger weight than a vacuum device in which a magnetic bearing has been mainly used, and a fluid reaction force acting on the rotor during operation is also large. Therefore, in order to secure the bearing reaction force against this, the bearing is increased in size and increased in current, and a rotor having a weight of several thousand kilograms is supported.

[Problems to be solved by the device]

As mentioned above, the magnetic bearings are always equipped with touchdown bearings, and when the bearing power supply is lost during operation and the bearings cannot be supported, or during transportation or transportation, the magnetic bearing surfaces make mechanical contact. It is used for the purpose of preventing damage from damage.
Normally, a ball bearing is used as the touchdown bearing, and a gap smaller than the gap of the magnetic bearing is provided between the shaft and the inner ring so that the magnetic bearing does not come into contact with each other in a normal operating state. It comes into contact with and supports the rotating body only when is not operating.

Therefore, if the power supply for the magnetic bearing is lost for some reason, the rotor will initially be driven at the specified speed due to inertia even if the main power supply for driving the rotor is also cut off by the safety circuit. As a result, the touchdown bearing has a problem that it is technically extremely difficult, although it is merely the nature of a safety device because it is exposed to a large inertial force.

The present invention solves the above problems and provides a rotary machine such as a turbo pump equipped with a magnetic bearing which can be used as a touchdown bearing at low cost for general industry and can maintain a long life. Is intended.

[Means for Solving the Problems]

In order to achieve the above object, the present invention provides a hydrostatic bearing using a hydraulic pressure in addition to a touchdown bearing provided in a rotating body of a magnetic bearing. It is characterized in that it has a part of the function and the gap between the touchdown bearing and the rotary shaft is smaller than the gap of the static pressure bearing.

The hydraulic pressure may be generated by the self-generated pressure of the turbo pump, or the hydraulic pressure may be generated by another pressure source.

[Action]

According to the present invention, in addition to the touch-down bearing provided side by side with the rotating body of the magnetic bearing as described above, a hydrostatic bearing is attached, and the gap between the touch-down bearing and the rotary shaft is a hydrostatic bearing gap. Since the hydrostatic bearing is made smaller, the hydrostatic bearing is operated by utilizing the pump discharge pressure or by guiding the pressure from another pressure source, so that the hydrostatic bearing operates as long as the liquid pressure exists. Has the ability to support. Therefore, even if the self pump discharge pressure is used, as long as the pump rotational speed is high, the bearing capacity is provided and the touchdown bearing is not burdened. The overall burden on the touchdown bearing is that
Since the number of revolutions has dropped considerably, the problem of rapid drive of the bearing at high speed, which has been the most problematic in the conventional touchdown bearing, is completely eliminated.

Further, regarding the axial direction of the pump, since the hydrodynamic equilibrium action is performed during the rotation of the pump by the impeller back surface and the balance disk, the rotation speed of the pump is also lowered to a certain position, and in the case of the vertical axis. Until the pump cannot support its own weight, the rotating body is suspended by hydraulic force, and until then, the touchdown bearing is not loaded. That is, also with respect to the axial load, the load is applied to the touchdown bearing only when the rotational speed is considerably reduced.

When the pump discharge pressure is used for the static pressure bearing as described above, the static pressure bearing in the radial direction and the balance disk in the axial direction are used as the bearing devices that utilize the pump discharge pressure to provide the touchdown bearing. Can significantly reduce the role of and increase the overall life.

Further, by making the gap between the touchdown bearing and the rotary shaft smaller than the static pressure bearing gap as described above, metal contact of the portion when the load capacity of the static pressure bearing is lost is avoided, and Touchdown bearings can complement each other and maintain a long life.

〔Example〕

 Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a vertical cross-sectional view of a turbo pump (motor pump) having a magnetic bearing according to an embodiment of the present invention, in which the same reference numerals as those shown in FIG. 2 are the same or similar. It indicates a part.

In the figure, a fixed throttle portion is formed between the outer peripheral surface of the liner ring 2a integrally formed on the back surface of the main plate of the single-stage impeller 2 and the inner peripheral surface of the casing 20, and the liner ring 2a and the boss portion of the main plate are formed. An intermediate chamber 18 is formed between the integrally formed balance disc 16 and the balance disc 16 and the casing 20.
A variable throttle portion is formed by a balance sheet (plate) 17 integrally attached to the inside of the motor, and the inner diameter side of the balance sheet 17 is introduced into the motor chamber through a ball gap portion of the ball bearing 4 as a touchdown bearing or a relief passage 21. The rotor shaft 3 is in communication with each other, and is supported by a radial magnetic bearing 5, a ball bearing 6 as a touchdown bearing, a radial magnetic bearing 7 and a thrust magnetic bearing 8 and driven by an electric motor including a stator 9 and a rotor 10. This point is the same as the conventional one (Fig. 2). In the figure, 11 and 12 are radial sensors, 13 is a thrust sensor, 22a is an annular member mounted on the shaft 3 with a displacement detection ring 22, and 23 is a ring-attached member facing the radial displacement sensor 12.

However, in the present embodiment, in addition to the touchdown bearings (ball bearings) 4 and 6, static pressure bearings 31 and 32 are provided adjacent to the touchdown bearings 4 and 6, respectively, and the touchdown bearings 4 and , 6 and the rotary shaft 3 are smaller than the static pressure bearings 31, 32. Then, the pressure fluid pressurized by the impeller 2 and rectified by the guide vanes 25 is introduced into the static pressure bearing 31 through the passage 33, and the static pressure bearing 32 is discharged from the discharge passage 35. The pressure fluid is introduced through the passage 34.

Next, the operation will be described. When the pump is started in a state where the magnetic bearings 5, 7, 8 are energized, the pump rotating body causes the axial thrust of the back surface of the impeller main plate to be irrespective of the neutral point of the thrust magnetic bearing 8. With the balance mechanism, the pump is operated at a position corresponding to the variable clearance of the balance sheet 17 portion which is determined by hydraulic factors of the pump.

Also, the radial load is normally 5 or 7 for radial magnetic bearings.
And the static pressure bearings 31 and 32, and the static pressure bearings 31 and 32 have the ability to support the rotating body as long as there is hydraulic pressure. Even when using, the bearing capacity is provided as long as the pump rotational speed is high, and therefore the touchdown bearings 4 and 6 are not burdened.

The total load on the touch-down bearings 4 and 6 is as described above after the rotation speed has considerably decreased.
The problem of rapid drive of the bearing at high speed, which has been the most problematic in the conventional touchdown bearing, is completely relieved.

This also applies to the above-mentioned axial direction of the pump. In the case of the vertical axis, when the pump rotation speed falls to a certain value and the vertical axis of the pump cannot support the pump's own weight, the rotating body keeps the pump's hydrodynamics. Floating due to the equilibrium action,
Until then, no load is applied to the touchdown bearing 4. That is, also with respect to the axial load, the load is applied to the touchdown bearing only when the rotational speed is considerably reduced.

According to this embodiment, the static pressure bearings 31 and 32 in the radial direction and the balance disc 16 in the axial direction are both provided with a supporting device for utilizing the pump discharge pressure. It can be significantly reduced and the life of the entire pump can be extended.

Further, by making the gap between the touchdown bearings 4 and 6 and the shaft 3 smaller than the hydrostatic bearing gap, avoiding metal contact of the hydrostatic bearings 31 and 32 when the load capacity is lost. You can That is, the hydrostatic bearings 31 and 32 and the touchdown bearings 4 and 6 can complement each other to maintain a long life.

In the above embodiments, the structure in which the discharge liquid of the pump is introduced into the static pressure bearings 31 and 32 has been described, but it is also possible to introduce pressure fluid from an external pressure source into these static pressure bearings 31 and 32. In this case, it is not affected by the decrease in the rotation speed of the pump, and can be widely applied to general turbo rotating machines such as compressors other than the pump. Further, it is needless to say that the same can be applied to the horizontal axis type.

If the loss due to the injection of the pressure liquid into the hydrostatic bearing is a problem, a solenoid valve is installed at the injection port to keep it closed so that the liquid is not injected. It is possible to reduce the loss without impairing the effect of the present invention as described above by starting the liquid injection by opening and causing the function of the hydrostatic bearing.

[Effect of device]

As described above, according to the present invention, in turbomachines such as pumps that use magnetic bearings, in addition to touchdown bearings for bearings in emergency situations such as loss of bearing excitation current, pump discharge pressure or A static pressure bearing that uses an external pressure source is installed side by side, and the gap between the touchdown bearing and the rotating shaft is made smaller than the static pressure bearing gap so that the touchdown bearing can start and drive contact with the shaft. The performance requirements for the touchdown bearing can be reduced, and not only can the life be extended and the price can be reduced, but the load on the hydrostatic bearing can also be reduced. Since metal contact of the hydrostatic bearing when capacity is lost can be avoided, the hydrostatic bearing and the touchdown bearing can complement each other and maintain a long life.

When the self-generated pressure liquid from the pump is used as the pressure liquid to be guided to the hydrostatic bearing as described above, the device becomes compact, and when an external pressure source is used, it should be widely applied to turbomachines other than the pump. Is possible.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a turbo pump provided with a magnetic bearing according to an embodiment of the present invention, and FIG. 2 is a vertical sectional view showing a conventional touchdown bearing application example. 2 …… impeller, 4,6 …… touchdown bearing, 5,7 …… radial magnetic bearing, 8 …… thrust magnetic bearing, 11,12 …… radial sensor, 13 …… thrust sensor, 16 …… balance disc , 17 …… Balance sheet, 31, 32 …… Hydrostatic bearing.

Claims (3)

[Scope of utility model registration request] 1. In a rotary machine such as a turbo pump which supports and operates a rotating body by a magnetic bearing, a static pressure bearing using hydraulic pressure is provided in addition to a touchdown bearing provided in addition to the magnetic bearing. A turbo bearing provided with a magnetic bearing characterized in that the pressure bearing is made to perform a part of the function of the touchdown bearing, and the gap between the touchdown bearing and the rotating shaft is made smaller than the static pressure bearing gap. Rotating machines such as pumps. 2. A rotary machine such as a turbo pump provided with a magnetic bearing according to claim 1, wherein the pressure liquid generated by the pump is introduced into the hydrostatic bearing. 3. A rotary machine such as a turbo pump provided with a magnetic bearing according to claim 1, wherein the pressure liquid is introduced into the hydrostatic bearing from another pressure source.