JPS5838301A - Centrifugal impeller device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a centrifugal impeller device in which an expansion action, a compression action, etc. can be obtained by rotating a centrifugal impeller.

In an expander or compressor using a conventional centrifugal impeller, a single impeller is fixed to one end of the rotating shaft l, as shown in Fig. 1. It is common to be equipped with a rotational energy absorption mechanism such as an IC generator (in the case of an expander O) or a rotational energy generation mechanism such as an electric motor (in the case of a compressor).

However, with just this, when the impeller 2 is rotated to exert an expansion action or a compression action, the impeller sag generated by the pressure acting on the surface 35LK of the hep 3 of the impeller 2 can be avoided. lII#IC between the force trying to move the impeller 2 to the right in the figure and the force generated by the pressure acting on the rear surface 31 of the hub 30 and trying to move the impeller 2 to the left in the figure. If a difference occurs and a large force is applied to the rotating shaft that supports the impeller 2, there is a problem that the impeller 2 will become distorted. In particular, for equipment that requires high pressure, high continuous rotation, high compression ratio, etc., such as helium expansion turbines and helium Sunderevna, it is necessary to support the powerful SFC force that acts on the rotating shaft IK. The problem is that it is difficult.

In other words, in this type of device where it is preferable to rotate the impeller at a high speed of 200,000 to 300,000 degrees, the rotating shaft 1 is replaced with a rolling bearing (not suitable for high-speed rotation) or a hydrodynamic gas bearing. It is necessary to support it using magnetic bearings, etc.
It is extremely difficult to support the enormous force acting on the rotating shaft using only such special bearings for high-speed rotation.Therefore, in this type of equipment, the dynamic pressure is Efforts have been made to use a combination of a gas bearing or a magnetic bearing and a ball bearing, but these also have the disadvantage of complicating the structure and increasing the size.

By the way, one way to solve this problem is, for example, as shown in FIG. It is conceivable to prevent the force from acting on 1.

However, if the impeller 2/ is of a double suction type,
Passage 4 for guiding fluid to the impeller on both sides of the impeller 2/
etc., it becomes difficult to set a short distance between the bearing 5 that supports the rotary shaft 1 and the blade 2/. Therefore, the natural frequency of the rotating system has to be low, and it is difficult to design a high-speed rotating system.

The present invention was made with attention to such circumstances, and
A pair of impellers having a mirror-symmetric shape and having equivalent performance are mounted back to back on a common rotating shaft, and a portion of the rotating shaft located between the two impellers is supported by a bearing. Therefore, it is an object of the present invention to provide a centrifugal impeller device that can eliminate the above-mentioned disadvantages.

An embodiment in which the present invention is applied to a compressor will be described below with reference to FIG.

A pair of centrifugal impellers 12 at both ends of a common rotating shaft 11.
0 impeller 12 fixed with 13 facing back to back
．． 13 is a disc-shaped bald surface 14.160 surface 14a, 15
aK multiple blades 1 g---2l 7. - is provided in a spiral shape. And these two impellers 1
2.13 They are designed to have mirror-symmetrical shapes and exhibit equivalent performance. A portion of the rotating shaft 1 located between the two impellers 12.13 is rotatably supported by a journal bearing 18.18 and a thrust bearing 19.19.

As each of the bearings 18, 18, 19, and 19, a dynamic pressure gas bearing such as a tilting puffed bearing or a foil bearing, a magnetic bearing, or the like is employed. Further, the rotating shaft 11
A rotational energy generating mechanism 21 such as a high frequency roller is installed in the center of the
The rotary shaft 11 is coupled to the impellers 12, 13, and 4 to rotate at high speed. Note that 22 is a casing, and in this casing 22 are suction holes 2g&, 22a, facing the inlet of the impeller 12, 13,
a diffuser 221) at the outlet of the impeller 12.13;
11/220,2 connected via 22't)
2Q and a discharge port 22d communicating with these scrolls 22C and 220.

zzl good = provision.

If it has such a configuration, it is the suction port 2! ! a, 22
Gas such as helium taken in from a - impeller 12.13
is energized by the diffuser dew 2'b122''lo and guided into the space a-A/22e, 22Q, and is compressed into the casing 22 from the discharge ports zzd, z2eL.
However, according to the present invention, a pair of impellers 1 having a common rotation axis 11K, mirror-symmetrical shapes, and equivalent performance! ! , 13 are mounted back-to-back, and both impellers 12 and 13 perform the same work, so that the force applied from one impeller 12 to the rotating shaft 1IY and the other impeller's 1
3 and the thrust force applied to the rotating shaft 11 cancel each other out, resulting in a state in which almost no thrust force is applied to the rotating shaft 11. Therefore, as the Sufst bearing 19.19 provided on this rotating shaft 11, it is sufficient to use a small one for mere positioning, and there is no need to adopt a large special bearing with a complicated structure.Practical 1 Excellent effect is obtained.

Moreover, since the portion of the rotating shaft 11 located between the impellers 12 and the back surface of the shaft 3 is supported by the bearings 18.18, these bearings 18.18 and the impeller 1
2.13 can be made extremely short.

Therefore, it is easy to increase the natural frequency of the rotating system composed of the rotating shaft 11 and the impellers 12 and 13), and there is also the advantage that high-speed operation can be performed without difficulty.

In the above embodiment, a case has been described in which a rotational energy generation mechanism is arranged between the inner impellers, but it goes without saying that the present invention is not limited to such a structure.For example, as shown in FIG. It may be something. That is, in the case shown in FIG. 4, the end of the rotating shaft 11 further protrudes from the front end surface of one impeller 13, and the protruding end 1l.
The aIC rotational energy generator tala21 is connected.

Further, in each of the above embodiments, the case where the present invention is applied to a compressor has been described, but the present invention is not necessarily applicable to such an expander such as a helium expansion turbine. It is possible. In this case, however, a rotational energy absorption mechanism must be attached to the rotating shaft.

Of course, the bearing is not limited to a hydrodynamic gas bearing, a magnetic bearing, etc.; for example, in the case of low-speed rotation specifications, a roller bearing or the like may be used.

[Brief explanation of the drawing]

FIGS. 1 and 2 are partial sectional views showing a conventional example. FIG. 3 is a sectional view showing one embodiment of the invention, and FIG. 4 is a sectional view showing another embodiment of the invention. 11----=-・Rotating shaft, 12.13-To-impeller, 1
8.19---One bearing1. t 1---One rotation energy generation mechanism. Agent Patent Attorney Hiroshi Akagi

Claims (1)

[Claims] Centrifugal impellers having a mirror-symmetrical shape, having equivalent performance, and forming a running pair are mounted on a common rotating shaft, facing each other back-to-back, and the centrifugal impellers are located in front of both of the impellers on this rotating shaft. 1. A centrifugal impeller device, characterized in that its parts are rotatably supported by bearings, and a rotary shaft K11 is equipped with a rotation energy absorption mechanism or a rotational energy generation mechanism.