JPH066238Y2 - Centrifugal compressor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a centrifugal compressor for compressing gas and the like.

[Conventional technology]

A sectional view of a conventional centrifugal compressor is shown in FIG. The rotating shaft 3 is supported by bearings 4 and 5 arranged in a bearing stand 1 installed on a stand 2. The compressor casings 6 and 7 are fixed to the bearing stand 1 by bolts or the like. The rotary impeller 9 is attached to the tip of the rotary shaft 3,
A shaft sealing device 8 is installed at a portion where the rotary shaft 3 penetrates the casing 6. When the compressor having such a configuration is driven by a driver (not shown) from the right end of the rotary shaft 3 via a joint, low-pressure gas is sucked through the suction port 10 and the impeller 9 rotates. The pressure is increased by the action, and the gas is discharged as high-pressure gas through the scroll 11.

In this way, the structure in which the shaft 3 to which the impeller 9 in the casings 6 and 7 is attached is supported by the two bearings 4 and 5 arranged on one outside of the casings 6 and 7 has a simple structure. The shaft 3 can be manufactured at low cost, and the shaft 3 penetrates the casing 6 only once, so that the shaft sealing device has high reliability. Further, since the suction gas is sucked in in the axial direction and flows into the vicinity of the center of the rotation shaft, the compression efficiency of the impeller is good, so that the suction gas is preferably used.

[Problems to be solved by the device]

The biggest drawback of the conventional method is that, due to the structural limitation of the shaft seal device on the rotary shaft supported by the two bearings, a heavy impeller must be attached to the shaft tip portion far from the bearing 5. It does not happen. Since the cantilever serves as the rotating shaft in this way, the shaft displacement at the impeller position becomes large during high-speed operation, and a vibration accident is likely to occur. Therefore,
High speed operation is impossible with the conventional method, and if the high speed operation is forcibly performed, the shaft may break. In order to suppress the rotational vibration of the part extended outside between both bearings in this way, it is preferable to attach another bearing to the end of the shaft, but if a normal oil film bearing is applied, it will flow inside. Since the lubricating oil leaks into the gas, it is necessary to attach a complicated shaft seal device, which has the drawback of extending the shaft length.

The present invention solves the above-mentioned drawbacks and prevents leakage of lubricating oil,
Further, it is intended to suppress the vibration at the tip of the shaft without extending the shaft length.

[Means for Solving the Problems]

The present invention has solved the above-mentioned problems, and has a casing having a gas inlet on one side and an impeller inside the casing at the tip thereof, and penetrates through the casing on the opposite side of the gas inlet. In a centrifugal compressor provided with a rotating shaft extending to the outside and two bearings for supporting the rotating shaft outside the casing, the centrifugal compressor is provided at a tip portion further than the impeller mounting position of the rotating shaft. The electromagnetic bearing, the shaft displacement detector provided at the tip of the same electromagnetic bearing mounting position of the rotary shaft, and the current supplied to the electromagnetic bearing are controlled by the displacement signal detected by the shaft displacement detector. The present invention relates to a centrifugal compressor having a control device.

[Action]

In the present invention, an electromagnetic bearing is provided at the tip of the impeller of the rotary shaft, and an axial displacement detector is provided at the tip of the impeller, and the current supplied to the electromagnetic bearing is supplied by the displacement signal detected by the detector. It controls and suppresses the vibration of the tip of the rotating shaft. Since the electromagnetic bearing and the shaft displacement detector do not use lubricating oil, leakage of lubricating oil does not occur. Also, because it is small, it does not require a great extension of the shaft.

[Embodiment] FIG. 1 is a sectional view of an embodiment of the centrifugal compressor of the present invention. In the figure, 20 is an electromagnetic bearing device provided at the tip of the shaft 3. The parts other than the same device have the same structure as the prior art and are given the same reference numerals, and therefore the description thereof is omitted. Even if the rotary shaft 3 is a cantilever beam, the swinging motion is suppressed by the action of the electromagnetic bearing device 20, so that high-speed rotation is possible.

FIG. 2 shows an enlarged sectional view of the electromagnetic bearing device 20. The electromagnetic bearing device 20 is composed of items 12 to 19. The stator 12 of the electromagnetic bearing is fixed in the housing 19 supported by the support 14 by the casing 7 at the gas suction port at the tip of the rotary shaft 3, and the rotor of the electromagnetic bearing is made of laminated steel plates on the rotary shaft 3. Fix 13 The signal of the axial position detected by the axial displacement detector 15 is transmitted to the control circuit 18 by the cable 16. The force for suppressing the vibration of the rotating shaft is generated by causing a current to flow from the control circuit 18 to the coil on the stator side through the cable 17, thereby stabilizing the shaft vibration.

As described in detail above, in the centrifugal compressor of this embodiment,
Vibration of the tip of the rotary shaft can be suppressed without leaking the lubricating oil into the gas or extending the rotary shaft excessively.

[Effect of device]

In the present invention, an electromagnetic bearing is provided at the tip of the impeller of the rotary shaft, and an axial displacement detector is provided at the tip of the impeller, and the current supplied to the electromagnetic bearing is supplied by the displacement signal detected by the detector. Since the vibration of the shaft is controlled to be suppressed, the vibration of the tip of the rotary shaft can be suppressed without causing leakage of the lubricating oil into the gas or causing excessive extension of the rotary shaft.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention, FIG. 2 is an enlarged sectional view of a main part of the embodiment, and FIG. 3 is a sectional view of a prior art. DESCRIPTION OF SYMBOLS 1 ... Bearing base, 2 ... Stand, 3 ... Rotating shaft, 4 ... Bearing, 5 ... Bearing, 6 ... Compressor casing, 7 ... Compressor casing, 8 ... Shaft sealing device, 9 ... … Impulse wheel, 10 …… Gas inlet, 11 …… Scroll, 12 …… Electromagnetic bearing stator, 13 …… Electromagnetic bearing rotor, 14 …… Post, 15 …… Axis displacement detector, 16 …… Cable , 17 ... Cable, 18 ... Control circuit, 19 ... Housing, 20 ... Electromagnetic bearing device

Claims (1)

[Scope of utility model registration request] 1. A rotation having a casing having a gas inlet on one side and an impeller inside the casing at its tip end and penetrating through the casing on the side opposite to the gas inlet and extending to the outside thereof. A centrifugal compressor provided with a shaft and two bearings for supporting the rotary shaft outside the casing,
An electromagnetic bearing is provided at a tip portion of the rotary shaft farther from the impeller attachment position, a shaft displacement detector is provided at a tip portion of the rotary shaft than the electromagnetic bearing attachment position, and the electromagnetic bearing is supplied. A centrifugal compressor comprising a control device for controlling an electric current according to a displacement signal detected by the shaft displacement detector.