JPH0486395A - Thrust force regulating device - Google Patents

Abstract

PURPOSE:To reduce a thrust force and facilitate its regulation by dividing the inner part of a casing by a disc into two spaces to form a balance piston, and communicating the fluid inlet side and back surface side of an impeller with the back surface side and front side of the disc by pipelines, respectively. CONSTITUTION:An impeller 10 is directly connected to an electric motor shaft 11, and its circumference is covered with a casing 12. The axial force adding to the electric motor shaft 11, or a thrust force is received by the thrust bearing 14 of the electric motor 13. In this case, a disc 15 is connected to the other end of the electric motor shaft 11, and the space in a casing 16 is divided into two spaces by the disc 15 and a labyrinth shield 17 around it to form a balance piston. A casing hole 20 in the impeller back surface part and a casing hole 21 situated on the front surface side of the disc 15 are connected to each other by a pipeline 19. A casing hole 23 situated on the impeller fluid inlet side and a casing hole 24 on the back surface side of the disc 15 are connected to each other by a pipeline 22.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a thrust force adjustment device, and can be applied to a turbo rotary fluid machine of the type in which an impeller is directly attached to the shaft end of an electric motor.

BACKGROUND ART FIG. 4 shows an example of a turbo-type rotary fluid machine. In a turbo-type rotary fluid machine such as a blower, when an impeller mounted directly on the shaft rotates, an axial force is generated due to the pressure difference between the fluid inlet side and the back side of the impeller. In other words, thrust force is generated. This thrust force is received by the thrust bearing, but it is necessary to prevent this from becoming excessive.

In the example shown in FIG. 4, a balance piston 1 is provided in a part of a turbo-type rotary fluid machine, and a casing 2 housing the balance piston 1 is provided.
An air pipe 4 called a balance pipe is provided between the intake part 3 and the intake part 3 . As the turbo rotary fluid machine rotates, a thrust force is generated in the direction of the suction section 3 on the shaft 6 to which the impeller 5 is directly attached. The pressure generated in the suction section 3 is guided to the balance piston 1 by the air pipe 4 and acts to attract the balance piston 1, thereby balancing the thrust force.

FIG. 5 shows another method of balancing thrust forces. According to FIG. 5, a labyrinth seal 8 is provided on the back surface of the impeller 7, and a hole 9 is formed in the impeller 7. This balances out the pressure difference between the front and back surfaces of the impeller 7, which are the fluid inlet sides, and balances the thrust force.

Problems to be Solved by the Invention In a turbo rotary fluid machine of the type in which an impeller is directly mounted on the shaft end of an electric motor, the conventional thrust I balance method has the following drawbacks.

(1) If a balance piston is provided on the main body side of a so-called turbo-type rotary fluid machine other than an electric motor, the overhang becomes long and vibration problems are likely to occur.

(2) In the type in which a labyrinth is provided on the back of the impeller as shown in FIG. 5, there is a problem in that the labyrinth is not long enough for disassembly, resulting in large leakage.

(3) It is difficult to adjust the thrust force when operating conditions change.

(4) If the thrust force is large, the power loss of the thrust bearing is large.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a thrust force adjusting device that eliminates the drawbacks mentioned above.

Means for Solving the Problems To achieve the above object, the present invention provides a device for adjusting the thrust force generated in a turbo-type rotary fluid machine in which an impeller is directly attached to the other shaft end. A balance piston is constructed by dividing the interior of the casing covering the disk into two spaces by the attached disk, and the fluid inlet side of the impeller and its back side, and the back side and front side of the disk, respectively. A thrust force adjustment device is provided in direct or controlled communication via piping.

According to the means described in item 1 of "Operation", since the pressure on the fluid inlet side of the impeller is lower than that on the back side thereof, a thrust force is generated that pulls the shaft to which the impeller is fastened toward the inlet side.

By connecting the fluid inlet side of the impeller to the back side of the disk via piping, a force is generated that pulls the shaft to which the disk is fastened toward the back side, which balances the thrust force from the impeller. Furthermore, by connecting the output side or the back side of the impeller to the front side of the disk via piping, it is possible to promote the force that tends to move the shaft toward the back side of the disk.

Embodiment FIG. 1 shows a first embodiment of a thrust force adjusting device according to the present invention, in which an impeller of a turbo-type rotary fluid machine such as a blower is directly connected to the end of a motor shaft.

In FIG. 1, an impeller 10 is directly connected to a motor shaft 11 and is surrounded by a casing 12.

The structure is such that the axial force applied to the motor shaft 11, that is, the thrust force, is received by the thrust bearing 14 of the motor 13.

A disc 15 is coupled to the other end of the motor shaft 11, and a casing 16 covers the disc 15. This casing 16
The inner space is divided into two spaces by a disk 15 and a labyrinth seal 17 around it, forming a balance piston. Reference numeral 18 is a support seal.

The pipe 19 is connected to the casing hole 20 on the back of the impeller.
4. The pipe 22 connects the casing hole 21 on the front side of the pipe 15 with the casing hole 23 located on the impeller fluid inlet side and the casing hole 24 on the back side of the disk 15. There is.

When the impeller 10 is rotating, the pressure on the fluid inlet side is lower than that on the back side, so a force is generated that pulls the motor shaft 11, to which the impeller 10 is connected, toward the front, which is the fluid inlet side. There is.

By connecting the back and front surfaces of the impeller 10 and the front and back surfaces of the disk 15 through the pipes 19 and 20, the thrust forces acting on the impeller 10 and the disk 15 are in opposite directions.

Therefore, by appropriately selecting the diameter of the disk 15, the vector sum of these thrust forces can be made zero. Generally, the vector sum of thrust forces acts on the thrust bearing 14, so if the thrust force is reduced, it is possible to reduce power loss.

Since the generated thrust force changes depending on the operating condition of the turbo-type rotary fluid machine, it is desirable that the force applied to the thrust bearing always act in a constant force and direction. Examples corresponding to this are shown in FIGS. 2 and 3.

According to FIG. 2, a pressure regulating valve 25 is inserted into the pipe 22,
A gap sensor 26 is installed in the disc casing 16 to detect changes in the distance between the disc casing 16 and the end face of the motor shaft 2. The output of the gap sensor 26 is connected to a displacement gauge 27, and the output of the displacement gauge 27 is further connected to a controller 28 to control the pressure regulating valve 25.

If the thrust bearing 14 is an oil bearing, the motor shaft 11 will be slightly displaced in the axial direction depending on the direction and magnitude of the thrust force applied to the motor shaft 11. This axial displacement is detected by the gap sensor 26, and the displacement meter 27 sends an electric signal corresponding to the amount of displacement to the controller 28, which controls the pressure regulating valve 25.

By controlling the pressure regulating valve 25, the pressure on the back side of the disk 15 can be changed, thereby changing the thrust force generated in the disk 15 in the opposite direction.
The force applied to the thrust bearing can be kept constant at all times.

According to the embodiment shown in FIG.
and a pressure transducer 293 in both piping 19.22.
Connect 0. The output of the pressure transducer 29,30 is connected via a controller 31 to control a pressure regulating valve.

The pressure transducers 29 , 30 detect the pressure on the back side and the fluid inlet side of the impeller 10 and send these values to the controller 31 .

The controller 31 inputs the detected pressure value and performs a preset calculation to determine the thrust force generated in the impeller 10 and controls the pressure regulating valve 25. Thereby, the thrust force acting on the disk 15 can be controlled by changing the pressure on the front surface of the disk.

In order to improve control accuracy, the pressure regulating system can also be configured by combining the embodiment shown in FIG. 2 and the embodiment shown in FIG.

Effects of the Invention According to the present invention, the following effects can be achieved.

(1) Even when excessive thrust force is applied to the motor shaft from a rotating fluid machine that acts as a load, this can be reduced, thereby preventing damage to the shaft and bearings and further reducing power loss. I can do it.

(2) By adjusting the pressure inside the piping, the thrust force can be controlled within an appropriate range of magnitude and direction.

(3) Thrust balance can be maintained at all times, so
There is no need to provide the electric motor with a large thrust bearing, and the cost of the electric motor can be reduced.

[Brief explanation of drawings]

FIG. 1 is a partial sectional view of a rotary fluid machine to which the thrust force adjusting device according to the present invention is applied, FIGS. 2 and 3 are partial sectional views showing other embodiments of the thrust force adjusting device according to the present invention, and FIG. The figure is a sectional view of a blower illustrating a conventional device.
The figure is a sectional view of a main part showing another conventional example. 10... Impeller, 11... Motor shaft, 12... Casing of rotating fluid machine, 13... Electric motor, 14... Thrust bearing, 15... - Sink, 17... - Le, 19.22... ・・Pressure regulating valve, displacement gauge, 28.31・ device. = 8 Disc, 16...Disc kerabilinse seal, 18...Shaft piping, 20, 21, 23.24...Hole, 2526...Gap sensor, 27...Controller, 29.30...Pressure conversion

Claims (1)

[Claims] In a device that adjusts the thrust force generated in a turbo-type rotary fluid machine with an impeller attached directly to the shaft end, the interior of the casing covering the disk is divided into two spaces by a disk attached to the other shaft end. A thrust force adjusting device comprising a balance piston, and the fluid inlet side and rear side of the impeller are in direct or controlled communication with the rear side and front side of the disk, respectively, through piping.