JP2005076511A - Oil free screw compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oil free screw compressor capable of improving working efficiency in maintenance of a bearing, reducing length of an output shaft of a motor, and improving assembly accuracy thereof. <P>SOLUTION: In the oil free screw compressor having a rotor shaft 25 of one of screw rotor 16 of a male and female pair of screw rotors rotatably stored in a compressor main body 11 and meshing mutually, and the output shaft 33 of the motor driving the same provided coaxially and in such a manner capable of rotating as one body, and having an end part opposite to a rotor shaft 25 of the output shaft 33 rotatably supported by a bearing 34 arranged inside of an end surface of a motor casing 13 of the motor 14, a cylindrical body 2 closed in a rotor 34 side, surrounding outer circumference part of the bearing 34 and opened in a side facing the inside of the end surface is put between the rotor 32 of the motor 14 and the bearing 34. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an oil-free screw compressor that does not lubricate a rotor chamber.

  Conventionally, of a pair of male and female screw rotors that are rotatably accommodated in a compressor body, the rotor shaft of one screw rotor and the output shaft of a motor that drives the same are coaxially provided so as to be integrally rotatable. An oil-free screw compressor in which an end portion of the output shaft opposite to the rotor shaft is rotatably supported by a bearing disposed inside an end surface of a motor casing of the motor is known ( For example, see Patent Document 1.) Patent Document 1 discloses an oil-free screw compressor 10 shown in FIG. 2, and this oil-free screw compressor 10 is integrally coupled to a compressor body 11 and a compressor casing 12 of the compressor body 11. The motor 14 is a drive unit having the motor casing 13.

  The rotor chamber 15 in the compressor casing 12 accommodates a pair of male and female screw rotors that are rotatably meshed with each other. In FIG. 2, only the screw rotor 16 on the drive side of the rotor rotor 15 is shown. The screw rotor 16 is a male rotor. Further, the compressor casing 12 is formed with a suction port 17 opened at one end of the rotor chamber 15 and a discharge port 18 opened at the other end. The rotor shaft 21 on the discharge side of the screw rotor 16 extends through a shaft seal portion 22 and is rotatably supported by bearings 23 and 24. The rotor shaft 25 on the suction side of the screw rotor 16 has a shaft seal portion. 26, and is rotatably supported by a bearing 27.

  The motor 14 includes a stator 31 and a rotor 32 in a motor casing 13 positioned on the suction side of the compressor body 11, and an output shaft 33 extending through the center of the rotor 32 is on the suction side of the screw rotor 16. The portion of the output shaft 33 extending toward the screw rotor 16 is also the rotor shaft 25. Further, the shaft end portion of the output shaft 33 extending to the opposite side is rotatably supported by a bearing 34 disposed inside the end surface of the motor casing 13. Further, a shaft seal member 35 is interposed in the portion of the output shaft 33 between the rotor 32 and the bearing 34, and the motor casing 13 surrounds the space portion between the bearing 34 and the shaft seal member 35. A protrusion 36 is formed on the end face member.

A piston 42 fitted in the fluid pressure space 41 is fixed to the end of the output shaft 33 on the bearing 34 side so that the pressure of the pressurized fluid that enters and exits the fluid inflow / outlet port 43 is increased. Thus, the output shaft 33 and the rotor shaft 25 are urged in the direction from the suction side toward the discharge side. The bearings 23, 24, 27 and 34 are lubricated through the through holes 44, 45, 46 and 47.
JP 2002-188586 A

  In general, in the case of the oil-free screw compressor including the oil-free screw compressor 10 described above, since the rotational speed of the screw rotor 16 is large, if the natural rotational speed of the screw rotor 16 is low, resonance easily occurs and resonance occurs. And it is impossible to continue driving. Therefore, not only the rotor shaft 25 and the output shaft 33 are supported by the bearings 23, 24, and 27, but also the end portion of the output shaft 32 opposite to the screw rotor 16 is provided with the bearing 34, thereby supporting the structure. It has been adopted.

Further, in the oil-free screw compressor 10, the output shaft 33 and the rotor shaft 25 are urged through the piston 42 in the direction from the suction side toward the discharge side, thereby causing the screw rotor 16 to be caused by the pressure of the compressed gas. Although a strong force in the direction from the acting discharge side toward the suction side is suppressed from acting on the bearing 34, it is inevitable that a force in the direction from the discharge side toward the suction side acts on the bearing 34 to some extent. . Therefore, for the oil-free screw compressor 10, when a certain period of operation has elapsed, the bearing 34 must be maintained, and parts near the bearing 34 need to be reduced to simplify the maintenance work. There is. In the case of the oil-free screw compressor 10, it is required to eliminate the shaft sealing member 35 and the protruding portion 36, but if these are eliminated, the oil supplied to the bearing 34 is discharged toward the rotor 32 of the motor 14, There is a problem that oil enters between the stator 31 and the rotor 32 of the motor 14 and causes power loss due to the viscosity of the oil.
Furthermore, in order to increase the assembling accuracy of the rotor 32, there is a demand for making the output shaft 33 penetrating the rotor 32 as short as possible.
The present invention has been made in order to eliminate the above-mentioned conventional problems and meet the above-mentioned demands, and is an oil that can improve the workability of bearing maintenance, shorten the motor output shaft, and improve its assembly accuracy. A free screw compressor is to be provided.

  In order to solve the above-mentioned problems, the present invention provides a rotor shaft of one screw rotor of a pair of male and female screw rotors that are rotatably accommodated in a compressor body and an output shaft of a motor that drives the screw shaft. And the end of the output shaft opposite to the rotor shaft is rotatably supported by a bearing disposed inside the end surface of the motor casing of the motor. In the oil-free screw compressor, a cylindrical body is formed between the rotor of the motor and the bearing, and the rotor side is closed, the outer periphery of the bearing is surrounded, and the side facing the inner end face is opened. An intervening configuration was adopted.

  According to the oil-free screw compressor of the present invention, power loss due to the ingress of oil between the rotor and stator of the motor is minimized, maintenance workability is improved, and the motor output shaft is shortened. There is an effect that it becomes possible.

Next, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows an oil-free screw compressor 1 according to the present invention, and portions common to the oil-free screw compressor 10 shown in FIG.
In the oil-free screw compressor 1, the cylindrical body 2 is interposed between the rotor 32 of the motor 14 and the bearing 34. The cylindrical body 2 includes a substantially circular flat surface through which the output shaft 33 passes and a cylindrical portion connected to the outer peripheral edge of the flat surface. The rotor 32 is closed and surrounds the outer peripheral portion of the bearing 34. And the side which faces the end surface inner side of the motor casing 13 is comprised so that it may open. The cylindrical body 2 can rotate integrally with the rotor 32 and the output shaft 33 without contacting the motor casing 13.

  With such a configuration, the interval between the rotor 32 and the bearing 34 is shortened, the output shaft 33 is shortened accordingly, and the assembly processing accuracy of the rotor 32 is easily improved. Further, the cylindrical body 2 prevents the oil supplied to the bearing 34 from entering between the stator 31 and the rotor 32, thereby minimizing power loss due to oil viscosity. Yes.

  The oil-free screw compressor 1 according to the present invention is suitable for semiconductor manufacturing equipment, precision equipment manufacturing equipment, food processing equipment, and the like that require clean compressed air, for example.

It is sectional drawing of the oil-free screw compressor which concerns on this invention. It is sectional drawing of the conventional oil-free screw compressor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Oil free screw compressor 2 Cylindrical body 10 Oil free screw compressor 11 Compressor main body 12 Compressor casing 13 Motor casing 14 Motor 15 Rotor chamber 16 Screw rotor 17 Suction port 18 Discharge port 21 Rotor shaft 22 Shaft seal 23, 24 Bearing 25 Rotor shaft 26 Shaft sealing portion 27 Bearing 31 Stator 32 Rotor 33 Output shaft 34 Bearing 35 Shaft sealing member 36 Protruding portion 41 Fluid pressure space 42 Piston 43 Fluid outflow inlet 44, 45, 46, 47 Through hole

Claims (1)

Of the pair of male and female screw rotors that are rotatably accommodated in the compressor main body, the rotor shaft of one screw rotor and the output shaft of the motor that drives the same are coaxially provided so as to be integrally rotatable, In the oil-free screw compressor, the end of the output shaft opposite to the rotor shaft is rotatably supported by a bearing disposed on the inner side of the end surface of the motor casing of the motor. The oil-free screw compression is characterized in that the rotor side is closed between the bearing and the bearing, the outer peripheral portion of the bearing is surrounded, and an open cylindrical body is interposed on the side facing the inner end face. Machine.

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