KR100829665B1 - Two stage type screw compressor - Google Patents

Abstract

The present invention forms a gas passage connecting the first stage compressor main body on the low pressure side, the second stage compressor main body on the high pressure side, and the discharge port of the first stage compressor main body and the suction port of the second stage compressor main body. Itself, a motor, a drive shaft driven by the motor, a rotor shaft extending into the box body from each of the first stage compressor body and the second stage compressor body, and the power of the drive shaft to the respective rotor shafts. And a mechanical seal disposed between the drive shaft and the casing of the box through which the drive shaft penetrates. In this two-stage screw compressor, intrusion of air and leakage of the working gas to the outside are prevented, and even if the working gas is toxic, it does not harm the outside.

2-stage screw compressor, pinion gear, gearbox, casing, rotor shaft, cap ring

Description

Two Stage Screw Compressor {TWO STAGE TYPE SCREW COMPRESSOR}

1 is a cross-sectional view of a two-stage screw compressor according to an embodiment of the present invention.

Fig. 2 is a sectional view of a two stage screw compressor according to another embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

1: two stage screw compressor

11: first stage compressor main body

12: gear box

13: second stage compressor body

14: motor

15, 16, 17: casing

21, 29: screw rotor

22, 31: inlet

23, 32: discharge port

24: rotor shaft

25, 34: pinion gear

27, 36: mechanical seal

35: output shaft

37: drive shaft

38: capping

39: fire gear

[Document 1] Japanese Utility Model Publication No. Hei 7-38683

The present invention relates to a two-stage screw compressor applied to a refrigerating device using, for example, a toxic substance such as NH ₃ as a refrigerant.

2. Description of the Related Art Conventionally, a two-stage screw compressor applied to a refrigerating device using a toxic substance such as NH ₃ as a refrigerant is known (see, for example, Japanese Utility Model Publication No. H7-38683).

Japanese Utility Model Laid-Open Publication No. 7-38683 discloses a refrigerating device in which a motor, a first stage compressor body, and a second stage compressor body are coaxially arranged, and each casing is integrally coupled to NH ₃ as a refrigerant. A two stage screw compressor is used. The motor is located on the suction side of the first stage compressor main body, and is coupled to the output shaft of the motor via a rotor shaft and a cap ring of one screw rotor in the first stage compressor main body.

In the circumference of the rotor shaft and the output shaft of the first stage compressor main body, a mechanical seal portion for cooling and lubricating oil is injected on the sliding surface between the rotating portion and the fixed portion, and the accommodation space of the capping and the first stage compressor It is formed so as to seal the gas leakage between the main body and the motor and the respective internal spaces.

The refrigeration unit is provided with a circulation passage of a refrigerant, as is known, comprising a compressor, a condenser, an expansion valve and an evaporator. And when the evaporation temperature of the refrigerant | coolant in this evaporator becomes low temperature of -45 degreeC--75 degreeC, the suction pressure of the 1st stage compressor main body which directly communicates with an evaporator becomes below atmospheric pressure. On the other hand, the capping accommodation space and the space in the motor are at atmospheric pressure, and there is a possibility that air may enter the first stage compressor main body, particularly on the suction side, from the accommodation space via the sliding surface of the mechanical seal. .

Lubricating oil is injected to this sliding surface as mentioned above, and when this lubricant contacts air from the said accommodation space, carbide of a lubricating oil will generate | occur | produce, and this will accumulate in the said sliding surface and, as a result, in the said sliding surface There exists a problem that sealing function falls.

When the compressor is stopped, the suction port of the first stage compressor main body is at a pressure higher than atmospheric pressure. If the sealing function is degraded as described above, NH _{3, which} is toxic from the site of the sliding surface, has a space for the capping. And leaking out of the device via the space of the motor.

Moreover, when NH ₃ leaks into a motor in this way, the problem arises that the coil winding line in a motor corrodes.

SUMMARY OF THE INVENTION The present invention has been made to solve such a conventional problem, and has a high reliability that prevents intrusion of air and leakage of working gas to the outside and does not cause harm to the outside even if the working gas is toxic. It is an object of the present invention to provide a single screw compressor.

In order to solve the above problems, the present invention connects the first stage compressor main body on the low pressure side, the second stage compressor main body on the high pressure side, and the discharge port of the first stage compressor main body and the suction port of the second stage compressor main body. A box forming a gas passage, a motor, a drive shaft driven by the motor, a rotor shaft extending into the box from each of the first stage compressor body and the second stage compressor body, and the drive shaft Is a two-stage screw compressor comprising a mechanical seal disposed between the drive shaft and the casing of the box through which the drive shaft penetrates, and transmits power to each of the rotor shafts.

In the two-stage screw compressor of the above configuration, the power transmission mechanism may consist of a pinion gear provided on each rotor shaft and a bull gear provided on the drive shaft, and the bull gear meshes with each pinion gear. .

In the two-stage screw compressor of the above configuration, the first stage compressor main body, the second stage compressor main body, and the box body may be integrated.

In addition to the above configuration, the motor may be configured to be controlled for rotation speed by an inverter.

According to the two-stage screw compressor according to the present invention, it is possible to prevent intrusion of air and leakage of working gas to the outside, and to improve reliability without causing harm to the outside even if the working gas is toxic.

Next, one Embodiment of this invention is described according to drawing.

Fig. 1 shows a two stage screw compressor 1 according to the present invention, which is composed of a first stage compressor main body 11 on the low pressure side and a first stage compressor main body 11. , The second stage compressor main body 13 of the high pressure side, which is integrally arranged via the gear box 12 and on the same side of the gear box 12, and on the side opposite to the side of the gear box 12; The motor 14 arrange | positioned is provided. In addition, "the same side of the gear box 12" and "the said side of the gear box 12" said here mean the left side on drawing from a reference | standard with respect to the gear box 12 as a reference. In addition, "an opposite side" means the right side on drawing from a reference | standard with respect to the gear box 12 as a reference | standard. Moreover, each casing 15, 16, 17 of the 1st stage compressor main body 11, the 2nd stage compressor main body 13, and the gear box 12 is formed integrally.

The first stage compressor main body 11 has a pair of male and female screw rotors 21 rotatably provided to each other, and has a suction port 22 on the side spaced from the gear box 12, while It has the discharge port 23 opened in the gear box 12 on the opposite side. In addition, one rotor shaft 24 of the screw rotor 21 extends into the gear box 12, and a pinion gear 25 is provided at the shaft end of the rotor shaft 24. In addition, the suction side of the first stage compressor main body 11 is on a non-drive side separated from the motor 14, and the end of the rotor shaft 28 on the suction side extending through the bearing is completely blocked from the outside.

The second stage compressor main body 13 has a pair of male and female screw rotors 29 rotatably provided to each other, and has a suction port 31 opened in the gear box 12, while on the opposite side to this. The discharge port 32 is provided in the side spaced apart from the gear box 12. In addition, one rotor shaft 33 of the screw rotor 29 extends into the gear box 12, and a pinion gear 34 is provided at the shaft end of the rotor shaft 33. Like the first stage compressor main body 11, the shaft end of the rotor shaft on the suction side of the second stage compressor main body 13 is also completely blocked from the outside.

The drive shaft 37 penetrating the casing 17 via the mechanical seal 36 of the gear box 12 is coupled to the output shaft 35 of the motor 14 by the cap ring 38. In addition, a bull gear 39 meshing with the pinion gears 25 and 34 is provided at the shaft end of the drive shaft 37 extending into the gear box 12. Moreover, it is preferable to provide the bearing which supports the drive shaft 37 rotatably in addition to the mechanical seal 36 in the site | part which shows the mechanical seal 36.

In the two-stage screw compressor 1 having the above configuration, the space in the gear box 12 forms an intermediate flow path, and the suction pressure and the second suction pressure in the suction port 22 of the first stage compressor main body 11. However, in the state of the intermediate pressure between the discharge pressures in the discharge port 32 of the compressor main body 13, even if the said suction pressure becomes below atmospheric pressure generally, the intermediate pressure becomes above atmospheric pressure.

In this two-stage screw compressor 1, even if the suction pressure of the first stage compressor main body is equal to or lower than the atmospheric pressure, the shaft end of the rotor shaft 28 on the suction side is completely blocked from the outside. Air does not enter from the end. In addition, since the space in the gear box 12, which is spaced apart from the outside via the mechanical seal 36, that is, the intermediate flow path is in a state above atmospheric pressure, air does not intrude from the outside, and the mechanical seal 36 is also here. The occurrence of the above-mentioned carbide prevents the deterioration of the sealing function, and also causes the corrosion of the coil winding line in the motor 14 separated from the gear box 12 without causing harm to the outside even if the working gas is toxic. Also, the reliability of the two-stage screw compressor 1 is improved.

In addition, from the viewpoint of energy saving, the two-stage screw compressor 1 may be capable of adjusting the capacity by controlling the rotation speed of the motor 14 by the inverter. For example, in the case where the slide valve is installed in the first stage compressor main body 11 on the low pressure side of the two-stage screw compressor 1 described above so that the capacity can be adjusted, in particular, the slide valve is kept in the state of so-called unloading. At this time, the amount of suction to the second stage compressor main body 13 becomes larger than the discharge amount from the first stage compressor main body 11, so that the intermediate pressure is lower than atmospheric pressure, which may cause the same problems as in the prior art.

However, in the case where the capacity can be adjusted using an inverter, even if the rotational speed is lowered and maintained in an unloaded state, the intermediate pressure is always at or above atmospheric pressure, and there is no fear that the same problems as in the prior art occur. In addition, when the capacity can be adjusted using an inverter, the structure is simpler than that of a screw compressor in which capacity adjustment is performed by a slide valve as in the prior art, and reliability is high, unlike a screw compressor that is performed by a slide valve. .

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

Fig. 2 shows a two stage screw compressor 1 'according to the present invention, which has a first stage compressor main body 11 on the low pressure side and the first stage compressor main body 11'. ), The second stage compressor main body 13 of the high pressure side, which is integrally arranged on the same side of the gear box 12 via the gear box 12, and the respective compressor side of the gear box 12; And a motor 14 are arranged on the same side. In other words, only the positions of the motor 14 and the drive shaft 37 (including the capping and the mechanical seal) are different from those of Fig. 1, and the remaining configuration is the same.

As described above, in the present invention, there is a box that forms a gas passage connecting the discharge port of the first stage compressor main body 11 and the suction port of the second stage compressor main body 13, which is a characteristic configuration of the present invention, and the motor ( 14, the drive shaft 37 penetrates the box after arranging the mechanical seal 36, and a mechanism for transmitting the power of the drive shaft 37 to both compressors is provided in the box. As long as it satisfy | fills, the positional relationship of the 1st stage compressor main body 11, the 2nd stage compressor main body 13, and the motor 14 may be comprised.

In addition, the mechanism which transmits the power of the drive shaft 37 to both the compressors 1 is not limited to the mechanism of the said embodiment as long as the said characteristic structure of this invention is satisfied. For example, the structure in which the drive shaft 37 is directly connected to the rotor shaft of one compressor and the power transmission to the rotor shaft of the other compressor is performed by a gear mechanism may be sufficient.

According to the present invention, it is possible to provide a highly reliable two-stage screw compressor which prevents the intrusion of air and leakage of the working gas to the outside and does not cause external harm even if the working gas is toxic.

Claims (4)

Two stage screw compressor, The first stage compressor main body on the low pressure side, The second stage compressor main body on the high pressure side, A box body forming a gas passage connecting the discharge port of the first stage compressor body and the suction port of the second stage compressor body; Motor, A drive shaft driven by the motor, A rotor shaft extending into the box body from each of the first stage compressor body and the second stage compressor body, A power transmission mechanism which transmits the power of the drive shaft to each of the rotor shafts and is in the box body; A two-stage screw compressor comprising a mechanical seal disposed between the drive shaft and a casing of the box through which the drive shaft passes. The method of claim 1, wherein the power transmission mechanism, Pinion gears installed on the rotor shafts, It is made of a bull gear installed on the drive shaft, And said bull gear engages said respective pinion gear. The two-stage screw compressor according to claim 1, wherein the first stage compressor body, the second stage compressor body, and the box body are integrated. The two-stage screw compressor of claim 1, wherein the motor is rotationally controlled by an inverter.

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