JPH06159280A - Cooling type two-stage oil-feedless type screw compressor - Google Patents

Abstract

PURPOSE:To miniaturize a cooling system, to lower the cost of a compressor, and to simplify the arrangement of a pipe line and the structure of the compressor without a liquid cooled jacket for cooling a compressor body being laid in a casing for the compressor body, and without a liquid cooling means being laid in the compressor body. CONSTITUTION:A pair of female and male rotors 5, 6 housed in a casing 7 are supported by bearings 9 to 11, and meshed with each other by means of a timing gear 12 while shaft seal devices 13, 14 prevents entrance of oil. In this arrangement, for example, a plurality of cooling fans 16 are formed on the outer wall of the casing 7, along planes orthogonal to the shafts of the rotors 5, 6 so as to increase the heat radiation area. Further, air subjected heat-exchange by the cooling fans 16 is led into a cooling fan through natural convention, and thereafter, is discharged outside from a discharge port. That is, it is possible to eliminate the necessity of a liquid cooled jacket which has been conventionally incorporated to the casing 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air-cooled two-stage oilless screw compressor in which compressors are connected in two stages, and a discharge gas is cooled by a cooler and discharged to a device to be used. Regarding

[0002]

2. Description of the Related Art A conventional technique is disclosed in Japanese Patent Laid-Open No. 1-116297, which has a structure in which a gas compressed by a compressor body is cooled by an air-cooled cooler.
A liquid for cooling (coolant) is circulated in the jacket of the casing of the compressor body to cool the entire compressor body,
A device (coolant cooler) for cooling this coolant with an air-cooled cooler and a coolant circulation device such as a coolant pump were provided.

[0003]

In the above prior art, the temperature difference between the coolant after cooling the inside of the casing of the casing and the air as the cooling medium is small, and the coolant cooler becomes large in size to cool the compressed gas. It required a heat transfer area almost the same as that of the vessel. Furthermore, a coolant circulating device such as a coolant pump for circulating the coolant in the machine, and a protective device such as a coolant temperature relay for protecting the coolant circulating system are required, which makes the compressor package compact and simplifies the equipment inside the package. It was hindered.

An object of the present invention is to provide an air-cooled two-stage oil-free type screw compressor with an optimal casing cooling method and structure in order to reduce the size and cost of the compressor cooling system. .

[0005]

In order to achieve the above object, an air-cooled two-stage oilless screw compressor according to the present invention comprises:
A low-pressure stage compressor body (one-stage compressor body) and a high-pressure stage compressor body (two-stage compressor body) that consist of a pair of male and female screw rotors that mesh with each other, a casing that houses the screw rotors, and an air-cooled low pressure It consists of a stage side cooler (intercooler) and a high-pressure stage side cooler (aftercooler), etc. Furthermore, the casing for cooling the compressor body is not attached to the casing, and cooling liquid (coolant) is supplied to the jacket. The inflow and heat exchange device was omitted.

Further, a plurality of cooling fins are provided on the outer wall of the casing of the air-cooled two-stage oil-free type screw compressor,
Means for sending cooling air to the outer surface of the casing between the fins is provided. Alternatively, the structure is not provided.

[0007]

In the single-stage oil-free compressor, the pressure of the gas is increased by only one compressor body, so the discharge gas temperature is high (about 35
(0 ° C.), and the ratio of the amount of heat exchanged in the casing jacket to the total amount of heat radiated from the compressor also increases. Therefore, if the heat exchange in the jacket portion is not sufficient, problems such as rise in discharge gas temperature, performance degradation, large increase / decrease in internal gap due to large thermal deformation of casing, and rise in bearing internal temperature are likely to occur. On the other hand, in a two-stage oil-free compressor, the gas pressure is boosted by two compressor bodies in series, so the temperature of each discharge gas is not as high as that of a single-stage compressor (about 150 ° C to 200 ° C). The ratio of the heat exchange amount in the casing jacket portion to the heat radiation amount becomes low. Therefore, even if the liquid cooling jacket is not provided, the cooling fins can be provided, and the problem can be prevented by allowing the compressor body to naturally cool or simply forced air cooling, and is equivalent to the case where liquid such as coolant is flowed into the jacket. The performance can be obtained.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. As shown in FIGS. 3 and 4, the first-stage compressor body 1 and the second-stage compressor body 2 are coupled to a gear casing 3 by a flange, and a speed increasing gear is housed in the gear casing 3. The shaft power is transmitted to the speed increasing gear from (not shown), and the first-stage compressor body 1 and the second-stage compressor body 2
Is driven.

As shown in FIG. 1, the one-stage compressor body 1 supports a casing 7, an S casing 8 for accommodating a male rotor 5 and a female rotor 6 meshing with each other, a male rotor 5 and a female rotor 6. Radial bearings 9 and 10, thrust bearings 1
1, two pairs of timing gears 12 that rotate the rotor tooth groove portions of the male rotor 5 and the female rotor 6 in a non-contact manner with each other,
Shaft sealing devices 13 and 14 for preventing oil from entering the rotor groove portion
Composed of. The shaft power is transmitted to a pinion gear 15 attached to the shaft end of the male rotor 5, and the male rotor 5 and the female rotor 6 rotate in synchronization with each other to compress and discharge the gas. On the other hand, the two-stage compressor body 2 also has a structure as shown in FIG. 1, the rotor diameter is smaller than that on the one-stage side, and the components are also scaled down.

In the prior art, as shown in FIG. 2, a casing 17 covers the rotors 5 and 6, and a jacket 17 for cooling the entire compressor body with a liquid such as a coolant.
Is provided. On the other hand, in this embodiment, as shown in FIG. 1, a plurality of cooling fins 16 are provided on the outer walls of the casings 7 of the first-stage compressor body 1 and the second-stage compressor body 2 so that the heat radiation area is increased. The structure is formed along substantially the plane perpendicular to the axes of the rotors 5 and 6. Although the radiating fin 16 may be configured as a separate component from the casing 7 and brought into close contact with the casing, in the present embodiment, the casing 7 and the cooling fin 16 are integrally formed by casting such as cast iron.

Further, in the present embodiment, as shown in FIGS. 3 and 4, natural heat radiation in which no cooling air is forced to flow on the outer surfaces of the first-stage compressor body 1 and the second-stage compressor body 2 or the cooling fins. It was a method. The air that has undergone heat exchange in the cooling fins
As a result of natural convection, the cooling fins 20 flow to the outside of the machine through the exhaust port.

In the air-cooled two-stage oilless compressor of the present embodiment, the pressure of the gas is increased in the order of the first-stage compressor body 1 and the second-stage compressor body 2, so that the discharge gas temperature of each is not as high as that of the single-stage compressor. No (Two-stage machine is about 150 ℃ -200 ℃, Single-stage machine is about 350 ℃)
℃), the ratio of the amount of heat exchange in the casing jacket to the total heat dissipation of the compressor is considerably lower than that of the single-stage machine.
Therefore, even if the liquid cooling jacket is not provided, if the first-stage compressor body 1 and the second-stage compressor body 2 are cooled by natural cooling or simple forced air cooling, the internal gap due to the rise in the discharge gas temperature and the large deformation of the casing will occur. It is possible to prevent a large increase / decrease in (gap between rotors, etc.) and a rise in bearing internal temperature, and to obtain the same performance as when liquid such as coolant flows into the jacket.

Next, the air cooling system of this embodiment will be described with reference to FIGS. FIG. 5 is an explanatory diagram showing the flow of compressed gas in the air-cooled two-stage oilless screw compressor according to this embodiment. The suction gas that has passed through the suction throttle valve 18 is, for example, about 3 kg in the first-stage compressor body 1.
/ Pressure is increased to about ² cm. This gas is pressure-fed to the intercooler 19, cooled by the cooling air generated by the cooling fan 20 in the intercooler 19, drained by the drain separator 21, and then flows into the two-stage compressor body 2. Here, the gas heated to a high temperature of about 9 kg / cm ² g flows into the aftercooler 23 via the check valve 22 and is cooled by the aftercooler 23.
Due to the cooling air generated by 0, the temperature becomes about +15 [deg.] C. of the atmospheric temperature and the air is supplied from the discharge port 24 to the outside of the machine. on the other hand,
In the oil circulation system, the lubricating oil in the oil sump below the gear casing 3 is suction-pressurized by the oil pump 25, pumped to the oil cooler 26, and cooled by the cooling air generated by the cooling fan 20 in the oil cooler 26. It Further, the oil cooler 26 flows into the oil filter 27 to be filtered, and is supplied to the bearing section and the gear meshing section in the first-stage compressor body 1, the second-stage compressor body 2, and the gear casing 3.

In the prior art, a cooling liquid (coolant) is circulated in the jacket of the casing of the compressor body to cool the casing, and further, a circulation of a coolant pump or the like for circulating this coolant in the machine. Equipment, a cooling device such as a coolant cooler to cool the coolant, various relays to protect the coolant circulation system, and a coolant filter to prevent clogging in the coolant circulation path were needed. On the other hand, according to the present invention,
Since it is not necessary to provide a jacket on the casing of the compressor body and all the above devices of the coolant circulation system can be omitted, the internal structure of the compressor can be simplified and the cost of the compressor can be reduced. Furthermore, there is no need to provide a coolant cooler, and the cooler can be configured with only three types of coolers, an intercooler, an aftercooler, and an oil cooler, which makes it possible to reduce the size and speed of the cooling system, and further Miniaturization can be realized.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 6 shows the structures of the main body of the single-stage compressor and the main body of the two-stage compressor, and is an example in which the casing and the cooling fin are not provided in the casing 7. In this case, the shape of the casting is simplified, and the casting can be manufactured at low cost.

Next, a third embodiment of the present invention will be described with reference to FIG. This embodiment is an example in which the casing outer surfaces of the first-stage compressor body 1 and the second-stage compressor body 2 and the cooling fins are forcibly cooled by the cooling air from the cooling fins. The second cooling fan 30 is provided around the rear portion of the main body 1 of the first compressor and the main body 2 of the two-stage compressor that are flange-connected to the gear casing 3.
And a suction port 31 for the cooling fan and a duct 32 are provided on the side surface of the compressor package. With this configuration, the heat generated in the compressor body can be removed by the cooling air, and the performance of the two-stage compressor can be improved.

[0017]

According to the present invention, an air-cooling system having a simple piping and structure which enables downsizing of the cooling system of the compressor and cost reduction of the compressor without deteriorating the performance of the compressor. A two-stage oil-free type screw compressor can be provided.

Specifically, (1) it is not necessary to provide a jacket in the casing of the compressor main body, and it is not necessary to allow the coolant to flow in, and all the coolant circulation system equipment such as the coolant pump and coolant filter can be omitted. It is possible to simplify the structure, simplify the piping inside the compressor, and reduce the compressor manufacturing cost.

(2) It is not necessary to provide a coolant cooler, and the cooler is an intercooler, an aftercooler,
The oil cooler can be configured with only three types of coolers, and the air-cooled cooling system can be downsized and simplified, and the compressor package can be downsized.

[Brief description of drawings]

FIG. 1 is a sectional view of a one-stage compressor body and a two-stage compressor body according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of a compressor body according to a conventional example.

FIG. 3 is an assembly diagram of a two-stage compressor.

FIG. 4 is an assembly diagram of a two-stage compressor.

FIG. 5 is an explanatory view showing the flow of discharge gas and lubricating oil.

FIG. 6 is a sectional view of a compressor body according to the second embodiment of the present invention.

FIG. 7 is an explanatory view of a two-stage compressor showing a third embodiment of the present invention.

[Explanation of symbols]

1 ... 1-stage compressor body, 2 ... 2-stage compressor body, 3 ... Gear casing, 5 ... Male rotor, 6 ... Female rotor, 7 ... Casing, 16 ... Cooling fin, 19 ... Intercooler, 20 ...
Cooling fan, 23 ... Aftercooler, 26 ... Oil cooler, 30 ... Second cooling fan.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Riichi Uchida 502 Jinmachi-cho, Tsuchiura-shi, Ibaraki Pref.

Claims (1)

[Claims] 1. A low pressure stage compressor body and a high pressure stage compressor body including a pair of male and female screw rotors meshing with each other, a casing accommodating the screw rotors, an air-cooled low pressure stage side cooler and a high pressure stage side cooling. In an air-cooled two-stage oil-free screw compressor equipped with a compressor, the casing is not provided with a liquid cooling jacket for cooling the compressor body, and liquid cooling means for the compressor body is not provided. An air-cooled two-stage oilless screw compressor.