Liquid supply gas compressor

Abstract

The present invention provides a liquid-supply type gas compressor capable of reducing shaft power. The oil-supply type air compressor comprises a compressor body (2) for compressing air while injecting oil into working chambers (11A, 11B), a separator (5) for separating oil from compressed air discharged from the compressor body (2), and an oil supply system (7) for supplying the oil separated by the separator (5) to the working chambers (11A, 11B) and bearings (9A to 9D) of the compressor body (2). The oil supply system (7) includes an oil cooler (17) having a cooling portion (19A) and a cooling portion (19B) connected to the downstream side thereof, an oil supply pipe (20A) connected to an outlet between the cooling portion (19A) and the cooling portion (19B) of the oil cooler (17) for supplying oil cooled by the cooling portion (19A) to bearings (9A to 9D) of a compressor body (2), and an oil supply pipe (20B) connected to an outlet on the downstream side of the cooling portion (19B) of the oil cooler (17) for supplying oil cooled by the cooling portions (19A, 19B) to working chambers (11A, 11B) of the compressor body (2).

Description

Technical Field

[0001] The present invention relates to a liquid-supply type gas compressor. Background Art

[0002] Patent Document 1 discloses an oil-supplied air compressor as a type of liquid-supplied gas compressor. The oil-supplied air compressor includes a compressor body, a separator, and an oil supply system (liquid supply system).

[0003] The compressor body has two screw rotors meshing with each other, a plurality of bearings that support the two screw rotors in a rotatable manner, and a housing that accommodates the two screw rotors and the plurality of bearings. A plurality of working chambers are formed between each screw rotor and the inner wall of the housing. Oil (liquid) is injected into the working chamber for the purpose of sealing the working chamber, cooling the compression heat, and lubricating the rotor, and air (gas) is compressed.

[0004] The separator separates and stores oil from the compressed air (compressed gas) discharged from the compressor body. The oil supply system supplies the oil stored in the separator to the working chamber and bearings of the compressor body. The oil supply system includes: an oil cooler (cooler) that cools the oil by heat exchange with cooling air generated by a cooling fan; a bypass pipe that bypasses the oil cooler; and a temperature regulating valve that adjusts the flow ratio of the oil cooler and the flow ratio of the bypass pipe according to the temperature of the oil.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2009-144685 Summary of the invention

[0008] Problems to be solved by the invention

[0009] In the above-mentioned prior art, the temperature of the oil supplied from the oil supply system to the working chamber of the compressor body is substantially the same as the temperature of the oil supplied from the oil supply system to the bearing of the compressor body.

[0010] Here, for example, if the temperature of the oil supplied to the working chamber of the compressor body is lowered, the compression power is reduced from adiabatic compression to isothermal compression. However, the temperature of the oil supplied to the bearing of the compressor body is also lowered, and the viscosity of the oil is increased, so the mechanical loss increases. Therefore, although the compression power is reduced, the mechanical loss increases, so the shaft power of the compressor cannot be fully reduced.

[0011] On the other hand, for example, if the temperature of the oil supplied to the bearing of the compressor body is increased, the viscosity of the oil is reduced, so the mechanical loss is reduced. However, the temperature of the oil supplied to the working chamber of the compressor body is also increased, and the isothermal compression is approached to the adiabatic compression, so the compression power increases. Therefore, although the mechanical loss is reduced, the compression power increases, and the shaft power of the compressor cannot be fully reduced.

[0012] The present invention has been made in view of the above circumstances, and one of the objects is to reduce the shaft power of the compressor.

[0013] Methods for solving problems

[0014] In order to solve the above-mentioned problems, the structure described in the claims is applied. The present invention includes a variety of means for solving the above-mentioned problems. As an example, it is a liquid supply type gas compressor, which includes: a compressor body, which includes a rotor, a bearing that supports the rotor in a rotatable manner, and a housing that accommodates the rotor and the bearing, while injecting liquid into a working chamber formed between the rotor and the inner wall of the housing, while compressing gas; a separator that separates liquid from the compressed gas discharged from the compressor body; and a liquid supply system that supplies the liquid separated by the separator to the working chamber and the bearing of the compressor body; characterized in that: The liquid supply system includes: a cooler having a first cooling part for cooling liquid and a second cooling part for cooling liquid connected to a downstream side thereof; a first liquid supply pipe connected to an outlet between the first cooling part and the second cooling part of the cooler to supply the liquid cooled by the first cooling part of the cooler to the bearing of the compressor body; and a second liquid supply pipe connected to an outlet on the downstream side of the second cooling part of the cooler to supply the liquid cooled by the first cooling part and the second cooling part of the cooler to the working chamber of the compressor body.

[0015] Effects of the Invention

[0016] According to the present invention, the shaft power of the compressor can be reduced.

[0017] In addition, the problems, structures and effects other than those described above will be explained in the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram showing the structure of an oil-supply type air compressor in one embodiment of the present invention.

[0019] Figure 2 It is a cross-sectional view showing the structure of a compressor body in one embodiment of the present invention.

[0020] Figure 3It is a schematic diagram showing the structure of an oil cooler in one embodiment of the present invention.

[0021] Figure 4 It is a schematic diagram showing the structure of an oil cooler in a first modified example of the present invention.

[0022] Figure 5 It is a schematic diagram showing the structure of an oil-supply type air compressor in a second modified example of the present invention.

[0023] Figure 6 It is a schematic diagram showing the structure of an oil-supply type air compressor in a third modified example of the present invention.

[0024] Figure 7 It is a schematic diagram showing the structure of an oil-supply type air compressor in a fourth modified example of the present invention. DETAILED DESCRIPTION

[0025] An embodiment of the present invention will be described with reference to the accompanying drawings.

[0026] Figure 1 It is a schematic diagram showing the structure of the oil-supply type air compressor in this embodiment. Figure 2 It is a cross-sectional view showing the structure of the compressor body in this embodiment. Figure 3 It is a schematic diagram showing the structure of the oil cooler in this embodiment.

[0027] The oil-supplied air compressor of this embodiment includes an electric motor 1, a compressor body 2 driven by the electric motor 1 to compress air (gas), an air filter 3 and an intake throttle valve 4 arranged on the suction side of the compressor body 2, a separator 5 arranged on the discharge side of the compressor body 2, a compressed air system 6 (compressed gas system) connected to the upper part of the separator 5, and an oil supply system 7 (liquid supply system) connected between the lower part of the separator 5 and the compressor body 2.

[0028] The compressor body 2 includes two screw rotors 8A and 8B (specifically, a male rotor 8A and a female rotor 8B) meshing with each other, bearings 9A and 9B for rotatably supporting the screw rotor 8A, bearings 9C and 9D for rotatably supporting the screw rotor 8B, and a housing 10 for accommodating the screw rotors 8A and 8B and the bearings 9A to 9D. A plurality of working chambers 11A are formed between the screw rotor 8A and the inner wall of the housing 10 (in other words, in the tooth grooves of the screw rotor 8A), and a plurality of working chambers 11B are formed between the screw rotor 8B and the inner wall of the housing 10 (in other words, in the tooth grooves of the screw rotor 8B).

[0029] A shaft seal 12A is disposed on the outer circumference of one shaft portion of the screw rotor 8A, and a shaft seal 12B is disposed on the outer circumference of the other shaft portion. A shaft seal 12C is disposed on the outer circumference of one shaft portion of the screw rotor 8B, and a shaft seal 12D is disposed on the outer circumference of the other shaft portion. A gear 13A is provided on one shaft portion of the screw rotor 8A, and a gear 13B is provided on the rotating shaft of the motor 1, and the gears 13A and 13B mesh with each other. A shaft seal 14 is disposed on the outer circumference of the rotating shaft of the motor 1.

[0030] The screw rotor 8A is rotated by the rotational force of the rotating shaft of the motor 1 transmitted via the gears 13A and 13B, and the screw rotor 8B rotates accordingly. As the screw rotors 8A and 8B rotate, the working chambers 11A and 11B move in the axial direction of the rotor ( Figure 2 The compressor body 2 moves in the left direction of the working chamber 11A (left direction) and performs the suction stroke, compression stroke, and discharge stroke in sequence. The working chamber of the suction stroke sucks air through the air filter 3 and the suction throttle valve 4. The working chamber of the compression stroke compresses the air. The working chamber of the discharge stroke discharges the compressed air (compressed gas) to the separator 5. The compressor body 2 injects oil into the working chambers 11A and 11B for the purpose of sealing the working chamber, cooling the compression heat, and lubricating the rotor.

[0031] The separator 5 separates oil from the compressed air discharged from the compressor body 2 and stores the oil. The compressed air system 6 supplies the compressed air separated by the separator 5 to the user's equipment (not shown). The compressed air system 6 includes a pressure regulating check valve 15 and an aftercooler 16 arranged on the downstream side of the pressure regulating check valve 15. The aftercooler 16 cools the compressed air by, for example, exchanging heat with cooling air generated by a cooling fan (not shown).

[0032] The oil supply system 7 supplies the oil stored in the separator 5 to the working chambers 11A and 11B, the bearings 9A to 9D, the shaft seals 12A to 12D, the gears 13A and 13B of the compressor body 2, and the shaft seal 14 of the motor 1 by the pressure in the separator 5. The oil supply system 7 includes an oil cooler 17 (cooler) for cooling the oil.

[0033] The oil cooler 17 is configured to connect, for example, a header 18A, a cooling portion 19A, a header 18B, a cooling portion 19B, and a header 18C in this order so that oil flows therethrough. The cooling portion 19A cools the oil flowing in from the header 18A by, for example, heat exchange with cooling air generated by a cooling fan, and causes the cooled oil to flow out to the header 18B. The cooling portion 19B cools the oil flowing in from the header 18B by, for example, heat exchange with cooling air generated by a cooling fan, and causes the cooled oil to flow out to the header 18C. The header 18A is provided with an inlet for the oil from the separator 5 to flow in. The header 18B is provided with an outlet for the oil cooled by the cooled portion 19A to flow out. The header 18C is provided with an outlet for the oil cooled by the cooled portions 19A and 19B to flow out. In addition, since the oil flows out from the outlet of the header 18B, the flow rate of the oil in the cooling portion 19B is smaller than the flow rate of the oil in the cooling portion 19A.

[0034] The oil supply system 7 further includes an oil supply piping 20A (liquid supply piping) connected to the outlet of the manifold 18B of the oil cooler 17 (in other words, between the cooling section 19A and the cooling section 19B), an oil filter 21A for removing impurities in the oil arranged in the oil supply piping 20A (in other words, on the downstream side of the oil cooler 17), a flow restriction section 22 arranged in the oil supply piping 20A, an oil supply piping 20B (liquid supply piping) connected to the outlet of the manifold 18C of the oil cooler 17 (in other words, on the downstream side of the cooling section 19B), and an oil filter 21B for removing impurities in the oil arranged in the oil supply piping 20B (in other words, on the downstream side of the oil cooler 17).

[0035] The oil supply pipe 20A supplies the oil cooled by the cooling portion 19A of the oil cooler 17 to the bearings 9A to 9D and the shaft seals 12A to 12D of the compressor body 2, the gears 13A and 13B, and the shaft seal 14 of the motor 1. The oil supply pipe 20B supplies the oil cooled by the cooling portions 19A and 19B of the oil cooler 17 to the working chambers 11A and 11B of the compressor body 2.

[0036] The oil supply system 7 includes: a bypass pipe 23A connected to the oil supply pipe 20A for bypassing the oil cooler 17; a bypass pipe 23B connected to the oil supply pipe 20B for bypassing the oil cooler 17; and a temperature regulating valve 24 for adjusting the diversion ratio of the oil cooler 17 and the diversion ratio of the bypass pipes 23A and 23B according to the temperature of the oil.

[0037] The temperature regulating valve 24 is a three-way valve, and is configured to change the opening ratio of the outlet on the oil cooler side and the opening ratio of the outlet on the bypass pipe side, for example, by changing the volume of wax in accordance with the temperature of the oil. Then, as the temperature of the oil increases, the flow rate of the oil cooler 17 is increased, and the flow rate of the bypass pipes 23A and 23B is reduced. As a result, the flow rate of the oil cooled by the cooling parts 19A and 19B of the oil cooler 17 and flowing out from the outlet of the manifold 18C is increased, and the flow rate of the oil in the bypass pipe 23B is reduced. As a result, the temperature of the oil supplied to the working chambers 11A and 11B of the compressor body 2 is adjusted, and the temperature of the compressed air is adjusted.

[0038] In the present embodiment constructed as described above, the oil cooled by the cooling section 19A of the oil cooler 17, that is, the oil which is not cooled by the cooling section 19B and therefore has a relatively high temperature, is supplied to the bearings 9A to 9D and the shaft seals 12A to 12D of the compressor body 2, the gears 13A and 13B, and the shaft seal 14 of the motor 1 via the oil supply pipe 20A. Therefore, compared with the case where oil with a relatively low temperature is supplied, the mechanical loss can be reduced. On the other hand, the oil with a relatively low temperature cooled by the cooling sections 19A and 19B of the oil cooler 17 is supplied to the working chambers 11A and 11B of the compressor body 2 via the oil supply pipe 20B. Therefore, compared with the case where oil with a relatively high temperature is supplied, the compression power can be reduced. Thus, the mechanical loss is reduced and the compression power is reduced, so the shaft power of the compressor can be reduced.

[0039] The effect of the present embodiment described above will be described using a specific numerical example. In the prior art, the temperature of the oil supplied to the bearings 9A to 9D and the shaft seals 12A to 12D of the compressor body 2, the gears 13A and 13B, and the shaft seal 14 of the motor 1 is substantially the same as the temperature of the oil supplied to the working chambers 11A and 11B of the compressor body 2, for example, 80°C. In the present embodiment, the temperature of the oil supplied to the bearings 9A to 9D and the shaft seals 12A to 12D of the compressor body 2, the gears 13A and 13B, and the shaft seal 14 of the motor 1 is higher, for example, 90°C, and the mechanical loss is reduced. The temperature of the oil supplied to the working chambers 11A and 11B of the compressor body 2 is lower, for example, 70°C, and the compression power is reduced. As a result, although it also depends on various parameters of the rotor, if the shaft power of the compressor of the prior art is assumed to be 100%, the shaft power of the compressor of the present embodiment can be reduced to 99.2%.

[0040] Furthermore, in the present embodiment, the following effects can be obtained. As a comparative example, it is assumed that the oil supply system includes a first oil supply pipe for supplying oil from the separator 5 to the bearings 9A to 9D and the shaft seals 12A to 12D of the compressor body 2, the gears 13A and 13B, and the shaft seal 14 of the motor 1, and a first oil cooler for cooling the oil arranged in the first oil supply pipe, and a second oil supply pipe for supplying oil from the separator 5 to the working chambers 11A and 11B of the compressor body 2, and a second oil cooler for cooling the oil arranged in the second oil supply pipe.

[0041] In the above-mentioned comparative example, the temperature of the oil supplied to the bearings 9A to 9D and the shaft seals 12A to 12D of the compressor body 2, the gears 13A and 13B, and the shaft seal 14 of the motor 1 can be made different from the temperature of the oil supplied to the working chambers 11A and 11B of the compressor body 2. However, in the comparative example, the compressor is enlarged because the number of oil coolers and the number of pipes and joints for connecting the oil coolers are increased. In contrast, in the present embodiment, the number of oil coolers and the number of pipes and joints for connecting the oil coolers are reduced, so that the compressor can be miniaturized. In addition, in the present embodiment, the flow rate of the oil in the cooling section 19B can be reduced relative to the flow rate of the oil in the cooling section 19A of the oil cooler 17. Therefore, the oil supplied to the working chambers 11A and 11B of the compressor body 2 can be efficiently cooled.

[0042] In addition, in one embodiment, as described above Figure 3 As shown in the figure, the oil cooler 17 is configured such that the cooling part 19A and the cooling part 19B are arranged in series, but the invention is not limited thereto. Figure 4 In the modification shown, the oil cooler 17 is generally configured such that a cooling portion 19A and a cooling portion 19B are arranged in parallel.

[0043] In addition, in the above embodiment, the oil supply system 7 includes the oil filters 21A and 21B respectively arranged in the oil supply pipes 20A and 20B, but the present invention is not limited to this. For example, if the influence of impurities in the oil is relatively low according to the location, the oil supply system 7 may include only one of the oil filters 21A and 21B, or may not include the oil filters 21A and 21B. Alternatively, for example, Figure 5 In the modified example shown, the oil supply system 7 generally includes an oil filter 21C disposed on the upstream side of the temperature control valve 24. In this modified example, the number of oil filters can be set to one, and impurities can be removed from the oil supplied to the working chambers 11A and 11B of the compressor body 2, the bearings 9A to 9D, the shaft seals 12A to 12D, the gears 13A and 13B, and the shaft seal 14 of the motor 1.

[0044] In addition, in the above-mentioned embodiment, the oil supply system 7 includes the bypass pipes 23A and 23B for bypassing the oil cooler 17 and the temperature regulating valve 24 for adjusting the flow ratio of the oil cooler 17 and the flow ratio of the bypass pipes 23A and 23B according to the temperature of the oil. However, the present invention is not limited to this. For example, the oil supply system 7 may also include the temperature regulating valve 24 for adjusting the flow ratio of the oil cooler 17 and the flow ratio of the bypass pipes 23A and 23B according to the temperature of the oil. Figure 6 In the modified example shown, the oil supply system 7 generally does not include the bypass pipes 23A, 23B and the temperature control valve 24. Then, the cooling capacity of the oil cooler 17 is adjusted by variably controlling the rotation speed of the cooling fan according to the temperature detected by the temperature sensor (not shown) in the separator 5, for example.

[0045] In addition, in the above embodiment, the aftercooler 16 and the oil cooler 17 are air-cooled and the compressed air and the oil are cooled respectively by heat exchange with the cooling air generated by the cooling fan, but the invention is not limited to this. Figure 7 In the modification shown, generally, the aftercooler 16 and the oil cooler 17 are water-cooled, and the compressed air and the oil are cooled respectively by heat exchange with the cooling water. In this modification, the oil cooler 17 is configured, for example, so that the cooling section 19A and the cooling section 19B are connected in such a way that the oil flows through in this order. The cooling sections 19A and 19B cool the oil by heat exchange with the cooling water. An outlet is formed between the cooling section 19A and the cooling section 19B for the oil cooled by the cooling section 19A to flow out, and the oil supply piping 20A is connected to the outlet. An outlet is formed on the downstream side of the cooling section 19B for the oil cooled by the cooling sections 19A and 19B to flow out, and the oil supply piping 20B is connected to the outlet. In this modification configured as described above, the same effect as described above can also be obtained.

[0046] In addition, in the above-mentioned embodiment, the case where the oil supply pipe 20A supplies the oil cooled by the cooling part 19A of the oil cooler 17 to the bearings 9A to 9D and the shaft seals 12A to 12D of the compressor body 2, the gears 13A and 13B, and the shaft seal 14 of the motor 1 is described as an example, but the present invention is not limited to this. For example, when the gears 13A and 13B and the shaft seal 14 of the motor 1 do not exist, the oil supply pipe 20A may also supply the oil cooled by the cooling part 19A of the oil cooler 17 to the bearings 9A to 9D and the shaft seals 12A to 12D of the compressor body 2. Alternatively, when the shaft seal 12A of the compressor body 2, the gears 13A and 13B and the shaft seal 14 of the motor 1 do not exist, the oil supply pipe 20A may also supply the oil cooled by the cooling part 19A of the oil cooler 17 to the bearings 9A to 9D of the compressor body 2.

[0047] In addition, in the above embodiment, the compressor body 2 is a screw type and includes two screw rotors 8A and 8B. However, the present invention is not limited to this. The compressor body may include, for example, one screw rotor and a plurality of gate rotors. Alternatively, the compressor body 2 may be other types other than the screw type.

[0048] In addition, the above description uses the case where the present invention is applied to an oil-supply air compressor (i.e., the compressor body 2 injects oil into the compression chamber and compresses air at the same time) as an example, but is not limited to this. The present invention can also be applied to other liquid-supply compressors (i.e., the compressor body 2 injects other liquids other than oil into the working chamber, or compresses other gases other than air).

[0049] Description of Reference Numerals

[0050] 1…Electric motor

[0051] 2…Compressor body

[0052] 5…Separator

[0053] 7…Oil supply system 7 (liquid supply system)

[0054] 8A, 8B…Screw rotor

[0055] 9A~9D…Bearings

[0056] 10…Housing

[0057] 11A, 11B…Studio

[0058] 12A~12D…Shaft seal part (1st shaft seal part)

[0059] 13A, 13B…Gear

[0060] 14…Shaft seal part (second shaft seal part)

[0061] 17…Oil cooler (cooler)

[0062] 19A, 19B…Cooling section

[0063] 20A, 20B…Oil supply piping (liquid supply piping)

[0064] 21A~21C…Oil filter

[0065] 23A, 23B…Bypass piping

[0066] 24…Temperature regulating valve.

Claims

1. A liquid supply type gas compressor, characterized in that: include: A compressor body including a rotor, a bearing for rotatably supporting the rotor, and a housing for housing the rotor and the bearing, wherein a gas is compressed while liquid is injected into a working chamber formed between the rotor and an inner wall of the housing; a separator that separates liquid from the compressed gas discharged from the compressor body; and a liquid supply system that supplies the liquid separated by the separator to the working chamber and the bearing of the compressor body, wherein The liquid supply system comprises: A cooler having a first cooling part for cooling a liquid and a second cooling part connected to the first cooling part via a header for further cooling the liquid cooled by the first cooling part; a first liquid supply pipe connected to an outlet of the header formed in the cooler and supplying the liquid cooled by the first cooling part of the cooler to the bearing of the compressor body; and A second liquid supply pipe is connected to an outlet on a downstream side of the second cooling portion of the cooler and supplies liquid cooled by the first cooling portion and the second cooling portion of the cooler to the working chamber of the compressor body.

2. The liquid supply type gas compressor according to claim 1, characterized in that: The compressor comprises a first shaft seal portion disposed on the outer peripheral side of the shaft portion of the rotor of the compressor body. The first liquid supply pipe supplies the liquid cooled by the first cooling portion of the cooler to the bearing and the first shaft seal portion of the compressor body.

3. The liquid supply type gas compressor according to claim 2, characterized in that: include: an electric motor that drives the compressor body; a plurality of gears disposed between a rotating shaft of the motor and the rotor of the compressor body; and a second shaft seal portion disposed on an outer peripheral side of the rotating shaft of the motor, The first liquid supply pipe supplies the liquid cooled by the first cooling portion of the cooler to the bearing and the first shaft seal portion of the compressor body, the plurality of gears, and the second shaft seal portion.

4. The liquid supply type gas compressor according to claim 1, characterized in that: The liquid supply system comprises: a first bypass pipe that bypasses the cooler and is connected to the first liquid supply pipe; a second bypass pipe that bypasses the cooler and is connected to the second liquid supply pipe; a temperature regulating valve for regulating a flow splitting ratio between the cooler and the first bypass pipe and the second bypass pipe according to a temperature of the liquid; and A filter is arranged on the upstream side of the temperature regulating valve.

5. The liquid supply type gas compressor according to claim 1, characterized in that: The liquid supply system includes a filter disposed on an upstream side of the cooler.

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