Oil-cooled compressor and its operating method

Abstract

To suppress retention of drain water in an air release flow passage in an oil cooling type compressor and an operating method for the same.SOLUTION: An oil cooling type compressor 1 includes: an oil cooling type compressor body 100 having a function for compressing air; an oil separator 10 for separating oil from compressed air discharged from the compressor body 100 and including oil; a main flow passage 5 in which the compressed air from which oil has been separated by the oil separator 10 flows toward a supply destination; an air release flow passage 7 that is branched from the main flow passage 5 and opened to the atmosphere and in which the compressed air to be discharged together with drain water flows; an air release valve 24 opening / closing the air release flow passage 7; and a control device 50 performing control to periodically open / close the air release valve 24.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an oil-cooled compressor and an operating method thereof. [Background technology]

[0002] In oil-cooled compressors, water vapor contained in the intake air can condense and produce drain water. If drain water accumulates, it can cause problems such as rust in the pipes, clogging of filters, and damage to the compressor itself. To prevent these problems, drain drying operation is sometimes performed even when the user is not using air, in order to sufficiently raise the discharge temperature.

[0003] Patent Document 1 discloses an oil-cooled compressor that prevents unnecessary drain drying operation. In this oil-cooled compressor, the amount of drain water is calculated while the compressor body is operating, and when the calculated amount of drain water is equal to or greater than a predetermined lower limit, the air release valve is opened to discharge the drain water. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-11426 Summary of the Invention [Problem to be solved by the invention]

[0005] In the oil-cooled compressor of Patent Document 1, the amount of drain water below a predetermined lower limit is not discharged, and the air release valve is not opened when the calculated amount of drain water is below the predetermined lower limit. When the air release valve is closed, there is a risk that drain water will accumulate in the air release flow path that branches off from the main flow path and reaches the air release valve.

[0006] An object of the present invention is to suppress the accumulation of drain water in an air discharge passage in an oil-cooled compressor and an operating method thereof. [Means for solving the problem]

[0007] A first aspect of the present invention provides an oil-cooled compressor comprising: an oil-cooled compressor body having a function of compressing air; an oil separator that separates oil from oil-containing compressed air discharged from the compressor body; a main flow path through which the compressed air from which oil has been separated by the oil separator flows to a supply destination; an air release flow path that branches off from the main flow path and is open to the atmosphere, through which the compressed air discharged together with drain water flows; an air release valve that opens and closes the air release flow path; and a control device that controls the air release valve to open and close periodically.

[0008] With this configuration, the control device periodically opens and closes the air release valve regardless of the amount of drain water, thereby preventing the accumulation of drain water in the air release flow path. Furthermore, since the amount of drain water is not detected, a complex sensor is not required, and even if a small amount of drain water accumulates, the drain water can be discharged. The interval at which the normally closed air release valve is periodically opened and the time for which the open state is maintained can be appropriately determined depending on the amount of accumulated drain water, the diameter of the pipes that make up the main flow path and the air release flow path, etc.

[0009] The control device may periodically control the opening and closing of the air release valve during a load operation of the compressor body.

[0010] With this configuration, the temperature of the discharge air becomes high when the compressor body is operating under load, making it difficult for the drain water to condense, and the amount of drain water that accumulates is generally small. However, the accumulation of the drain water can be a problem even with such a small amount of drain water, so being able to suppress the accumulation of the drain water is effective.

[0011] A second aspect of the present invention provides a method for operating an oil-cooled compressor comprising: an oil-cooled compressor body having a function of compressing air; an oil separator that separates oil from oil-containing compressed air discharged from the compressor body; a main flow path through which the compressed air from which the oil has been separated by the oil separator flows to a supply destination; an air release flow path that branches off from the main flow path and is open to the atmosphere, through which the compressed air discharged together with drain water flows; and an air release valve that opens and closes the air release flow path, wherein the method comprises periodically opening and closing the air release valve.

[0012] According to this method, it is possible to suppress the accumulation of drain water in the air release passage in the same manner as described above. [Effects of the Invention]

[0013] According to the present invention, in an oil-cooled compressor and an operating method thereof, retention of drain water in the air release passage can be suppressed. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a schematic configuration diagram of an oil-cooled compressor according to an embodiment of the present invention; [Figure 2] FIG. 2 is a schematic enlarged cross-sectional view of a portion II circled by a dashed line in FIG. 1; [Figure 3] 4 is a flowchart showing a method of operating the oil-cooled compressor. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0016] FIG. 1 is a schematic configuration diagram of an oil-cooled compressor 1 according to an embodiment of the present invention.

[0017] The oil-cooled compressor 1 has a compressor body 100 disposed within a package wall 2. The compressor body 100 draws in air from the outside, compresses the drawn-in air inside, and discharges the compressed air.

[0018] The compressor body 100 of this embodiment includes an intake adjustment valve 110, a compression section 120, and a motor 130 that drives the compression section 120.

[0019] The intake adjustment valve 110 is attached to the intake port 121a of the compression section 120. The intake adjustment valve 110 adjusts the amount of air taken in through the intake port 121a. A filter 110a is provided on the inlet side of the intake adjustment valve 110. This filter 110a removes unwanted matter such as dust. The intake adjustment valve 110 is a well-known piston valve type, and a detailed description thereof will be omitted here.

[0020] In this embodiment, the compression section 120 is of a screw type. The exterior of the compression section 120 is formed by a rotor casing 121. The rotor casing 121 is provided with an intake port 121a and an exhaust port 121b. A screw rotor 122 is housed within the rotor casing 121. Although not shown in detail, the screw rotor 122 includes a male rotor and a female rotor that mesh with each other.

[0021] A shaft member 123 serving as a rotation shaft extends from one end of the screw rotor 122. The shaft member 123 passes through the rotor casing 121 and extends to the motor 130, and is mechanically connected to the motor 130. Similarly, a shaft member 124 serving as a rotation shaft extends from the other end of the screw rotor 122. The shaft member 124 terminates inside the rotor casing 121.

[0022] Bearings 125 and 126 are housed within the rotor casing 121. The bearings 125 and 126 support the shaft members 123 and 124, respectively.

[0023] The motor 130 includes a motor casing 131, a stator 132 fixed inside the motor casing 131, a rotor 133 arranged inside the stator 132, and a shaft member 134 that serves as the rotation shaft of the rotor 133. Bearings 135 and 136 are arranged on both sides of the rotor 133 in the direction in which the shaft member 134 extends. The bearings 135 and 136 support the shaft member 134. The shaft member 134 extends through the motor casing 131 toward the compression section 120.

[0024] A gear casing 140 is disposed between the rotor casing 121 and the motor casing 131. A connecting gear 141 is housed in the gear casing 140. The connecting gear 141 connects the shaft member 123 and the shaft member 134. This allows rotational power from the motor 130 to be transmitted to the screw rotor 122. In addition, the interior of the gear casing 140 and the interior of the motor casing 131 are fluidly isolated by a seal device 142. Therefore, oil is prevented from flowing between the interior of the gear casing 140 and the interior of the motor casing 131.

[0025] With the above configuration, when the motor 130 is operated, rotational power is transmitted to the screw rotor 122 via the shaft member 134, the connecting gear 141, and the shaft member 123. As the screw rotor 122 rotates, air is drawn in through the intake control valve 110, compressed, and discharged from the discharge port 121b. The discharged air is sent to the oil separator 10 through the piping 5a.

[0026] The oil-cooled compressor 1 includes a main flow path 5 through which compressed air, from which oil has been separated in an oil separator 10, flows to a supply destination (not shown). The main flow path 5 is provided with the oil separator 10, a pressure-maintaining check valve 21, a gas cooler 22, and a dryer 23. The main flow path 5 is made up of pipes 5b to 5e.

[0027] The oil separator 10 is connected to a pressure-maintaining check valve 21 through a pipe 5b, and the compressed air from which the oil has been separated in the oil separator 10 is sent to the pressure-maintaining check valve 21 through the pipe 5b.

[0028] The pressure maintenance check valve 21 has the function of maintaining a constant pressure inside the oil tank 12, which will be described later. The pressure maintenance check valve 21 is connected to the gas cooler 22 through the pipe 5c, and the compressed air whose pressure has been adjusted by the pressure maintenance check valve 21 is sent to the gas cooler 22 through the pipe 5c.

[0029] The gas cooler 22 is an air-cooled heat exchanger. Here, the air flowing in through the pipe 5c is cooled by obtaining cold energy from the surrounding air. However, the gas cooler 22 is not limited to this air-cooled heat exchanger and may be in any other form. The gas cooler 22 is connected to the dryer 23 through the pipe 5d, and the compressed air cooled by the dryer 23 is sent to the supply destination through the pipe 5e.

[0030] An air release flow path 7, which is open to the atmosphere and through which compressed air discharged together with drain water branches off from the pipe 5b connecting the oil separator 10 and the pressure maintenance check valve 21. The air release flow path 7 is provided with an air release valve 24 that opens and closes the air release flow path 7 to release air and discharge drain water, and a silencer 25 for noise reduction. The air release flow path 7 is made up of pipes 7a and 7b, and the pipe 7a branches off from the main flow path 5 (more specifically, the pipe 5b) and extends to the air release valve 24. The pipe 7b extends from the air release valve 24 to the silencer 25. The silencer 25 is open to the atmosphere.

[0031] Furthermore, in the oil-cooled compressor 1, oil is supplied into the rotor casing 121 during compression in the compression section 120 to lubricate the screw rotor 122, cool the compressed air, and provide sealing during compression. The rotor casing 121 is provided with an oil supply port 121c for supplying oil. The oil supplied through the oil supply port 121c is discharged from the discharge port 121b together with the compressed air and sent to the oil separator 10 through the piping 5a.

[0032] The oil-cooled compressor 1 includes an oil flow path 6, which is a flow path for oil. The oil flow path 6 includes a compressor body 100, an oil separator 10, an oil cooler 31, and an oil filter 32. The oil flow path 6 is made up of pipes 6a to 6c.

[0033] The oil separator 10 includes a separator filter 11, an oil tank 12, and a centrifugal separation unit 13. The separator filter 11 performs secondary separation of oil from the compressed air from which oil has been primarily separated in the centrifugal separation unit 13. The oil separated in the centrifugal separation unit 13 and the separator filter 11 is stored in the oil tank 12. The oil tank 12 is connected to an oil cooler 31 via piping 6a, and the oil stored in the oil tank 12 is sent to the oil cooler 31 via piping 6a.

[0034] The oil cooler 31 is an air-cooled heat exchanger. Here, the oil is cooled by obtaining cold energy from the air. However, the oil cooler 31 is not limited to this type of air-cooled heat exchanger and may be in any other form. The oil cooler 31 is connected to the oil filter 32 through piping 6b, and the oil cooled by the oil cooler 31 is sent to the oil filter 32 through piping 6b.

[0035] The oil filter 32 is a filter that filters out unwanted substances such as dust from the oil. The oil filter 32 is connected to the oil supply port 121c through the pipe 6c, and the oil from which unwanted substances have been removed by the oil filter 32 is sent into the rotor casing 121 through the pipe 6c.

[0036] The oil-cooled compressor 1 also includes a control device 50. The control device 50 is configured by hardware such as a CPU (Central Processing Unit), RAM (Random Access Memory), and ROM (Read Only Memory), and software such as a program implemented in the hardware.

[0037] The control device 50 controls the air release valve 24 to periodically open and close. For example, the air release valve 24 is normally closed, opened at regular intervals (e.g., 30 minutes), and maintained in an open state for a predetermined time (e.g., 2 seconds). Here, the time interval for opening the air release valve 24 and the time for which the air release valve 24 is maintained in an open state can be appropriately determined depending on the amount of accumulated drain water, the diameters of the pipes 5b to 5e, 7a, and 7b that constitute the main flow path 5 and the air release flow path 7, etc.

[0038] Fig. 2 is a schematic enlarged cross-sectional view of the portion II circled by the broken line in Fig. 1. Fig. 2 shows how the air release flow path 7 branches off from the main flow path 5.

[0039] Under normal circumstances, compressed air flows through the main flow path 5 to the supply destination through the pressure maintenance check valve 21 (see dashed-dotted arrow A), but the air release flow path 7 is closed by the air release valve 24. At this time, an area S where the flow of compressed air stagnates is created on the upstream side of the air release valve 24 of the air release flow path 7 (i.e., in the piping 7a), as indicated by the dashed-line arrow B. In this area S, not only compressed air but also drain water is likely to stagnate, meaning that there is a risk of drain water accumulating.

[0040] In this embodiment, the control device 50 periodically opens and closes the air release valve 24, so that drain water that may accumulate in the region S is periodically discharged from the air release passage 7. This prevents the drain water from accumulating and accumulating.

[0041] FIG. 3 is a flowchart showing a method of operating the oil-cooled compressor 1.

[0042] When the oil-cooled compressor 1 starts operating, that is, when the motor 130 starts to start (step S3-1), the air release valve 24 is closed or it is confirmed that it is closed (step S3-2). Then, normal operation is performed with the air release valve 24 closed (step S3-3). For example, when the rotation speed of the motor 130 reaches the rated rotation speed, the normal operation is initiated. In normal operation, the compressor body 100 performs load operation. Thereafter, while performing normal operation, the compressor waits for a certain period of time (e.g., 30 minutes) (step S3-4), and then the air release valve 24 is opened for a predetermined period of time (e.g., 2 seconds) (step S3-5). During this time, drain water is discharged to the outside from the air release passage 7 together with the compressed air. Thereafter, the air release valve 24 is closed (step S3-6). Then, the processes of steps S3-4 to S3-6 are repeated.

[0043] The oil-cooled compressor 1 of this embodiment has the following advantages.

[0044] Since the control device 50 periodically opens and closes the air release valve 24 regardless of the amount of drain water, it is possible to prevent the accumulation of drain water in the air release flow path 7 (particularly in the area S). In addition, since the amount of drain water is not detected, a complex sensor is not required, and the drain water can be discharged even if a small amount of drain water accumulates.

[0045] Furthermore, since the temperature of the discharge air becomes high during load operation of the compressor body 100, the drain water does not condense easily and the amount of accumulated drain water is generally small. However, the accumulation of drain water in the above-mentioned region S can be a problem even with such a small amount of drain water, and therefore it is effective to be able to suppress the accumulation of the drain water as in this embodiment.

[0046] Although specific embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and can be implemented with various modifications within the scope of the present invention.

[0047] In addition to the periodic opening and closing of the air release valve 24, the control device 50 may calculate the amount of drain water, and when the calculated amount of drain water is equal to or greater than a predetermined lower limit, control the oil-cooled compressor 1 to perform drain drying operation by opening the air release valve 24 to discharge the drain water. [Explanation of symbols]

[0048] 1 Oil-cooled compressor 2 Package Wall 5 Main channel 5a~5e Piping 6 Oil flow path 6a~6c Piping 7 Air discharge channel 7a,7b Piping 10 Oil separator 11 Separator filter 12 Oil Tank 13 Centrifugal separation section 21 Pressure-retaining check valve 22 Gas cooler 23 Dryer 24 Air release valve 25 silencer 31 Oil cooler 32 Oil filter 50 Control device 100 Compressor body 110 Intake adjustment valve 110a filter 120 Compression section 121 rotor casing 121a Air intake 121b Discharge port 121c fuel filler 122 screw rotor 123,124 Shaft member 125,126 Bearings 130 Motor 131 Motor casing 132 Stator 133 Rotor 134 Shaft member 135,136 Bearings 140 Gear casing 141 Connected Gear 142 Sealing device

Claims

1. an oil-cooled compressor body having a function of compressing air; an oil separator that separates oil from the oil-containing compressed air discharged from the compressor body; a gas cooler that cools the compressed air from which oil has been separated in the oil separator; a pressure-maintaining check valve that maintains the pressure of the oil separator and adjusts the pressure of the compressed air sent to the gas cooler; a main flow path through which the compressed air from which oil has been separated by the oil separator flows to a supply destination; an air release flow path that branches off from the main flow path at a position connecting the oil separator and the pressure-maintaining check valve, extends to a silencer, and is open to the atmosphere, and through which compressed air flows; An air release valve controlled to open and close the air release flow path; a control device that controls the air release valve to periodically open and close based on a predetermined time interval for opening the air release valve and a time for which the air release valve is maintained in an open state; An oil-cooled compressor comprising:

2. The oil-cooled compressor according to claim 1 , wherein the control device periodically controls the opening and closing of the air release valve during a load operation of the compressor body.

3. an oil-cooled compressor body having a function of compressing air; an oil separator that separates oil from the oil-containing compressed air discharged from the compressor body; a gas cooler that cools the compressed air from which oil has been separated in the oil separator; a pressure-maintaining check valve that maintains the pressure of the oil separator and adjusts the pressure of the compressed air sent to the gas cooler; a main flow path through which the compressed air from which oil has been separated by the oil separator flows to a supply destination; an air release flow path that branches off from the main flow path at a position connecting the oil separator and the pressure-maintaining check valve, extends to a silencer, and is open to the atmosphere, and through which compressed air flows; an air release valve controlled to open and close the air release flow path; In an oil-cooled compressor comprising: A method for operating an oil-cooled compressor, comprising periodically opening and closing the air release valve based on a predetermined time interval for opening the air release valve and a predetermined time for maintaining the air release valve in an open state.

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