Drain discharge device

Abstract

To provide a drain discharge device capable of normally discharging drain without causing the backflow of air and the drain into equipment even when the internal pressure of the equipment for discharging the drain becomes a negative pressure.SOLUTION: The drain discharge device for discharging drain out of an intercooler of a two stage compression type air compressor includes a pressure detection part, a power source on-off part, and a drain trap part, the drain trap part having a solenoid valve for discharging the drain, a drain residence part where the drain resides, a water level sensor for detecting an upper limit level and a lower limit level of the drain in the drain residence part, and a control part. The control part opens the solenoid valve until the water level sensor does not detect the lower limit level after detecting the upper limit level. The solenoid valve is opened when energized and closed when non-energized. The pressure detection part detects an air pressure in the drain residence part. The power on-off part has means for cutting off a power source for the drain trap part when the pressure detection part detects that the air pressure is a negative pressure.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a drain discharge device, and more particularly to a technique for preventing drain from flowing back from the drain discharge device into the equipment when the inside of the equipment that generates the drain becomes negative pressure.

Background Art

[0002] Conventionally, when connecting a drain trap to the drain outlet of an intercooler, which is a device incorporated in a two-stage compression type air compressor or the like, the inside of the equipment becomes negative pressure during unloading due to unloaded operation or the like. Then, the air and drain in the drain trap may flow back into the equipment. Particularly in the case of a drain trap incorporating a water level sensor, the sensor may malfunction due to negative pressure, and the drain valve may continue to open. As a preventive measure, it is conceivable to attach a general check valve to the piping to the drain trap. However, with a check valve, the water level sensor may malfunction when negative pressure occurs, and there is a risk of hindering the drain discharge operation. Therefore, there has been a demand for a structure that prevents the backflow of drain into the equipment and reduces the influence of malfunction of the water level sensor when the equipment is under negative pressure.

[0003] In response to such problems, various techniques have been proposed conventionally. For example, a device for controlling an electromagnetic valve (see Patent Document 1) has been proposed when negative pressure occurs. More specifically, during unloaded operation, the three-way electromagnetic valve is switched, the primary side of the intermediate stage drain pipe is closed, and the cooled positive pressure system air that is open to the atmosphere is led to the secondary side of the intermediate stage drain pipe, and the secondary side of the intermediate stage drain pipe is always kept in a positive pressure state. The secondary side of the intermediate stage drain pipe can always be kept in a positive pressure state, enabling the installation of a drain trap to the intermediate stage drain pipe, and it is a configuration that can prevent the continuous discharge of compressed air. However, there is no description regarding the malfunction of the water level sensor, and the above problems have not been solved.

Prior Art Documents

Patent Documents

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 9-79160 [Summary of the Invention] [Problems to be Solved by the Invention]

[0005] An object of the present invention is to provide a drain discharge device that can normally discharge drain without causing air or drain to flow back into the device even when the inside of the device for discharging drain becomes negative pressure. [Means for Solving the Problems]

[0006] In order to solve the above problems, the present invention provides a drain discharge device for discharging drain in an intercooler of a two-stage compression type air compressor, which comprises a pressure detection unit, a power supply switch unit, and a drain trap unit. The drain trap unit includes a solenoid valve for discharging the drain, a drain retention unit for retaining the drain, a water level sensor for detecting the upper limit water level and the lower limit water level of the drain in the drain retention unit, and a control unit. The control unit opens the solenoid valve after detecting the upper limit water level of the water level sensor until the detection of the lower limit water level stops. The solenoid valve opens when energized and closes when de-energized. The pressure detection unit detects the air pressure in the drain retention unit, and the power supply switch unit takes means to cut off the power supply of the drain trap unit when the pressure detection unit detects that the pressure is negative.

[0007] Further, the present invention provides a drain discharge device for discharging drain in an intercooler of a two-stage compression type air compressor, which comprises a pressure detection unit and a drain trap unit. The drain trap unit includes a solenoid valve for discharging the drain, a drain retention unit for retaining the drain, a water level sensor for detecting the upper limit water level and the lower limit water level of the drain in the drain retention unit, and a control unit. After detecting the upper limit water level of the water level sensor, the control unit opens the solenoid valve until the lower limit water level is no longer detected. The pressure detection unit detects the air pressure in the drain retention part. When the control unit detects that the pressure detection unit is in a negative pressure state, the control unit stops the detection of the water level sensor and closes the solenoid valve.

[0008] Furthermore, the present invention adopts a means in which the pressure detection unit is arranged on the upper surface of the drain retention part or above the water level sensor.

[0009] Moreover, the present invention adopts a means in which the pressure detection unit detects a pressure of 0 MPa or less, or 0 MPa or more.

[0010] In addition, the present invention adopts a means in which the drain trap part periodically performs an air discharge operation of opening the solenoid valve for a certain period of time, and when the pressure detection unit detects that the pressure is negative, the air discharge operation is stopped.

[0011] Moreover, the present invention adopts a means in which the solenoid valve can withstand a backflow of 0.1 Mpa when the valve is closed.

[0012] And also, the present invention has a pressure detection control unit that controls the pressure detection unit and the drain trap part. The pressure detection control unit is connected to a commercial power supply, has a power supply circuit for the pressure detection unit, supplies power to the drain trap part, supplies power from the power supply circuit for the pressure detection unit to the pressure detection unit, and adopts a means for performing either an operation of turning on and off the power supply of the drain trap part or an operation of turning on and off the detection line of the water level sensor.

Advantages of the Invention

[0013] According to the drain discharge device of the present invention, even if the inside of the device for discharging drain becomes negative pressure, the drain can be discharged normally without allowing air or drain to flow back into the device.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0015] The drain discharge device according to the present invention is characterized in that when the inside of the device becomes negative pressure, it prevents the backflow of the drain and also prevents the malfunction of the water level sensor. Hereinafter, embodiments of the drain discharge device according to the present invention will be described with reference to the drawings. Note that the overall configuration of the drain discharge device and the configurations of each part shown below are not limited to the embodiments described below, and can be changed within the scope of the technical idea of the present invention, that is, within the scope of shapes, dimensions, structures, etc. that can exhibit the same operational effects.

[0016] The present invention will be described according to FIGS. 1 to 4. FIG. 1 is a front partial cross-sectional view showing an embodiment of a drain discharge device according to the present invention. FIG. 2 is a system diagram showing an embodiment of a drain discharge device according to the present invention, where (a) shows the case of using a power on / off section, and (b) shows the case where the control section uses the detection result of the pressure detection section. FIG. 3 is a process diagram showing the operation process of a drain discharge device according to the present invention. FIG. 4 is a process diagram showing the conventional operation process of a drain discharge device. The drain discharging device 1 discharges the drain D generated in the compressed air pressure circuit. In this embodiment, it mainly discharges the drain D generated in the intercooler disposed in the middle part of the two-stage compression type air compressor. The drain discharging device 1 is composed of a drain trap part 30, a pressure detection part 10, and a power supply switch part 20.

[0017] The drain trap part 30 is a part that discharges the drain D from the equipment of the compressed air pressure circuit. In this embodiment, it discharges the drain D from the intercooler disposed in the middle part of the two-stage compression type air compressor. As the drain trap part 30, there are those that discharge when the accumulated drain D reaches a certain amount or more, and those that discharge regularly. The drain trap of this embodiment is a drain trap with a water level sensor, and uses an upper limit water level sensor 33 and a lower limit water level sensor 34 to grasp the amount of drain and adjust the discharge amount of the drain D. The drain trap part 30 mainly consists of a drain retention part 32, a water level sensor, a solenoid valve 40, and a control part 60.

[0018] The drain retention part 32 is a part that temporarily retains the drain D flowing from the intercooler or the like. The drain D flows in from the drain inlet part 31 at the upper part of the drain retention part 32. The retained drain D is appropriately discharged from the bottom of the drain retention part 32 via the solenoid valve 40 to the drain discharge port 50.

[0019] The water level sensor detects the upper limit water level and the lower limit water level of the drain in the drain retention part. It is composed of an upper limit water level sensor 33, a lower limit water level sensor 34, and a common terminal 35, and is disposed on the side surface of the drain retention part 32. The signals from the upper limit water level sensor 33, the lower limit water level sensor 34, and the common terminal 35 are transmitted to the control part 60 through the detection line. The control part 60 detects the presence or absence of the drain D according to the current amount between the upper limit water level sensor 33, the lower limit water level sensor 34, and the common terminal 35. The upper limit water level sensor 33 is a sensor that detects that the amount of the drain D in the drain retention part 32 has reached the upper limit. When the water level of the drain D reaches the upper limit water level sensor 33, the drain D is discharged. The lower limit water level sensor 34 is a sensor that detects that the drain D in the drain retention part 32 has been almost discharged. When the drain D is discharged and the water level of the drain D drops below the position of the lower limit water level sensor 34, the discharge of the drain D is stopped.

[0020] The electromagnetic valve 40 is a valve that controls the discharge of the drain D. Electrically, it controls the opening and closing of the valve. The part that drives the valve of the electromagnetic valve 40 consists of a solenoid 41, a plunger 42, and a spring 43. The electromagnetic valve 40 of this embodiment is of the valve-opening type when energized. The electromagnetic valve 40 opens when energized and closes when de-energized. When energized, the solenoid 41 is energized, and a magnetic force is generated by the solenoid 41. By the magnetic force, the plunger 42 is attracted and moves away from the orifice 44 of the pipe. When the orifice 44 is opened, the pipe is opened, and the drain D is discharged through the electromagnetic valve 40. When de-energized, the magnetic force of the solenoid 41 stops. The plunger 42 abuts against the orifice 44 of the pipe by the force of the spring 43. When the orifice 44 is closed, the pipe is blocked, and the drain D is not discharged from the drain outlet 50.

[0021] The control unit 60 is a part that controls the movement of draining water from the drain trap part 30 and the like. It is configured on the circuit board 62 at the upper part of the device. The control unit 60 operates electrically. Commercial power is supplied through a socket and a cable, and is converted into an appropriate voltage by the power supply circuit in the circuit board and supplied to the control unit 60 as power. When the power is stopped, all functions of the control unit 60 stop, and the electromagnetic valve 40 closes. The electromagnetic valve 40 is controlled by the detection signals of the upper limit water level sensor 33 and the lower limit water level sensor 34. After detecting the upper limit water level based on the signal from the upper limit water level sensor 33, the control unit 60 opens the solenoid valve 40 to discharge the drain D until the lower limit water level is no longer detected based on the signal from the lower limit water level sensor 34. In other words, the discharge state of the drain D is maintained until the water level of the drain D becomes lower than the lower limit.

[0022] Also, the control unit 60 has a timer 61. The timer 61 measures time by counting at regular time intervals. The timer 61 is used periodically for operations such as discharging air and detecting abnormalities by measuring the opening time of valves. The air discharge operation controls the solenoid valve 40 periodically to open the valve for a short time to discharge a certain amount of the drain D and air in the drain retention part 32, and it is an operation to prevent air lock (air binding). The abnormality detection by measuring the opening time of the valve, for example, issues an alarm for discharge abnormality when the drain discharge time significantly exceeds the scheduled time.

[0023] The pressure detection unit 10 detects the air pressure in the drain retention part 32. In this embodiment, the pressure detection unit 10 is a pressure switch and is composed of a sensor that changes with pressure and an electric switch. The contact opens and closes at a specific pressure. In this embodiment, when negative pressure is detected, the contact opens or closes. The pressure detection unit 10 is arranged above the upper surface of the drain retention part 32 or above the water level sensor that detects the water level of the drain D in the drain retention part 32. By arranging the pressure detection unit 10 at this position, it is possible to reliably detect the air pressure in the drain retention part 32 without being affected by the drain D. The pressure detection unit 10 detects 0 MPa or less, or 0 MPa or more. The detection signal of the pressure detection unit 10 is sent to the power on / off unit 20. For elements that require power, power is supplied appropriately from the circuit board.

[0024] The power supply switch section 20 is a section that turns the power supply of the drain trap section 30 on and off according to a signal from the pressure detection section 10. Turning the power supply on and off is performed, for example, by a relay, a switching semiconductor element, or the like. One of the elements is connected to the power supply section 70, and the other is connected to the power supply of the drain trap section 30. The power supply section 70 is part of a commercial power supply (100 V or 200 V) and is supplied on the circuit board. In Fig. 2(a), the fact that the power supply switch section 20 is arranged on the circuit board 62 in the same manner as the control section 60 is represented by a dotted line. With this configuration, the connection of the power supply section 70, the control section 60, and the power supply switch section 20 is completed on the circuit board 62, and the circuit relationship can be made compact. Since the commercial power supply is alternating current, two circuits are required for the on-off circuit. When the power supply switch section 20 is turned on, power is supplied to the drain trap section 30, and the drain trap section 30 starts operating.

[0025] When the pressure detection section 10 detects a negative pressure, a relay or the like is turned off, the power to the drain trap section 30 is cut off, and the solenoid valve 40 closes. When the pressure detection section 10 detects that the negative pressure has disappeared, a relay or the like is turned on, power is supplied to the drain trap section 30, and the solenoid valve 40 opens appropriately. Also, the power supply switch section 20 receives the pressure detection signal from the pressure detection section 10. When the pressure detection section 10 is a component that requires power, the power supply switch section 20 supplies power to the pressure detection section 10. At that time, power of a voltage suitable for the pressure detection section 10 is supplied from the commercial power in the power supply switch section 20 using an AC / DC converter or the like.

[0026] As one of the devices of the compressed air pressure circuit, there is an air compressor. As one of the air compressors, there is a two-stage compression type air compressor. The two-stage compression type air compressor compresses air to an intermediate pressure in the low-pressure side cylinder, sends it to the intermediate part, and compresses the air in the intermediate part to the maximum pressure in the high-pressure side cylinder. The water vapor of the air in the intermediate part is discharged as drain D by the intercooler. The drainage of the drain D discharges the drain D accumulated at the bottom of the device through a drain trap, like other devices. When the pressure control method is of the automatic unloading type, when stopping the air compression, the intake part of the air compressor is throttled and unloaded operation is performed. Then, air is not supplied from the low-pressure side cylinder to the intermediate part and only sucked out from the high-pressure side cylinder, so the intermediate part becomes a negative pressure. The negative pressure is approximately -0.1 Mps. The timing and period when the negative pressure occurs vary depending on the usage status of the air compressor.

[0027] The system configuration will be described along FIG. 2(a). The power from the power supply unit 70 in the control unit 60 within the drain trap section 30 enters the control unit 60 again via the power on / off unit 20. The control unit 60 operates by this power. The power on / off unit 20 is enclosed by a dotted line as being on the circuit board constituting the control unit 60. The power on / off unit 20 controls the power on and off according to the pressure detection content of the pressure detection unit 10. When the pressure detection unit 10 does not detect a negative pressure, power is supplied to the control unit 60. The control unit 60 grasps the water level of the drain D based on the signals of the upper limit water level sensor 33 and the lower limit water level sensor 34, and controls the electromagnetic valve 40 accordingly. A timer 61 is provided in the control unit 60, and this timer 61 is used for measuring time for discharging drain air regularly. When the pressure detection unit 10 detects a negative pressure, power is not supplied to the control unit 60. Therefore, the control unit 60 stops and power is not supplied to the electromagnetic valve 40 either, so the electromagnetic valve 40, which is closed when de-energized, always closes the valve. In this way, the control unit 60 and the electromagnetic valve 40 can be controlled according to the pressure state within the drain retention section 32.

[0028] The problems in the conventional negative pressure situation will be described along FIG. 4. A drain discharge device for discharging the drain D of the intercooler attached to the intermediate part of a two-stage compression type air compressor is shown. The same reference numerals are used for the same elements as in the present invention. As shown in Fig. 4(a), drain D is stored in the drain retention part 32 of the drain trap part 30 through the drain pipe 80 from the intercooler. This figure shows a state where the water level of drain D has become higher than the upper limit water level sensor 33, the solenoid valve 40 is opened, and drainage has started.

[0029] Fig. 4(b) shows a state where the air compressor is in an unloaded operation. The inside of the intercooler becomes a negative pressure and acts in a direction to suck air and drain D into the intercooler. Also, since the solenoid valve 40 is open, it moves in a direction to take in air from the drain outlet 50. The air that enters the drain retention part 32 from the drain outlet 50 becomes bubbles and greatly disturbs the water surface of drain D. Therefore, drain D continues to be applied to the upper limit water level sensor 33 etc., and false detection occurs where the water level of drain D is above the upper limit. Furthermore, since air continues to enter from the drain outlet 50, the state where the discharge process of drain D does not progress continues, and a part of drain D and air will flow back into the device. Depending on the drain trap part 30, if the discharge is not completed within a certain time after starting the drain discharge process, a warning may be issued as an abnormality of the drain outlet 50. Therefore, due to the problem caused by the negative pressure, a warning is generated even though there is no abnormality in the drain outlet 50, which becomes an obstacle in management.

[0030] Fig. 4(c) shows a case where a negative pressure occurs in a state where the drain trap part 30 is not performing the drain discharge process. Since the drain discharge process is not being performed, the solenoid valve 40 is closed. When a negative pressure occurs, since the solenoid valve 40 is closed, there is no inflow of air from the drain outlet 50 and it seems to be problem-free. However, if the water surface of drain D undulates due to the negative pressure and a part of drain D is applied to the upper limit water level sensor 33, the control part 60 of the drain trap part 30 determines that the water level of drain D is above the upper limit position and opens the valve of the solenoid valve 40. Then, the same state as Fig. 4(b) is reached and a problem occurs. Thus, in a conventional drain trap, the generation of negative pressure causes problems in drain drainage.

[0031] Along with FIG. 3, the operation during negative pressure in this embodiment will be described while comparing it with the conventional example in FIG. 4. It is the operation of discharging the drain D of the intercooler attached to the middle part of the two-stage compression type air compressor. As shown in FIG. 3(a), similar to FIG. 4(a), since the water level of the drain D is higher than the upper limit water level sensor 33, the solenoid valve 40 is open and the drainage has started. Since the inside of the drain retention part 32 is filled with the drain D and high-pressure air equivalent to the compressed air pressure circuit, the pressure detection part 10 does not detect negative pressure. Basically, it is the same operation as in FIG. 4(a).

[0032] As shown in FIG. 3(b), similar to FIG. 4(b), the air compressor is in no-load operation, the inside of the intercooler is in a negative pressure state, and the inside of the drain retention part 32 is also in a negative pressure state. The pressure detection part 10 detects negative pressure, and the power on / off part 20 stops the power supply to the drain trap part 30. The drain trap part 30 stops electrically, the solenoid valve 40 becomes in a non-energized state, and the valve closes. Therefore, the air from the drain outlet 50 does not flow back into the inside of the drain retention part 32, and this state is maintained during the period of negative pressure.

[0033] Considering the performance of the solenoid valve, due to the characteristics of the solenoid valve, in a solenoid valve that closes when not energized, it is a condition that the pressure of the fluid flowing back is within a specified range. This is because if the pressure of the fluid flowing back is greater than the specified pressure, the plunger in contact with the orifice is pushed up and the fluid flows back inside the solenoid valve. In this embodiment, since the upstream of the solenoid valve 40 is in a negative pressure state and the downstream is at atmospheric pressure, the maximum reverse flow pressure is 0.1 MPa. Therefore, it is a condition that the solenoid valve in this embodiment is a valve that can withstand a reverse flow of 0.1 Mpa when the valve is closed.

[0034] When the negative pressure is eliminated, the power supply switch unit 20 starts supplying power to the drain trap unit 30. The drain trap unit 30 starts operating from its initial state after power-on. Fig. 3(c) shows a case where negative pressure occurs without performing the drain discharge process, similar to Fig. 4(c). Since the drain discharge process is not being performed, the solenoid valve 40 is closed. When negative pressure occurs, the pressure detection unit 10 detects the negative pressure, and the power supply switch unit 20 stops supplying power to the drain trap unit 30. The solenoid valve 40 is in a non-energized state, and the valve remains closed. Due to the negative pressure, the water surface of the drain D may undulate, and a part of the drain D may reach the upper limit water level sensor 33. However, since the drain trap unit 30 is stopped, the upper limit water level sensor 33 will not detect falsely, and the control unit 60 will not malfunction. While the negative pressure continues, this state continues, so the drain trap unit 30 will not malfunction, and air will not enter from the drain outlet 50. When the negative pressure is eliminated, power is supplied to the drain trap unit 30, and normal operation starts.

[0035] Regarding Example 2, it will be described along Fig. 2(b) while comparing it with Example 1 (Fig. 2(a)). The system of Example 1 turns on / off the entire drain trap unit 30 by the pressure detection unit 10 and the power supply switch unit 20. With this system, regardless of the operation performed by the control unit 60, when negative pressure occurs, all operations can be urgently stopped, and the solenoid valve 40 can be closed. However, depending on the content of the operation of the control unit 60, when the negative pressure state is eliminated, it may be considered to resume operation from the state before the negative pressure. Therefore, in this embodiment, control during negative pressure is performed while the drain trap unit 30 itself remains in operation.

[0036] As an operation, when the pressure detection unit 10 detects negative pressure, the control unit 30 stops detecting the water level sensor, closes the solenoid valve 40, and temporarily stops the timer 61. The timer 61 measures time and is used to define the time for detecting abnormal discharge or for the air discharge operation of periodically discharging the drain D. In the air discharge operation, the timer 61 is used to manage the cycle and opening time of opening the solenoid valve 40. After the negative pressure is eliminated, the timer 61 is operated. The value of the timer 61 becomes the value that had stopped during the period of negative pressure. Therefore, by the operation of temporarily stopping the timer 61, regardless of the length of the period of negative pressure, measurement by the timer 61 can be performed excluding the period of negative pressure, and the air discharge operation can be performed periodically. Similarly, regardless of the length of the period of negative pressure, a warning that the discharge abnormality is equal to or longer than the specified time can also be given at the specified time.

[0037] Regarding Example 3, it will be described with reference to FIGS. 5 and 6(a) while comparing with Example 1 (FIG. 2(a)). FIG. 5 is a front partial cross-sectional view showing an embodiment of Example 3 of the drain discharge device according to the present invention. Further, FIG. 6(a) is a system diagram showing an embodiment of Example 3 of the drain discharge device according to the present invention. The system of Example 1 turns on / off the entire drain trap portion 30 by the pressure detection portion 10 and the power on / off portion 20. The power on / off portion 20 is arranged on the circuit board 62 where the control portion 60 in the drain trap portion 30 is arranged, and turns on and off the power of the control portion 60. As the appearance of the drain trap, as a whole, it has a shape in which the pressure detection portion 10 is added to an existing drain trap, and has a compact and simple configuration. However, with this configuration, modification of the inside of the existing drain trap is necessary. Therefore, the already installed drain trap cannot be used as it is, and it was necessary to use a modified or new drain trap. Therefore, a configuration that can make use of an existing drain trap has been demanded.

[0038] In this embodiment, as shown in Fig. 6(a), the power supply switch unit 20 is arranged inside an independent housing called the pressure detection control unit 90 and connected to a conventional drain trap, so that a drain trap capable of coping with negative pressure can be easily constructed.

[0039] Along with Fig. 5, an example of the shape of this embodiment will be described. The pressure detection control unit 90 is a housing separate from the drain trap body. The pressure detection control unit 90 controls the pressure detection unit 10 and the drain trap unit 30. The pressure detection control unit 10 is connected to a commercial power supply, has an AC / DC converter which is a power supply circuit for the pressure detection unit, supplies power to the drain trap unit 30 via a power cable 92, and supplies power from the power supply circuit for the pressure detection unit to the pressure detection unit 10 via a pressure detection cable 91. Commercial power via an outlet is supplied to one side of the switch of the power supply switch unit 20, and the power cable 92 is connected to the other side. The pressure detection cable 91 from the pressure detection unit 10 is also connected to the pressure detection control unit 90. The pressure detection signal line in the pressure detection cable 91 is connected to the switch control part of the power supply switch unit 20. According to the state of the pressure detection signal line, the power supply switch unit 20 is turned on / off, and the power supply of the drain trap unit 30 is turned on / off.

[0040] The significant difference between this embodiment and Embodiment 1 is that the power supply switch unit 20 is in a separate housing. Functionally, it is almost equivalent to Embodiment 1. If the whole is to be made compact, Embodiment 1 is more advantageous. However, with the form of this embodiment, an existing drain trap can be easily utilized. If an attempt is made to modify an existing drain trap to make a device like that in Embodiment 1, it is necessary to modify the power supply circuit part of the circuit board in the drain trap, add a switch circuit such as a relay, make holes in the housing near the circuit, connect the cable from the pressure detection unit 10 to the power supply switch unit 20 on the circuit board, make a hole in the upper part of the drain retention part 32, and fix the pressure detection unit 10. Modifying the circuit board is difficult for the user of the device. Therefore, it is not easy to divert the existing drain trap. On the other hand, in the case of this embodiment, by simply opening a hole in the upper part of the drain retention part 32, fixing the pressure detection part 10, and taking the power supply of the drain trap from the pressure detection control part 90, a negative pressure compatible drain trap can be obtained.

[0041] In this way, by making a part of the system a separate housing, a device using the existing drain trap can be easily constructed, so that the equipment usage efficiency of the user can be improved. Therefore, it is possible to flexibly make many drain traps compatible with negative pressure.

[0042] Regarding Example 4, it will be described along with FIG. 6(b) while comparing it with Example 3 (FIG. 6(a)). FIG. 6(b) is a system diagram showing an embodiment of Example 4 of the drain discharge device according to the present invention. In the system of Example 3, the power supply on / off part 20 is arranged in the pressure detection control part 90 which is a housing separate from the drain trap part 30. Inside the pressure detection control part 90, commercial power from a power outlet is supplied to one of the switches of the power supply on / off part 20, and on the other hand, a power cable 92 for supplying power to the drain trap part 30 is connected. By making the power supply on / off part 20 a separate housing, the existing drain trap can be utilized. However, turning the entire power supply of the drain trap on and off is a relatively large power on and off. Therefore, a switching element such as a relay needs to be capable of handling large power. Therefore, a configuration that does not turn the power supply of the drain trap on and off and utilizes the existing drain trap has been required. In this embodiment, as shown in FIG. 6(b), the water level sensor on / off part 21 is arranged in the pressure detection control part 90 and connected to the conventional drain trap as an independent housing, thereby easily constructing a drain trap compatible with negative pressure.

[0043] The outline of the operation is that the water level sensor on / off unit 21 turns on and off all of the upper limit water level sensor 33, the lower limit water level sensor 34, and the common terminal 35, which are water level sensors, or the detection line from the common terminal 35. By cutting the detection line of the water level sensor with the water level sensor on / off unit 21, the control unit 60 determines that there is no drain D and operates in the direction of stopping the drainage of the drain D. The pressure detection control unit 90 is a housing separate from the drain trap main body. The water level sensor on / off unit 21 is arranged inside the pressure detection control unit 90. One of the switches of the water level sensor on / off unit 21 is connected to the line from the common terminal, and the other is connected to the line corresponding to the common terminal of the control unit 60. The commercial power from the power outlet first enters the pressure detection control unit 90 and is connected as power to the drain trap unit 30 via the power cable 92. The detection result of the pressure detection unit 10 enters the pressure detection control unit 90 via the pressure detection cable 91, and further controls the switch of the water level sensor on / off unit 21. Power is supplied from the pressure detection control unit 90 to the pressure detection unit 10. At this time, power of a voltage suitable for the pressure detection unit 10 is generated from the commercial power in the pressure detection control unit 90 using an AC / DC converter or the like, and is supplied to the pressure detection unit 10 via the pressure detection cable 91. The other parts are generally the same as those in the third embodiment.

[0044] By adopting the configuration according to this embodiment, a small-capacity switch element for control lines can be used as the switch element, so that the pressure detection control unit 90 can be made compact. In addition, compared with the case where the power is turned on / off by a switch, the noise at the moment of turning on / off can be reduced.

[0045] The operation example of this embodiment will be described. When the pressure in the drain retention part 32 is a positive pressure, the pressure detection unit 10 sends a signal indicating the positive pressure to the water level sensor on / off unit 21 of the pressure detection control unit 90. The water level sensor on / off unit 21 turns on, and the line of the common terminal 35 is connected to the control unit 60. The water level sensor operates normally, and the control unit 60 stores and drains the drain D according to the amount of the drain D. When the pressure is negative, the pressure detection unit 10 sends a signal indicating the negative pressure to the water level sensor on / off unit 21 of the pressure detection control unit 90. The water level sensor on / off unit 21 turns off, and the wire of the common terminal 35 is disconnected from the control unit 60. As seen from the control unit 60, since the water level sensor is in a state where it does not detect the water level, the control unit 60 determines that there is no drain D and closes the solenoid valve 40. Therefore, when the negative pressure occurs, the solenoid valve 40 is always closed, so the backflow from the drain drain port 50 does not occur, and the problem can be avoided. In this way, when dealing with negative pressure using the pressure detection control unit 90 and the existing drain trap, the control of the solenoid valve 40 can be performed only by turning on / off the detection line of the water level sensor, so the circuit configuration of the pressure detection control unit 90 can be made compact.

[0046] Also, as a modification of this embodiment, it is also possible to place the water level sensor on / off unit 21 on the circuit board 62 as in the first embodiment. By adopting such a configuration, when manufacturing a new drain trap, the whole can be made more compact. Also, in this embodiment, the water level sensor on / off unit 21 is not limited to the resistance value type using the common terminal 35, and the detection method such as the capacitance type is not limited.

[0047] In this way, according to the drain discharge device 1 according to the present invention, even if the device for discharging the drain D becomes negative pressure, the drain D can be normally discharged without allowing air or the drain D to flow back into the device.

[0048] Also, according to the present invention, when the negative pressure is detected, the power supply of the entire drain trap is turned off. Therefore, even if a plurality of processes are performed in the drain trap, the solenoid valve 40 can be surely closed, and high reliability can be obtained.

[0049] Furthermore, according to the present invention, when negative pressure is detected, the control unit 60 appropriately stops the detection of the water level sensor and closes the solenoid valve 40. Therefore, after the return, the process can be continuously performed, and the processing efficiency can be improved.

[0050] Still further, according to the present invention, since the pressure switch, which is the pressure detection unit 10, is disposed above the upper surface of the drain stay portion 32 or the upper limit water level sensor 33, the possibility of the drain D being applied to the pressure detection unit 10 is reduced, and deterioration of the detection performance of the pressure detection unit 10 can be prevented.

[0051] Moreover, according to the present invention, as the pressure detection unit 10, a detection unit that detects 0 MPa or less, or 0 MPa or more can be selected, so that a wide range of selections is available, which is preferable.

[0052] Still further, according to the present invention, when negative pressure is detected, a periodic air discharge operation can be stopped. Therefore, a stable air discharge operation can be performed without the occurrence of backflow of air and the drain D.

[0053] Moreover, according to the present invention, since a solenoid valve 40 having appropriate pressure resistance during backflow can be selected, leakage from the solenoid valve 40 does not occur during negative pressure, which is preferable.

[0054] And also, according to the present invention, by making the pressure detection control unit 90 a separate housing, it becomes possible to divert an existing drain trap, and efficient utilization of the equipment becomes possible.

Industrial Applicability

[0055] The drain discharge device according to the present invention can be used as a drain discharge device in an intercooler in any compressed air pressure circuit as a technique for normally discharging drain without backflow of air or drain into a device even when a device that generates drain becomes negative pressure. Therefore, the industrial applicability of the present invention is considered to be great.

Explanation of Signs

[0056] 1 Drain discharge device 10 Pressure detection unit 11 Power supply for pressure detection unit 20 Power on / off unit 21 Water level sensor on / off unit 30 Drain trap section 31 Drain inlet 32 Drain retention section 33 Upper limit water level sensor 34 Lower limit water level sensor 35 Common terminal 40 Electromagnetic valve 41 Solenoid 42 Plunger 43 Spring 44 Orifice 50 Drain outlet 60 Control unit 61 Timer 62 Circuit board 70 Power supply unit 80 Drain pipe 90 Pressure detection control unit 91 Cable for pressure detection 92 Power cable D Drain

Claims

1. In a drain discharge device for discharging drain in an intercooler of a two-stage compression type air compressor, comprising a pressure detection unit, a power supply switch unit, and a drain trap unit, the drain trap unit has a solenoid valve for discharging the drain, a drain retention unit for retaining the drain, a water level sensor for detecting the upper limit water level and the lower limit water level of the drain in the drain retention unit, and a control unit, the control unit opens the solenoid valve after detecting the upper limit water level of the water level sensor until the lower limit water level is no longer detected, the solenoid valve opens when energized and closes when de-energized, the pressure detection unit detects the air pressure in the drain retention unit, the power supply switch unit is characterized in that when the pressure detection unit detects that the pressure is negative pressure, it cuts off the power supply of the drain trap unit.

2. In a drain discharge device for discharging drain in an intercooler of a two-stage compression type air compressor, comprising a pressure detection unit and a drain trap unit, the drain trap unit has a solenoid valve for discharging the drain, a drain retention unit for retaining the drain, a water level sensor for detecting the upper limit water level and the lower limit water level of the drain in the drain retention unit, and a control unit, the control unit opens the solenoid valve after detecting the upper limit water level of the water level sensor until the lower limit water level is no longer detected, the pressure detection unit detects the air pressure in the drain retention unit, the control unit is characterized in that when the pressure detection unit detects that the pressure is negative pressure, it stops the detection of the water level sensor and closes the solenoid valve.

3. The drain discharge device according to claim 1 or claim 2, wherein the pressure detection unit is disposed on the upper surface of the drain retention unit or above the water level sensor.

4. The drain discharge device according to claim 3, wherein the pressure detection unit detects a pressure of 0 MPa or less, or 0 MPa or more.

5. The drain trap unit of the drain discharge device according to claim 2 is characterized in that it periodically performs an air discharge operation of opening the solenoid valve for a certain period of time, and stops the air discharge operation when the pressure detection unit detects that the pressure is negative pressure.

6. The drain discharge device according to claim 3, wherein the solenoid valve is capable of withstanding a backflow of 0.1 Mpa when the valve is closed.

7. having a pressure detection control unit for controlling the pressure detection unit and the drain trap unit, The pressure detection control unit is connected to a commercial power supply, has a power supply circuit for the pressure detection unit, supplies power to the drain trap unit, and supplies power from the power supply circuit for the pressure detection unit to the pressure detection unit. The drain discharge device according to claim 3, characterized in that it performs either an operation of turning on and off the power supply of the drain trap unit or an operation of turning on and off the detection line of the water level sensor.

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