Air supply system, method for controlling air supply system, and program for controlling air supply system

Abstract

Provided are an air supply system capable of maintaining a dry state of compressed dry air, a method for controlling the air supply system, and a program for controlling the air supply system. An air supply system (10) is provided with: an air drying circuit (11) that is provided between a compressor (4) that sends compressed air and an air tank (30) that stores compressed dry air, and that has a filter (17) that contains a drying agent that captures moisture; and an ECU (80) that controls the air drying circuit (11). When a compressor (4) is driven to send compressed air to a filter (17) to supply compressed air to an air tank (30), an ECU (80) determines the dry state of compressed dry air stored in the air tank (30) according to the moisture content and determines whether or not to execute a regeneration operation. This regeneration operation causes the compressed dry air to pass through the filter (17) in the reverse direction and discharges the discharged liquid that has passed through the filter (17) from the discharged liquid discharge port (27).

Description

[0001] This application is a divisional application of a Chinese invention patent application filed on February 25, 2020, with application number 2020800301708 (PCT / JP2020 / 007465), and invention name “Air supply system, control method of air supply system, and control program of air supply system”. Technical Field

[0002] The present disclosure relates to an air supply system, a control method of the air supply system, and a control program of the air supply system. Background Art

[0003] In vehicles such as trucks, buses, and construction machinery, compressed air delivered from a compressor is used to control air pressure systems including brake systems and suspension systems. The compressed air contains moisture contained in the atmosphere and liquid impurities such as oil used to lubricate the compressor. If compressed air containing a large amount of moisture and oil enters the air pressure system, it may cause rust and swelling of rubber components, which may cause malfunction. Therefore, a compressed air drying device for removing impurities such as moisture and oil in the compressed air is provided downstream of the compressor.

[0004] The compressed air drying device includes a desiccant and various valves. The compressed air drying device performs a load operation (dehumidification operation) of removing moisture and the like from the compressed air. The compressed dry air generated by the dehumidification operation is stored in a storage unit. In addition, the purification function of the compressed air drying device decreases according to the amount of compressed dry air passing through. Therefore, the compressed air drying device performs an unloading operation (regeneration operation) as follows: oil and moisture adsorbed on the desiccant are removed from the desiccant and the removed oil and moisture are discharged as drainage (for example, refer to Patent Document 1).

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2010-201323 Summary of the invention

[0008] Problem that the invention aims to solve

[0009] In addition, the compressed air drying device switches between the dehumidification operation and the regeneration operation based on the pressure of the storage unit. There is a risk that when the consumption of the compressed dry air stored in the storage unit continues, the dehumidification operation is continued without switching to the regeneration operation, and the moisture content of the compressed dry air stored in the storage unit increases. Therefore, it is required to maintain the dry state of the compressed dry air.

[0010] An object of the present disclosure is to provide an air supply system and a control method of the air supply system capable of maintaining a dry state of compressed dry air.

[0011] Solutions for solving problems

[0012] An air supply system for solving the above-mentioned problem comprises: an air drying circuit, which is arranged between a compressor that sends out compressed air and an air tank that stores compressed dry air, the air drying circuit having a filter including a desiccant that captures moisture; and a control device, which controls the air drying circuit, wherein the control device performs the following processing: during a supply action, determining the dryness state of the compressed dry air stored in the air tank based on the moisture content, the supply action being an action of driving the compressor to send the compressed air to the filter and thereby supplying the compressed air to the air tank, and determining whether to perform a regeneration action, the regeneration action being an action of causing the compressed dry air to pass through the filter in a reverse direction to discharge the fluid that has passed through the filter from an exhaust port.

[0013] A control method for an air supply system for solving the above-mentioned problem, the air supply system comprising: an air drying circuit, which is arranged between a compressor for delivering compressed air and an air tank for storing compressed dry air, the air drying circuit having a filter including a desiccant for capturing moisture; and a control device, which controls the air drying circuit, in which the control device is caused to perform the following processing: during a supply action, determining the dryness state of the compressed dry air stored in the air tank based on the moisture content, the supply action being an action of driving the compressor to deliver the compressed air to the filter and thereby supplying the compressed air to the air tank, and determining whether to perform a regeneration action, the regeneration action being an action of causing the compressed dry air to pass through the filter in a reverse direction and thereby discharging the fluid that has passed through the filter from an exhaust port.

[0014] A control program for an air supply system for solving the above-mentioned problem, the air supply system comprising: an air drying circuit, which is arranged between a compressor for delivering compressed air and an air tank for storing compressed dry air, the air drying circuit having a filter including a desiccant for capturing moisture; and a control device, which controls the air drying circuit, the control program causing the control device to function as the following parts: a dryness state determination unit, which determines the dryness state of the compressed dry air stored in the air tank according to the moisture content during a supply action, the supply action being an action of driving the compressor to deliver the compressed air to the filter and thereby supplying the compressed air to the air tank; and a regeneration action execution determination unit, which determines whether to execute a regeneration action based on the dryness state of the compressed dry air, the regeneration action being an action of causing the compressed dry air to pass through the filter in a reverse direction to discharge the fluid that has passed through the filter from an exhaust port.

[0015] According to the above structure, during the supply operation, the dryness of the compressed dry air is determined according to the moisture content to determine whether to perform the regeneration operation. Therefore, when the supply operation is performed and the regeneration of the desiccant is insufficient, the regeneration operation is performed. Therefore, the dryness of the compressed dry air can be maintained.

[0016] Regarding the above-mentioned air supply system, the control device may be configured to: obtain pressure information of the gas tank and the air discharge volume of the compressor, calculate the consumption of the compressed dry air stored in the gas tank based on the pressure change of the gas tank, and use the consumption of the compressed dry air and the air discharge volume to calculate the moisture content of the compressed dry air.

[0017] When compressed dry air is consumed by braking or regeneration while being supplied to the air tank, it is difficult to calculate the moisture content of the compressed dry air in the air tank. Therefore, according to the above structure, the consumption of compressed dry air is calculated based on the pressure change of the air tank and the air discharge amount of the compressor, and the moisture content of the consumed compressed dry air is calculated, thereby accurately estimating the moisture content of the air tank after the compressed dry air is consumed by braking or regeneration.

[0018] Regarding the air supply system, the control device may be configured to execute the regeneration operation when the pressure of the compressed dry air reaches a cut-out pressure for performing the regeneration operation and the dry state of the compressed dry air does not satisfy a predetermined condition.

[0019] If the compressed dry air is supplied and consumed, and the compressed dry air pressure does not reach the cut-out pressure and the compressed dry air continues to be supplied, the drying capacity of the filter decreases. Therefore, according to the above structure, when the compressed dry air pressure does not reach the cut-out pressure and the dry state of the compressed dry air does not meet the prescribed conditions, the desiccant is regenerated by performing the regeneration operation, thereby maintaining the dry state of the compressed dry air.

[0020] Regarding the above-mentioned air supply system, the control device may be configured to perform a purge action when the pressure of the compressed dry air reaches the cut-out pressure and the dry state of the compressed dry air satisfies specified conditions. The purge action is an action of passing the compressed dry air of the air drying circuit through the filter in the reverse direction to discharge the fluid that has passed through the filter from the exhaust port.

[0021] According to the above structure, when the dry state of the compressed dry air satisfies the specified conditions, the compressed dry air in the air tank is not regenerated by passing the filter in the reverse direction, but the compressed dry air in the air drying circuit is purged by passing the filter in the reverse direction. Therefore, the consumption of the compressed dry air in the air tank can be suppressed.

[0022] Regarding the above-mentioned air supply system, it may be that it is further equipped with: a discharge valve, which connects the branch road connected to the air drying circuit with the discharge port; and a regeneration control valve, which switches between a flow in a forward direction from the filter toward the gas tank and a flow in a reverse direction from the gas tank toward the filter. It may be that the control device is configured to control the discharge valve and the regeneration control valve.

[0023] According to the above configuration, the control device controls the discharge valve and the regeneration control valve to perform the supply operation and the regeneration operation.

[0024] Effects of the Invention

[0025] According to the present disclosure, it is possible to maintain the dry state of the compressed dry air. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a structural diagram showing a schematic structure of a first embodiment of the air supply system.

[0027] Figure 2A It is shown Figure 1 FIG. 1 shows a first operation mode and a seventh operation mode of an air drying circuit according to an embodiment of the present invention. Figure 2B It is shown Figure 1 FIG. 1 is a diagram of a second operating mode of an air drying circuit of an embodiment of the present invention, Figure 2C It is shown Figure 1FIG. 3 is a diagram of a third operation mode and an eighth operation mode of an air drying circuit according to an embodiment of the present invention, Figure 2D to Figure 2F are shown separately Figure 1 FIG. 4 is a diagram showing fourth to sixth operation modes of the air drying circuit according to the embodiment.

[0028] Figure 3 It is shown Figure 1 A migration diagram showing the migration of the action of the air drying circuit of an embodiment.

[0029] Figure 4 It is shown Figure 1 Flowchart of the migration of the air drying circuit from the first operation mode according to an embodiment of the present invention.

[0030] Figure 5 It is shown Figure 1 Flow chart of the transition of the air drying circuit from the second operation mode and the third operation mode according to the embodiment.

[0031] Figure 6 It is shown Figure 1 Flowchart of the migration of the air drying circuit from the fifth operation mode in an embodiment.

[0032] Figure 7 It is shown Figure 1 Flow chart of the migration of the air drying circuit from the seventh operation mode in an embodiment.

[0033] Figure 8 It is shown Figure 1 Flow chart of the migration of the air drying circuit from the eighth operation mode in an embodiment.

[0034] Fig. 9 1 is a schematic diagram showing a process of calculating the tank air moisture saturation level in the second embodiment of the air supply system. DETAILED DESCRIPTION

[0035] (First Embodiment)

[0036] Reference Figures 1 to 8 A first embodiment of the air supply system will be described. The air supply system is mounted on a vehicle such as a truck, a bus, or an engineering machine. The compressed dry air supplied by the air supply system is used in air compression equipment such as a brake system mounted on the vehicle.

[0037] <Air supply system 10>

[0038] Reference Figure 1 The air supply system 10 will be described. The air supply system 10 includes a compressor 4, an air drying circuit 11, and an ECU (Electronic Control Unit) 80 as a control device.

[0039] ECU 80 is connected to the air drying circuit 11 via a plurality of wirings E61 to E67. ECU 80 includes a computing unit, a communication interface unit, a volatile storage unit, and a non-volatile storage unit. The computing unit is a computer processor configured to control the air drying circuit 11 according to an air supply program stored in a non-volatile storage unit (storage medium). The computing unit may implement at least a portion of the processing performed by itself through a circuit such as an ASIC. The air supply program may be executed by one computer processor or by a plurality of computer processors. In addition, ECU 80 includes a storage unit 80A which stores the results of the operation of the air drying circuit 11. The storage unit 80A is a non-volatile storage unit or a volatile storage unit, and may be the same as or different from the storage unit storing the above-mentioned control program.

[0040] The ECU 80 is connected to other ECUs (not shown) mounted on the vehicle, such as the engine ECU and the brake ECU, via an in-vehicle network such as a CAN (Controller Area Network). The ECU 80 obtains information indicating the vehicle status from these ECUs. The information indicating the vehicle status includes, for example, information indicating whether the ignition switch is turned off, the vehicle speed, and engine driving information.

[0041] The state of the compressor 4 is switched between an operating state (load operation) of compressing air and delivering the air and a non-operating state (idle operation) of not compressing air based on a command value from the ECU 80. The compressor 4 is operated by power transmitted from a rotational drive source such as an engine.

[0042] The air drying circuit 11 is a so-called air dryer. The air drying circuit 11 is connected to the ECU 80 and removes moisture and the like contained in the compressed air from the compressor 4 in load operation. The air drying circuit 11 sends the dried compressed air (hereinafter, compressed dry air) to the supply circuit 12. The compressed dry air supplied to the supply circuit 12 is stored in the air tank 30.

[0043] The compressed dry air stored in the air tank 30 is supplied to air compressor equipment such as the brake system mounted on the vehicle. For example, when the frequency of brake operation is high, such as when the vehicle is traveling downhill or in an urban area, the consumption of the compressed dry air stored in the air tank 30 increases. On the contrary, when the frequency of brake operation is low, the consumption of the compressed dry air stored in the air tank 30 decreases.

[0044] The air drying circuit 11 has a maintenance port P12. The maintenance port P12 is a port for supplying air to the air drying circuit 11 during maintenance.

[0045] <Air drying circuit 11>

[0046] In the housing 11A of the air drying circuit 11 (see Figure 2A ) is provided with a filter 17 inside. The filter 17 is provided in the middle of the air supply passage 18 connecting the compressor 4 and the supply circuit 12. In addition, the filter 17 includes a desiccant. In addition, the filter 17 may include an oil capture part for capturing oil in addition to the desiccant. The oil capture part can be any foam such as polyurethane foam, a metal material with a plurality of vents, a glass fiber filter, etc., which can capture oil while allowing air to pass through.

[0047] The filter 17 allows the compressed air sent from the compressor 4 to pass through a desiccant, thereby removing the moisture contained in the compressed air to dry the compressed air. In addition, the desiccant or oil capture unit captures the oil contained in the compressed air to purify the compressed air. The compressed air passing through the filter 17 is supplied to the supply circuit 12 via the downstream one-way valve 19, and the downstream one-way valve 19 serves as a check valve that only allows air to flow downstream relative to the filter 17. That is, when the filter 17 side is set to the upstream and the supply circuit 12 side is set to the downstream, the downstream one-way valve 19 only allows air to flow from the upstream to the downstream. In addition, the downstream one-way valve 19 has a specified valve opening pressure (closing pressure), so when the compressed air flows, the pressure upstream is higher than the pressure downstream by the valve opening pressure.

[0048] In addition, a bypass flow path 20 is provided downstream of the filter 17 in parallel with the downstream check valve 19 as a bypass path for bypassing the downstream check valve 19. The bypass flow path 20 is provided with a regeneration control valve 21.

[0049] The regeneration control valve 21 is a solenoid valve controlled by the ECU 80. The ECU 80 controls the power supply of the regeneration control valve 21 to be turned on / off (driven / non-driven) via the wiring E64, thereby switching the operation of the regeneration control valve 21. The regeneration control valve 21 closes the valve to block the bypass flow path 20 when the power supply is turned off, and opens the valve to connect the bypass flow path 20 when the power supply is turned on. For example, the ECU 80 receives the value of the air pressure in the gas tank 30, and operates the regeneration control valve 21 when the value of the air pressure exceeds a predetermined range.

[0050] A throttle hole 22 is provided in the bypass flow path 20 between the regeneration control valve 21 and the filter 17. When the regeneration control valve 21 is energized, the compressed dry air on the supply circuit 12 side is delivered to the filter 17 via the bypass flow path 20 in a state where the flow rate is limited by the throttle hole 22. The compressed dry air delivered to the filter 17 flows back in the filter 17 from downstream to upstream and passes through the filter 17. Such a process is an action to regenerate the filter 17, which is called a regeneration action of the dryer. At this time, the compressed dry air delivered to the filter 17 is the dried and purified air supplied to the supply circuit 12 from the air supply passage 18 through the filter 17, etc., so that the moisture and oil captured by the filter 17 can be removed from the filter 17. In normal control, the ECU 80 opens the regeneration control valve 21 when the pressure in the air tank 30 reaches the upper limit value (cut-out pressure). On the other hand, when the pressure in the gas tank 30 reaches the lower limit value (cut-in pressure), the regeneration control valve 21 that has been opened is closed.

[0051] A branch passage 16 branches off from a portion between the compressor 4 and the filter 17. The branch passage 16 is provided with a waste liquid discharge valve 25, and a waste liquid discharge port 27 is connected to the terminal end of the branch passage 16.

[0052] The drain liquid, which is a fluid containing water and oil removed from the filter 17, is transported to the drain liquid discharge valve 25 together with the compressed air. The drain liquid discharge valve 25 is an air pressure driven valve driven by air pressure, and is provided between the filter 17 and the drain liquid discharge port 27 in the branch passage 16. The drain liquid discharge valve 25 is a two-position two-way valve that changes its position between a closed valve position and an open valve position. When the drain liquid discharge valve 25 is in the open valve position, the drain liquid is transported to the drain liquid discharge port 27. The drain liquid discharged from the drain liquid discharge port 27 can also be recovered by an oil separator not shown. In addition, the drain liquid is equivalent to the fluid that has passed through the filter 17 in the reverse direction.

[0053] The drain valve 25 is controlled by the regulator 26A. The regulator 26A is a solenoid valve controlled by the ECU 80. The ECU 80 switches the operation of the regulator 26A by controlling the power on / off (driving / non-driving) of the regulator 26A via the wiring E63. When the power is turned on, the regulator 26A inputs an air pressure signal to the drain valve 25 to open the drain valve 25. In addition, when the power is turned off, the regulator 26A does not input an air pressure signal to the drain valve 25, but opens the drain valve 25 to the atmospheric pressure, thereby closing the drain valve 25.

[0054] The drain valve 25 is maintained in the closed position when no air pressure signal is input from the regulator 26A, and is switched to the open position when an air pressure signal is input from the regulator 26A. In addition, when the pressure of the input port of the drain valve 25 connected to the compressor 4 exceeds the upper limit value, the drain valve 25 is forcibly switched to the open position.

[0055] An upstream check valve 15 is provided between the compressor 4 and the filter 17 and between the compressor 4 and the branch passage 16. When the compressor 4 side is set to the upstream and the filter 17 side is set to the downstream, the upstream check valve 15 only allows air to flow from the upstream to the downstream. The upstream check valve 15 has a specified valve opening pressure (closing pressure), so when the compressed air flows, the pressure upstream is higher than the pressure downstream by the valve opening pressure. In addition, a reed valve at the outlet of the compressor 4 is provided upstream of the upstream check valve 15. A branch passage 16 and a filter 17 are provided downstream of the upstream check valve 15.

[0056] <Compressor 4>

[0057] The compressor 4 is controlled by the unloading control valve 26B. The unloading control valve 26B is a solenoid valve controlled by the ECU 80. The ECU 80 switches the operation of the unloading control valve 26B by controlling the power on / off (driving / non-driving) of the unloading control valve 26B via the wiring E62. When the power is cut off, the unloading control valve 26B is switched to the open position to open the flow path between the unloading control valve 26B and the compressor 4 to the atmosphere. In addition, when the power is turned on, the unloading control valve 26B is switched to the supply position to deliver an air pressure signal consisting of compressed air to the compressor 4.

[0058] When an air pressure signal is input from the unloading control valve 26B, the state of the compressor 4 is switched to a non-operating state (idling). For example, when the pressure of the supply circuit 12 reaches the cut-out pressure, it is not necessary to supply compressed dry air. When the pressure on the supply circuit 12 side reaches the cut-out pressure and the ECU 80 turns on the power of the unloading control valve 26B (drives the unloading control valve 26B), the unloading control valve 26B switches to the supply position. As a result, an air pressure signal is supplied from the unloading control valve 26B to the compressor 4, and the state of the compressor 4 is switched to a non-operating state.

[0059] <Sensor>

[0060] A pressure sensor 50 is provided between the compressor 4 and the upstream check valve 15. The pressure sensor 50 is connected to the air supply passage 18 to measure the air pressure of the air supply passage 18 and transmits the measured result to the ECU 80 via the wiring E61.

[0061] A humidity sensor 51 and a temperature sensor 52 are provided between the downstream check valve 19 and the supply circuit 12. The humidity sensor 51 measures the humidity of the compressed dry air downstream of the filter 17, and outputs the measured result to the ECU 80 via the wiring E65. The temperature sensor 52 measures the temperature of the compressed dry air downstream of the filter 17, and outputs the measured result to the ECU 80 via the wiring E66. The ECU 80 determines the dryness state of the compressed dry air based on the humidity and temperature of the compressed dry air input from the humidity sensor 51 and the temperature sensor 52. That is, the humidity and temperature of the compressed dry air are indicators indicating the dryness state of the compressed dry air.

[0062] A pressure sensor 53 is provided between the downstream check valve 19 and the supply circuit 12. The pressure sensor 53 is provided, for example, to detect the air pressure in the gas tank 30 storing compressed dry air, and the pressure sensor 53 is connected to the ECU 80 via the wiring E67. The pressure between the downstream check valve 19 and the supply circuit 12 is the same as the pressure in the gas tank 30, and the detection result of the pressure sensor 53 can be used as the pressure in the gas tank 30. In addition, the pressure sensor 53 can be provided in either the supply circuit 12 or the gas tank 30.

[0063] The ECU 80 obtains the pressure information of the gas tank 30 and the air discharge amount of the compressor 4, and calculates the air consumption of the compressed dry air stored in the gas tank 30 based on the pressure change of the gas tank 30. Then, the ECU 80 calculates the moisture content of the compressed dry air using the air consumption and the air discharge amount of the compressed dry air.

[0064] Specifically, the ECU 80 obtains the air pressure in the gas tank 30 from the pressure sensor 53 as pressure information. In addition, the ECU 80 calculates the air discharge amount based on the rotation speed of the compressor 4. The ECU 80 calculates the air consumption of the compressed dry air stored in the gas tank 30 based on the atmospheric pressure according to the formula (1). In addition, the pressure reduction value can be obtained based on the difference between the previous value detected by the pressure sensor 53 and the current value.

[0065] Air consumption = (decompression value [kPa] / atmospheric pressure [kPa]) × tank capacity [L] + air discharge volume (previous value) [L]… (1)

[0066] The amount of moisture contained in the consumed air is calculated according to equation (2). The amount of moisture contained in the tank is the absolute value of the amount of moisture contained in the tank 30 calculated based on the compressed air temperature and compressed air humidity in the tank 30 at the end of regeneration.

[0067] Moisture content of consumed air [g] = Moisture content of tank [g] × Air consumption between cycles [L] × (Atmospheric pressure [kPa] / (Cut-out pressure [kPa] + Atmospheric pressure [kPa])) ÷ Tank capacity [L]… (2)

[0068] In addition, when there is no air ejection amount, the air consumption amount can be directly calculated from the pressure change (decompression value). In addition, when there is air ejection amount, the air consumption amount can be calculated from the pressure change (decompression value) and the air ejection amount.

[0069] <Description of Operation of Air Drying Circuit 11>

[0070] like Figure 2A to Figure 2F As shown, the air drying circuit 11 has a plurality of operation modes including at least a first operation mode to an eighth operation mode.

[0071] (First action mode)

[0072] like Figure 2A As shown, the first action mode is a mode for performing a "supply" action, which performs normal dehumidification (load). In this first action mode, the regeneration control valve 21, the regulator 26A, and the unloading control valve 26B are closed (recorded as "CLOSE" in the figure). At this time, no power is supplied to the regeneration control valve 21, the regulator 26A, and the unloading control valve 26B. In addition, the regulator 26A and the unloading control valve 26B respectively open the port of the compressor 4 connected to their downstream and the port of the drain valve 25 to the atmosphere. In the first action mode, when compressed air is supplied from the compressor 4 (recorded as "ON" in the figure), the compressed air is supplied to the supply circuit 12 after the moisture, etc. are removed by the filter 17.

[0073] (Second action mode)

[0074] like Figure 2BAs shown in FIG. 1 , the second operation mode is a mode for performing a "purge" operation of passing the compressed dry air in the air drying circuit 11 through the filter 17 to purify the filter 17. In this second operation mode, the regeneration control valve 21 is closed, and the regulator 26A and the unloading control valve 26B are opened (represented as "OPEN" in the figure). At this time, power is supplied to the regulator 26A and the unloading control valve 26B, respectively, and the port of the compressor 4 and the port of the drain discharge valve 25 connected to the downstream of them are connected to the upstream (supply circuit 12 side) respectively. As a result, the compressor 4 is switched to a non-operating state (represented as "OFF" in the figure), and the drain discharge valve 25 is opened. As a result, the compressed dry air between the downstream check valve 19 and the filter 17 flows through the filter 17 in the opposite direction to the air flow in the first operation mode (supply) (counterflow), and the moisture captured by the filter 17 is discharged from the drain discharge port 27 as drain. In addition, the air pressure of the filter 17 and the air supply passage 18 is opened to atmospheric pressure.

[0075] (Third Action Mode)

[0076] like Figure 2C As shown in FIG. 1 , the third operation mode is a mode for performing a "regeneration" operation for regenerating the filter 17. In the third operation mode, the regeneration control valve 21, the regulator 26A, and the unloading control valve 26B are opened. At this time, in addition to supplying power to the regulator 26A and the unloading control valve 26B, power is also supplied to the regeneration control valve 21. In the third operation mode, the compressor 4 is set to a non-operating state, and the compressed dry air stored in the supply circuit 12 or the gas tank 30 is reversed through the filter 17 and discharged from the drain outlet 27. Thus, the moisture captured by the filter 17 is removed. The second operation mode and the third operation mode are both modes for purifying the filter 17, but the third operation mode is different from the second operation mode at least in that the regeneration control valve 21 is opened. Thus, in the third operation mode, the compressed dry air in the gas tank 30 can pass through the filter 17 via the supply circuit 12 and the bypass flow path 20. Therefore, the effect of purifying the filter 17 is higher than that in the second operation mode. Furthermore, in the third operation mode, the air pressure of the filter 17 and the air supply passage 18 is also released to the atmospheric pressure.

[0077] (Fourth Action Mode)

[0078] like Figure 2DAs shown in FIG. 1 , the fourth operation mode is a mode in which a "de-oiling" operation is performed to discharge the compressed air supplied from the compressor 4 while the compressor 4 is operated. When the compressor 4 is in a non-operating state, oil may accumulate in the compression chamber of the compressor 4. If the state of the compressor 4 is switched to an operating state while oil accumulates in the compression chamber, the amount of oil contained in the compressed air delivered from the compression chamber may increase. The de-oiling operation is performed for the purpose of discharging the compressed air with excessive oil through the drain valve 25 to reduce the load on the filter 17. In the fourth operation mode, the regeneration control valve 21 and the unloading control valve 26B are closed, and the regulator 26A is closed after the valve is opened for a fixed period. In the fourth operation mode, when the state of the compressor 4 is in an operating state, the compressed air supplied from the compressor 4 is discharged from the drain outlet 27 for a fixed period. Therefore, it is possible to suppress the increase in the amount of water and oil captured by the filter 17 immediately after the compressor 4 is switched from the non-operating state to the operating state. The de-oiling operation can also be performed when the oil content from the compressor 4 increases, such as when the engine speed increases during operation or when the engine load is high.

[0079] (Fifth Action Mode)

[0080] like Figure 2E As shown in FIG. 1 , the fifth operation mode is a mode for performing a "no-purge supply stop" operation in which the compressor 4 is stopped in a no-purge state. In the fifth operation mode, the regeneration control valve 21 and the regulator 26A are closed, and the unloading control valve 26B is opened. In the fifth operation mode, when the compressor 4 is not in operation, the compressed air or compressed dry air remaining in the air supply passage 18 or the desiccant of the filter 17 is not discharged from the drain outlet 27, thereby maintaining the air pressure.

[0081] (Sixth Action Mode)

[0082] like Figure 2FAs shown, the sixth action mode is a mode for performing a "compressor assist" action, and the "compressor assist" action performs a pressurization process. In the sixth action mode, the regeneration control valve 21 and the unloading control valve 26B are opened, and the regulator 26A is closed. In the sixth action mode, when the compressor 4 is in a non-operating state, the compressed air of the supply circuit 12 is supplied (made to flow back) to the air supply passage 18 and the desiccant of the filter 17, thereby making the pressure of the air supply passage 18 and the filter 17 higher than the atmospheric pressure, so that the back pressure (air pressure) of the upstream check valve 15 is maintained at a pressure higher than the atmospheric pressure. In this way, the generation of negative pressure in the cylinder can be suppressed, thereby reducing the operating load of the compressor 4 during idling. Specifically, when the compressor 4 is in idling, the drain discharge valve 25 is closed, and the air pressure in the desiccant of the filter 17 and the air supply passage 18 is maintained at a pressure higher than the atmospheric pressure by the compressed air supplied by the compressor 4.

[0083] (Seventh Action Mode)

[0084] like Figure 2A As shown in FIG. 1 , the seventh operation mode is a mode for performing a "regeneration supply" operation, which performs dehumidification (load) during regeneration driven by the compressor 4 when the engine is in an unloaded state. In the seventh operation mode, similarly to the first operation mode, the regeneration control valve 21, the regulator 26A, and the unloading control valve 26B are closed (represented as "CLOSE" in the figure).

[0085] (Eighth Action Mode)

[0086] like Figure 2C As shown, the eighth operation mode is a mode for performing a "forced regeneration" operation for forcibly regenerating the filter 17. In the eighth operation mode, similarly to the third operation mode, the regeneration control valve 21, the regulator 26A, and the unloading control valve 26B are opened.

[0087] (Transition of action mode)

[0088] like Figure 3 As shown, the eight operation modes of the air drying circuit 11 are changed based on the respective determinations of the ECU 80 .

[0089] Reference Figures 4 to 8 The following describes the transition from each action mode.

[0090] The ECU 80 performs a supply process for supplying the compressed air outputted from the compressor 4 to the supply circuit 12. The supply process is started in accordance with conditions such as when the engine is driven. In the supply process, the air drying circuit 11 is in the supply (first operation) mode M1.

[0091] like Figure 4 As shown, in the supply (first operation) mode M1, the ECU 80 determines whether the pressure of the supply circuit 12 is higher than the cut-out pressure (step S11). That is, the ECU 80 obtains the pressure of the gas tank 30 detected by the pressure sensor 53 and determines whether the pressure reaches the cut-out pressure.

[0092] Then, when the ECU 80 determines that the pressure of the supply circuit 12 has reached the cut-out pressure (step S11: Yes), it determines whether the moisture content of the gas tank 30 is high (step S12). That is, when the moisture content of the gas tank 30 is equal to or greater than a predetermined value, the ECU 80 needs to regenerate the desiccant of the filter 17, so the ECU 80 determines the moisture content of the gas tank 30.

[0093] Then, when the ECU 80 determines that the moisture content of the gas tank 30 is greater than the specified value (step S12: "Yes"), it transfers to the regeneration (third action) mode M3. The regeneration (third action) mode M3 allows the compressed dry air stored in the gas tank 30 to pass through the filter 17, thereby regenerating the desiccant in the filter 17.

[0094] In addition, when the ECU 80 determines that the moisture content of the gas tank 30 is less than the specified value (step S12: "No"), it transfers to the purge (second action) mode M2. The purge (second action) mode M2 ​​allows the compressed dry air between the downstream one-way valve 19 and the filter 17 to pass through the filter 17, and discharges the moisture captured by the filter 17 as exhaust liquid from the exhaust outlet 27.

[0095] On the other hand, when the ECU 80 determines that the pressure of the supply circuit 12 has not reached the cut-out pressure (step S11: No), it determines whether the condition for shifting to the de-oiling (fourth operation) mode M4 is satisfied (step S13). That is, the ECU 80 determines whether the passage of a predetermined time, the number of de-oiling operations being less than a predetermined number, and the low operating rate of the compressor 4 are all satisfied as the condition for shifting to the de-oiling (fourth operation) mode M4. Then, when the ECU 80 determines that the condition for shifting to the de-oiling (fourth operation) mode M4 is not satisfied (step S13: No), it returns the process to step S11.

[0096] On the other hand, when ECU 80 determines that the conditions for transferring to deoiling (fourth action) mode M4 are met (step S13: "Yes"), it transfers to deoiling (fourth action) mode M4, and deoiling (fourth action) mode M4 discharges the compressed air supplied from compressor 4 while operating compressor 4.

[0097] After shifting to the degreasing (fourth operation) mode M4, the ECU 80 determines whether a predetermined time has elapsed (step S14). That is, the ECU 80 performs the degreasing (fourth operation) mode M4 for a predetermined time. Then, when the ECU 80 determines that the predetermined time has elapsed (step S14: Yes), it shifts to the supply (first operation) mode M1.

[0098] like Figure 5 As shown, in the purge (second operation) mode M2 ​​and the regeneration (third operation) mode M3, the ECU 80 determines whether a predetermined time has elapsed (step S21). That is, the ECU 80 performs the purge (second operation) mode M2 ​​and the regeneration (third operation) mode M3 for a predetermined time.

[0099] Then, when the ECU 80 determines that the predetermined time has not elapsed (step S21: No), it determines whether the pressure of the supply circuit 12 is lower than the cut-in pressure (step S24). That is, the ECU 80 obtains the pressure of the gas tank 30 detected by the pressure sensor 53 to determine whether the pressure has reached the cut-in pressure.

[0100] Then, when the ECU 80 determines that the pressure of the supply circuit 12 has reached the cut-in pressure (step S24: Yes), the ECU 80 shifts to the supply (first operation) mode M1 because the compressed dry air is insufficient. On the other hand, when the ECU 80 determines that the pressure of the supply circuit 12 has not reached the cut-in pressure (step S24: No), the processing returns to step S21.

[0101] On the other hand, when the ECU 80 determines that the predetermined time has elapsed (step S21: Yes), it determines whether or not the compressor assist (sixth operation) process is enabled (step S22).

[0102] Then, when the ECU 80 determines that the compressor assist (sixth action) processing is set to be invalid (step S22: "No"), it shifts to the non-purge supply stop (fifth action) mode M5, and the non-purge supply stop (fifth action) mode M5 stops the compressor 4 in a non-purge state.

[0103] When the ECU 80 determines that the compressor assist (sixth operation) process is enabled (step S22: YES), the ECU 80 shifts to the compressor assist (sixth operation) mode M6 in which the pressurizing process is performed.

[0104] After the transition to the compressor assist (sixth operation) mode M6, the ECU 80 determines whether a predetermined time has elapsed (step S23). That is, the ECU 80 performs the compressor assist (sixth operation) mode M6 for a predetermined time. Then, when the ECU 80 determines that the predetermined time has elapsed (step S23: Yes), it transitions to the non-purge supply stop (fifth operation) mode M5.

[0105] like Figure 6 As shown, in the non-purge supply stop (fifth operation) mode M5, the ECU 80 determines whether the pressure of the supply circuit 12 is lower than the cut-in pressure (step S31). That is, the ECU 80 obtains the pressure of the gas tank 30 detected by the pressure sensor 53 and determines whether the pressure reaches the cut-in pressure.

[0106] Then, when the ECU 80 determines that the pressure of the charge circuit 12 has reached the cut-in pressure (step S31 : YES), the ECU 80 shifts to the charge (first operation) mode M1 because the compressed dry air is insufficient.

[0107] On the other hand, when the ECU 80 determines that the pressure of the supply circuit 12 has not reached the cut-in pressure (step S31: No), it determines whether the condition for shifting to the regenerative supply (seventh action) mode M7 is satisfied (step S32). That is, the ECU 80 determines whether the vehicle is running, no fuel is consumed, and the pressure of the supply circuit 12 is less than the threshold value are all satisfied as the shift condition to the regenerative supply (seventh action) mode M7. Then, when the ECU 80 determines that the condition for shifting to the regenerative supply (seventh action) mode M7 is not satisfied (step S32: No), it returns the process to step S31.

[0108] On the other hand, when the ECU 80 determines that the condition for shifting to the regenerative supply (seventh operation) mode M7 is satisfied (step S32: YES), the ECU 80 shifts to the regenerative supply (seventh operation) mode M7 for performing dehumidification (load) during regeneration.

[0109] like Figure 7 As shown, in the regenerative supply (seventh action) mode M7, the ECU 80 determines whether the condition for shifting to the non-purge supply stop (fifth action) mode M5 is satisfied (step S41). That is, the ECU 80 determines whether at least one of the following conditions is satisfied: the pressure of the supply circuit 12 is higher than the cut-out pressure, a predetermined time has passed, and the fuel consumption of the engine is high, as a condition for shifting to the non-purge supply stop (fifth action) mode M5. Then, when the ECU 80 determines that the condition for shifting to the non-purge supply stop (fifth action) mode M5 is satisfied (step S41: "Yes"), it shifts to the non-purge supply stop (fifth action) mode M5.

[0110] On the other hand, when the ECU 80 determines that the condition for shifting to the non-purge supply stop (fifth operation) mode M5 is not satisfied (step S41: No), it determines whether the pressure of the supply circuit 12 is lower than the cut-in pressure (step S42). That is, the ECU 80 obtains the pressure of the gas tank 30 detected by the pressure sensor 53 to determine whether the pressure reaches the cut-in pressure.

[0111] Then, when the ECU 80 determines that the pressure of the charge circuit 12 has reached the cut-in pressure (step S42: YES), the ECU 80 shifts to the charge (first operation) mode M1 because the compressed dry air is insufficient.

[0112] On the other hand, when the ECU 80 determines that the pressure of the supply circuit 12 has not reached the cut-in pressure (step S42: "No"), it determines whether the condition for shifting to the forced regeneration (eighth action) mode M8 is satisfied (step S43). That is, the ECU 80 determines whether the pressure of the supply circuit 12 is higher than the threshold value and the amount of moisture in the gas tank 30 is high as the condition for shifting to the forced regeneration (eighth action) mode M8. In the regeneration supply (seventh action) mode M7, the ECU 80 determines the dryness of the compressed dry air by the amount of moisture in the tank air in the gas tank 30. That is, the amount of moisture in the tank air in the gas tank 30 is an indicator of the dryness of the compressed dry air. If the amount of moisture in the tank air is greater than the prescribed value, the ECU 80 determines that the amount of moisture in the gas tank 30 is high, and if the amount of moisture in the tank air is less than the prescribed value, the ECU 80 determines that the amount of moisture in the gas tank 30 is low. Then, when the ECU 80 determines that the condition for shifting to the forced regeneration (eighth operation) mode M8 is not satisfied (step S43: No), the ECU 80 returns the process to step S42.

[0113] On the other hand, when the ECU 80 determines that the conditions for shifting to the forced regeneration (eighth action) mode M8 are met (step S43: Yes), it shifts to the forced regeneration (eighth action) mode M8 for forcibly regenerating the filter 17. When the ECU 80 determines that the amount of moisture is high and other conditions are met, it executes the forced regeneration (eighth action) mode M8 for flowing the compressed dry air in the reverse direction.

[0114] like Figure 8 As shown, in the forced regeneration (eighth operation) mode M8, the ECU 80 determines whether a predetermined time has elapsed (step S51). That is, the ECU 80 performs the forced regeneration (eighth operation) mode M8 for a predetermined time.

[0115] When the ECU 80 determines that the predetermined time has not elapsed (step S51: No), it determines whether the pressure of the supply circuit 12 is lower than the cut-in pressure (step S55). That is, the ECU 80 obtains the pressure of the gas tank 30 detected by the pressure sensor 53 and determines whether the pressure has reached the cut-in pressure.

[0116] Then, when the ECU 80 determines that the pressure of the supply circuit 12 has reached the cut-in pressure (step S55: Yes), the ECU 80 shifts to the supply (first operation) mode M1 because the compressed dry air is insufficient. On the other hand, when the ECU 80 determines that the pressure of the supply circuit 12 has not reached the cut-in pressure (step S55: No), the process returns to step S51.

[0117] On the other hand, when the ECU 80 determines that the predetermined time has elapsed (step S51: YES), it determines whether the operating rate of the compressor 4 is high (step S52). That is, the ECU 80 determines whether the load of the compressor 4 when driving is high based on the operating rate of the compressor 4.

[0118] Then, when the ECU 80 determines that the operating rate of the compressor 4 is high (step S52: YES), the compressor assist (sixth operation) is not necessary, and thus the mode is shifted to the supply (first operation) mode M1.

[0119] On the other hand, when the ECU 80 determines that the operating rate of the compressor 4 is low (step S52: No), it determines whether to enable the compressor assist (sixth operation) process to perform the compressor assist (sixth operation) (step S53).

[0120] Then, when the ECU 80 determines that the compressor assist (sixth action) process is set to invalid (step S53: No), it shifts to the non-purge supply stop (fifth action) mode M5. In addition, when the ECU 80 determines that the compressor assist (sixth action) process is set to valid (step S53: Yes), it shifts to the compressor assist (sixth action) mode M6.

[0121] After shifting to the compressor assist (sixth operation) mode M6, the ECU 80 determines whether a predetermined time has elapsed (step S54). That is, the ECU 80 performs the compressor assist (sixth operation) mode M6 for a predetermined time. Then, when the ECU 80 determines that the predetermined time has elapsed (step S54: Yes), it shifts to the non-purge supply stop (fifth operation) mode M5.

[0122] Next, the effects of the first embodiment will be described.

[0123] (1) During supply (first action), the dryness of the compressed dry air is determined based on the moisture content, and then whether to perform regeneration (third action) is determined. Therefore, when supply (first action) is performed and the regeneration of the desiccant is insufficient, regeneration (third action) is performed. Therefore, the dryness of the compressed dry air can be maintained.

[0124] (2) The consumption of compressed dry air is calculated based on the pressure change of the air tank 30 and the air discharge volume of the compressor 4, and the moisture content of the consumed compressed dry air is calculated, thereby accurately estimating the moisture content of the air tank 30 after the compressed dry air is consumed due to braking or regeneration action.

[0125] (3) When the pressure of the compressed dry air does not reach the cut-out pressure, the dry state of the compressed dry air does not satisfy specified conditions such as a specified value, that is, when the index representing the dry state of the compressed dry air is not within a specified range, the desiccant is regenerated by performing regeneration (third action), thereby maintaining the dry state of the compressed dry air.

[0126] (4) When the dry state of the compressed dry air satisfies the predetermined condition, the compressed dry air in the air tank 30 is not regenerated by passing the filter 17 in the reverse direction (third operation), but the compressed dry air in the air supply passage 18 is purged by passing the filter 17 in the reverse direction (second operation). Therefore, the consumption of the compressed dry air in the air tank 30 can be suppressed.

[0127] (5) The ECU 80 controls the waste liquid discharge valve 25 and the regeneration control valve 21 to perform supply (first operation) and regeneration (third operation).

[0128] (Second Embodiment)

[0129] Below, refer to Fig. 9 A second embodiment of the air supply system will be described. The air supply system of this embodiment uses the tank air moisture saturation as the moisture content to determine the dryness state of the compressed dry air in the air tank 30, which is different from the first embodiment described above. The following description will focus on the differences from the first embodiment.

[0130] Conventionally, the air supply system switches between the dehumidification operation and the regeneration operation based on the pressure of the storage unit regardless of the dryness of the compressed air. Depending on the atmospheric temperature, the dryness of the compressed air in the storage unit eventually becomes excessive, resulting in an increase in the consumption of compressed air required to promote and maintain the dryness, and a risk of increasing the work of the compressor. Therefore, it is required to maintain the dryness of the compressed dry air to a required degree according to the atmospheric conditions without being excessive.

[0131] like Fig. 9As shown, the ECU 80 calculates the target dew point by subtracting the dew point drop from the reference outside temperature according to equation (11). For example, the dew point drop is basically set to 17°C, but the dew point drop may be larger than 17°C in spring and autumn when the temperature difference in a day is large, and smaller than 17°C in summer and winter when the temperature difference in a day is small.

[0132] Target dew point [℃] = External air temperature [℃] - Dew point drop [℃] (11)

[0133] At this time, the dew point drop degree can be set according to the outside temperature, thereby changing the target moisture content of dehumidification. Therefore, for example, the moisture content of the compressed dry air in the gas tank 30 according to the outside temperature can be freely set to obtain the best dehumidification effect, and the consumption of compressed dry air consumed during regeneration in a year can be reduced.

[0134] The ECU 80 calculates the "amount of moisture that can be contained in the tank air" by converting the "target dew point" according to the equation (12).

[0135] Tank air moisture content [g] = (target dew point [g / m 3 ]×tank capacity [L]) / unit conversion factor (L / m 3 )…(12)

[0136] The ECU 80 calculates the “tank air moisture content reference amount” as the moisture content of the tank 30 based on the compressed dry air that flows back through the filter 17 when the filter 17 is regenerated according to the equation (13).

[0137] Tank air moisture content [g] = {(regeneration air temperature [g / m 3 ]×regeneration air humidity [%RH]) / unit conversion factor (%)}×tank capacity [L] / unit conversion factor (L / m 3 )…(13)

[0138] The ECU 80 calculates the "water content in the supply air" taking into account the ventilation volume of the dry air flowing into the filter 17 during dry air supply, based on the inter-cycle supply air volume, the saturated water vapor volume at the supply air temperature, and the supply air humidity according to equation (14).

[0139] Moisture content of supply air [g] = {(saturated water vapor content [g / m 3 ]×supply air humidity [%RH]) / unit conversion factor (%)}×{supply air volume between cycles [L] / unit conversion factor (L / m 3 )}×{atmospheric pressure [kPa] / (cut-out pressure [kPaG]+atmospheric pressure [kPa])}…(14)

[0140] The ECU 80 calculates the "moisture content of the consumed air" according to the equation (15) from the decompression value of the cylinder 30 taking into account the water discharge when the compressed dry air is consumed and the amount of air consumed between cycles.

[0141] Moisture content of consumed air [g] = Moisture content of tank [g] × Air consumption between cycles × {Atmospheric pressure [kPa] / (Cut-out pressure [kPaG] + Atmospheric pressure [kPa])} ÷ Tank capacity [L]… (15)

[0142] The ECU 80 calculates the "tank air moisture content change amount" which is the difference between the "supply air moisture content" and the "consumption air moisture content" according to the equation (16).

[0143] Change in water content of tank air [g] = water content of supplied air [g] - water content of consumed air [g] (16)

[0144] The ECU 80 calculates the “tank air moisture content”, which is the moisture content of the gas tank 30 at the time when the supply of dry air is completed, from the “tank air moisture content change” according to the equation (17).

[0145] Tank air moisture content [g] = Tank air moisture content reference value [g] + Tank air moisture content change [g] (17)

[0146] In addition, ECU 80 calculates "tank air moisture saturation" according to formula (18) using the above-mentioned "tank air moisture amount" and "tank air moisture amount" as an indicator of the margin of moisture amount that the compressed dry air of the gas tank 30 can contain, so as to obtain a dehumidification effect of the compressed dry air of the gas tank 30.

[0147] Tank air moisture saturation [-] = Tank air moisture content [g] / Tank air moisture content [g] (18)

[0148] The ECU 80 uses the "tank air moisture saturation" calculated as described above to determine whether the "moisture content" in the first embodiment is large or small, and performs control. In this case, the value of the "predetermined value" is changed in accordance with the "tank air moisture saturation". For example, when the "tank air moisture saturation" exceeds the threshold value at the time when the supply of dry air ends, the ECU 80 assumes that the compressed dry air is not in a dry state and performs regeneration of the filter 17. That is, the tank air moisture saturation is an indicator indicating the dry state of the compressed dry air.

[0149] Next, the effects of the second embodiment will be described. The second embodiment has the following effects in addition to the effects (1) to (5) of the first embodiment.

[0150] (6) Since the amount of water is determined by the tank air water saturation, the best dehumidification effect can be obtained, and the amount of compressed dry air consumed when regenerating the filter 17 in a year can be reduced.

[0151] (Other embodiments)

[0152] The above-mentioned embodiments can be modified and implemented as follows. The above-mentioned embodiments and the following modified examples can be combined and implemented within the scope of no technical contradiction.

[0153] In the first embodiment, the dryness of the compressed dry air is determined based on the moisture content of the consumed air. However, the dryness of the compressed dry air may be determined by estimating the moisture content of the tank air based on the humidity and temperature of the compressed dry air in the gas tank 30 .

[0154] In the second embodiment, the target dew point is calculated using the dew point drop when the outside air temperature is used as a reference, but the target dew point may be calculated using the dew point drop when the ambient temperature of the gas cylinder 30 is used as a reference. In addition, the target dew point may be set according to the month and day. In this way, the moisture content of the compressed dry air of the gas cylinder 30 can be freely set according to the seasonal changes, and the best dehumidification effect can be obtained, and the consumption of compressed dry air when the filter 17 is regenerated in a year can be reduced.

[0155] In the above-mentioned embodiments, the purge (second operation) mode M2, the regeneration (third operation) mode M3, the degreasing (fourth operation) mode M4, the compressor assist (sixth operation) mode M6, the regenerative supply (seventh operation) mode M7, and the forced regeneration (eighth operation) mode M8 are performed at a predetermined time. However, the predetermined time in each mode may be arbitrarily set.

[0156] In step S13 of each of the above-mentioned embodiments, the conditions for shifting to the de-oiling (fourth operation) mode M4 are that all of the following conditions are satisfied: the passage of a prescribed time, the number of times the de-oiling is performed is less than a prescribed number of times, and the operating rate of the compressor 4 is low. Alternatively, the ECU 80 may shift to the de-oiling (fourth operation) mode M4 when at least one of the conditions is satisfied. That is, in step S13, the ECU 80 determines whether at least one of the following conditions is satisfied: the passage of a prescribed time, the number of times the de-oiling is performed is less than a prescribed number of times, and the operating rate of the compressor 4 is low, as a condition for shifting to the de-oiling (fourth operation) mode M4.

[0157] In step S32 of each of the above-mentioned embodiments, the conditions for shifting to the regenerative supply (seventh operation) mode M7 are that the vehicle is running, no fuel is consumed, and the pressure of the supply circuit 12 is less than the threshold value. Alternatively, the ECU 80 may shift to the regenerative supply (seventh operation) mode M7 when at least one of the conditions is satisfied. That is, in step S32, the ECU 80 determines whether at least one of the conditions of the vehicle being running, no fuel is consumed, and the pressure of the supply circuit 12 is less than the threshold value is satisfied as the condition for shifting to the regenerative supply (seventh operation) mode M7.

[0158] In step S43 of each of the above-mentioned embodiments, the condition for shifting to the forced regeneration (eighth action) mode M8 is that the pressure of the supply circuit 12 is higher than the threshold value and the water content of the gas tank 30 is high. Alternatively, the ECU 80 may shift to the forced regeneration (eighth action) mode M8 when at least the water content of the gas tank 30 is high. That is, in step S43, the ECU 80 determines whether the water content of the gas tank 30 is high as a condition for shifting to the forced regeneration (eighth action) mode M8.

[0159] In each of the above-described embodiments, the filter 17 includes the oil-capturing portion, but the oil-capturing portion may be omitted from the filter 17 .

[0160] In each of the above embodiments, the air drying circuit is not limited to the above structure. In short, the air drying circuit can be configured to execute the supply (first action) mode M1, the purge (second action) mode M2, and the regeneration (third action) mode M3. Therefore, the air drying circuit does not set the degreasing (fourth action) mode M4, the non-purge supply stop (fifth action) mode M5, the compressor assist (sixth action) mode M6, the regenerative supply (seventh action) mode M7, and the forced regeneration (eighth action) mode M8 as necessary actions.

[0161] In the above-mentioned embodiment, the purge (second operation) mode M2 ​​may be omitted.

[0162] In the above-mentioned embodiments, the air supply system 10 is described as being mounted on a vehicle such as a truck, a bus, or a construction machine. In other embodiments, the air supply system 10 may be mounted on another mobile body such as a car or a railway vehicle.

[0163] ECU 80 is not limited to software processing of all the processes executed by itself. For example, ECU 80 may also have a dedicated hardware circuit (such as an application-specific integrated circuit: ASIC), which performs hardware processing on at least a part of the processes executed by ECU 80 itself. That is, ECU 80 can be constructed to include the following circuits: 1) one or more processors that act according to a computer program (software), 2) one or more dedicated hardware circuits that execute at least a part of various processes, or 3) a combination thereof. The processor includes a CPU and a memory such as RAM and ROM, and the memory stores program codes or instructions configured to enable the CPU to execute processes. The memory, i.e., computer-readable media, includes all available media that can be accessed by general-purpose or special-purpose computers.

[0164] Description of Reference Numerals

[0165] 4: compressor; 10: air supply system; 11: air drying circuit; 12: supply circuit; 15: upstream check valve; 16: branch passage; 17: filter; 18: air supply passage; 19: downstream check valve; 20: bypass flow path; 21: regeneration control valve; 22: throttle hole; 25: drain valve; 26A: regulator; 26B: unloading control valve; 27: drain outlet as a drain outlet; 30: gas tank; 50: pressure sensor; 51: humidity sensor; 52: temperature sensor; 53: pressure sensor; 80: ECU; 80A: storage unit; E61~E67: wiring.

Claims

1. An air supply system comprising: an air drying circuit provided between a compressor that delivers compressed air and an air tank that stores compressed dry air, the air drying circuit having a filter including a desiccant that captures moisture; and a control device, which controls the air drying circuit, in, The control device is composed of: During a supply operation, the dryness of the compressed dry air stored in the air tank is determined based on the moisture content. The supply operation is an operation of driving the compressor to send the compressed air to the filter to supply the compressed air to the air tank. Whether to perform a regeneration operation is determined based on the dry state of the compressed dry air. The regeneration operation is an operation of passing the compressed dry air through the filter in a reverse direction to discharge the fluid that has passed through the filter from a discharge port.

2. The air supply system according to claim 1, characterized in that: The control device is composed of: Obtaining the pressure information of the gas tank and the air discharge volume of the compressor, calculating the consumption of the compressed dry air stored in the gas tank based on the pressure change of the gas tank, The moisture content of the compressed dry air is calculated using the consumption amount of the compressed dry air and the air ejection amount.

3. The air supply system according to claim 1 or 2, characterized in that: The control device is configured to execute the regeneration operation when the pressure of the compressed dry air reaches a cut-out pressure for performing the regeneration operation and the dry state of the compressed dry air does not satisfy a predetermined condition.

4. The air supply system according to claim 3, characterized in that: The control device is configured to perform a purge action when the pressure of the compressed dry air reaches the cut-out pressure and the dry state of the compressed dry air satisfies a specified value. The purge action is an action of passing the compressed dry air of the air drying circuit through the filter in the reverse direction to discharge the fluid that has passed through the filter from the exhaust port.

5. The air supply system according to any one of claims 1 to 4, characterized in that: Also available: a discharge valve connecting a branch path connected to the air drying circuit to the discharge port; and a regeneration control valve that switches between a forward flow from the filter toward the gas tank and a reverse flow from the gas tank toward the filter, The control device is configured to control the discharge valve and the regeneration control valve.

6. A control method for an air supply system, the air supply system comprising: an air drying circuit provided between a compressor for delivering compressed air and an air tank for storing compressed dry air, the air drying circuit having a filter including a desiccant for capturing moisture; and a control device for controlling the air drying circuit, In the control method of the air supply system, The control device performs the following processing: During a supply operation, the dryness of the compressed dry air stored in the air tank is determined based on the moisture content. The supply operation is an operation of driving the compressor to send the compressed air to the filter to supply the compressed air to the air tank. Whether to perform a regeneration operation is determined based on the dry state of the compressed dry air. The regeneration operation is an operation of passing the compressed dry air through the filter in a reverse direction to discharge the fluid that has passed through the filter from a discharge port.

7. A control program for an air supply system, the air supply system comprising: an air drying circuit provided between a compressor for delivering compressed air and an air tank for storing compressed dry air, the air drying circuit having a filter including a desiccant for capturing moisture; and a control device for controlling the air drying circuit, The control program of the air supply system causes the control device to function as the following parts: a dryness determination unit, which determines the dryness state of the compressed dry air stored in the gas tank according to the moisture content during a supply action, wherein the supply action is an action of driving the compressor to deliver the compressed air to the filter and thereby supplying the compressed air to the gas tank; and a regeneration action execution determination unit, which determines whether to execute a regeneration action based on the dryness state of the compressed dry air, wherein the regeneration action is an action of passing the compressed dry air through the filter in a reverse direction to discharge the fluid that has passed through the filter from a discharge port.

Images