Air supply system, control method of the same, and control program of the same

Abstract

To maintain good dehumidification performance and reduce consumption of compressed dry air.SOLUTION: An air supply system (10) is provided between a compressor (4) which sends out compressed air and an air tank (30) which stores compressed dry air and includes: an air dry circuit (11) having a filter (17) which captures moisture; and an ECU (80) which controls the air dry circuit (11). The ECU (80) carries out dehumidification operation in which the air dry circuit (11) is controlled to cause compressed air sent from the compressor (4) to pass through the filter (17) in a forward direction and be supplied to the air tank (30) and carries out reproduction operation in which the air dry circuit (11) is controlled to cause compressed dry air stored in the air tank (30) to pass through the filter (17) in a reverse direction and a fluid which has passed through the filter (17) is discharged from a drain discharge port (27). A reproduced air amount to be consumed in the reproduction operation is set according to an operation state of the compressor (4).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to an air supply system, a control method for an air supply system, and a control program for an air supply system. [Background technology]

[0002] In vehicles such as trucks, buses, and construction machines, pneumatic systems, including brake systems and suspension systems, are controlled using compressed air sent from a compressor. This compressed air contains liquid impurities such as moisture contained in the atmosphere and oil that lubricates the inside of the compressor. If compressed air containing a lot of moisture and oil enters a pneumatic system, it may cause rust and swelling of rubber components, which may lead to malfunctions. For this reason, a compressed air dryer is provided downstream of the compressor to remove impurities such as moisture and oil from the compressed air.

[0003] The compressed air dryer includes a filter containing a desiccant and various valves. The compressed air dryer performs a dehumidification operation in which compressed air passes through a filter to remove moisture and the like from the compressed air. The compressed dry air generated by the dehumidification operation is stored in an air tank. The cleaning function of the compressed air dryer decreases according to the supply amount of compressed dry air. For this reason, the compressed air dryer performs a regeneration operation in which the oil and moisture adsorbed in the filter are removed from the filter and the removed oil and moisture are released as drain (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2010-201323 A Summary of the Invention [Problem to be solved by the invention]

[0005] For example, the execution conditions such as the time to execute the regeneration operation, the amount of regeneration air to pass through the filter, etc. are set to be constant or are determined according to the amount of compressed air sent out from the compressor, etc. However, the inventors have found that in either case, excess or deficiency occurs. If the regeneration time or the amount of regeneration air is insufficient, the moisture capturing ability of the desiccant does not return to its original level, and the amount of moisture contained in the air sent out from the compressed air drying device may be high. On the other hand, if the regeneration time or the amount of regeneration air is excessive, it leads to wasteful consumption of compressed dry air in the air tank, which is originally supplied to the pneumatic system. Since compressed dry air is generated by a compressor driven by a rotary drive source such as an engine, excessive consumption of compressed dry air increases the load on the rotary drive source and reduces the fuel efficiency of the vehicle.

[0006] An object of the present disclosure is to reduce the consumption of compressed dry air by an air supply system while maintaining the dehumidification performance of the air supply system. [Means for solving the problem]

[0007] An air supply system that solves the above problem includes an air drying circuit that is arranged between a compressor that sends out compressed air and a storage section that stores compressed, dry air and has a filter that captures moisture, and a control device that controls the air drying circuit, wherein the control device controls the air drying circuit to perform a dehumidification operation in which the compressed air sent out from the compressor passes through the filter in a forward direction and is supplied to the storage section, and controls the air drying circuit to perform a regeneration operation in which the compressed, dry air stored in the storage section passes through the filter in a reverse direction and the fluid that has passed through the filter is discharged from an outlet, and is configured to set the amount of regeneration air consumed in one regeneration operation depending on the operating state of the compressor.

[0008] A control method for an air supply system that solves the above problem includes an air drying circuit that is arranged between a compressor that sends out compressed air and a storage section that stores compressed, dry air and has a filter that captures moisture, and a control device that controls the air drying circuit, in which the control device controls the air drying circuit to perform a dehumidification operation in which the compressed air sent out from the compressor passes through the filter in a forward direction and is supplied to the storage section, controls the air drying circuit to perform a regeneration operation in which the compressed, dry air stored in the storage section passes through the filter in a reverse direction and the fluid that has passed through the filter is discharged from an outlet, and sets the amount of regeneration air consumed in one regeneration operation depending on the operating state of the compressor.

[0009] A control program for an air supply system that solves the above-mentioned problems is a control program for an air supply system that includes an air drying circuit that is provided between a compressor that sends out compressed air and a storage section that stores compressed, dry air and has a filter that captures moisture, and a control device that controls the air drying circuit, and causes the control device to function as a dehumidification operation execution unit that controls the air drying circuit to perform a dehumidification operation in which the compressed air sent out from the compressor passes through the filter in a forward direction and is supplied to the storage section, a regeneration operation execution unit that controls the air drying circuit to perform a regeneration operation in which the compressed, dry air stored in the storage section passes through the filter in a reverse direction and the fluid that has passed through the filter is discharged from an outlet, and a setting unit that sets the amount of regeneration air to be consumed in one regeneration operation depending on the operating state of the compressor.

[0010] According to the above configuration, the control device sets the amount of regeneration air consumed in the regeneration operation based on the operating state of the compressor. Since the compressor is driven according to the supply state of compressed dry air to devices other than the air drying circuit, by changing the amount of regeneration air, it is possible to prioritize either the supply of compressed dry air from the storage unit to devices other than the air drying circuit or cleaning of the filter.

[0011] For the above air supply system, the control device may be configured to reduce the amount of regenerated air when the operating rate of the compressor within a certain period of time is high, and to increase the amount of regenerated air when the operating rate of the compressor is low.

[0012] According to the above configuration, when the operating rate of the compressor is high and the supply rate of compressed dry air from the storage unit to devices other than the air drying circuit is high, the amount of regenerated air is reduced to suppress consumption of the compressed dry air stored in the storage unit and prioritize the supply of compressed dry air to devices other than the air drying circuit. Also, when the operating rate of the compressor is low and the supply rate of compressed dry air from the storage unit to devices other than the air drying circuit is low, priority can be given to cleaning the filter.

[0013] For the above air supply system, the control device may be configured to increase the amount of regenerated air when an index indicating the humidity state of the compressed dry air in the storage section is high, and to reduce the amount of regenerated air when an index indicating the humidity state of the compressed dry air in the storage section is low.

[0014] According to the above configuration, when the humidity of the compressed dry air is high, the amount of regenerated air is increased to prioritize cleaning of the filter, and when the humidity is low, the consumption of the compressed dry air stored in the storage section is suppressed to prioritize supply of the compressed dry air to devices other than the air drying circuit.

[0015] For the above air supply system, the control device may be configured to set an upper limit pressure, which is the pressure in the storage section and is used to start the regeneration operation, high when the operating rate of the compressor is high, and to set the upper limit pressure low when the operating rate of the compressor is low, to reduce the amount of regeneration air when the upper limit pressure is high, and to increase the amount of regeneration air when the upper limit pressure is low.

[0016] According to the above configuration, the upper limit pressure for starting the regeneration operation is set according to the operating state of the compressor. Also, the amount of regeneration air is determined according to the upper limit pressure. When the operating rate of the compressor is high, the upper limit pressure is set high and the amount of regeneration air is set small, so that the frequency of the regeneration operation is reduced and the consumption of the compressed dry air stored in the storage section is suppressed, and the supply of compressed dry air to devices other than the air drying circuit can be prioritized. Also, when the operating rate of the compressor is low, the upper limit pressure is set low and the amount of regeneration air is set large, so that the frequency of the regeneration operation is increased and the effect of cleaning the filter is improved.

[0017] An air supply system that solves the above problem includes an air drying circuit that is arranged between a compressor that sends out compressed air and a storage section that stores compressed, dry air and has a filter that captures moisture, and a control device that controls the air drying circuit, wherein the control device controls the air drying circuit to perform a dehumidification operation in which the compressed air sent out from the compressor passes through the filter in a forward direction and is supplied to the storage section, and controls the air drying circuit to perform a regeneration operation in which the compressed, dry air stored in the storage section passes through the filter in a reverse direction and the fluid that has passed through the filter is discharged from an outlet, and is configured to set the amount of regeneration air consumed in one regeneration operation depending on the temperature of the compressed air or the compressed, dry air.

[0018] A control method for an air supply system that solves the above problem is a control method for an air supply system that includes an air drying circuit that is arranged between a compressor that sends out compressed air and a storage section that stores compressed, dry air and has a filter that captures moisture, and a control device that controls the air drying circuit, in which the control device controls the air drying circuit to perform a dehumidification operation in which the compressed air sent out from the compressor passes through the filter in a forward direction and is supplied to the storage section, controls the air drying circuit to perform a regeneration operation in which the compressed, dry air stored in the storage section passes through the filter in a reverse direction and the fluid that has passed through the filter is discharged from an outlet, and sets the amount of regeneration air consumed in one regeneration operation depending on the temperature of the compressed air or the temperature of the compressed, dry air.

[0019] A control program for an air supply system that solves the above-mentioned problems is a control program for an air supply system that includes an air drying circuit that is provided between a compressor that sends out compressed air and a storage section that stores compressed, dry air and has a filter that captures moisture, and a control device that controls the air drying circuit, and causes the control device to function as a dehumidification operation execution unit that controls the air drying circuit to perform a dehumidification operation in which the compressed air sent out from the compressor passes through the filter in a forward direction and is supplied to the storage section, a regeneration operation execution unit that controls the air drying circuit to perform a regeneration operation in which the compressed, dry air stored in the storage section passes through the filter in a reverse direction and the fluid that has passed through the filter is discharged from an outlet, and a setting unit that sets the amount of regeneration air to be consumed in one regeneration operation depending on the temperature of the compressed air or the temperature of the compressed, dry air.

[0020] According to the above configuration, the control device sets the amount of regeneration air consumed in the regeneration operation according to the temperature of the compressed air or the temperature of the compressed dry air. As the temperature of the compressed air or the temperature of the compressed dry air increases, the amount of moisture contained in the air also increases, so by changing the amount of regeneration air according to the amount of moisture contained in the air, it is possible to prioritize either the supply of compressed dry air from the storage unit to devices other than the air drying circuit, or the cleaning of the filter.

[0021] In the above air supply system, the control device may be configured to reduce the amount of regeneration air when the temperature is low, and to increase the amount of regeneration air when the temperature is high.

[0022] According to the above configuration, when the air temperature is low and the amount of saturated water vapor is small, the amount of regeneration air is reduced, thereby suppressing consumption of the compressed dry air stored in the storage section and giving priority to supplying the compressed dry air to devices other than the air drying circuit. Also, when the air temperature is high and the amount of saturated water vapor is large, the amount of regeneration air is increased, giving priority to cleaning the filter. Effect of the Invention

[0023] According to the present disclosure, it is possible to reduce the amount of compressed dry air consumed by an air supply system while maintaining the dehumidification performance of the air supply system. [Brief description of the drawings]

[0024] [Figure 1] 1 is a diagram showing a schematic configuration of an air supply system according to a first embodiment; [Diagram 2] 2A to 2F are diagrams showing first to sixth operation modes of the air drying circuit of the embodiment in FIG. 1, respectively. [Diagram 3] 3A is a map of a standard regeneration air amount for calculating the regeneration air amount in the embodiment of FIG. 1, and FIG. 3B is a map of a corrected unit air amount for calculating the regeneration air amount in the embodiment of FIG. [Figure 4] FIG. 2 is a schematic diagram of excess / deficiency coefficient information in the embodiment of FIG. 1; [Diagram 5] 4 is a flowchart showing an example of a procedure for supplying compressed air in the embodiment of FIG. 1. [Figure 6] 4 is a flowchart showing an example of a procedure for performing a reproducing operation in the embodiment of FIG. 1; [Figure 7] 4 is a flowchart showing an example of a procedure for determining the amount of regeneration air in the embodiment of FIG. 1. [Figure 8]FIG. 8A is a map of a standard regeneration air amount for calculating the regeneration air amount of the second embodiment, and FIG. 8B is a map of a corrected unit air amount for calculating the regeneration air amount of the second embodiment. [Figure 9] 9 is a flowchart showing an example of a procedure for determining the amount of regeneration air in the embodiment of FIG. 8. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] (First embodiment) A first embodiment of an air supply system will be described with reference to Fig. 1 to Fig. 6. The air supply system is mounted on automobiles such as trucks, buses, construction machines, etc. Compressed, dry air generated by the air supply system is used in pneumatic systems such as the brake system or suspension system of the automobile.

[0026] <Air Supply System 10> An air supply system 10 will be described with reference to Fig. 1. The air supply system 10 includes a compressor 4, an air drying circuit 11, and an ECU (Electronic Control Unit) 80. The ECU 80 functions as a control device, a dehumidification operation execution unit, a regeneration operation execution unit, and a setting unit.

[0027] The ECU 80 is connected to the air drying circuit 11 via a plurality of wirings E61 to E67. The ECU 80 includes a calculation unit, a communication interface unit, a volatile storage unit, and a nonvolatile storage unit. The calculation unit is a computer processor, and is configured to control the air drying circuit 11 according to an air supply program stored in the nonvolatile storage unit (storage medium). The calculation unit may realize at least a part of the processing executed by itself by a circuit such as an ASIC. The air supply program may be executed by one computer processor or may be executed by a plurality of computer processors. The ECU 80 also includes a storage unit 80A that stores information for determining the execution frequency of each operation of the air drying circuit 11. The storage unit 80A is a nonvolatile storage unit or a volatile storage unit, and may be the same as or different from the storage unit in which the control program is stored.

[0028] The ECU 80 is connected to other ECUs (not shown) mounted on the vehicle, such as an engine ECU and a brake ECU, via an in-vehicle network such as a CAN (Controller Area Network). The ECU 80 acquires information indicating the vehicle state from those ECUs. The information indicating the vehicle state includes, for example, ignition switch off information, vehicle speed, engine drive information, and the like.

[0029] The state of the compressor 4 is switched between an operating state (load operation) in which air is compressed and sent out, and a non-operating state (idle operation) in which air is not compressed, based on a command from the ECU 80. The compressor 4 is operated by power transmitted from a rotary drive source such as an engine.

[0030] 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 sent from the compressor 4 during load operation. The air drying circuit 11 supplies the compressed air after being dried (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.

[0031] The compressed dry air stored in the air tank 30 is supplied to an air pressure system, such as a brake system, mounted on the vehicle. For example, when the brakes are applied frequently, such as when the vehicle is traveling downhill or in an urban area, the amount of compressed dry air stored in the air tank 30 is increased. Conversely, when the brakes are applied infrequently, the amount of compressed dry air stored in the air tank 30 is reduced.

[0032] The air drying circuit 11 has a maintenance port P12. The maintenance port P12 is a port through which air is supplied to the air drying circuit 11 during maintenance.

[0033] The air drying circuit 11 includes a filter 17 inside the case 11A (see FIG. 2A ). The filter 17 is provided in the air supply passage 18 that connects the compressor 4 and the supply circuit 12. The filter 17 includes a desiccant. The filter 17 also includes an oil capture section that captures oil, in addition to the desiccant. The oil capture section may be any material that can capture oil while allowing air to pass through, such as a foam such as urethane foam, a metal material with multiple air holes, or a glass fiber filter.

[0034] The filter 17 removes moisture contained in the compressed air from the compressed air by passing the compressed air sent out from the compressor 4 through a desiccant, thereby drying the compressed air. The oil trapping section traps oil contained in the compressed air to purify the compressed air. The compressed air that has passed through the filter 17 is supplied to the supply circuit 12 via the downstream check valve 19. When the filter 17 side is the upstream side and the supply circuit 12 side is the downstream side, the downstream check valve 19 only allows air to flow from upstream to downstream. Since the downstream check valve 19 has a predetermined valve opening pressure (sealing pressure), when the compressed air flows, the upstream pressure is higher than the downstream pressure by the valve opening pressure.

[0035] Further, downstream of the filter 17, a bypass passage 20 serving as a detour around the downstream check valve 19 is provided in parallel to the downstream check valve 19. The bypass passage 20 is provided with a regeneration control valve 21.

[0036] The regeneration control valve 21 is an electromagnetic valve controlled by the ECU 80. The ECU 80 switches the operation of the regeneration control valve 21 by controlling the on / off (drive / non-drive) of the power supply to the regeneration control valve 21 via a wire E64. The regeneration control valve 21 closes to block the bypass flow path 20 when the power supply is off, and opens to communicate the bypass flow path 20 when the power supply is on. The ECU 80, for example, receives the value of the air pressure in the air tank 30 and operates the regeneration control valve 21 when the air pressure value exceeds a predetermined range.

[0037] The bypass flow passage 20 is provided with an orifice 22 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 sent to the filter 17 through the bypass flow passage 20 with the flow rate regulated by the orifice 22. The compressed dry air sent to the filter 17 flows backward from downstream to upstream through the filter 17 and passes through the filter 17. Such a process is an operation for regenerating the filter 17, and is called a regeneration operation of the air drying circuit 11. At this time, the compressed dry air sent to the filter 17 is dried and purified air that has passed through the filter 17 and the like from the air supply passage 18 and been supplied to the supply circuit 12, so that 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 an upper limit value (cutout pressure). On the other hand, when the pressure in the air tank 30 reaches a lower limit value (cut-in pressure), the regeneration control valve 21 that has been opened is closed.

[0038] A branch passage 16 branches off from a portion between the compressor 4 and the filter 17. A drain discharge valve 25 is provided in the branch passage 16, and a drain discharge port 27 is connected to an end of the branch passage 16.

[0039] Drain, which is a fluid containing water and oil removed from the filter 17, is sent to the drain discharge valve 25 together with compressed air. The drain discharge valve 25 is an air-pressure-driven valve that is driven by air pressure, and is provided in the branch passage 16 between the filter 17 and a drain discharge port 27. The drain discharge valve 25 is a two-port two-position valve that changes its position between a closed position and an open position. When the drain discharge valve 25 is in the open position, the drain is sent to the drain discharge port 27. The drain discharged from the drain discharge port 27 may be collected by an oil separator (not shown). The drain corresponds to the fluid that has passed through the filter 17 in the reverse direction.

[0040] The drain discharge valve 25 is controlled by a governor 26A. The governor 26A is a solenoid valve controlled by the ECU 80. The ECU 80 switches the operation of the governor 26A by controlling the on / off (drive / non-drive) of the power supply to the governor 26A via a wiring E63. When the power supply is turned on, the governor 26A switches to an input position for inputting an air pressure signal to the drain discharge valve 25, thereby opening the drain discharge valve 25. When the power supply is turned off, the governor 26A switches to an open position for not inputting an air pressure signal to the drain discharge valve 25 and opening a port of the drain discharge valve 25 to atmospheric pressure, thereby closing the drain discharge valve 25.

[0041] When no air pressure signal is input from the governor 26A, the drain discharge valve 25 is maintained in a closed position blocking the branch passage 16, and when an air pressure signal is input from the governor 26A, the drain discharge valve 25 switches to an open position communicating with the branch passage 16. When the pressure of the input port connected to the compressor 4 in the drain discharge valve 25 exceeds an upper limit value, the drain discharge valve 25 is forcibly switched to the open position.

[0042] 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 the upstream and the filter 17 side is the downstream, the upstream check valve 15 only allows air to flow from upstream to downstream. Since the upstream check valve 15 has a predetermined valve opening pressure (sealing pressure), when compressed air flows, the upstream pressure is higher than the downstream pressure by the valve opening pressure. 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.

[0043] 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 on / off (drive / non-drive) of the power supply to the unloading control valve 26B via the wiring E62. When the power supply is turned off, the unloading control valve 26B switches to the open position and opens the flow path between the unloading control valve 26B and the compressor 4 to the atmosphere. When the power supply is turned on, the unloading control valve 26B switches to the supply position and sends an air pressure signal consisting of compressed air to the compressor 4.

[0044] 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 (idle operation). For example, when the pressure in the air tank 30 reaches the cutout pressure, it is not necessary to supply compressed dry air. When the pressure on the supply circuit 12 side reaches the cutout 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 is switched 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.

[0045] 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, measures the air pressure in the air supply passage 18, and transmits the measurement result to the ECU 80 via a wiring E61.

[0046] 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 may detect either absolute humidity or relative humidity. The humidity sensor 51 and the temperature sensor 52 measure the humidity and temperature of the compressed air downstream of the filter 17, respectively, and output the measurement results to the ECU 80 via wirings E65 and E66. The ECU 80 determines the wet state of the compressed dry air based on the humidity and temperature input from the humidity sensor 51 and the temperature sensor 52.

[0047] Furthermore, a pressure sensor 53 is provided between the downstream check valve 19 and the supply circuit 12. The pressure sensor 53 is provided to be able to detect the air pressure in the air tank 30, and outputs the detected pressure value to the ECU 80 via a wire E67. The pressure between the downstream check valve 19 and the supply circuit 12 is the same as the pressure in the air tank 30, and the detection result of the pressure sensor 53 can be used as the pressure in the air tank 30. The pressure sensor 53 may be provided in the supply circuit 12 or in the air tank 30.

[0048] <Operation of the air drying circuit 11> As shown in FIGS. 2A to 2F, the air drying circuit 11 has a plurality of operation modes including at least a first operation mode to a sixth operation mode.

[0049] (First operation mode) As shown in FIG. 2A, the first operation mode is a mode in which a normal dehumidification operation (load operation) is performed. In the first operation mode, the regeneration control valve 21 and the unloading control valve 26B are closed (indicated as "CLOSE" in the figure), and the governor 26A is set to an open position in which no air pressure signal is input to the compressor 4 (indicated as "CLOSE" in the figure). At this time, no power is supplied to the regeneration control valve 21, the governor 26A, and the unloading control valve 26B. In addition, the governor 26A and the unloading control valve 26B open the port of the compressor 4 and the port of the drain discharge valve 25 connected downstream thereof to the atmosphere, respectively. In the first operation mode, when compressed air is supplied from the compressor 4 (indicated as "ON" in the figure), moisture and the like are removed by the filter 17, and the compressed air is supplied to the supply circuit 12.

[0050] (Second operating mode) As shown in FIG. 2B, the second operation mode is a mode in which the compressed dry air in the air drying circuit 11 is passed through the filter 17 to perform a purge operation to purify the filter 17. In the second mode, the regeneration control valve 21 is closed, the unloading control valve 26B is set to the supply position (indicated as "OPEN" in the figure), and the governor 26A is set to the input position (indicated as "OPEN" in the figure). At this time, power is supplied to the governor 26A and the unloading control valve 26B, and the port of the compressor 4 and the port of the drain discharge valve 25 connected downstream of them are connected upstream (to the supply circuit 12). As a result, the compressor 4 is switched to a non-operating state (indicated 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 (backflows) through the filter 17 in the opposite direction to the air flow in the first operation mode (dehumidification mode), and moisture and the like captured by the filter 17 are discharged as drain from the drain outlet 27. Also, the air pressure in the filter 17 and the air supply passage 18 is released to atmospheric pressure.

[0051] (Third operation mode) As shown in FIG. 2C, the third operation mode is a mode in which a regeneration operation for regenerating the filter 17 is performed. In the third operation mode, the regeneration control valve 21 is opened, the governor 26A is set to the input position, and the unloading control valve 26B is set to the supply position (each is indicated as "OPEN" in the figure). At this time, power is supplied to the regeneration control valve 21 as well as the governor 26A and the unloading control valve 26B. In the third operation mode, the compressor 4 is put into a non-operating state, and the compressed dry air stored in the supply circuit 12 or the air tank 30 is caused to flow back through the filter 17 and discharged from the drain outlet 27. This removes moisture and the like captured by the filter 17. Although the second operation mode and the third operation mode are both modes in which the filter 17 is purified, the third operation mode differs from the second operation mode in that at least the regeneration control valve 21 is opened. As a result, in the third operation mode, the compressed dry air in the air tank 30 can be passed through the filter 17 via the supply circuit 12 and the bypass flow path 20. Therefore, the effect of cleaning the filter 17 is higher than in the second operation mode. Also in the third operation mode, the air pressure in the filter 17 and the air supply passage 18 is released to atmospheric pressure.

[0052] (4th operation mode) As shown in FIG. 2D, the fourth operation mode is a mode in which an oil cut operation is performed. In the fourth operation mode, while the compressor 4 is operating, the air with an excess of oil sent from the compressor 4 is discharged from the drain outlet 27 without passing through the filter 17. When the compressor 4 is not operating, oil may accumulate in the compression chamber of the compressor 4. If the state of the compressor 4 is switched to the operating state with oil accumulated in the compression chamber, the amount of oil contained in the compressed air sent from the compression chamber increases. If the oil adheres to the desiccant, the dehumidification performance of the desiccant decreases. Therefore, an oil cut operation is performed to discharge the compressed air with an excess of oil. In the fourth operation mode, the regeneration control valve 21 is closed, the unload control valve 26B is set to the open position (indicated as "CLOSE" in the figure), and the governor 26A is set to the open position after a certain period of operation (indicated as "CLOSE" in the figure). As a result, even if compressed air containing a relatively large amount of oil is sent out from the compressor 4, the compressed air can be discharged from the drain outlet 27 without passing through the filter 17. This makes it possible to suppress a decrease in the dehumidification performance of the filter 17 immediately after the compressor 4 is switched from a non-operating state to an operating state. When the engine speed increases in an operating state and when the amount of oil from the compressor 4 increases due to high engine load, etc., an oil cut operation can also be performed.

[0053] (5th operation mode) As shown in Fig. 2E, the fifth operation mode is a mode in which the compressor is stopped without purging. In the fifth operation mode, the regeneration control valve 21 is closed, the governor 26A is set to the open position (indicated as "CLOSE" in the figure), and the unload control valve 26B is set to the supply position (indicated as "OPEN" in the figure). 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.

[0054] (6th operation mode) As shown in FIG. 2F, the sixth operation mode is a mode in which an assist operation is performed for pressurization. In the sixth operation mode, the regeneration control valve 21 is opened, the unload control valve 26B is set to the supply position (indicated as "OPEN" in the figure), and the governor 26A is set to the open position (indicated as "CLOSE" in the figure). In the sixth operation mode, when the compressor 4 is not in operation, the compressed air of the supply circuit 12 is supplied (backflowed) into the desiccant of the air supply passage 18 and the filter 17, thereby making the pressure of the air supply passage 18 and the filter 17 higher than atmospheric pressure and maintaining the back pressure (air pressure) of the upstream check valve 15 higher than atmospheric pressure.

[0055] (Setting execution conditions) Next, a method for determining the amount of air consumed in the regeneration operation (third operation mode) (hereinafter referred to as the regeneration air amount) will be described with reference to Fig. 3. The ECU 80 executes a control program to calculate the regeneration air amount Am according to the following formula (1). The regeneration air amount Am may be calculated in volume units or mass units. Various coefficients for converting units may be used on the right side (or left side) of this formula (1).

[0056] Regenerated air volume Am = Standard regeneration air volume Am1 - Correction unit air volume Am2 x Excess / deficiency coefficient α…(1) The "standard regeneration air amount Am1" is set to be larger than the "correction unit air amount Am2 × excess / deficiency coefficient α" so that the regeneration air amount Am exceeds "0". The standard regeneration air amount Am1 is an air amount basically determined by the specifications (specs) of the air drying circuit 11, but is changed according to the cutout pressure, which is the upper limit of the pressure of the air tank 30. As described above, the cutout pressure is a pressure that is a condition for starting the regeneration operation and the purge operation, and the higher the operating rate of the compressor 4, the higher the value is set and stored in the storage unit 80A. For example, when the operating rate is less than a predetermined value R1 (e.g., 30%), a relatively low cutout pressure Po1 is set, and when the operating rate is equal to or greater than the predetermined value R1 and less than a predetermined value R2 (e.g., 60%), a cutout pressure Po2 higher than the cutout pressure Po1 is set (Po2>Po1). Furthermore, when the operating rate is equal to or greater than the predetermined value R2, a cutout pressure Po3 higher than the cutout pressure Po2 is set (Po3>Po2). In this embodiment, the cutout pressure is set in three stages according to the operation rate of the compressor 4, but it may be set in two stages or in four or more stages. Alternatively, the cutout pressure may be changed continuously according to the operation rate of the compressor 4.

[0057] The reason why the cutout pressure Po is increased as the operating rate of the compressor 4 increases will be described. The compressor 4 is driven according to the amount of compressed dry air in the air tank 30, and therefore, when the operating rate is low, it is estimated that the consumption of compressed dry air by the pneumatic system, such as the brake system, is relatively low. In such a situation, the cutout pressure is set to a relatively low value, the frequency of the regeneration operation is relatively high, and the filter 17 is actively cleaned. On the other hand, when the operating rate of the compressor 4 is high, it is estimated that the consumption of compressed dry air by the pneumatic system, such as the brake system, is relatively high. In such a situation, the cutout pressure is set to a relatively high value, the frequency of the regeneration operation is relatively low, and the supply of compressed dry air to the pneumatic system is prioritized.

[0058] FIG. 3A shows a map 100 in which the standard regeneration air volume Am1 is set according to the limit airflow and the cutout pressure. This map 100 is stored in the storage unit 80A. The horizontal axis of the map 100 is the limit airflow, and the vertical axis is the standard regeneration air volume Am1. In the figure, the unit is volume (liters), but the unit may be mass. The limit airflow is a value indicating the limit of the amount of air passing through the air drying circuit 11, and is an amount determined according to the specifications of the air drying circuit 11 (air dryer). The standard regeneration air volume Am1 decreases as the limit airflow increases, and increases as the limit airflow decreases. In addition, when the limit airflow is constant, the standard regeneration air volume Am1 decreases as the cutout pressure increases, and increases as the cutout pressure decreases. In other words, since a higher value is set for the cutout pressure as the operating rate of the compressor 4 increases, it can be said that the standard regeneration air volume Am1 decreases as the operating rate of the compressor 4 increases. As described above, when the operating rate of the compressor 4 is high, it is estimated that the consumption of compressed dry air by the pneumatic system, such as the brake system, is relatively high. Therefore, when the operating rate of the compressor 4 is high, the standard regeneration air volume Am1 is reduced, and priority is given to supplying compressed dry air to the pneumatic system. Moreover, the standard regeneration air volume Am1 increases as the operating rate of the compressor 4 decreases. When the operating rate is low, it is estimated that the consumption of compressed dry air by the pneumatic system, such as the brake system, is relatively low. Therefore, when the operating rate of the compressor 4 is low, the standard regeneration air volume Am1 is increased, and the cleaning effect of the filter 17 per regeneration operation is improved.

[0059] 3B is a map 101 showing the relationship between the corrected unit air volume Am2 according to the cutout pressure and the limit airflow rate. This map 101 is stored in the memory unit 80A. The horizontal axis is the limit airflow rate, and the vertical axis is the corrected unit air volume Am2. In the figure, the unit is volume (liters), but the unit may be mass. The corrected unit air volume Am2 decreases as the limit airflow rate increases, like the standard regeneration air volume Am1, but when the limit airflow rate is constant, it increases as the cutout pressure increases and decreases as the cutout pressure decreases.

[0060] The excess / deficiency coefficient α (regeneration excess / deficiency coefficient) is a coefficient multiplied by the correction unit air volume Am2, and is set to a negative value, a positive value, or "0". This excess / deficiency coefficient α is set based on the tendency of the moist state of the compressed dry air stored in the air tank 30. The excess / deficiency of the regeneration operation can be determined by the amount of moisture captured by the filter 17, but since the amount of moisture contained in the compressed air varies depending on the temperature and humidity of the air, it is difficult to estimate the amount of moisture captured by the filter 17 using only the execution time of the regeneration operation or the amount of air that has passed through the filter 17. In addition, it is also difficult to directly measure the amount of moisture captured by the filter 17. As in this embodiment, by determining the excess / deficiency of the regeneration operation based on the moist state of the compressed dry air in the storage section, the excess / deficiency of the regeneration operation can be appropriately determined, even if indirectly.

[0061] The tendency of the wet state, which is the basis of the excess / deficiency coefficient α, is determined for the period from the previous regeneration operation to the time before the next regeneration operation. In addition, although the index for determining the wet state is not limited, in this embodiment, the saturation degree of the moisture content (hereinafter, the moisture content) contained in the compressed dry air in the air tank 30 is calculated, and the saturation degree of the current moisture content is subtracted from the saturation degree of the moisture content at the end of the previous regeneration operation. If the saturation degree of the moisture content is higher at the end of the current regeneration than at the end of the previous regeneration, that is, if the wet state of the compressed dry air tends to increase, it is determined that the amount of moisture captured by the filter 17 tends to increase. For this reason, in the above formula (1), the excess / deficiency coefficient α is set to a negative value less than "0". If the excess / deficiency coefficient α is a negative value, the regeneration air volume is corrected to be larger than the standard regeneration air volume.

[0062] On the other hand, if the saturation level of the moisture content is lower at the end of the current regeneration than at the end of the previous regeneration, that is, if the humidity state of the compressed dry air is tending to decrease, it is determined that the amount of moisture captured by the filter 17 is tending to decrease. Therefore, the excess / deficiency coefficient α is set to a positive value greater than "0", and the regeneration air volume is corrected to be smaller than the standard regeneration air volume. Also, if it is determined that the humidity state of the compressed dry air is appropriate, the excess / deficiency coefficient is set to "0", and the regeneration air volume Am is not corrected from the standard regeneration air volume Am1.

[0063] FIG. 4 shows excess / deficiency coefficient information 200 illustrating an example of excess / deficiency coefficient α. The excess / deficiency coefficient information 200 is stored in the memory unit 80A. The excess / deficiency coefficient information 200 includes excess / deficiency condition 200A and excess / deficiency coefficient 200C. State 200B conveniently shows the state indicated by excess / deficiency condition 200A and can be omitted. In excess / deficiency condition 200A, a range of the regeneration excess / deficiency degree is set. The regeneration excess / deficiency degree is an index indicating whether the saturation degree of moisture contained in the compressed dry air in the air tank 30 is on an increasing or decreasing trend.

[0064] The excess / deficiency coefficient 200C is obtained by multiplying the degree of excess / deficiency of reproduction by a weighting coefficient. The excess / deficiency coefficient 103 corresponds to the excess / deficiency condition 200A, which is the range of the degree of excess / deficiency of reproduction. Note that, although the weighting coefficient is a positive integer in FIG. 4, it does not have to be a positive integer.

[0065] In the excess / deficiency coefficient information 200, when the amount of regeneration air is significantly insufficient, i.e., when the moisture content is large, the regeneration excess / deficiency degree is, for example, "-1" or less, a negative value with a large absolute value. In this case, the weighting coefficient is also set to a relatively large value, for example, "2". Furthermore, when the amount of regeneration air is insufficient, but cannot be said to be "significantly insufficient," the regeneration excess / deficiency degree is, for example, in a range greater than "-1" and smaller than "-0.5," a smaller absolute value than "significantly insufficient." Furthermore, the weighting coefficient value is also set to a value smaller than "significantly insufficient," for example, "1."

[0066] Furthermore, when the amount of regeneration air is significantly excessive, i.e., when the moisture content is small, the degree of over- or under-regeneration is, for example, "1" or more, a positive value, and a large absolute value. In this case, the weighting coefficient is also set to a relatively large value, for example, "2." Furthermore, when the amount of regeneration air is excessive but not to the extent that it can be said to be "significantly excessive," the degree of over- or under-regeneration is, for example, "0.5" or more, in the range smaller than "1," and has a smaller absolute value than "significantly excessive." Furthermore, the value of the weighting coefficient is also set to a value smaller than "significantly insufficient," for example, "1."

[0067] When the degree of reproduction surplus / deficiency is within the range of, for example, "-0.5" or more and less than "0.5", the surplus / deficiency coefficient is set to "0". The regeneration air volume Am calculated using the standard regeneration air volume, the corrected unit air volume, and the excess / deficiency coefficient will be explained for two cases: when the operating rate of the compressor 4 is low and when it is high, and when the humidity level in the air tank 30 is low and when it is high. Note that it is assumed that the limit ventilation volume is constant.

[0068] (A) Operating rate of compressor 4: low, humidity state in air tank 30: high When the operating rate of the compressor 4 is low, the cutout pressure is set low. This increases the frequency of the regeneration and purging operations. Also, the standard regeneration air amount Am1 increases as the cutout pressure is set low.

[0069] Furthermore, the corrected unit air volume Am2 is smaller because the cutout pressure is set low. Also, the excess / deficiency coefficient α is a negative value because the humidity level inside the air tank 30 is high, resulting in a "significant shortage" or "shortage" state. Therefore, a positive correction value is added to the standard regeneration air volume, and the regeneration air volume Am becomes larger. Note that the regeneration air volume Am is larger in the "significant shortage" state than in the "shortage" state.

[0070] (B) Compressor 4 operating rate: low, humidity in air tank 30: low The standard regeneration air volume Am1 and the corrected unit air volume Am2 are the same as those in the above state (A). On the other hand, the excess / deficiency coefficient α is in a "significant excess" or "excess" state because the humidity level in the air tank 30 is low, and is a positive value. Therefore, the correction value is subtracted from the standard regeneration air volume, and the regeneration air volume Am becomes smaller than the regeneration air volume Am in state (A).

[0071] (C) Operating rate of compressor 4: high, humidity state in air tank 30: high When the operating rate of the compressor 4 is high, the cutout pressure is set high. This reduces the frequency of the regeneration and purging operations. In addition, the standard regeneration air volume Am1 is reduced by setting the cutout pressure high.

[0072] Furthermore, the corrected unit air volume Am2 becomes larger as the cutout pressure is set higher. Also, since the humidity state inside the air tank 30 is high, the excess / deficiency coefficient α becomes a negative value, resulting in a "significant deficiency" or "deficiency" state. Therefore, a positive correction value is added to the standard regeneration air volume, but the regeneration air volume Am becomes smaller than the regeneration air volume Am in state (A). The regeneration air volume Am in state (C) may be smaller or larger than the regeneration air volume Am in state (B). Also, the regeneration air volume Am in state (B) and the regeneration air volume Am in state (C) may be the same.

[0073] (D) Compressor 4 operating rate: high, humidity in air tank 30: low The standard regeneration air volume Am1 and the corrected unit air volume Am2 are the same as in the above-mentioned state (C). On the other hand, the excess / deficiency coefficient α is a positive value, indicating a "significant excess" or "excess" state, since the humidity state inside the air tank 30 is low. Therefore, the correction value is subtracted from the standard regeneration air volume, and the regeneration air volume Am becomes smaller than the regeneration air volume Am in state (C). In other words, although it depends on the setting value of the excess / deficiency coefficient α, basically, the regeneration air volume Am is largest in state (A) and smallest in state (D).

[0074] (Control of air drying circuit 11) Next, a procedure for the ECU 80 to control the air drying circuit 11 will be described with reference to FIGS.

[0075] The overall control procedure will be described with reference to Fig. 5. The ECU 80 performs an air supply process in which compressed air output from the compressor 4 is supplied to the supply circuit 12 (step S1). The air supply process is started under a predetermined condition, for example, when the engine is driven. The air supply process may also be started when the pressure in the air tank 30 reaches a predetermined pressure, such as a cut-in pressure, which is a lower limit value. In the air supply process, the air drying circuit 11 is in the first operation mode and performs a dehumidification operation.

[0076] When the air supply process is started, the ECU 80 determines whether or not to stop the supply of air (step S2). More specifically, the ECU 80 acquires the pressure in the air tank 30 detected by the pressure sensor 53, and determines whether or not the pressure has reached the cutout pressure. If the ECU 80 determines that the pressure in the air tank 30 has not reached the cutout pressure (step S2: NO), the process returns to the air supply process (step S1).

[0077] When the ECU 80 determines that the pressure in the air tank 30 has reached the cutout pressure (step S2: YES), it ends the air supply process, puts the compressor 4 into a non-operating state, and executes the purification process (step S3). In the purification process, the ECU 80 determines whether or not a regeneration operation and a purge operation are required according to preset conditions, and if it determines that a regeneration operation is required, it executes the regeneration operation, and if it determines that a purge operation is required, it executes the purge operation.

[0078] When the purification process (step S3) is completed, the ECU 80 performs an air non-supply process (step S4). In the air non-supply process, when the compressor 4 is not in operation, the ECU 80 adjusts the pressure in the air drying circuit 11, such as adjusting the back pressure of the upstream check valve 15. For example, in the air non-supply process, the ECU 80 executes at least one of the second operation mode, the fifth operation mode, and the sixth operation mode one or more times to adjust the air pressure in the air drying circuit 11. When the pressure adjustment is completed, the ECU 80 determines whether or not to end the air supply based on the vehicle state (step S5). The end of the air supply is determined based on the vehicle state, such as the engine being stopped.

[0079] When it is determined not to end the air supply (step S5: NO), the ECU 80 returns the process to step S1 and executes the air supply step (step S1) and subsequent processes. On the other hand, when it is determined to end the air supply (step S5: YES), the air supply is stopped.

[0080] Next, the procedure for controlling the regeneration operation will be described with reference to Fig. 6. The ECU 80 judges whether or not the regeneration operation is necessary according to a predetermined condition (step S100). At this time, the ECU 80 judges whether or not the regeneration operation is necessary based on the wetness state of the compressed dry air in the air tank 30. For example, the ECU 80 calculates the amount of moisture contained in the compressed dry air in the air tank 30 (the moisture content in the tank), and judges that the regeneration operation is necessary if the moisture content in the tank is equal to or greater than a predetermined value, and judges that the regeneration operation is not necessary if the moisture content in the tank is less than the predetermined value.

[0081] When the ECU 80 determines that the regeneration operation is not necessary (step S100: NO), the ECU 80 ends the process. On the other hand, when the ECU 80 determines that the regeneration operation is necessary (step S100: YES), the ECU 80 acquires the determined regeneration air amount (step S101). Then, the ECU 80 uses the acquired regeneration air amount to switch the air drying circuit 11 to the third operation mode and executes the regeneration operation (step S102). Here, the change in the pressure value detected by the pressure sensor 53 may be converted into the amount of air consumed in the regeneration operation, and when the converted amount of air reaches the regeneration air amount, the regeneration operation may be terminated. Alternatively, the air drying circuit 11 may be switched to the third operation mode and the regeneration operation may be performed for only the regeneration time corresponding to the regeneration air amount. The regeneration time may be calculated using a map that associates the regeneration air amount with the regeneration time, or may be calculated using a conversion formula on the assumption that the amount of air per unit time passing through the filter 17 during regeneration is constant. When the regeneration operation is completed, the purification step (step S3) is completed, and the process proceeds to the next step.

[0082] Next, the process for determining the regeneration air amount will be described with reference to FIG. 7. The ECU 80 defines one cycle as the period from the end of a regeneration operation to the start of the next regeneration operation. The regeneration air amount is updated at a predetermined timing in one cycle. The timing of updating the regeneration air amount is not particularly limited. For example, the regeneration air amount may be updated at the start of one cycle, at the end of one cycle, between the start and end of one cycle, or at a predetermined interval, such as a period shorter than the average time of one cycle.

[0083] The ECU 80 determines whether or not to update the regeneration air amount (step S110). For example, the ECU 80 determines whether or not a predetermined timing for a new cycle has been reached. If the ECU 80 determines that the predetermined timing has not been reached (step S110: NO), the process ends.

[0084] When the ECU 80 determines to update the regeneration air amount (step S110: YES), it calculates the regeneration excess / deficiency degree (step S111). As described above, the regeneration excess / deficiency degree may be calculated based on the change in the tank air moisture saturation degree. The tank air moisture saturation degree can be calculated from the humidity detected by the humidity sensor 51, the temperature detected by the temperature sensor 52, etc.

[0085] After calculating the regeneration excess / deficiency degree, the ECU 80 acquires an excess / deficiency coefficient using the excess / deficiency coefficient information 200 (step S112). Furthermore, the ECU 80 acquires a cutout pressure, which is the start pressure of the regeneration operation (step S113). Furthermore, the ECU 80 acquires a standard regeneration air amount using the map 100 based on the acquired cutout pressure (step S114), and acquires a corrected unit air amount using the map 101 (step S115). Then, the ECU 80 calculates the regeneration air amount according to the above-mentioned formula (1) using the standard regeneration air amount, the corrected unit air amount, and the excess / deficiency coefficient (step S116). The regeneration air amount calculated here is used in step S101 of FIG. 6. The ECU 80 performs the regeneration operation using the regeneration air amount calculated here.

[0086] As described above, according to the first embodiment, the following effects can be obtained. (1) The ECU 80 sets the amount of regeneration air consumed in the regeneration operation based on the operating state of the compressor 4. The compressor 4 is driven according to the supply state of compressed dry air to pneumatic systems other than the air drying circuit 11. Therefore, by changing the amount of regeneration air, it is possible to give priority to either the supply of compressed dry air from the air tank 30 to other pneumatic systems or the cleaning of the filter 17.

[0087] (2) When the operating rate of the compressor 4 is high and the supply rate of compressed dry air from the air tank 30 to the pneumatic system is high, the amount of regenerated air is reduced to suppress consumption of the compressed dry air stored in the air tank 30 and prioritize the supply of compressed dry air to the pneumatic system. Also, when the operating rate of the compressor 4 is low and the supply rate of compressed dry air from the air tank 30 to the pneumatic system is low, cleaning of the filter 17 can be prioritized.

[0088] (3) When the humidity of the compressed dry air in the air tank 30 is high, the amount of regenerated air is increased, thereby giving priority to cleaning the filter 17. When the humidity of the compressed dry air is low, the consumption of the compressed dry air stored in the air tank 30 is suppressed, thereby giving priority to the supply of compressed dry air to the pneumatic system.

[0089] (4) The cutout pressure, which is the upper limit pressure for starting the regeneration operation, is set according to the operating state of the compressor 4, and the amount of regeneration air is determined according to the cutout pressure. When the operating rate of the compressor 4 is high, the cutout pressure is set high and the amount of regeneration air is set small, so that the frequency of the regeneration operation is reduced and the consumption of the compressed dry air stored in the air tank 30 is suppressed, and the supply of compressed dry air to the pneumatic system is prioritized. When the operating rate of the compressor 4 is low, the cutout pressure is set low and the amount of regeneration air is set large, so that the frequency of the regeneration operation is increased and the effect of cleaning the filter 17 is improved.

[0090] Second embodiment The second embodiment will be described with reference to Fig. 8 and Fig. 9. The second embodiment is common to the first embodiment in that the standard regeneration air amount and the corrected unit air amount are changed according to the state of the air drying circuit 11 to calculate the regeneration air amount. In the first embodiment, the standard regeneration air amount and the corrected unit air amount are changed according to the cutout pressure, but the second embodiment differs from the first embodiment in that the standard regeneration air amount and the corrected unit air amount are changed according to the temperature of the compressed dried air. Therefore, the following mainly describes in detail the configurations that differ from the first embodiment, and for the sake of convenience, detailed descriptions of similar configurations are omitted.

[0091] FIG. 8A shows a map 110 in which the standard regeneration air amount Am1 is set according to the limit airflow and the temperature, and is stored in the storage unit 80A. The map 110 is different in that the map 100 (see FIG. 3) of the first embodiment determines the standard regeneration air amount according to the cutout pressure, whereas the map 110 determines the standard regeneration air amount according to the temperature. The value detected by the temperature sensor 52 can be used for the temperature. Alternatively, a temperature sensor may be provided on the inlet side of the air drying circuit 11 and upstream of the filter 17, and the temperature detected by the temperature sensor may be used. When the limit airflow is constant, the standard regeneration air amount Am1 decreases as the temperature decreases and increases as the temperature increases. In other words, when the temperature is high, the amount of saturated water vapor (saturated water vapor pressure) of the air increases, so the amount of moisture contained in the compressed air tends to increase. Therefore, it is expected that the amount of moisture captured by the filter 17 will also increase, so the standard regeneration air amount Am1 is increased to improve the effect of removing moisture from the filter 17 in one regeneration operation. Furthermore, when the temperature is low, the amount of saturated water vapor in the air (saturated water vapor pressure) is small, so the amount of moisture contained in the compressed air tends to be small. Therefore, it is expected that the amount of moisture captured by the filter 17 will also be small, so by reducing the standard regeneration air amount Am1, the amount of compressed dry air consumed in one regeneration operation is reduced.

[0092] 8B shows a map 111 in which the corrected unit air volume Am2 is set according to the limit airflow rate and temperature, and is stored in the storage unit 80A. The corrected unit air volume Am2 is a value subtracted from the standard regeneration air volume Am1, and therefore, like the standard regeneration air volume Am1, the corrected unit air volume Am2 decreases as the limit airflow rate increases, but when the limit airflow rate is constant, the corrected unit air volume Am2 decreases as the temperature increases and increases as the temperature decreases.

[0093] Next, the process for determining the regeneration air amount will be described with reference to Fig. 9. The process for determining the regeneration air amount in the second embodiment is common to steps S110 to S112 and steps S114 to S116 in the process of the first embodiment, and therefore a detailed description thereof will be omitted.

[0094] In step S120, the ECU 80 acquires the temperature of the compressed dry air detected by the temperature sensor 52 (step S120). Then, the ECU 80 acquires a standard regeneration air volume using the acquired temperature and the map 110 (step S114). Furthermore, the ECU 80 acquires a corrected unit air volume (step S115) using the acquired temperature and the map 111. Then, the ECU 80 calculates the regeneration air volume using the standard regeneration air volume, the corrected unit air volume, and the excess / deficiency coefficient (step S116).

[0095] In the second embodiment, the following effects can be obtained. (5) The ECU 80 sets the amount of regeneration air consumed in the regeneration operation according to the temperature of the compressed air or the temperature of the compressed dry air. As the temperature of the compressed air or the temperature of the compressed dry air increases, the amount of moisture contained in the air also increases. Therefore, by changing the amount of regeneration air according to the amount of moisture contained in the air, it is possible to give priority to either the supply of compressed dry air from the air tank 30 to the pneumatic system or the cleaning of the filter 17.

[0096] (6) When the air temperature is low and the amount of saturated water vapor is small, the amount of regenerated air is reduced, thereby suppressing consumption of the compressed dry air stored in the air tank 30 and giving priority to the supply of compressed dry air to the pneumatic system. Also, when the air temperature is high and the amount of saturated water vapor is large, the amount of regenerated air is increased, giving priority to cleaning the filter 17.

[0097] The above-described embodiments may be modified as follows: The above-described embodiments and the following modifications may be combined with each other to the extent that no technical contradiction occurs. In the first embodiment, the regeneration air amount is determined according to the degree of regeneration excess or deficiency, but the regeneration time may be determined according to the degree of regeneration excess or deficiency. In this case, the correction unit time is multiplied by the excess or deficiency coefficient to calculate the corrected regeneration time, and the corrected regeneration time is added to the standard regeneration time.

[0098] In the first embodiment, the excess / deficiency coefficient α is calculated by multiplying the regeneration excess / deficiency degree by a weighting coefficient, but the regeneration excess / deficiency degree itself may be used as the excess / deficiency coefficient α. Even in this case, the regeneration air volume can be increased or decreased according to the excess / deficiency of regeneration.

[0099] In the first embodiment, the degree of over- or under-regeneration is an index showing whether the saturation degree of the moisture contained in the compressed dry air in the air tank 30 is increasing or decreasing, but humidity may be used as an index instead of the degree of over- or under-regeneration. Also, the amount of moisture contained in the tank may be used as an index instead of the degree of over- or under-regeneration.

[0100] The degree of over- or under-regeneration in the first embodiment may be an average value over several cycles. If the average value is a negative value, it is estimated that the amount of moisture in the air tank 30 is increasing, and therefore it is determined that the amount of regeneration air is insufficient.

[0101] In the first embodiment, the cutout pressure is set according to the operation rate of the compressor 4, and the standard regeneration air volume and the corrected unit air volume constituting the regeneration air volume are set according to the cutout pressure. In addition to this aspect, the standard regeneration air volume and the corrected unit air volume may be set using a map or the like that associates the operation rate of the compressor 4 with the standard regeneration air volume and the corrected unit air volume.

[0102] In the second embodiment, the standard regeneration air volume and the correction unit air volume are set according to the temperature. In addition to this, the standard regeneration air volume and the correction unit air volume may be set using humidity in addition to temperature. Alternatively, the standard regeneration air volume and the correction unit air volume may be set using only the humidity detected by the humidity sensor 51 or the like.

[0103] In the above embodiments, when the humidity of the compressed dry air in the air tank 30 is high, the excess / deficiency coefficient is set to a negative value to increase the amount of regeneration air, and when the humidity of the compressed dry air in the air tank 30 is low, the excess / deficiency coefficient is set to a positive value to decrease the amount of regeneration air. In addition to this embodiment, the amount of regeneration air may be changed using the humidity of the compressed dry air sent out from the compressor 4 or the humidity of the outside air.

[0104] The amount of regeneration air may be determined based on the cutout pressure and the temperature of the compressed air or the compressed dry air. In this embodiment, a map correlating the cutout pressure, temperature, and standard regeneration air amount, or a map correlating the cutout pressure, temperature, and corrected unit air amount, or the like is used.

[0105] In each of the above embodiments, the regeneration air amount is calculated by correcting the standard regeneration air amount with a correction amount obtained by multiplying the correction unit air amount by the excess / deficiency coefficient, but the regeneration air amount may be calculated directly from a map, etc. In this case, the map may associate the cutout pressure (or temperature), an index indicating the moist state of the compressed dry air, and the regeneration air amount.

[0106] In each of the above embodiments, the filter 17 includes an oil trapping portion. However, the oil trapping portion may be omitted from the filter 17. The air drying circuit is not limited to the above configuration. The air drying circuit may have any configuration as long as it can perform the dehumidification operation and the regeneration operation. Therefore, the second operation mode and the fourth operation mode to the sixth operation mode are not essential operations for the air drying circuit.

[0107] In each of the above embodiments, the air supply system 10 has been described as being mounted on a vehicle such as a truck, a bus, a construction machine, etc. In other aspects, the air supply system 10 may be mounted on other moving bodies such as a passenger car, a railway vehicle, etc.

[0108] The ECU 80 is not limited to a circuit that performs software processing for all of the processes it executes. For example, the ECU 80 may be equipped with a dedicated hardware circuit (e.g., an application specific integrated circuit (ASIC)) that performs hardware processing for at least a part of the processes it executes. That is, the ECU 80 may be configured as a circuit including: 1) one or more processors that operate according to a computer program (software); 2) one or more dedicated hardware circuits that execute at least a part of the various processes; or 3) a combination thereof. The processor includes a CPU and memory such as RAM and ROM, and the memory stores program code or instructions configured to cause the CPU to execute the processes. The memory, i.e., computer-readable medium, includes any available medium that can be accessed by a general-purpose or dedicated computer. [Explanation of symbols]

[0109] 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...orifice, 25...drain discharge valve, 26A...governor, 26B...unload control valve, 27...drain discharge port as discharge port, 30...air tank as storage section, 50...pressure sensor, 51...humidity sensor, 52...temperature sensor, 53...pressure sensor, 80...ECU, 80A...memory section, E61 to E67...wiring.

Claims

1. an air drying circuit disposed between a compressor for delivering compressed air and a storage section for storing compressed dry air, the air drying circuit having a filter for trapping moisture; A control device for controlling the air drying circuit, The control device includes: Controlling the air drying circuit to perform a dehumidification operation in which the compressed air delivered from the compressor is passed in a forward direction through the filter and supplied to the storage section; controlling the air drying circuit to perform a regeneration operation in which the compressed dry air stored in the storage section is passed through the filter in a reverse direction to discharge the fluid that has passed through the filter from an outlet; The amount of regeneration air consumed in one regeneration operation is set according to the operating state of the compressor. Air supply system.

2. The control device includes: When the operating rate of the compressor within a certain period of time is high, the amount of regeneration air is reduced, and when the operating rate of the compressor is low, the amount of regeneration air is increased.

2. The air supply system of claim 1.

3. The control device includes: When the index indicating the wetness of the compressed dry air in the storage unit is high, the amount of regenerated air is increased, and when the index indicating the wetness of the compressed dry air in the storage unit is low, the amount of regenerated air is decreased.

3. An air supply system according to claim 1 or 2.

4. The control device includes: When the operating rate of the compressor is high, an upper limit pressure of the pressure in the storage section for starting the regeneration operation is set high, and when the operating rate of the compressor is low, the upper limit pressure is set low; When the upper limit pressure is high, the amount of regeneration air is reduced, and when the upper limit pressure is low, the amount of regeneration air is increased. An air supply system according to any one of claims 1 to 3.

5. an air drying circuit disposed between a compressor for delivering compressed air and a storage section for storing compressed dry air, the air drying circuit having a filter for trapping moisture; A control device for controlling the air drying circuit, The control device includes: Controlling the air drying circuit to perform a dehumidification operation in which the compressed air delivered from the compressor is passed in a forward direction through the filter and supplied to the storage section; controlling the air drying circuit to perform a regeneration operation in which the compressed dry air stored in the storage section is passed through the filter in a reverse direction to discharge the fluid that has passed through the filter from an outlet; The amount of regeneration air consumed in one regeneration operation is set according to the temperature of the compressed air or the compressed dry air. Air supply system.

6. The control device includes: When the temperature is low, the amount of regeneration air is reduced, and when the temperature is high, the amount of regeneration air is increased.

6. An air supply system according to claim 5.

7. A method for controlling an air supply system including an air drying circuit provided between a compressor that delivers compressed air and a storage section that stores compressed dry air and has a filter that captures moisture, and a control device that controls the air drying circuit. The control device, Controlling the air drying circuit to perform a dehumidification operation in which the compressed air delivered from the compressor is passed in a forward direction through the filter and supplied to the storage section; controlling the air drying circuit to perform a regeneration operation in which the compressed dry air stored in the storage section is passed through the filter in a reverse direction to discharge the fluid that has passed through the filter from an outlet; an amount of regeneration air consumed in one regeneration operation is set according to an operating state of the compressor; A method for controlling an air supply system.

8. A method for controlling an air supply system including an air drying circuit provided between a compressor that delivers compressed air and a storage section that stores compressed dry air and has a filter that captures moisture, and a control device that controls the air drying circuit. The control device, Controlling the air drying circuit to perform a dehumidification operation in which the compressed air delivered from the compressor is passed in a forward direction through the filter and supplied to the storage section; controlling the air drying circuit to perform a regeneration operation in which the compressed dry air stored in the storage section is passed through the filter in a reverse direction to discharge the fluid that has passed through the filter from an outlet; an amount of regeneration air consumed in one regeneration operation is set according to the temperature of the compressed air or the temperature of the compressed dry air. A method for controlling an air supply system.

9. A control program for an air supply system including an air drying circuit provided between a compressor that delivers compressed air and a storage section that stores compressed dry air and has a filter that captures moisture, and a control device that controls the air drying circuit. The control device, a dehumidification operation execution unit that controls the air drying circuit to execute a dehumidification operation of passing the compressed air sent out from the compressor through the filter in a forward direction and supplying the compressed air to the storage unit; a regeneration operation execution unit that controls the air drying circuit to execute a regeneration operation in which the compressed dry air stored in the storage unit is passed through the filter in a reverse direction to discharge the fluid that has passed through the filter from an outlet; and a setting unit that sets the amount of regeneration air consumed in one regeneration operation according to the operating state of the compressor; Air supply system control program.

10. A control program for an air supply system including an air drying circuit provided between a compressor that delivers compressed air and a storage section that stores compressed dry air and has a filter that captures moisture, and a control device that controls the air drying circuit. The control device, a dehumidification operation execution unit that controls the air drying circuit to execute a dehumidification operation of passing the compressed air sent out from the compressor through the filter in a forward direction and supplying the compressed air to the storage unit; a regeneration operation execution unit that controls the air drying circuit to execute a regeneration operation in which the compressed dry air stored in the storage unit is passed through the filter in a reverse direction to discharge the fluid that has passed through the filter from an outlet; and a setting unit that sets an amount of regeneration air to be consumed in one regeneration operation in accordance with the temperature of the compressed air or the temperature of the compressed dry air. Air supply system control program.

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