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

Abstract

To optimize an amount of air to be consumed by reproduction operation to reduce consumption of compressed dry air with good dehumidification performance maintained.SOLUTION: An ECU (80) carries out dehumidification operation in which an air dry circuit (11) is controlled to cause compressed air sent from a compressor (4) to pass through a filter (17) in a forward direction and be supplied to an air tank (30), and reproduction operation in which compressed dry air stored in the air tank (30) is caused 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). Every time the reproduction operation ends, a reproduction result, a result of the reproduction operation of the air dry circuit (11), is stored in a storage part (80A). When a new reproduction operation starts, the reproduction result of the air dry circuit stored in the storage part (80A) is obtained and the obtained reproduction result is reflected on reproduction conditions of the new reproduction operation.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 is passed 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 amount of compressed dry air passing through. For this reason, the compressed air dryer performs a regeneration operation in which the oil and moisture adsorbed on 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 increase. 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, etc. Since the 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 while maintaining good dehumidification performance by optimizing the amount of air consumed in the regeneration operation. [Means for solving the problem]

[0007] An air supply system that solves the above problem 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, 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 store a regeneration result, which is a result of the regeneration operation of the air drying circuit, in a memory section each time the regeneration operation is completed, and when a new regeneration operation is started, the regeneration result of the air drying circuit stored in the memory section is obtained, and the obtained regeneration result is reflected in the regeneration conditions of the new regeneration operation.

[0008] A control method for an air supply system that solves the above-mentioned problems is a control method for an air supply system including 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, in which the control device executes the following steps: controlling 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; controlling 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; storing a regeneration result, which is a result of the regeneration operation of the air drying circuit, in a memory section each time the regeneration operation is completed; acquiring the regeneration result of the air drying circuit stored in the memory section when starting a new regeneration operation; and reflecting the acquired regeneration result in the regeneration conditions of the new regeneration operation.

[0009] A control program for an air supply system that solves the above-mentioned problems is a control program for an air supply system including an air drying circuit that is provided between a compressor that sends out compressed air and a storage unit 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 functions as a dehumidification operation execution unit that controls the air drying circuit to execute 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 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 passes through the filter in a reverse direction and the fluid that has passed through the filter is discharged from an outlet, a result storage unit that stores in a storage unit a regeneration result that is a result of the regeneration operation of the air drying circuit each time the regeneration operation is completed, an acquisition unit that acquires the regeneration result of the air drying circuit stored in the storage unit when a new regeneration operation is started, and a reflection unit that reflects the acquired regeneration result in the regeneration conditions of the new regeneration operation.

[0010] According to the above configuration, the regeneration result stored each time a regeneration operation is completed is reflected in the execution conditions for the next regeneration operation. In the air drying circuit, the regeneration operation is repeatedly performed under conditions of different temperatures, humidity, etc., so if the past regeneration result is reflected in a new regeneration operation, it is possible to prevent insufficient regeneration of the filter and to prevent wasteful consumption of compressed dry air.

[0011] In the above air supply system, the control device may be configured to determine whether the regeneration operation is excessive or insufficient based on an index showing the humidity state of the compressed dry air in the storage section, and if it is determined that the regeneration operation is insufficient, to increase the regeneration air amount, which is the amount of air passing through the filter by the regeneration operation, or the regeneration time, which is the time for performing the regeneration operation, and if it is determined that the regeneration operation is excessive, to decrease the regeneration air amount or the regeneration time.

[0012] According to the above configuration, when it is determined that the regeneration operation is insufficient, the amount of regeneration air or the regeneration time is increased to restore the dehumidification performance of the filter. Also, when it is determined that the regeneration operation is excessive, the amount of regeneration air or the regeneration time is decreased to suppress consumption of the compressed dry air in the storage section. Furthermore, since the regeneration operation is judged to be excessive or insufficient based on the humidity state of the compressed dry air in the storage section, it is possible to indirectly but appropriately judge the excess or insufficiency of the regeneration operation.

[0013] For the above air supply system, the control device may be configured to calculate a degree of surplus or deficiency indicating the amount of surplus or deficiency in the regeneration operation, and calculate the amount of regeneration air by multiplying the degree of surplus or deficiency by a coefficient weighted according to the magnitude of the surplus or deficiency in the regeneration operation and adding the result to a reference air amount.

[0014] According to the above-described configuration, a coefficient weighted according to the degree of excess or deficiency is used, so that an amount of regeneration air according to the degree of excess or deficiency can be passed through the filter. In the above air supply system, the air drying circuit may be provided with a humidity detection unit between the filter and the storage unit, and the control device may be configured to calculate an index indicating the humidity state of the compressed dried air based on humidity information detected by the humidity detection unit during the regeneration operation.

[0015] According to the above configuration, an index indicating the humidity state of the compressed dry air in the storage section is calculated using the humidity of the compressed dry air flowing back from the storage section toward the filter, so that the humidity state of the compressed dry air can be appropriately calculated.

[0016] In the above air supply system, the control device may be configured to set a regeneration time for executing the regeneration operation before starting the regeneration operation, and if the regeneration operation is interrupted, to store the remaining time of the regeneration time in a memory unit, and, when starting a new regeneration operation, to obtain the remaining time from the memory unit and reflect the remaining time in the regeneration time of the new regeneration operation.

[0017] According to the above configuration, when the regeneration operation is interrupted, the remaining time of the regeneration operation is reflected in the next regeneration operation. Therefore, it is possible to maintain good filter performance while allowing the regeneration operation to be interrupted.

[0018] With respect to the above air supply system, the control device may be configured, when the regeneration operation is completed, to calculate a corrected remaining time by adding the remaining time of the regeneration operation to the remaining time of the regeneration operation performed before the regeneration operation, and to reflect the corrected remaining time in the regeneration time of the next regeneration operation.

[0019] According to the above configuration, when the n-th regeneration operation is completed, the remaining time of the n-1-th regeneration operation and the remaining time of the n-th regeneration operation are added together and reflected in the n+1-th regeneration operation. Since the remaining time of the n-1-th regeneration operation is reflected in the regeneration time of the n-th regeneration operation, if the remaining time of the n-1-th regeneration operation is offset by the n-th regeneration operation, the remaining time is not carried over, and if the remaining time of the n-1-th regeneration operation is not offset, the remaining time is carried over. Furthermore, if the n-th regeneration operation is not interrupted, the remaining time of the n-th regeneration operation is not carried over to the n+1-th regeneration operation, and if the n-th regeneration operation is interrupted, the remaining time of the n-th regeneration operation is carried over to the n+1-th regeneration operation. Therefore, the remaining time is carried over until the remaining time in the past regeneration operation is offset. Therefore, the dehumidification performance of the filter can be maintained well. Effect of the Invention

[0020] According to the present disclosure, by optimizing the amount of regeneration air consumed in the desiccant regeneration operation, it is possible to reduce the amount of compressed dry air consumed while maintaining good desiccant performance. [Brief description of the drawings]

[0021] [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] FIG. 2 is a schematic diagram of excess / deficiency coefficient information in the embodiment of FIG. 1; [Figure 4] 4 is a flowchart showing an example of a procedure for supplying compressed air in the embodiment of FIG. 1. [Diagram 5] 4 is a flowchart showing an example of a procedure for performing a reproducing operation in the embodiment of FIG. 1; [Figure 6] 4 is a flowchart showing an example of a procedure for determining the amount of regeneration air in the embodiment of FIG. 1. [Figure 7]10 is a flowchart showing an example of a procedure for determining a playback time in the second embodiment. [Figure 8] 8 is a flowchart showing an example of a procedure for updating a shortage time in the embodiment of FIG. 7. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] (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.

[0023] <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 as a control device.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] <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.

[0046] (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.

[0047] (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.

[0048] (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.

[0049] (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.

[0050] (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.

[0051] (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.

[0052] (Setting execution conditions) Next, a method for determining the amount of regeneration air consumed in the regeneration operation (third operation mode) will be described with reference to Fig. 3. The amount of regeneration air Am is calculated by the following formula (1). The amount of regeneration air 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).

[0053] 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 (standard regeneration capacity) is an air amount that is basically determined by the specifications (specs) of the air drying circuit 11, but may be changed depending on the temperature of the compressed dry air, the upper limit of the pressure of the air tank 30, etc. The corrected unit air amount Am2 (reference regeneration capacity) is an amount that serves as a unit for correcting the regeneration air amount. The corrected unit air amount Am2 may also be changed depending on the temperature of the compressed dry air, the upper limit of the pressure of the air tank 30, etc.

[0054] The excess / deficiency coefficient α (regeneration excess / deficiency coefficient) is set based on the change (trend) in the wetness 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. However, since the amount of moisture contained in the compressed air varies depending on the temperature and humidity, 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 passed through the filter by the regeneration operation. In addition, it is also difficult to directly measure the amount of moisture captured by the filter 17. If the excess / deficiency of the regeneration operation is determined based on the wetness state of the compressed dry air in the storage unit as in this embodiment, the excess / deficiency of the regeneration operation can be appropriately determined, even if indirectly.

[0055] The change (tendency) in the wetness state, which is the basis of the excess / deficiency coefficient α, is determined for the period from after the previous regeneration operation to before the next regeneration operation. In addition, the index for determining the wetness state is not limited, but in this embodiment, the wetness state is determined by calculating the amount of moisture contained in the compressed dry air in the air tank 30 (hereinafter, the moisture content). When the index indicating the wetness state of the compressed dry air stored in the air tank 30 after the previous regeneration operation is high, that is, when the moisture content is high, it is determined that the amount of moisture captured by the filter 17 is on the increase. For this reason, in the above formula (1), the excess / deficiency coefficient α is set to a negative value less than "0" and the amount of regeneration air is increased.

[0056] On the other hand, when the index indicating the moisture state of the compressed dry air stored in the air tank 30 is low, i.e., when the moisture content is small, 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 reduced. Also, when it is determined that the moisture state of the compressed dry air is appropriate, the excess / deficiency coefficient is set to "0", and the standard regeneration air volume Am1 is not corrected.

[0057] As shown in Fig. 3, the ECU 80 stores excess / deficiency coefficient information 100 in a non-volatile storage unit. The excess / deficiency coefficient information 100 includes an excess / deficiency condition 101 and an excess / deficiency coefficient 103. A state 102 conveniently indicates the state indicated by the excess / deficiency condition 101 and can be omitted. A range of the regeneration excess / deficiency degree is set in the excess / deficiency condition 101. 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.

[0058] The excess / deficiency coefficient 103 is obtained by multiplying the reproduction excess / deficiency degree by a weighting coefficient. The excess / deficiency coefficient 103 corresponds to the excess / deficiency condition 101, which is the range of the reproduction excess / deficiency degree. Note that, although the weighting coefficient is a positive integer in FIG. 3, it does not have to be a positive integer.

[0059] In the excess / deficiency coefficient information 100, 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."

[0060] 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."

[0061] 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". Next, the degree of over- or under-regeneration will be described. In this embodiment, the degree of over- or under-regeneration is calculated by the following formula (2). The tank air moisture saturation S indicates the saturation degree of moisture contained in the compressed dry air in the air tank 30. The tank air moisture saturation S is stored in the non-volatile storage unit or the volatile storage unit every time a regeneration operation is completed. The tank air moisture saturation S(n-1) is a value calculated after the previous (n-1th) regeneration operation is completed, and the tank air moisture saturation S(n) is a value calculated after the next (nth) regeneration operation is completed. Note that various coefficients for converting units may be used on the right side (or left side) of this formula (2).

[0062] Regeneration excess / deficiency degree D =Tank air moisture saturation S(n-1) - Tank air moisture saturation S(n)…(2) The tank air moisture saturation level S is calculated using the following formula (3). The tank moisture content Mtk is a calculated value of the moisture content contained in the compressed dry air in the air tank 30, and the moisture change amount ΔM is the moisture content contained in the air volume discharged from the air tank 30 from the moisture content contained in the air volume discharged from the air drying circuit 11 during one cycle. The tank maximum moisture content Mmax is the maximum amount of moisture contained in the compressed dry air in the air tank 30 (the maximum moisture content of the tank air). Various coefficients for converting units may be used on the right side (or left side) of formula (3).

[0063] Tank air saturation S = (Tank moisture content Mtk + moisture change ΔM) / (Maximum tank moisture content Mmax) ... (3) The tank moisture content Mtk can be calculated, for example, from the humidity detected by the humidity sensor 51 during the regeneration operation and the temperature detected by the temperature sensor 52. The moisture content contained in the air volume discharged from the air drying circuit 11 can be calculated from the humidity detected by the humidity sensor 51 during the dehumidification operation and the temperature detected by the temperature sensor 52. The moisture content contained in the air volume discharged from the air tank 30 can be calculated from the tank moisture content Mtk and the consumed air volume, which is the volume of air supplied from the air tank 30 to each pneumatic system, etc.

[0064] (Air drying circuit control) Next, a procedure for the ECU 80 to control the air drying circuit 11 will be described with reference to FIGS.

[0065] The overall control procedure will be described with reference to Fig. 4. 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.

[0066] 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).

[0067] 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.

[0068] 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.

[0069] 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.

[0070] Next, the procedure for controlling the regeneration operation will be described with reference to Fig. 5. The ECU 80 judges whether or not the regeneration operation is necessary according to a predetermined condition (step S100). For example, the ECU 80 judges that the regeneration operation is necessary when the water content amount Mtk of the tank is equal to or greater than a predetermined value, and judges that the regeneration operation is not necessary when the water content amount Mtk of the tank is less than the predetermined value.

[0071] 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.

[0072] Next, the process for determining the regeneration air amount will be described with reference to FIG. 6. 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.

[0073] 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 S111: NO), the process ends.

[0074] 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 is calculated based on the change in the tank air moisture saturation. The tank air moisture saturation degree is calculated from the tank moisture content Mtk, the moisture change amount ΔM, and the tank maximum moisture content Mmax.

[0075] When the ECU 80 calculates the regeneration over- or under-degree, it acquires the over- or under-coefficient by using the over- or under-coefficient information 100 (step S112). Then, it calculates the regeneration air amount by using the acquired over- or under-coefficient, the standard regeneration air amount, and the correction unit air amount (step S113). For example, when the regeneration over- or under-degree corresponds to the "significantly under- or under-degree" state, in step S113, a regeneration air amount larger than the standard regeneration air amount is calculated, and a relatively large amount of compressed dry air passes through the filter 17. Also, when the regeneration over- or under-degree corresponds to the "significantly over- or under-degree" state, in step S113, a regeneration air amount smaller than the standard regeneration air amount is calculated, and a relatively small amount of compressed dry air passes through the filter 17. Furthermore, when the regeneration over- or under-degree corresponds to the "optimal" state, in step S113, a regeneration air amount equal to the standard regeneration air amount is calculated, and an amount of compressed dry air smaller than the amount of air when the regeneration over- or under-degree is under- or over-state passes through the filter 17.

[0076] As described above, according to the first embodiment, the following effects can be obtained. (1) The tank air moisture saturation S, which is the regeneration result stored each time a regeneration operation is completed, is reflected in the regeneration air volume for the next regeneration operation. In the air drying circuit 11, the regeneration operation is repeatedly performed under conditions of different temperatures, humidity, etc., so if the past regeneration result is reflected in a new regeneration operation, it is possible to prevent insufficient regeneration of the filter 17 and to prevent wasteful consumption of compressed dry air.

[0077] (2) If it is determined that the regeneration operation is insufficient, the amount of regeneration air is increased to restore the dehumidification performance of the filter 17. Also, if it is determined that the regeneration operation is excessive, the amount of regeneration air is decreased to suppress consumption of the compressed dry air in the air tank 30. Furthermore, since the excess or deficiency of the regeneration operation is determined based on the moist state of the compressed dry air in the air tank 30, it is possible to appropriately determine the excess or deficiency of the regeneration operation, even if indirectly.

[0078] (3) The amount of regeneration air is calculated using a coefficient weighted according to the degree of over- or under-regeneration. This allows the amount of regeneration air to pass through the filter 17 according to the degree of over- or under-regeneration.

[0079] (4) The tank air moisture saturation S, which indicates the humidity state of the compressed dry air in the air tank 30, is calculated using the humidity of the compressed dry air flowing back from the air tank 30 to the filter 17 during regeneration operation, so that the humidity state of the compressed dry air can be appropriately calculated.

[0080] Second embodiment The second embodiment will be described with reference to Figures 7 and 8. The second embodiment is common to the first embodiment in that it uses the regeneration execution state of the air drying circuit 11, which is the state when a regeneration operation was previously performed. In addition, while the first embodiment reflects the past regeneration execution state in the regeneration air amount, the second embodiment differs from the first embodiment in that the past regeneration execution state is reflected in the regeneration time. Therefore, the following mainly describes in detail the configurations that differ from the first embodiment, and for convenience of explanation, detailed explanations of similar configurations are omitted.

[0081] In this embodiment, it is assumed that the ECU 80 determines that a regeneration operation is necessary, calculates a planned regeneration time based on the regeneration air volume calculated before performing the regeneration operation, and performs the regeneration operation based on the planned regeneration time.

[0082] This regeneration operation usually ends when the elapsed time from the start of regeneration reaches a predetermined regeneration time, but may be interrupted at other times based on the air drying circuit 11 or the vehicle state. The timing at which the regeneration operation is interrupted is, for example, when the pressure in the air tank 30 reaches the cut-in pressure due to the consumption of compressed dry air by an air pressure system constituting a brake system or the like, or when a command is received from an ECU that controls another system. When the ECU 80 determines that the condition for interrupting the regeneration operation is met, it interrupts the regeneration operation by prioritizing the supply of compressed dry air over the regeneration operation, while storing the remaining regeneration time in a storage unit such as a non-volatile storage unit or a volatile storage unit. Then, when the regeneration operation is started next time, the remaining regeneration time is added to the regeneration time calculated according to the tank moisture content Mtk or the like.

[0083] The procedure of the regeneration time correction process for correcting the regeneration time will be described with reference to Fig. 7. The regeneration time correction process is performed before the regeneration operation is executed. Here, the case immediately before the start of the nth (n≧2) regeneration operation after the air supply system 10 starts its operation will be described.

[0084] The ECU 80 acquires the planned regeneration time Tp(n) (specified regeneration time (calculated value)) calculated based on the water content Mtk in the tank, etc. (step S210). The planned regeneration time Tp(n) acquired here is the time when the regeneration air amount calculated in step S113 of FIG. 6 is changed to the time when regeneration is performed.

[0085] Further, the ECU 80 acquires the previous shortage time Ts(n - 1) stored in the storage unit (step S211). Here, the explanation will be given assuming that the acquired previous shortage time Ts(n - 1) is "0". The case where the previous shortage time Ts(n - 1) is "0" is, for example, when the previous shortage time Ts(n - 1) has been reset, or when the playback operation has not been interrupted during the past playback operation, etc. Note that the previous shortage time Ts(n - 1) may be reset at a predetermined timing such as when the state in which the air supply system 10 is stopped continues for a predetermined period, when maintenance of the air supply system 10 is performed, or when the ignition switch of the vehicle is turned off.

[0086] When the ECU 80 determines that the previous shortage time Ts(n - 1) is "0 sec" (step S212: NO), it sets the scheduled playback time Tp(n) as the playback time T(n) and ends the process. That is, the playback operation is executed according to the scheduled playback time Tp(n). When the ECU 80 starts the playback operation, it measures the playback execution time Tac (current state continuation time), which is the elapsed time since the start of playback.

[0087] Assume that during the nth playback operation, the interruption condition is satisfied and the playback operation is interrupted by the ECU 80 (Tac < T(n)). When the playback operation is interrupted in this way, the ECU 80 performs a shortage time calculation process. Note that the shortage time calculation process is also performed when the elapsed time since the start of the playback operation reaches the playback time T(n) and the playback operation ends as scheduled.

[0088] With reference to FIG. 8, the shortage time calculation process will be described. When the ECU 80 ends the playback operation including interruption of the playback operation, it acquires the previous shortage time Ts(n - 1) stored in the storage unit (step S250). Further, the ECU 80 acquires the added time Tad (playback regulation time (added value)) calculated by the process of correcting the playback time in the current (nth) playback operation (step S251). Here, when the previous shortage time Ts(n - 1) is "0", the added time Tad is also "0".

[0089] Furthermore, the ECU 80 acquires the regeneration execution time Tac(n), which is the elapsed time since the nth regeneration operation was started (step S252).Then, the ECU 80 adds a first term obtained by subtracting the added time Tad from the previous (n-1th) shortage time Ts(n-1) and a second term obtained by subtracting the regeneration execution time Tac(n) from the current regeneration time T(n) to calculate the current (nth) shortage time Ts(n) as shown in the following formula (4) (step S253).

[0090] Ts(n)={Ts(n-1)-Tad}+{T(n)-Tac(n)}…(4) The first term indicates whether the current (nth) regeneration operation was performed to make up for the shortage time up to the previous (n-1th) regeneration operation, and if there was no shortage time in the previous operation, the first term is "0". The second term indicates whether a shortage time occurred in the current (nth) regeneration operation. Therefore, the shortage time here is "Ts(n)=T(n)-Tac(n)". The ECU 80 stores the calculated shortage time Ts(n) in the non-volatile storage unit or the volatile storage unit, and ends the shortage time calculation process.

[0091] Next, it is assumed that the ECU 80 determines that the (n+1)th regeneration operation is necessary. The ECU 80 calculates the regeneration time based on the regeneration air amount calculated based on the state of the air drying circuit 11 at that time, and performs a regeneration time correction process.

[0092] 7, the ECU 80 acquires the planned regeneration time Tp(n+1th) scheduled for the current (n+1th) regeneration operation (step S210). In addition, the ECU 80 acquires the shortage time Ts(n) of the previous (nth) regeneration operation (step S211) and determines whether the shortage time Ts(n) of the previous regeneration operation is greater than "0 sec" (step S212). Note that the previous (nth) regeneration operation was interrupted, and the shortage time Ts(n) is greater than "0 sec."

[0093] When the ECU 80 determines that the previous shortage time Ts(n) is greater than "0 sec" (step S212: YES), it adds the previous shortage time Ts(n) to the planned regeneration time Tp(n+1) to calculate a corrected regeneration time T'(n+1) (prescribed regeneration time (effective value)) (step S213). The ECU 80 also determines whether the corrected regeneration time T'(n+1) is greater than or equal to the maximum regeneration time Tmax (step S214). The maximum regeneration time Tmax is the upper limit of the regeneration time.

[0094] When the ECU 80 determines that the corrected regeneration time T'(n+1) is equal to or greater than the maximum regeneration time Tmax (step S214: YES), it sets the maximum regeneration time Tmax as the corrected regeneration time T'(n+1) (step S215). Furthermore, the ECU 80 sets the difference between the corrected regeneration time T'(n+1) and the maximum regeneration time Tmax as the added time Tad as the time newly added to the planned regeneration time Tp(n+1) (step S216). In other words, the time that is reduced from the corrected regeneration time T'(n+1) because it is greater than the maximum regeneration time Tmax is set as the added time Tad.

[0095] On the other hand, when the ECU 80 determines that the corrected regeneration time T'(n+1) is less than the maximum regeneration time Tmax (step S214: NO), it sets the corrected regeneration time T'(n+1) as the time to execute the regeneration operation. That is, it plans to execute the regeneration operation for the corrected regeneration time T'(n+1). Then, the ECU 80 sets the previous shortage time Ts(n) to the addition time Tad (step S217). After setting the corrected regeneration time T'(n+1) and the addition time Tad in this way, the regeneration time correction process ends and the process proceeds to the shortage time calculation process. When the ECU 80 starts the (n+1)th regeneration operation, it measures the regeneration execution time Tac, which is the elapsed time from the start.

[0096] As shown in Fig. 8, when the (n+1)th regeneration operation is completed, the shortage time in the (n+1)th regeneration operation is calculated. The ECU 80 acquires the shortage time in the previous (n)th regeneration operation (step S250) and acquires the added time Tad (step S251). The ECU 80 also acquires the regeneration execution time Tac(n+1) of the (n+1)th regeneration operation (step S252). The ECU 80 then calculates the shortage time Ts(n+1) according to the above formula (3) (step S253).

[0097] For example, if the added time Tad set when starting the nth regeneration operation is "0", the first term (Ts(n)-Tad) is the shortage time Ts(n) of the interrupted nth regeneration operation. In addition, the second term (T(n+1)-Tac(n+1)) is set to "0" if the n+1th regeneration operation is not interrupted, and is set to a value greater than "0" if the n+1th regeneration operation is interrupted. In other words, since the first term indicates the shortage time up to the previous time and the second term indicates the shortage time that has occurred this time, if a shortage time occurs this time as well as the previous time, the shortage time will be accumulated in the regeneration time of the next regeneration operation. Therefore, the compressed dry air is sufficiently stored in the air tank 30, and the regeneration operation is performed for the accumulated regeneration time at a timing when a sufficient regeneration time can be secured, so that the supply of compressed dry air to the brake system and the like is prioritized while the performance of the filter 17 can be maintained at a good level.

[0098] In the second embodiment, the following effects can be obtained. (5) When the regeneration operation is interrupted, the remaining time of the regeneration time is stored in the memory unit, and when the regeneration operation is newly started, the remaining time is reflected in the regeneration time of the new regeneration operation. Therefore, the regeneration operation can be interrupted and the consumption of compressed dry air from the air tank 30 is prioritized, while maintaining the dehumidification performance of the filter 17 in a good state.

[0099] (6) When the n-th regeneration operation is completed, the remaining time of the n-1-th regeneration operation and the remaining time of the n-th regeneration operation are added together and reflected in the n+1-th regeneration operation. Since the remaining time of the n-1-th regeneration operation is reflected in the regeneration time of the n-th regeneration operation, if the remaining time of the n-1-th regeneration operation is offset by the n-th regeneration operation, the remaining time is not carried over, and if the remaining time of the n-1-th regeneration operation is not offset, the remaining time is carried over. Also, if the n-th regeneration operation is not interrupted, the remaining time of the n-th regeneration operation is not carried over to the n+1-th regeneration operation, and if the n-th regeneration operation is interrupted, the remaining time of the n-th regeneration operation is carried over to the n+1-th regeneration operation. Therefore, the remaining time is carried over until the remaining time in the past regeneration operation is offset. Therefore, the dehumidification performance of the filter 17 can be maintained in a good condition.

[0100] The above-described embodiments can be modified as follows: The present embodiment and the following modifications can 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.

[0101] 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 depending on the excess / deficiency of regeneration.

[0102] 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 Mtk may be used as an index instead of the degree of over- or under-regeneration.

[0103] 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.

[0104] In the first embodiment, the regeneration result stored each time the regeneration operation is completed is the tank air moisture saturation, but other indices may be used, such as the humidity of the compressed dry air, the amount of moisture contained in the tank Mtk, etc.

[0105] In the second embodiment, when setting the playback time T, the shortage time Ts of the past playback operation is added to the reference playback time. Alternatively, a part of the shortage time Ts of the past playback operation may be added to the reference playback time. Also, the shortage time Ts of the past playback operation may be corrected and added to the reference playback time.

[0106] In the second embodiment, if the remaining time of the n-1th playback operation is not offset in the nth playback operation, the remaining time is reflected in the playback time of the next n+1th playback operation. In addition to this mode, if the remaining time of the n-1th playback operation is not offset, a part of the remaining time may be reflected in the playback time of the n+1th playback operation, or the remaining time of the n-1th playback operation may be reflected in the playback time of the nth playback operation but not reflected in the playback time of the n+1th playback operation.

[0107] In the second embodiment, the regeneration result stored each time the regeneration operation was completed was the remaining time of the regeneration operation, but it may be another regeneration result. For example, the regeneration result may be the amount of regeneration air.

[0108] In the second embodiment, the regeneration time is calculated using the regeneration air amount calculated in the first embodiment, and the regeneration operation is performed using the regeneration time, but the regeneration time is not limited to this. For example, the regeneration time may be calculated based on the amount of compressed air sent out from the compressor 4, or may be calculated based on the humidity detected by the humidity sensor 51 when the air drying circuit 11 is in the regeneration operation or dehumidification operation. The regeneration time may also be calculated based on the execution interval of the regeneration operation. When the regeneration time is calculated based on the compressed air amount, the regeneration time is shortened when the amount of compressed air in a certain period is small, and is lengthened when the amount of compressed air is large. When the regeneration time is calculated based on the humidity, the regeneration time is shortened when the humidity is low, and is lengthened when the humidity is high. When the regeneration time is calculated based on the execution interval of the regeneration operation, the regeneration time is shortened when the execution interval is short, and is lengthened when the execution interval is long. Alternatively, the regeneration time may be constant, regardless of the moisture content or moisture saturation in the air tank 30.

[0109] 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.

[0110] 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 embodiments, the air supply system 10 may be mounted on other moving bodies such as a passenger car, a railway vehicle, etc.

[0111] 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]

[0112] 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; storing a regeneration result, which is a result of the regeneration operation of the air drying circuit, in a storage unit each time the regeneration operation is completed; When starting a new regeneration operation, the regeneration result of the air drying circuit stored in the storage unit is obtained; The acquired playback result is reflected in a playback condition of the new playback operation. Air supply system.

2. The control device includes: determining whether the regeneration operation is excessive or insufficient based on an index indicating a wetness state of the compressed dry air in the storage section; When it is determined that the regeneration operation is insufficient, the regeneration air amount, which is the amount of air passing through the filter by the regeneration operation, or the regeneration time, which is the time for performing the regeneration operation, is increased; When it is determined that the regeneration operation is excessive, the regeneration air amount or the regeneration time is reduced.

2. The air supply system of claim 1.

3. The control device includes: Calculating a degree of excess or deficiency indicating an excess or deficiency of the reproducing operation; The regeneration air amount is calculated by multiplying the degree of excess or deficiency by a coefficient weighted according to the magnitude of excess or deficiency of the regeneration operation and adding the resultant value to a reference air amount.

3. An air supply system according to claim 2.

4. the air drying circuit includes a humidity detector between the filter and the storage section; The control device is configured to calculate an index indicating a wet state of the compressed dry air based on humidity information detected by the humidity detection unit during the regeneration operation.

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

5. The control device includes: Before starting the playback operation, a playback time for executing the playback operation is set; When the playback operation is interrupted, the remaining playback time is stored in a storage unit; When the playback operation is newly started, the remaining time is acquired from the storage unit, and the remaining time is reflected in a playback time of the new playback operation. An air supply system according to any one of claims 1 to 4.

6. The control device includes: When the reproducing operation is completed, the remaining time of the reproducing operation is added to the remaining time of the reproducing operation executed before the reproducing operation to calculate a corrected remaining time, and the corrected remaining time is reflected in the reproducing time of the next reproducing operation.

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, the air drying circuit having a filter that captures moisture, and a control device that controls the air drying circuit, comprising: The control device, controlling the air drying circuit to perform a dehumidification operation in which the compressed air delivered from the compressor is passed forward 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; storing a regeneration result, which is a result of the regeneration operation of the air drying circuit, in a storage unit each time the regeneration operation is completed; acquiring a regeneration result of the air drying circuit stored in the storage unit when starting a new regeneration operation; and reflecting the acquired playback result in the playback conditions of the new playback operation. A method for controlling an air supply system.

8. A control program for an air supply system including an air drying circuit provided between a compressor that delivers compressed air and a storage unit that stores compressed dry air and having a filter that captures moisture, and a control device that controls the air drying circuit, comprising: The control device, a dehumidification operation execution unit that controls the air drying circuit to perform 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; a result storage unit that stores a regeneration result, which is a result of the regeneration operation of the air drying circuit, in a storage unit each time the regeneration operation is completed; an acquisition unit that acquires the regeneration result of the air drying circuit stored in the storage unit when starting a new regeneration operation; and a reflection unit that reflects the acquired playback result in a playback condition of a new playback operation; Air supply system control program.

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