Compressed air supply system for vehicles, control method for a compressed air supply system for vehicles, and control program for a compressed air supply system for vehicles

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 Vehicle compression an air supply system, Vehicle compression a control method for an air supply system, and Vehicle compression a control program for an air supply system.

Background Art

[0002] In vehicles such as trucks, buses, and construction machinery, pneumatic systems including brake systems, suspension systems and the like are controlled using compressed air delivered 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 large amounts of moisture and oil enters the pneumatic system, it may cause rusting, swelling of rubber members, and the like, which may lead to malfunctions. For this reason, a compressed air drying device for removing impurities such as moisture and oil in the compressed air is provided downstream of the compressor.

[0003] The compressed air drying device includes a filter containing a desiccant and various valves. The compressed air drying device performs a dehumidification operation of passing compressed air through the 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. In addition, the cleaning function of the compressed air drying device decreases in accordance with the supply amount of the compressed dry air. For this reason, the compressed air drying device performs a regeneration operation of removing the oil and moisture adsorbed to the filter from the filter, and discharging the removed oil and moisture as drain (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of Invention

Problems to be Solved by the Invention

[0005] For example, the execution conditions, such as the time to perform the regeneration operation and the amount of regenerated air that passes through the filter, are set to be constant or determined according to the amount of compressed air delivered from the compressor. However, the inventors have found that in either case, excesses or deficiencies can occur. If the regeneration time or amount of regenerated air is insufficient, the moisture-capturing capacity of the desiccant may not return to its original level, potentially leading to a higher moisture content in the air delivered from the compressed air dryer. On the other hand, if the regeneration time or amount of regenerated air is excessive, it leads to the wasteful consumption of compressed dry air in the air tank, which is intended to be supplied to the pneumatic system. Since compressed dry air is generated by a compressor driven by a rotational drive source such as an engine, excessive consumption of compressed dry air increases the load on the rotational drive source and reduces the vehicle's fuel efficiency.

[0006] The purpose of this disclosure is, Vehicle compression While maintaining the dehumidifying performance of the air supply system, Vehicle compression The objective is to reduce the consumption of compressed dry air by the air supply system. [Means for solving the problem]

[0007] An air supply system that solves the above problems comprises an air drying circuit provided between a compressor that sends out 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, wherein the control device controls the air drying circuit to perform a dehumidification operation in which the compressed air sent out from the compressor is passed forward through the filter and supplied to the storage unit, and controls the air drying circuit to perform a regeneration operation in which the compressed dry air stored in the storage unit is passed backward through the filter and the fluid that has passed through the filter is discharged from the outlet, and is configured to set the amount of regenerated air to be consumed in one regeneration operation according to the operating state of the compressor.

[0008] A control method for an air supply system that solves the above problems comprises an air drying circuit provided between a compressor that sends out compressed air and a storage unit that stores compressed dry air, and having a filter for capturing 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 is passed forward through the filter and supplied to the storage unit, and controls the air drying circuit to perform a regeneration operation in which the compressed dry air stored in the storage unit is passed backward through the filter and the fluid that has passed through the filter is discharged from the outlet, and sets the amount of regenerated air to be consumed in one regeneration operation according to the operating state of the compressor.

[0009] A control program for an air supply system that solves the above problems comprises an air drying circuit provided between a compressor that sends out compressed air and a storage unit that stores compressed dry air, and having a filter for capturing moisture, and a control device that controls the air drying circuit, wherein the control device functions 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 is passed forward through the filter and supplied to the storage unit, 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 unit is passed backward through the filter and the fluid that has passed through the filter is discharged from the outlet, and a setting unit that sets the amount of regenerated air to be consumed in one regeneration operation according to the operating state of the compressor.

[0010] According to the above configuration, the control device sets the amount of regenerated air consumed in the regeneration operation based on the operating status of the compressor. Since the compressor is driven according to the supply status of compressed dry air to devices other than the air drying circuit, by changing the amount of regenerated 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.

[0011] Regarding 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 is high during a certain period, and to increase the amount of regenerated air when the operating rate of the compressor is low.

[0012] With the above configuration, when the compressor is operating at a high rate and the amount of compressed dry air supplied from the storage unit to devices other than the air drying circuit is large, the amount of regenerated air can be reduced to suppress the consumption of compressed dry air stored in the storage unit and prioritize the supply of compressed dry air to devices other than the air drying circuit. Conversely, when the compressor is operating at a low rate and the amount of compressed dry air supplied from the storage unit to devices other than the air drying circuit is small, filter cleaning can be prioritized.

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

[0014] With the above configuration, when the humidity level of the compressed dry air is high, the amount of regenerated air can be increased to prioritize the cleaning of the filter. Also, when the humidity level is low, the consumption of compressed dry air stored in the storage unit can be suppressed to prioritize the supply of compressed dry air to devices other than the air drying circuit.

[0015] With respect to the above air supply system, the control device may be configured to set a higher upper limit pressure for starting the regeneration operation in the storage section when the operating rate of the compressor is high, set a lower upper limit pressure when the operating rate of the compressor is low, reduce the amount of regenerated air when the upper limit pressure is high, and increase the amount of regenerated air when the upper limit pressure is low.

[0016] According to the above configuration, an upper pressure limit is set to initiate the regeneration operation according to the operating status of the compressor. The amount of regenerated air is also determined according to the upper pressure limit. When the compressor is operating at a high rate, the upper pressure limit is set high and the amount of regenerated air is set low, thereby reducing the frequency of regeneration operations and suppressing the consumption of compressed dry air stored in the storage unit, allowing priority to be given to supplying compressed dry air to devices other than the air drying circuit. Conversely, when the compressor is operating at a low rate, the upper pressure limit is set low and the amount of regenerated air is set high, thereby increasing the frequency of regeneration operations and enhancing the effect of purifying the filter.

[0017] An air supply system that solves the above problems comprises an air drying circuit provided between a compressor that sends out 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, wherein the control device controls the air drying circuit to perform a dehumidification operation in which the compressed air sent out from the compressor is passed forward through the filter and supplied to the storage unit, and controls the air drying circuit to perform a regeneration operation in which the compressed dry air stored in the storage unit is passed backward through the filter and the fluid that has passed through the filter is discharged from the outlet, and is configured to set the amount of regenerated air to be consumed in one regeneration operation according to the temperature of the compressed air or the compressed dry air.

[0018] A control method for an air supply system that solves the above problems comprises an air drying circuit provided between a compressor that sends out compressed air and a storage unit that stores compressed dry air, and having a filter for capturing 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 is passed forward through the filter and supplied to the storage unit, and controls the air drying circuit to perform a regeneration operation in which the compressed dry air stored in the storage unit is passed backward through the filter and the fluid that has passed through the filter is discharged from the outlet, and the amount of regenerated air to be consumed in one regeneration operation is set according to 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 problems comprises an air drying circuit provided between a compressor that sends out compressed air and a storage unit that stores compressed dry air, and having a filter for capturing moisture, and a control device that controls the air drying circuit, wherein the control device functions 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 is passed forward through the filter and supplied to the storage unit, 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 unit is passed backward through the filter and the fluid that has passed through the filter is discharged from the outlet, and a setting unit that sets the amount of regenerated air to be consumed in one regeneration operation according to 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 regenerated 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 compressed dry air rises, the amount of moisture contained in the air also increases. By changing the amount of regenerated 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 regeneration air amount when the temperature is low, and increase the regeneration air amount when the temperature is high.

[0022] According to the above configuration, when the air temperature is low and the saturated water vapor amount is small, the regeneration air amount is reduced, so that the consumption of the compressed dry air stored in the storage section is suppressed, and the supply of the compressed dry air to devices other than the air drying circuit can be prioritized. Further, when the air temperature is high and the saturated water vapor amount is large, the regeneration air amount can be increased to prioritize the cleaning of the filter. Effects of the Invention

[0023] According to the present disclosure, it is possible to reduce the consumption of compressed dry air by the air supply system while maintaining the dehumidification performance of the air supply system. Brief Description of the Drawings

[0024] [Figure 1] A configuration diagram showing the schematic configuration of the first embodiment of the air supply system. [Figure 2] Figures 2A to 2F are diagrams respectively showing the first to sixth operation modes of the air drying circuit of the embodiment of Figure 1. [Figure 3] Figure 3A is a map of the standard regeneration air amount for calculating the regeneration air amount of the embodiment of Figure 1, and Figure 3B is a map of the corrected unit air amount for calculating the regeneration air amount of the embodiment of Figure 1. [Figure 4] A schematic diagram of the excess / deficiency coefficient information of the embodiment of Figure 1. [Figure 5] A flowchart showing an example of the procedure for supplying compressed air in the embodiment of Figure 1. [Figure 6] A flowchart showing an example of the procedure for performing the regeneration operation in the embodiment of Figure 1. [Figure 7] A flowchart showing an example of the procedure for determining the regeneration air amount in the embodiment of Figure 1. [Figure 8]Figure 8A is a map of the standard regenerated air amount for calculating the regenerated air amount in the second embodiment, and Figure 8B is a map of the corrected unit air amount for calculating the regenerated air amount in the second embodiment. [Figure 9] A flowchart showing an example of the procedure for determining the amount of regenerated air in the embodiment shown in Figure 8. [Modes for carrying out the invention]

[0025] (First Embodiment) A first embodiment of the air supply system will be described with reference to Figures 1 to 6. The air supply system is installed in vehicles such as trucks, buses, and construction machinery. The compressed dry air generated by the air supply system is used, for example, in pneumatic systems such as the brake system or suspension system of the vehicle.

[0026] <Air supply system 10> The air supply system 10 will be described with reference to Figure 1. The air supply system 10 comprises 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 wires E61 to E67. The ECU 80 comprises a calculation unit, a communication interface unit, a volatile memory unit, and a non-volatile memory unit. The calculation unit is a computer processor configured to control the air drying circuit 11 according to an air supply program stored in the non-volatile memory unit (storage medium). The calculation unit may implement at least a portion of the processing it performs using a circuit such as an ASIC. The air supply program may be executed by one computer processor or by multiple 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 either a non-volatile memory unit or a volatile memory unit, and may be the same as or different from the storage unit in which the control program is stored.

[0028] ECU80 is connected to other ECUs (not shown) installed in the vehicle, such as the engine ECU and brake ECU, via an in-vehicle network such as CAN (Controller Area Network). ECU80 acquires information indicating the vehicle status from these ECUs. This information includes, for example, ignition switch off information, vehicle speed, and engine drive information.

[0029] The state of compressor 4 is switched between an operating state (load operation) in which it compresses and delivers air, and a non-operating state (dry operation) in which it does not compress air, based on commands from ECU 80. Compressor 4 is operated by power transmitted from a rotational 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 other contaminants from the compressed air sent from the compressor 4 during load operation. The air drying circuit 11 supplies the dried compressed air (hereinafter referred to as 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 pneumatic systems such as the brake system installed in the vehicle. For example, when the brakes are frequently applied, such as when the vehicle is driving downhill or in urban areas, the amount of compressed dry air stored in the air tank 30 consumed increases. Conversely, when the brakes are not frequently applied, the amount of compressed dry air stored in the air tank 30 consumed decreases.

[0032] The air drying circuit 11 has a maintenance port P12. The maintenance port P12 is a port for supplying air to the air drying circuit 11 during maintenance.

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

[0034] The filter 17 dries the compressed air by passing it through a desiccant, thereby removing moisture from the compressed air. The oil capture unit also purifies the compressed air by capturing oil contained in it. The compressed air that has passed through the filter 17 is supplied to the supply circuit 12 via the downstream check valve 19. The downstream check valve 19 allows air to flow only from upstream to downstream, with the filter 17 side as the upstream and the supply circuit 12 side as the downstream. Since the downstream check valve 19 has a predetermined opening pressure (sealing pressure), when compressed air flows, the upstream pressure is higher than the downstream pressure by the opening pressure.

[0035] Furthermore, downstream of the filter 17, a bypass channel 20 is provided in parallel with the downstream check valve 19 as a detour that bypasses the downstream check valve 19. A regeneration control valve 21 is provided in the bypass channel 20.

[0036] The regeneration control valve 21 is a solenoid valve controlled by the ECU 80. The ECU 80 switches the operation of the regeneration control valve 21 by controlling the power supply to the regeneration control valve 21 (driven / de-driven) via the wiring E64. When the power supply to the regeneration control valve 21 is off, it closes to seal the bypass passage 20, and when the power supply is on, it opens to open the bypass passage 20. For example, the ECU 80 receives the value of the air pressure in the air tank 30 and operates the regeneration control valve 21 when the value of the air pressure exceeds a predetermined range.

[0037] An orifice 22 is provided between the regeneration control valve 21 and the filter 17 in the bypass flow path 20. When the regeneration control valve 21 is energized, compressed dry air from the supply circuit 12 is sent to the filter 17 via the bypass flow path 20, with its 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 it. This process is an operation that regenerates the filter 17 and is called the regeneration operation of the air drying circuit 11. At this time, the compressed dry air sent to the filter 17 is the dried and purified air supplied to the supply circuit 12 from the air supply passage 18, passing through the filter 17, etc., so moisture and oil captured by the filter 17 can be removed from the filter 17. In normal control, the ECU 80 opens the regeneration control valve 21 when the pressure in the air tank 30 reaches the upper limit (cutout pressure). On the other hand, when the pressure inside the air tank 30 reaches the lower limit (cut-in pressure), the open regeneration control valve 21 is closed.

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

[0039] The drain, which is a fluid containing water and oil removed from the filter 17, is sent to the drain valve 25 along with compressed air. The drain valve 25 is a pneumatically driven valve, located in the branch passage 16 between the filter 17 and the drain outlet 27. The drain valve 25 is a two-port, two-position valve that changes position between a closed position and an open position. When the drain valve 25 is in the open position, the drain is sent to the drain outlet 27. The drain discharged from the drain outlet 27 may be recovered 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 valve 25 is controlled by a governor 26A. The governor 26A is a solenoid valve controlled by an ECU 80. The ECU 80 switches the operation of the governor 26A by controlling the power supply to the governor 26A (driven / de-driven) via wiring E63. When power is turned on, the governor 26A switches to the input position, which inputs an air pressure signal to the drain valve 25, thereby opening the drain valve 25. When power is turned off, the governor 26A switches to the open position, which opens the port of the drain valve 25 to atmospheric pressure without inputting an air pressure signal to the drain valve 25, thereby closing the drain valve 25.

[0041] When no air pressure signal is received from the governor 26A, the drain valve 25 is maintained in a closed position that blocks the branch passage 16. When an air pressure signal is received from the governor 26A, it switches to an open position that opens the branch passage 16. In addition, if the pressure at the input port connected to the compressor 4 exceeds the upper limit, the drain valve 25 is forcibly switched to an 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. The upstream check valve 15 allows air to flow only from upstream to downstream, when the compressor 4 side is considered upstream and the filter 17 side is considered downstream. Since the upstream check valve 15 has a predetermined opening pressure (sealing pressure), when compressed air flows, the upstream pressure is higher than the downstream pressure by the opening pressure. A reed valve for the outlet of the compressor 4 is provided upstream of the upstream check valve 15. The branch passage 16 and the filter 17 are provided downstream of the upstream check valve 15.

[0043] The compressor 4 is controlled by an unload control valve 26B. The unload control valve 26B is a solenoid valve controlled by an ECU 80. The ECU 80 switches the operation of the unload control valve 26B by controlling the power supply to the unload control valve 26B (driven / de-driven) via wiring E62. When the power to the unload control valve 26B is turned off, it switches to the open position, opening the passage between the unload control valve 26B and the compressor 4 to the atmosphere. When the power to the unload control valve 26B is turned on, it switches to the supply position, sending a pneumatic signal consisting of compressed air to the compressor 4.

[0044] The state of compressor 4 switches to a non-operating state (dry running) when an air pressure signal is input from the unload control valve 26B. For example, when the pressure in the air tank 30 reaches the cutout pressure, the supply of compressed dry air is not required. When the pressure on the supply circuit 12 side reaches the cutout pressure and the ECU 80 turns on the power to the unload control valve 26B (drives the unload control valve 26B), the unload control valve 26B switches to the supply position. As a result, an air pressure signal is supplied from the unload control valve 26B to compressor 4, and the state of compressor 4 switches 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 measured result to the ECU 80 via 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 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 measured results to the ECU 80 via wiring E65 and E66. The ECU 80 determines the humid 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 configured to detect the air pressure in the air tank 30 and outputs the detected pressure value to the ECU 80 via wiring 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. Note that the pressure sensor 53 may be provided in the supply circuit 12 or in the air tank 30.

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

[0049] (First operating mode) As shown in Figure 2A, the first operating mode is the mode for normal dehumidification operation (load operation). In the first operating mode, the regeneration control valve 21 and the unload control valve 26B are closed (indicated as "CLOSE" in the figure), and the governor 26A is set to an open position that does not input an air pressure signal to the compressor 4 (indicated as "CLOSE" in the figure). At this time, power is not supplied to the regeneration control valve 21, the governor 26A, and the unload control valve 26B. In addition, the governor 26A and the unload control valve 26B open the ports of the compressor 4 and the drain discharge valve 25 connected downstream to the atmosphere, respectively. In the first operating mode, when compressed air is supplied from the compressor 4 (indicated as "ON" in the figure), moisture and other substances are removed by the filter 17, and compressed air is supplied to the supply circuit 12.

[0050] (Second operating mode) As shown in Figure 2B, the second operating mode is a purging mode in which compressed dry air in the air drying circuit 11 is passed through the filter 17 to purify the filter 17. In the second mode, the regeneration control valve 21 is closed, 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 input position (indicated as "OPEN" in the figure). At this time, power is supplied to the governor 26A and the unload control valve 26B, and the ports of the compressor 4 and the drain discharge valve 25 connected downstream of them are connected to the upstream side (supply circuit 12 side). 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 through the filter 17 in the opposite direction to the airflow in the first operating mode (dehumidification mode), and the moisture captured by the filter 17 is discharged as condensate from the drain outlet 27. In addition, the air pressure in the filter 17 and the air supply passage 18 is released to atmospheric pressure.

[0051] (Third operating mode) As shown in Figure 2C, the third operating mode is a mode that performs a regeneration operation to regenerate the filter 17. In the third operating mode, the regeneration control valve 21 is opened, the governor 26A is set to the input position, and the unload control valve 26B is set to the supply position (each indicated as "OPEN" in the figure). At this time, power is supplied to the governor 26A and the unload control valve 26B, as well as the regeneration control valve 21. In the third operating mode, the compressor 4 is kept in a non-operating state, and compressed dry air stored in the supply circuit 12 or air tank 30 is backflowed into the filter 17 and discharged from the drain outlet 27. This removes moisture and other substances captured by the filter 17. Both the second and third operating modes are modes that purify the filter 17, but the third operating mode differs from the second operating mode in that it opens the regeneration control valve 21. As a result, in the third operating mode, compressed dry air in the air tank 30 can be passed through the filter 17 via the supply circuit 12 and the bypass passage 20. Therefore, the effect of purifying the filter 17 is higher than in the second operating mode. In addition, even in the third operating mode, the air pressure in the filter 17 and the air supply passage 18 is released to atmospheric pressure.

[0052] (Fourth operating mode) As shown in Figure 2D, the fourth operating mode is a mode in which an oil cut operation is performed. In the fourth operating mode, while the compressor 4 is running, the oily air sent from the compressor 4 is discharged from the drain outlet 27 without passing through the filter 17. When the compressor 4 is not running, oil may accumulate in the compression chamber of the compressor 4. If the compressor 4 is switched to the operating state while oil has accumulated in the compression chamber, the amount of oil contained in the compressed air sent from the compression chamber will increase. If the oil adheres to the desiccant, the dehumidifying performance of the desiccant will decrease. Therefore, an oil cut operation is performed to discharge the oily compressed air. In the fourth operating 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 being driven for a certain period of time (indicated as "CLOSE" in the figure). As a result, even if compressed air containing a relatively large amount of oil is sent from the compressor 4, that compressed air can be discharged from the drain outlet 27 without passing through the filter 17. Therefore, it is possible to suppress the 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 the operating state, or when the engine is under high load, the amount of oil from the compressor 4 increases, an oil cut operation can also be performed.

[0053] (5th operating mode) As shown in Figure 2E, the fifth operating mode is a mode in which the compressor is stopped without purging. In the fifth operating 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 operating mode, when the compressor 4 is not operating, the air pressure is maintained by not discharging the compressed air or compressed dry air remaining in the desiccant in the air supply passage 18 or filter 17 from the drain outlet 27.

[0054] (6th operating mode) As shown in Figure 2F, the sixth operating mode is a mode that performs assist operations for pressurization. In the sixth operating 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 operating mode, when the compressor 4 is not operating, compressed air from the supply circuit 12 is supplied (backflowed) into the desiccant in the air supply passage 18 and the filter 17, thereby raising the pressure in the air supply passage 18 and the filter 17 to above atmospheric pressure and maintaining the back pressure (air pressure) of the upstream check valve 15 at a pressure higher than atmospheric pressure.

[0055] (Setting execution conditions) Next, with reference to Figure 3, the method for determining the amount of air consumed during the regeneration operation (third operating mode) (hereinafter referred to as the regeneration air amount) will be explained. The ECU80 calculates the regeneration air amount Am according to the following equation (1) by executing the control program. The regeneration air amount Am may be calculated in volume units or mass units. Various coefficients for unit conversion may also be used on the right-hand side (or left-hand side) of equation (1).

[0056] Recycled air volume Am = Standard regenerated air volume Am1 - Corrected unit air volume Am2 × Excess / deficiency coefficient α…(1) The "standard regenerated air amount Am1" is set to be greater than the "corrected unit air amount Am2 × excess / deficit coefficient α", so that the regenerated air amount Am exceeds "0". The standard regenerated air amount Am1 is basically the amount of air determined by the specifications of the air drying circuit 11, but it is changed according to the cutout pressure, which is the upper limit of the pressure in the air tank 30. As mentioned above, the cutout pressure is the pressure that triggers the start of regeneration and purging operations, and the higher the operating rate of the compressor 4, the higher the value set and stored in the memory unit 80A. For example, if the operating rate is less than a predetermined value R1 (e.g., 30%), a relatively low cutout pressure Po1 is set, and if the operating rate is between a predetermined value R1 and a predetermined value R2 (e.g., 60%), a cutout pressure Po2 higher than the cutout pressure Po1 is set (Po2>Po1). Furthermore, if the operating rate is above a 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 operating rate of the compressor 4, but it may also be set in two stages, or in four or more stages. Alternatively, the cutout pressure may be continuously changed according to the operating rate of the compressor 4.

[0057] The reason for increasing the cutout pressure Po as the operating rate of compressor 4 increases is explained below. Since compressor 4 is driven according to the amount of compressed dry air in the air tank 30, when its operating rate is low, it is presumed that the consumption of compressed dry air by pneumatic systems 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 regeneration operations is relatively increased, and the filter 17 is actively cleaned. On the other hand, when the operating rate of compressor 4 is high, it is presumed that the consumption of compressed dry air by pneumatic systems 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 regeneration operations is relatively decreased, and the supply of compressed dry air to the pneumatic systems is prioritized.

[0058] Figure 3A is a map 100 in which the standard regenerated air volume Am1 is set according to the limit airflow rate and cutout pressure. This map 100 is stored in the memory unit 80A. The horizontal axis of map 100 is the limit airflow rate, and the vertical axis is the standard regenerated air volume Am1. In the figure, the unit is volume (liters), but the unit may also be mass. The limit airflow rate is a value that indicates the limit of the amount of air that passes through the air drying circuit 11, and is a quantity determined according to the specifications of the air drying circuit 11 (air dryer). The standard regenerated air volume Am1 decreases as the limit airflow rate increases and increases as the limit airflow rate decreases. Also, when the limit airflow rate is kept constant, the standard regenerated air volume Am1 decreases as the cutout pressure increases and increases as the cutout pressure decreases. In other words, since the cutout pressure is set to a higher value as the operating rate of the compressor 4 increases, it can be said that the standard regenerated air volume Am1 decreases as the operating rate of the compressor 4 increases. As described above, when the operating rate of compressor 4 is high, it is presumed that the consumption of compressed dry air by pneumatic systems such as the brake system is relatively high. For this reason, when the operating rate of compressor 4 is high, the standard regeneration air amount Am1 is reduced to prioritize supplying compressed dry air to the pneumatic system. Also, the standard regeneration air amount Am1 increases as the operating rate of compressor 4 decreases. When the operating rate is low, it is presumed that the consumption of compressed dry air by pneumatic systems such as the brake system is relatively low. For this reason, when the operating rate of compressor 4 is low, the standard regeneration air amount Am1 is increased to enhance the cleaning effect of filter 17 per regeneration operation.

[0059] Figure 3B is map 101, which shows the relationship between the corrected unit air rate Am2 and the critical airflow rate according to the cutout pressure. This map 101 is stored in the memory unit 80A. The horizontal axis represents the critical airflow rate, and the vertical axis represents the corrected unit air rate Am2. In the figure, the unit is volume (liters), but the unit may also be mass. Similar to the standard regenerated air rate Am1, the corrected unit air rate Am2 decreases as the critical airflow rate increases. However, when the critical airflow rate is kept constant, it increases as the cutout pressure increases and decreases as the cutout pressure decreases.

[0060] The excess / deficit coefficient α (regeneration excess / deficit coefficient) is a coefficient multiplied by the corrected unit air amount Am2, and is set to a negative value, a positive value, or "0". This excess / deficit coefficient α is set based on the trend of the humidity state of the compressed dry air stored in the air tank 30. The excess or 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 compressed air changes 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 and the amount of air that has passed through the filter 17. Furthermore, it is also difficult to directly measure the amount of moisture captured by the filter 17. As in this embodiment, by determining the excess or deficiency of the regeneration operation based on the humidity state of the compressed dry air in the storage section, the excess or deficiency of the regeneration operation can be appropriately determined, albeit indirectly.

[0061] The trend in humidity, which forms the basis of the excess / deficit coefficient α, is determined based on the period from the previous regeneration operation to the time before the next regeneration operation. While there are no limitations on the indicators used to determine humidity, in this embodiment, the degree of saturation of the moisture content in the compressed dry air within the air tank 30 (hereinafter referred to as "moisture content") is calculated, and the saturation of the current moisture content is subtracted from the saturation of the moisture content at the end of the previous regeneration operation. If the saturation of the moisture content is higher at the end of the current regeneration operation than at the end of the previous regeneration operation, i.e., if the humidity of the compressed dry air is tending to increase, it is determined that the amount of moisture captured by the filter 17 is increasing. Therefore, in equation (1) above, the excess / deficit coefficient α is set to a negative value less than "0". When the excess / deficit coefficient α is a negative value, the amount of regenerated air is corrected to be greater than the standard amount of regenerated air.

[0062] On the other hand, if the saturation level of the moisture content is lower at the end of the current regeneration process than at the end of the previous regeneration process, that is, if the humidity level of the compressed dry air tends to decrease, it is determined that the amount of moisture captured by the filter 17 is decreasing. For this reason, the excess / deficit coefficient α is set to a positive value greater than "0", and the amount of regenerated air is corrected to be smaller than the standard amount of regenerated air. Also, if it is determined that the humidity level of the compressed dry air is in a suitable state, the excess / deficit coefficient is set to "0", and the amount of regenerated air Am is not corrected from the standard amount of regenerated air Am1.

[0063] Figure 4 shows an example of the excess / deficiency coefficient α, which is excess / deficiency coefficient information 200. The excess / deficiency coefficient information 200 is stored in the memory unit 80A. The excess / deficiency coefficient information 200 includes the excess / deficiency condition 200A and the excess / deficiency coefficient 200C. The state 200B is a convenient representation of the state indicated by the excess / deficiency condition 200A and is optional. The excess / deficiency condition 200A has a range set for the regeneration excess / deficiency degree. The regeneration excess / deficiency degree is an index that indicates whether the saturation level of moisture contained in the compressed dry air in the air tank 30 is increasing or decreasing.

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

[0065] In the surplus / deficit coefficient information 200, if the amount of recycled air is significantly insufficient, i.e., if the moisture content is high, the recycling surplus / deficit degree is, for example, "-1" or less, is a negative value, and has a large absolute value. In this case, the weighting coefficient is also set to a relatively large value, such as "2". Furthermore, if the amount of recycled air is insufficient, even if it is not "significantly insufficient", the recycling surplus / deficit degree is, for example, in the range greater than "-1" and less than "-0.5", and has a smaller absolute value than "significantly insufficient". The weighting coefficient is also set to a smaller value than "significantly insufficient", such as "1".

[0066] Furthermore, if the amount of recycled air is significantly excessive, that is, if the moisture content is low, the recycling surplus / deficit degree is, for example, "1" or higher, is a positive value, and has a large absolute value. In this case, a relatively large value such as "2" is set for the weighting coefficient. Also, if the amount of recycled air is excessive, even if not "significantly excessive," the recycling surplus / deficit degree is, for example, "0.5" or higher, which is less than "1," and has a smaller absolute value than "significantly excessive." In addition, the value of the weighting coefficient is set to a smaller value such as "1" than "significantly insufficient."

[0067] If the degree of over- or under-reproduction is in the range of, for example, "-0.5" or more and less than "0.5", the over- or under-reproduction coefficient is set to "0". The amount of regenerated air Am calculated using these standard regenerated air amounts, corrected unit air amounts, and excess / deficit coefficients will be explained separately for cases where the operating rate of the compressor 4 is low and high, and for cases where the humidity level inside the air tank 30 is low and high. It is assumed that the limit airflow rate is constant.

[0068] (A) Compressor 4 operating rate: low, Humidity level inside air tank 30: high When the operating rate of compressor 4 is low, the cutout pressure is set low. This increases the frequency of regeneration and purging operations. Also, the standard regeneration air volume Am1 increases when the cutout pressure is set low.

[0069] Furthermore, the corrected unit air volume Am2 decreases as the cutout pressure is set lower. Also, the excess / deficit coefficient α becomes a negative value because the humidity inside the air tank 30 is high, resulting in a "severely insufficient" or "insufficient" state. Therefore, a positive correction value is added to the standard regenerated air volume, and the regenerated air volume Am increases. Note that the regenerated air volume Am is larger in the "severely insufficient" state than in the "insufficient" state.

[0070] (B) Operating rate of compressor 4: Low, Humidity level inside air tank 30: Low The standard regenerated air volume Am1 and the corrected unit air volume Am2 are the same as in state (A) described above. On the other hand, the excess / deficit coefficient α becomes a positive value because the humidity level inside the air tank 30 is low, resulting in a state of "significant excess" or "excess." Therefore, the correction value is subtracted from the standard regenerated air volume, and the regenerated air volume Am becomes smaller than the regenerated air volume Am in state (A).

[0071] (C) Compressor 4 operating rate: High, Humidity level inside air tank 30: High When compressor 4 is operating at a high rate, the cutout pressure is set higher. This reduces the frequency of regeneration and purging operations. Additionally, the standard regeneration air volume Am1 is reduced due to the higher cutout pressure.

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

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

[0074] (Control of the air drying circuit 11) Next, with reference to Figures 5 to 7, the procedure by which the ECU 80 controls the air drying circuit 11 will be described.

[0075] Referring to Figure 5, the overall control procedure will be described. The ECU 80 performs an air supply process (step S1) in which it supplies compressed air output from the compressor 4 to the supply circuit 12. The air supply process is started under predetermined conditions, such as when the engine is driven. Alternatively, the air supply process may be started when the pressure in the air tank 30 reaches a predetermined pressure, such as the cut-in pressure which is the lower limit. During the air supply process, the air drying circuit 11 is in the first operating mode and performs a dehumidification operation.

[0076] When the air supply process begins, the ECU 80 determines whether or not to stop the air supply (step S2). More specifically, the ECU 80 obtains 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 terminates the air supply process, deactivates the compressor 4, and executes the purification process (step S3). In the purification process, the ECU 80 determines whether a regeneration operation and a purge operation are necessary according to preset conditions. If it determines that a regeneration operation is necessary, it executes the regeneration operation; if it determines that a purge operation is necessary, it executes the purge operation.

[0078] Once the purification process (step S3) is complete, the ECU 80 performs an air de-supply process (step S4). In the air de-supply process, when the compressor 4 is not operating, 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 de-supply process, the ECU 80 adjusts the air pressure in the air drying circuit 11 by executing at least one of the second, fifth, and sixth operating modes one or more times. Once the pressure adjustment is complete, the ECU 80 determines whether or not to terminate the air supply based on the vehicle status (step S5). The termination of the air supply is determined based on the vehicle status, such as the vehicle's engine being stopped.

[0079] If it is determined that the air supply should not be terminated (Step S5: NO), the ECU 80 returns to Step S1 and executes the processes following the air supply process (Step S1). On the other hand, if it is determined that the air supply should be terminated (Step S5: YES), the air supply is stopped.

[0080] Next, with reference to Figure 6, the procedure for controlling the regeneration operation will be explained. The ECU 80 determines whether or not a regeneration operation is necessary according to predetermined conditions (step S100). At this time, the ECU 80 determines whether or not a regeneration operation is necessary based on the humidity 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 (tank moisture content), and determines that a regeneration operation is necessary if the tank moisture content is above a predetermined value, and determines that a regeneration operation is unnecessary if the tank moisture content is below a predetermined value.

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

[0082] Next, with reference to Figure 7, the process for determining the amount of regenerated air will be explained. 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 amount of regenerated air is updated at a predetermined timing within one cycle. The timing of updating the amount of regenerated air is not particularly limited. For example, the amount of regenerated air 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 predetermined intervals, such as a period shorter than the average time of one cycle.

[0083] The ECU80 determines whether or not to update the amount of regenerated air (step S110). For example, the ECU80 determines whether or not a predetermined timing for a new cycle has been reached. If the ECU80 determines that the predetermined timing has not been reached (step S110: NO), it terminates the process.

[0084] When the ECU 80 determines that the amount of regenerated air should be updated (step S110: YES), it calculates the degree of regeneration surplus or deficit (step S111). The degree of regeneration surplus or deficit may be calculated based on the change in the moisture saturation of the tank air, as described above. The moisture saturation of the tank air can be calculated from the humidity detected by the humidity sensor 51, the temperature detected by the temperature sensor 52, etc.

[0085] When ECU80 calculates the regeneration surplus / deficit degree, it obtains the surplus / deficit coefficient using the surplus / deficit coefficient information 200 (step S112). Furthermore, ECU80 obtains the cutout pressure, which is the starting pressure for the regeneration operation (step S113). Based on the obtained cutout pressure, ECU80 obtains the standard regeneration air amount using map 100 (step S114) and the corrected unit air amount using map 101 (step S115). Then, ECU80 calculates the regeneration air amount according to equation (1) above using the standard regeneration air amount, the corrected unit air amount, and the surplus / deficit coefficient (step S116). The regeneration air amount calculated here is used in step S101 in Figure 6. ECU80 performs the regeneration operation using the regeneration air amount calculated here.

[0086] As described above, the first embodiment provides the following effects. (1) The ECU 80 sets the amount of regenerated air consumed in the regeneration operation based on the operating status of the compressor 4. Since the compressor 4 is driven according to the supply status of compressed dry air to pneumatic systems other than the air drying circuit 11, by changing the amount of regenerated air, it is possible to prioritize 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 amount of compressed dry air supplied from the air tank 30 to the pneumatic system is large, the amount of regenerated air can be reduced to suppress the consumption of 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 amount of compressed dry air supplied from the air tank 30 to the pneumatic system is small, priority can be given to cleaning the filter 17.

[0088] (3) When the humidity level of the compressed dry air in the air tank 30 is high, the cleaning of the filter 17 can be prioritized by increasing the amount of regenerated air. Also, when the humidity level of the compressed dry air is low, the supply of compressed dry air to the pneumatic system can be prioritized by suppressing the consumption of the compressed dry air stored in the air tank 30.

[0089] (4) A cutout pressure, which is the upper limit pressure for starting the regeneration operation, is set according to the operating status of the compressor 4, and the amount of regenerated 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 regenerated air is set low, so that the frequency of performing the regeneration operation is reduced and the consumption of compressed dry air stored in the air tank 30 is suppressed, and the supply of compressed dry air to the pneumatic system can be prioritized. Also, when the operating rate of the compressor 4 is low, the cutout pressure is set low and the amount of regenerated air is set high, so that the frequency of performing the regeneration operation is increased and the effect of purifying the filter 17 can be enhanced.

[0090] (Second Embodiment) The second embodiment will be described with reference to Figures 8 and 9. The second embodiment is similar to the first embodiment in that it calculates the amount of regenerated air by changing the standard regenerated air amount and the corrected unit air amount according to the state of the air drying circuit 11. In addition, while the standard regenerated air amount and the corrected unit air amount were changed according to the cutout pressure in the first embodiment, the second embodiment differs from the first embodiment in that the standard regenerated air amount and the corrected unit air amount are changed according to the temperature of the compressed dry air. Therefore, in the following, we will mainly describe in detail the configurations that differ from the first embodiment, and for the sake of convenience, we will omit detailed explanations of similar configurations.

[0091] Figure 8A shows map 110, which is stored in the storage unit 80A, and sets the standard regenerated air amount Am1 according to the limit airflow rate and temperature. Map 110 differs from map 100 (see Figure 3) of the first embodiment in that it determines the standard regenerated air amount according to the temperature, whereas map 100 determines the standard regenerated air amount according to the cutout pressure. The temperature can be a value detected by the temperature sensor 52. Alternatively, a temperature sensor may be installed on the inlet side of the air drying circuit 11 and upstream of the filter 17, and the temperature detected by that temperature sensor may be used. The standard regenerated air amount Am1 decreases as the temperature decreases and increases as the temperature increases, when the limit airflow rate is kept constant. In other words, when the temperature is high, the saturated water vapor amount (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 regenerated air amount Am1 is increased to enhance the effect of removing moisture from the filter 17 in a single regeneration operation. Furthermore, at lower temperatures, the amount of saturated water vapor (saturated water vapor pressure) in the air decreases, which tends to reduce the amount of moisture contained in the compressed air. Therefore, it is expected that the amount of moisture captured by the filter 17 will also decrease, and by reducing the standard regeneration air amount Am1, the amount of compressed dry air consumed in one regeneration operation is reduced.

[0092] Figure 8B shows map 111, in which the corrected unit air rate Am2 is set according to the limit airflow rate and temperature, and is stored in the memory unit 80A. Since the corrected unit air rate Am2 is a value subtracted from the standard regenerated air rate Am1, it decreases as the limit airflow rate increases, similar to the standard regenerated air rate Am1. However, when the limit airflow rate is kept constant, it decreases as the temperature increases and increases as the temperature decreases.

[0093] Next, with reference to Figure 9, the process for determining the amount of regenerated air will be described. The process for determining the amount of regenerated air in the second embodiment is the same as steps S110 to S112 and steps S114 to S116 of the process in the first embodiment, so a detailed explanation 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 the standard regenerated air amount using the acquired temperature and map 110 (step S114). Furthermore, the ECU 80 acquires the corrected unit air amount using the acquired temperature and map 111 (step S115). Then, the ECU 80 calculates the regenerated air amount using the standard regenerated air amount, the corrected unit air amount, and the excess / deficit coefficient (step S116).

[0095] In the second embodiment, the following effects can be obtained. (5) The ECU 80 sets the amount of regenerated 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 rises, the amount of moisture contained in the air also increases. By changing the amount of regenerated 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 air tank 30 to the pneumatic system or the cleaning of the filter 17.

[0096] (6) When the air temperature is low and the saturated water vapor content is low, the amount of regenerated air can be reduced to suppress the consumption of compressed dry air stored in the air tank 30 and prioritize the supply of compressed dry air to the pneumatic system. Conversely, when the air temperature is high and the saturated water vapor content is high, the amount of regenerated air can be increased to prioritize the cleaning of the filter 17.

[0097] Each of the above embodiments can be implemented with the following modifications. Each of the above embodiments and the following modifications can be combined with each other to the extent that they do not contradict each other technically. In the first embodiment, the amount of regeneration air was determined according to the degree of regeneration excess or deficiency, but the regeneration time may also be determined according to the degree of regeneration excess or deficiency. In this case, the corrected regeneration time is calculated by multiplying the correction unit time by the excess or deficiency coefficient, and the corrected regeneration time is added to the standard regeneration time.

[0098] In the first embodiment, the excess / deficit coefficient α was calculated by multiplying the regeneration excess / deficit degree by a weighting coefficient, but the regeneration excess / deficit degree itself may also be used as the excess / deficit coefficient α. In this case as well, the amount of regenerated air can be increased or decreased according to the excess / deficit of regeneration.

[0099] In the first embodiment, the degree of regeneration excess or deficiency was defined as an indicator showing whether the saturation level of moisture contained in the compressed dry air in the air tank 30 is increasing or decreasing. However, humidity may be used as an indicator instead of the degree of regeneration excess or deficiency. Alternatively, the amount of moisture contained in the tank may be used as an indicator instead of the degree of regeneration excess or deficiency.

[0100] • In the first embodiment, the degree of regeneration excess or deficiency may be determined by using the average value over several cycles. If the average value is negative, it is estimated that the amount of moisture in the air tank 30 is increasing, and therefore it is determined that the amount of regenerated air is insufficient.

[0101] In the first embodiment, the cutout pressure was set according to the operating rate of the compressor 4, and the standard regenerated air amount and the corrected unit air amount constituting the regenerated air amount were set according to the cutout pressure. In addition to this embodiment, the standard regenerated air amount and the corrected unit air amount may be set using a map or the like that associates the operating rate of the compressor 4 with the standard regenerated air amount and the corrected unit air amount.

[0102] In the second embodiment, the standard regenerated air volume and the corrected unit air volume were set according to the temperature. In addition to this embodiment, the standard regenerated air volume and the corrected unit air volume may also be set using humidity in addition to temperature. Alternatively, the standard regenerated air volume and the corrected unit air volume may be set using only the humidity detected by the humidity sensor 51, etc.

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

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

[0105] In the above embodiments, the amount of regenerated air was calculated by correcting the standard amount of regenerated air with a correction amount obtained by multiplying the corrected unit amount of air by an excess / deficiency coefficient. However, the amount of regenerated air may also be calculated directly from a map or the like. In this case, the map may associate the cutout pressure (or temperature), an index indicating the humidity state of the compressed dry air, and the amount of regenerated air.

[0106] In each of the above embodiments, the filter 17 includes an oil-capturing section, but the oil-capturing section may be omitted from the filter 17. The air drying circuit is not limited to the configuration described above. Essentially, any air drying circuit that can perform both dehumidification and regeneration operations is acceptable. Therefore, the air drying circuit does not necessarily require the second operating mode, fourth operating modes to sixth operating modes to function.

[0107] In the embodiments described above, the air supply system 10 was described as being mounted on a vehicle such as a truck, bus, or construction machinery. In other embodiments, the air supply system 10 may be mounted on other mobile vehicles such as passenger cars or railway vehicles.

[0108] The ECU80 is not limited to performing software processing for all of the processes it executes. For example, the ECU80 may have dedicated hardware circuits (e.g., application-specific integrated circuits: ASICs) that perform hardware processing for at least some of the processes it executes. In other words, the ECU80 can 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 perform at least some 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 processes. Memory, or computer-readable media, includes any available media 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 passage, 21...Regeneration control valve, 22...Orifice, 25...Drain discharge valve, 26A...Governor, 26B...Unload control valve, 27...Drain discharge port as outlet, 30...Air tank as storage unit, 50...Pressure sensor, 51...Humidity sensor, 52...Temperature sensor, 53...Pressure sensor, 80...ECU, 80A...Memory unit, E61~E67...Wiring.

Claims

1. An air drying circuit is provided between a compressor that delivers compressed air and a storage unit that stores compressed dry air, and has a filter that captures moisture. The system includes a control device for controlling the air drying circuit, The control device is The air drying circuit is controlled to perform a dehumidification operation in which the compressed air discharged from the compressor is passed forward through the filter and supplied to the storage unit. The air drying circuit is controlled to perform a regeneration operation in which the compressed dry air stored in the storage section is passed through the filter in the reverse direction, and the fluid that has passed through the filter is discharged from the outlet. When the operating rate of the compressor is high, the cutout pressure, which is the pressure in the storage section and is the upper limit pressure for starting the regeneration operation, is set high, and when the operating rate of the compressor is low, the cutout pressure is set low. The system is configured to set the amount of regenerated air consumed in a single regeneration operation to be small in response to a high cutout pressure, and to set the amount of regenerated air to be large in response to a low cutout pressure. Compressed air supply system for vehicles.

2. The control device is The system is configured to increase the amount of regenerated air when the indicator of the humidity state of the compressed dry air in the storage section is high, and to decrease the amount of regenerated air when the indicator of the humidity state of the compressed dry air in the storage section is low. The vehicle compressed air supply system according to claim 1.

3. A control method for a vehicle compressed air supply system comprising an air drying circuit, which is provided between a compressor for supplying compressed air and a storage unit for storing compressed dry air, and which has a filter for capturing moisture, and a control device for controlling the air drying circuit, The control device, The air drying circuit is controlled to perform a dehumidification operation in which the compressed air discharged from the compressor is passed forward through the filter and supplied to the storage unit. The air drying circuit is controlled to perform a regeneration operation in which the compressed dry air stored in the storage section is passed through the filter in the reverse direction, and the fluid that has passed through the filter is discharged from the outlet. When the operating rate of the compressor is high, the cutout pressure, which is the pressure in the storage section and is the upper limit pressure for starting the regeneration operation, is set high, and when the operating rate of the compressor is low, the cutout pressure is set low. Depending on the high cutout pressure, the amount of regenerated air consumed in one regeneration operation is set to be small, and depending on the low cutout pressure, the amount of regenerated air is set to be large. A control method for a compressed air supply system for vehicles.

4. A control program for a vehicle compressed air supply system comprising an air drying circuit, which is provided between a compressor for supplying compressed air and a storage unit for storing compressed dry air, and which has a filter for capturing moisture, and a control device for controlling the air drying circuit, The control device described above, A dehumidification operation execution unit controls the air drying circuit to perform a dehumidification operation in which the compressed air discharged from the compressor is passed forward through the filter and supplied to the storage unit. A regeneration operation execution unit controls the air drying circuit to perform a regeneration operation in which the compressed dry air stored in the storage unit is passed through the filter in the reverse direction and the fluid that has passed through the filter is discharged from the outlet, and When the operating rate of the compressor is high, the cutout pressure, which is the pressure in the storage section and the upper limit pressure for starting the regeneration operation, is set high; when the operating rate of the compressor is low, the cutout pressure is set low; the amount of regenerated air consumed in one regeneration operation is set to be small according to the high cutout pressure; and the amount of regenerated air is set to be large according to the low cutout pressure. Control program for a vehicle compressed air supply system.

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