CN113710552B

CN113710552B - Air supply system, control method of air supply system, and control program of air supply system

Info

Publication number: CN113710552B
Application number: CN202080030113.XA
Authority: CN
Inventors: 杉尾卓也; 除田和也
Original assignee: Nabtesco Automotive Corp
Current assignee: Nabtesco Automotive Corp
Priority date: 2019-02-25
Filing date: 2020-02-25
Publication date: 2024-08-23
Anticipated expiration: 2040-02-25
Also published as: JP2024177424A; WO2020175470A1; JP7568610B2; CN113710552A; CN119078773A; JPWO2020175470A1

Abstract

Maintaining good dehumidification performance and reducing the consumption of compressed dry air. An air supply system (10) comprises: an air drying circuit (11) which is arranged between a compressor (4) that sends out compressed air and an air tank (30) that stores the compressed dry air and has a filter (17) that captures moisture; and an ECU (80) that controls the air drying circuit (11). The ECU (80) controls the air drying circuit (11) to perform a dehumidification action, wherein the compressed air sent out from the compressor (4) passes through the filter (17) in the forward direction and is supplied to the air tank (30). The ECU (80) controls the air drying circuit (11) to perform a regeneration action, wherein the compressed dry air stored in the air tank (30) passes through the filter (17) in the reverse direction and discharges the fluid that has passed through the filter from the liquid discharge port (27). The ECU (80) sets the amount of regeneration air consumed in the regeneration action according to the operating state of the compressor (4).

Description

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

Technical Field

The present disclosure relates to an air supply system, a control method of the air supply system, and a control program of the air supply system.

Background

In vehicles such as trucks, buses, and construction machines, compressed air sent from a compressor is used to control an air pressure system including a brake system and a suspension system. The compressed air contains moisture contained in the atmosphere and liquid impurities such as oil for lubricating the inside of the compressor. If compressed air containing a large amount of water and oil enters the air pressure system, rust may occur, swelling of the rubber member may occur, and the like, which may cause a malfunction. Therefore, a compressed air drying device for removing impurities such as moisture and oil in the compressed air is provided downstream of the compressor.

The compressed air drying device is provided with various valves and a filter containing a desiccant. The compressed air drying device performs a dehumidifying operation of passing compressed air through a filter to remove moisture and the like from the compressed air. Compressed dry air generated by the dehumidification operation is stored in the air tank. In addition, the purification function of the compressed air drying device is lowered according to the supply amount of the compressed air. Therefore, the compressed air drying device performs the following regenerating operation: the oil and water adsorbed to the filter are removed from the filter, and the removed oil and water are discharged as a drain (for example, refer to patent document 1).

Prior art literature

Patent literature

Patent document 1: japanese patent application laid-open No. 2010-201323

Disclosure of Invention

Problems to be solved by the invention

For example, the execution conditions such as the time for executing the regeneration operation, the amount of regenerated air passing through the filter, and the like are set to be constant or determined based on the amount of compressed air sent from the compressor, and the like. However, the inventors have clarified that in any case, an excess shortage is generated. If the regeneration time and the regeneration air amount are insufficient, the moisture capturing ability of the desiccant cannot be restored to the original levels, and there is a possibility that the amount of moisture contained in the air sent from the compressed air drying device increases. On the other hand, when the regeneration time and the regeneration air amount are excessive, the compressed dry air in the air tank that is originally supplied to the air pressure system is consumed wastefully. Since the compressed dry air is generated by a compressor driven by a rotary drive source such as an engine, excessive consumption of the compressed dry air increases the load of the rotary drive source, and thus reduces the fuel consumption rate of the vehicle.

The present disclosure is directed to maintaining dehumidifying performance of an air supply system and reducing consumption of compressed dry air of the air supply system.

Solution for solving the problem

An air supply system for solving the above problems, comprising: an air drying circuit provided between a compressor that sends out compressed air and a storage unit 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, wherein the control device is configured to: the air drying circuit is controlled to perform a dehumidifying operation of supplying the compressed air sent from the compressor to the storage unit through the filter in the forward direction, and a regenerating operation of discharging the fluid having passed through the filter from the discharge port by passing the compressed dry air stored in the storage unit through the filter in the reverse direction, wherein the amount of regenerated air consumed in one regenerating operation is set according to the operation state of the compressor.

A control method for an air supply system for solving the above problems, the air supply system comprising: an air drying circuit provided between a compressor that sends out compressed air and a storage unit 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, wherein in the control method of the air supply system, the control device is caused to perform: the air drying circuit is controlled to perform a dehumidifying operation of supplying the compressed air sent from the compressor to the storage unit through the filter in the forward direction, and a regenerating operation of discharging the fluid having passed through the filter from the discharge port by passing the compressed dry air stored in the storage unit through the filter in the reverse direction, wherein the amount of regenerated air consumed in one regenerating operation is set according to the operation state of the compressor.

A control program for an air supply system that solves the above problems, the air supply system comprising: an air drying circuit provided between a compressor that sends out compressed air and a storage unit 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, wherein a control program of the air supply system causes the control device to function as: a dehumidification operation execution unit that controls the air drying circuit to execute a dehumidification operation of supplying the compressed air sent from the compressor to the storage unit by passing the compressed air in a forward direction through the filter; a regeneration operation execution unit that controls the air drying circuit to execute a regeneration operation of causing the compressed dry air stored in the storage unit to pass through the filter in a reverse direction and discharging the fluid having passed through the filter from a discharge port; and a setting unit that sets the amount of regeneration air consumed in one regeneration operation, according to the operation state of the compressor.

According to the above configuration, the control device sets the amount of regeneration air consumed in the regeneration operation based on the operation state of the compressor. The compressor is driven in accordance with the supply state of the compressed dry air to the device other than the air drying circuit, and therefore, by changing the regeneration air amount, it is possible to preferentially perform one of the supply of the compressed dry air from the storage unit to the device other than the air drying circuit and the purification of the filter.

In the air supply system, the control device may be configured to: the regeneration air amount is decreased when the operation rate of the compressor is high during a fixed period, and is increased when the operation rate of the compressor is low.

According to the above configuration, when the operation rate of the compressor is high and the degree of supply of compressed dry air from the storage unit to the device other than the air drying circuit is large, the consumption of compressed dry air stored in the storage unit can be suppressed by reducing the regeneration air amount, and the supply of compressed dry air to the device other than the air drying circuit can be preferentially performed. In addition, when the operation rate of the compressor is low and the degree of supply of compressed dry air from the reservoir to the device other than the air drying circuit is small, the filter can be cleaned preferentially.

In the air supply system, the control device may be configured to: the regeneration air amount is increased when an index indicating a wet state of the compressed dry air in the storage unit is high, and the regeneration air amount is decreased when an index indicating a wet state of the compressed dry air in the storage unit is low.

According to the above configuration, when the wet state of the compressed dry air is high, the regeneration air amount is increased, so that the filter can be preferentially cleaned. In addition, when the wet state is low, the compressed dry air can be preferentially supplied to the device other than the air drying circuit by suppressing the consumption of the compressed dry air stored in the storage unit.

In the air supply system, the control device may be configured to: when the operation rate of the compressor is high, an upper limit pressure for starting the regeneration operation, which is the pressure of the reservoir, is set high, when the operation rate of the compressor is low, the upper limit pressure is set low, when the upper limit pressure is high, the regeneration air amount is reduced, and when the upper limit pressure is low, the regeneration air amount is increased.

According to the above configuration, the upper limit pressure for starting the regenerating operation is set according to the operating state of the compressor. The regeneration air amount is determined based on the upper limit pressure. When the operation rate of the compressor is high, the upper limit pressure is set high and the regeneration air amount is reduced, so that the execution frequency of the regeneration operation is reduced and the consumption of the compressed dry air stored in the storage unit is suppressed, thereby making it possible to preferentially supply the compressed dry air to the devices other than the air drying circuit. In addition, when the operation rate of the compressor is low, the upper limit pressure is set low and the regeneration air amount is increased, so that the execution frequency of the regeneration operation can be increased to improve the effect of the purification filter.

An air supply system for solving the above problems, comprising: an air drying circuit provided between a compressor that sends out compressed air and a storage unit 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, wherein the control device is configured to: the air drying circuit is controlled to perform a dehumidifying operation of supplying the compressed air sent from the compressor to the storage unit through the filter in the forward direction, and a regenerating operation of discharging the fluid having passed through the filter from the discharge port by passing the compressed dry air stored in the storage unit through the filter in the reverse direction, wherein the amount of regenerated air consumed in one regenerating operation is set according to the temperature of the compressed air or the compressed dry air.

A control method for an air supply system for solving the above problems, the air supply system comprising: an air drying circuit provided between a compressor that sends out compressed air and a storage unit 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, wherein in the control method of the air supply system, the control device is caused to perform: the air drying circuit is controlled to perform a dehumidifying operation of supplying the compressed air sent from the compressor to the storage unit through the filter in the forward direction, and a regenerating operation of discharging the fluid having passed through the filter from the discharge port by passing the compressed dry air stored in the storage unit through the filter in the reverse direction, wherein the regeneration air amount consumed in one regeneration operation is set according to the temperature of the compressed air or the temperature of the compressed dry air.

A control program for an air supply system that solves the above problems, the air supply system comprising: an air drying circuit provided between a compressor that sends out compressed air and a storage unit 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, wherein a control program of the air supply system causes the control device to function as: a dehumidification operation execution unit that controls the air drying circuit to execute a dehumidification operation of supplying the compressed air sent from the compressor to the storage unit by passing the compressed air in a forward direction through the filter; a regeneration operation execution unit that controls the air drying circuit to execute a regeneration operation of causing the compressed dry air stored in the storage unit to pass through the filter in a reverse direction and discharging the fluid having passed through the filter from a discharge port; and a setting unit that sets the amount of regeneration air consumed in one regeneration operation, based on the temperature of the compressed air or the temperature of the compressed dry air.

According to the above configuration, the control device sets the regeneration air amount consumed in the regeneration operation based on the temperature of the compressed air or the temperature of the compressed dry air. Since the amount of moisture contained in the air increases when the temperature of the compressed air or the temperature of the compressed dry air increases, it is possible to preferentially supply either the compressed dry air or the filter from the storage unit to the device other than the air drying circuit by changing the regeneration air amount in accordance with the amount of moisture contained in the air.

In the air supply system, the control device may be configured to: the regeneration air amount is decreased when the temperature is low, and the regeneration air amount is increased when the temperature is high.

According to the above configuration, when the temperature of the air is low and the saturated water vapor amount is small, the consumption of the compressed dry air stored in the storage unit is suppressed by reducing the regeneration air amount, so that the compressed dry air can be preferentially supplied to the device other than the air drying circuit. In addition, when the temperature of the air is high and the saturated water vapor amount is large, the regeneration air amount can be increased to preferentially perform the purification of the filter.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present disclosure, it is possible to maintain dehumidifying performance of an air supply system and reduce the consumption of compressed dry air of the air supply system.

Drawings

Fig. 1 is a schematic configuration diagram showing a first embodiment of an air supply system.

Fig. 2A to 2F are diagrams showing a first operation mode to a sixth operation mode of the air drying circuit according to the embodiment of fig. 1, respectively.

Fig. 3A is a map of a standard regeneration air amount for calculating the regeneration air amount of the embodiment of fig. 1, and fig. 3B is a map of a correction unit air amount for calculating the regeneration air amount of the embodiment of fig. 1.

Fig. 4 is a schematic diagram of the excess and deficiency coefficient information of the embodiment of fig. 1.

Fig. 5 is a flowchart showing an example of a process of supplying compressed air in the embodiment of fig. 1.

Fig. 6 is a flowchart showing an example of a process of performing a regenerating operation in the embodiment of fig. 1.

Fig. 7 is a flowchart showing an example of a process of determining the regeneration air amount in the embodiment of fig. 1.

Fig. 8A is a map of a standard regeneration air amount for calculating the regeneration air amount of the second embodiment, and fig. 8B is a map of a corrected unit air amount for calculating the regeneration air amount of the second embodiment.

Fig. 9 is a flowchart showing an example of a process of determining the regeneration air amount in the embodiment of fig. 8.

Detailed Description

(First embodiment)

A first embodiment of the air supply system will be described with reference to fig. 1to 6. The air supply system is mounted on an automobile such as a truck, a bus, or a construction machine. The compressed dry air generated by the air supply system is used in an air pressure system such as a brake system (brake device) or a suspension system (suspension device) of an automobile.

< Air supply System 10>

An air supply system 10 is 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: electronic control unit) 80. The ECU 80 functions as a control device, a dehumidifying operation execution unit, a regenerating operation execution unit, and a setting unit.

The ECU 80 is connected to the air drying circuit 11 via a plurality of wirings E61 to E67. The ECU 80 includes an arithmetic unit, a communication interface unit, a volatile memory unit, and a nonvolatile memory unit. The arithmetic unit is a computer processor, and is configured to control the air drying circuit 11 in accordance with an air supply program stored in a nonvolatile memory unit (storage medium). The arithmetic 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 further includes a storage unit 80A, and the storage unit 80A stores information for determining the execution frequency of each operation of the air drying circuit 11. The storage unit 80A may be a nonvolatile storage unit or a volatile storage unit, and may be the same as or different from the storage unit storing the control program.

The ECU80 is connected to other ECUs (not shown) mounted on the vehicle, such as an engine ECU and a brake ECU, via a vehicle network such as CAN (Controller Area Network: controller area network). The ECU80 acquires information indicating the state of the vehicle from these ECUs. The information indicating the state of the vehicle includes, for example, off information of an ignition switch, a vehicle speed, driving information of an engine, and the like.

Based on the command value from the ECU 80, the state of the compressor 4 is switched between an operating state (load operation) in which air is compressed to send out air and a non-operating state (idle operation) in which air is not compressed. The compressor 4 is operated by power transmitted from a rotational drive source such as an engine.

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 in the load operation. The air drying circuit 11 supplies the dried compressed air (hereinafter, compressed dry air) to the supply circuit 12. The compressed dry air supplied to the supply circuit 12 is stored in the air tank 30.

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 frequency of brake operation is high, such as in a condition where the vehicle is traveling on a downhill road or urban area, the consumption amount of compressed dry air stored in the air tank 30 increases. Conversely, when the frequency of the brake operation is low, the consumption amount of the compressed dry air stored in the air tank 30 becomes small.

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 at the time of maintenance.

The filter 17 is provided in the housing 11A (see fig. 2A) of the air drying circuit 11, for example. The filter 17 is provided in the middle of an air supply passage 18 connecting the compressor 4 and the supply circuit 12. In addition, the filter 17 includes a desiccant. The filter 17 includes an oil trap for trapping oil in addition to the desiccant. The oil trapping portion may be any foam such as polyurethane foam, a metal material having a plurality of ventilation holes, a glass fiber filter, or the like, as long as it can trap oil while allowing air to pass therethrough.

The filter 17 removes moisture contained in the compressed air from the compressed air by passing the compressed air sent from the compressor 4 through a desiccant, and dries the compressed air. The oil trapping unit traps the oil contained in the compressed air to purify the compressed air. The compressed air passing through the filter 17 is supplied to the supply circuit 12 via a downstream check valve 19. When the filter 17 side is set upstream and the supply circuit 12 side is set downstream, the downstream check valve 19 allows only air to flow from upstream to downstream. Further, since the downstream check valve 19 has a predetermined valve opening pressure (closing pressure), the pressure of the upstream is higher than the pressure of the downstream by the valve opening pressure when the compressed air flows.

A bypass flow path 20 is provided downstream of the filter 17 in parallel with the downstream check valve 19 as a bypass path for bypassing the downstream check valve 19. The bypass passage 20 is provided with a regeneration control valve 21.

The regeneration control valve 21 is a solenoid valve controlled by the ECU 80. The ECU 80 controls on/off (driving/non-driving) of the power supply of the regeneration control valve 21 via the wiring E64, thereby switching the operation of the regeneration control valve 21. The regeneration control valve 21 closes the bypass passage 20 by closing the valve when the power supply is turned off, and communicates the bypass passage 20 by opening the valve when the power supply is turned on. The ECU 80 receives, for example, 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.

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, the compressed dry air on the side of the supply circuit 12 is sent to the filter 17 via the bypass flow path 20 in a state where the flow rate is restricted by the orifice 22. The compressed dry air delivered to the filter 17 is counter-flowed in the filter 17 from downstream toward upstream and passes through the filter 17. Such a process is an operation of regenerating the filter 17, and is referred to as a regeneration operation of the air drying circuit 11. At this time, the compressed dry air supplied to the filter 17 is the air supplied from the air supply passage 18 to the supply circuit 12 through the filter 17 and the like after being dried and purified, and therefore, the moisture and the oil trapped 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 gas tank 30 reaches an upper limit value (cut out pressure). On the other hand, when the pressure in the gas tank 30 reaches the lower limit value (cut in pressure), the regeneration control valve 21 after opening the valve is closed.

The branch passage 16 branches off from a portion between the compressor 4 and the filter 17. The branch passage 16 is provided with a drain discharge valve 25, and a drain discharge port 27 is connected to the end of the branch passage 16.

The drain, which is a fluid containing the water and oil removed from the filter 17, is sent to the drain discharge valve 25 together with the compressed air. The drain discharge valve 25 is an air pressure driven valve driven by air pressure, and the drain discharge valve 25 is provided between the filter 17 and the drain discharge port 27 in the branch passage 16. The drain valve 25 is a two-position two-way valve whose position is changed between a valve-closing position and a valve-opening position. When the drain discharge valve 25 is in the valve-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 passing through the filter 17 in the reverse direction.

The drain discharge valve 25 is controlled by a regulator 26A. Regulator 26A is a solenoid valve controlled by ECU 80. ECU 80 switches the operation of regulator 26A by controlling on/off (drive/non-drive) of the power supply of regulator 26A via wiring E63. When the power supply is turned on, the regulator 26A switches to an input position at which an air pressure signal is input to the drain valve 25, thereby opening the drain valve 25. When the power supply is turned off, the regulator 26A switches to an open position in which the port of the drain valve 25 is opened to the atmospheric pressure without inputting an air pressure signal to the drain valve 25, thereby closing the drain valve 25.

The drain discharge valve 25 is maintained at a valve closing position for blocking the branch passage 16 in a state where the air pressure signal is not input from the regulator 26A, and is switched to a valve opening position for communicating the branch passage 16 when the air pressure signal is input from the regulator 26A. In addition, in the drain discharge valve 25, when the pressure of the input port connected to the compressor 4 exceeds the upper limit value, the drain discharge valve 25 is forcibly switched to the valve opening position.

An upstream check valve 15 is provided between the compressor 4 and the filter 17 and between the compressor 4 and the branch passage 16. When the compressor 4 side is set upstream and the filter 17 side is set downstream, the upstream check valve 15 allows only air to flow from upstream to downstream. Since the upstream check valve 15 has a predetermined valve opening pressure (sealing pressure), the upstream pressure is higher than the downstream pressure by the valve opening pressure when the compressed air flows. Further, a reed valve for the outlet of the compressor 4 is provided upstream of the upstream check valve 15. Downstream of the upstream check valve 15, a branching passage 16 and a filter 17 are provided.

The compressor 4 is controlled by an 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 discharge control valve 26B by controlling the power on/off (driving/non-driving) of the discharge control valve 26B via the wiring E62. When the power supply is turned off, the discharge control valve 26B is switched to the open position, and the flow path atmosphere between the discharge control valve 26B and the compressor 4 is opened. When the power supply is turned on, the unload control valve 26B is switched to the supply position, and sends an air pressure signal composed of compressed air to the compressor 4.

When an air pressure signal is input from the unloading control valve 26B, the state of the compressor 4 is switched to the non-operating state (idle operation). For example, when the pressure in the gas tank 30 reaches the cut-out pressure, the compressed dry air does not need to be supplied. When the pressure on the side of the supply circuit 12 reaches the cut-out pressure and the ECU 80 turns on the power supply of the unloading control valve 26B (drives the unloading control valve 26B), the unloading control valve 26B switches to the supply position. Thereby, 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 the non-operating state.

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 of the air supply passage 18, and transmits the measurement result to the ECU 80 via the line E61.

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

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

< Description of operation of air drying Circuit 11 >

As shown in fig. 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.

(First operation mode)

As shown in fig. 2A, the first operation mode is a normal mode in which a dehumidification operation (load operation) is performed. In the first operation mode, the regeneration control valve 21 and the unloading control valve 26B are closed (referred to as "CLOSE" in the figure), and the regulator 26A is set to an open position (referred to as "CLOSE" in the figure) in which the air pressure signal is not input to the drain discharge valve 25. At this time, no power is supplied to the regeneration control valve 21, the regulator 26A, and the unloading control valve 26B. The regulator 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 (shown as "ON"), the compressed air is supplied to the supply circuit 12 after water and the like are removed by the filter 17.

(Second operation mode)

As shown in fig. 2B, the second operation mode is a mode in which a purge operation is performed in which compressed and dried air in the air drying circuit 11 is passed through the filter 17 to clean 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 regulator 26A is set to the input position (indicated as "OPEN" in the figure). At this time, power is supplied to the regulator 26A and the unloading control valve 26B, respectively, and the port of the compressor 4 and the port of the drain discharge valve 25 connected downstream thereof are connected upstream (the supply circuit 12 side), respectively. Thereby, the compressor 4 is switched to the non-operating state (in the figure, it is described as "OFF"), and the drain valve 25 is opened. As a result, the compressed dry air between the downstream check valve 19 and the filter 17 flows (flows back) in the filter 17 in the opposite direction to the air flow in the first operation mode (dehumidification mode), and the moisture or the like captured by the filter 17 is discharged as a drain from the drain outlet 27. The air pressure of the filter 17 and the air supply passage 18 is opened to the atmospheric pressure.

(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 regulator 26A is set to the input position, and the unloading control valve 26B is set to the supply position (each of which is referred to as "OPEN"). At this time, power is supplied to the regeneration control valve 21 in addition to the regulator 26A and the unloading control valve 26B. In the third operation mode, the compressor 4 is set to the inactive state, and the compressed dry air stored in the supply circuit 12 or the air tank 30 is discharged from the drain outlet 27 through the filter 17 in a reverse flow. Thereby, the water or the like captured by the filter 17 is removed. The second operation mode and the third operation mode are both modes of the purge filter 17, but the third operation mode is different from the second operation mode at least in that the regeneration control valve 21 is opened. In this way, in the third operation mode, the compressed dry air in the air tank 30 can be made to pass through the filter 17 via the supply circuit 12 and the bypass flow path 20. Therefore, the effect of the purge filter 17 is higher than that of the second operation mode. In the third operation mode, the air pressure of the filter 17 and the air supply passage 18 is also opened to the atmospheric pressure.

(Fourth operation mode)

As shown in fig. 2D, the fourth operation mode is a mode in which the oil removal operation is performed. In the fourth operation mode, the compressor 4 is operated, and air having excessive oil supplied from the compressor 4 is discharged from the drain outlet 27 without passing through the filter 17. When the compressor 4 is in the non-operating state, oil may accumulate in the compression chamber of the compressor 4. If the state of the compressor 4 is switched to the operating state in a state where oil is accumulated in the compression chamber, the amount of oil contained in the compressed air sent from the compression chamber increases. If oil is attached to the desiccant, the desiccant's dehumidification performance is reduced. Therefore, the oil removal operation for discharging the compressed air having excessive oil is performed. In the fourth operation mode, the regeneration control valve 21 is closed, the unloading control valve 26B is set to an open position (referred to as "CLOSE" in the figure), and the regulator 26A is set to an open position (referred to as "CLOSE" in the figure) after the drive for the fixed period. Thus, even if compressed air containing a large amount of oil is sent from the compressor 4, the compressed air can be discharged from the drain outlet 27 without passing through the filter 17. Thus, it is possible to suppress a decrease in the dehumidifying performance of the filter 17 immediately after the compressor 4 is switched from the non-operating state to the operating state. The oil removal operation can be performed when the oil content from the compressor 4 increases, for example, when the engine speed increases and when the engine is under high load.

(Fifth mode of operation)

As shown in fig. 2E, the fifth operation mode is a mode in which the compressor is stopped without purge. In the fifth operation mode, the regeneration control valve 21 is closed, the regulator 26A is set to an OPEN position (shown as "CLOSE") and the unloading control valve 26B is set to a supply position (shown as "OPEN"). In the fifth operation mode, when the compressor 4 is in the non-operation state, the compressed air or the compressed dry air remaining in the air supply passage 18 or the drying agent of the filter 17 is not discharged from the drain outlet 27, thereby maintaining the air pressure.

(Sixth operation mode)

In the sixth operation mode, the regeneration control valve 21 is opened, the unloading control valve 26B is set to the supply position (indicated as "OPEN" in the drawing), and the regulator 26A is set to the OPEN position (indicated as "CLOSE" in the drawing). In the sixth operation mode, when the compressor 4 is in the non-operation state, the compressed air of the supply circuit 12 is supplied (caused to flow reversely) to the air supply passage 18 and the desiccant of the filter 17, whereby the pressure of the air supply passage 18 and the filter 17 is made higher than the atmospheric pressure, and the back pressure (air pressure) of the upstream check valve 15 is maintained at a pressure higher than the atmospheric pressure.

(Setting of execution conditions)

Next, a method for determining the amount of air consumed in the regeneration operation (hereinafter referred to as the regeneration air amount) is described with reference to fig. 3A to 3B. The ECU 80 calculates the regeneration air amount Am according to the following expression (1) by executing a control program. The regeneration air amount Am may be calculated in volume units or mass units. Further, various coefficients of the transform unit may be used on the right (or left) side of the expression (1).

Regeneration air amount am=standard regeneration air amount Am 1-correction unit air amount Am2 x excess and deficiency coefficient α (1)

The "standard regeneration air amount Am1" is set to be larger than the "correction unit air amount Am2 x excess/deficiency coefficient α" so that the regeneration air amount Am exceeds "0". The standard regeneration air amount Am1 is basically an air amount determined by the type (specification) of the air drying circuit 11, but the standard regeneration air amount Am1 is changed according to the cut-out pressure, which is the upper limit value of the pressure of the air tank 30. As described above, the cut-out pressure is a pressure that is a condition for starting the regeneration operation and the purge operation, and is set to a higher value as the operating rate of the compressor 4 is higher, and is stored in the storage unit 80A. For example, if the operating rate is smaller than a predetermined value R1 (for example, 30%), the cut-out pressure Po1 is set to a relatively low value, and if the operating rate is equal to or larger than the predetermined value R1 and smaller than a predetermined value R2 (for example, 60%), the cut-out pressure Po2 higher than the cut-out pressure Po1 is set (Po 2> Po 1). If the operating rate is equal to or higher than the predetermined value R2, the cut-out pressure Po3 is set to be higher than the cut-out pressure Po2 (Po 3> Po 2). In the present embodiment, the cut-out pressure is set to three stages according to the operating rate of the compressor 4, but the cut-out pressure may be set to two stages or four or more stages. Alternatively, the cutting pressure may be continuously changed according to the operating rate of the compressor 4.

The reason why the cut-out pressure Po increases as the operation rate of the compressor 4 increases will be described. Since the compressor 4 is driven in accordance with the amount of compressed dry air in the air tank 30 or the like, when the operation rate of the compressor 4 is low, it is estimated that the consumption amount of compressed dry air consumed by an air pressure system such as a brake system is small. In such a case, the cut-out pressure is set to a relatively low value to relatively increase the execution frequency of the regeneration operation, thereby positively purging the filter 17. On the other hand, when the operating rate of the compressor 4 is high, it is estimated that the consumption amount of compressed dry air consumed by the air pressure system such as the brake system is large. In such a case, the cut-out pressure is set to a relatively high value to relatively reduce the execution frequency of the regeneration operation, and the supply of the compressed dry air to the air pressure system is preferentially performed.

Fig. 3A is a map 100 in which the standard regeneration air amount Am1 is set based on the limit ventilation amount and the cut-out pressure. The map 100 is stored in the storage unit 80A. The horizontal axis of the map 100 represents the limit ventilation, and the vertical axis represents the standard regeneration air amount Am1. In the figure, the unit is volume (liter), but may be the unit is mass. The limit ventilation amount is a value indicating the limit of the amount of air passing through the air drying circuit 11, and is determined according to the type of the air drying circuit 11 (air dryer). The standard regeneration air amount Am1 becomes smaller as the limit ventilation becomes larger, and becomes larger as the limit ventilation becomes smaller. When the limit ventilation is fixed, the standard regeneration air amount Am1 decreases as the cut-out pressure increases, and increases as the cut-out pressure decreases. That is, since the cut-out pressure is set to a high value as the operation rate of the compressor 4 increases, it can be said that the standard regeneration air amount Am1 becomes smaller as the operation rate of the compressor 4 increases. As described above, when the operating rate of the compressor 4 is high, it is estimated that the consumption amount of compressed dry air consumed by the air pressure system such as the brake system is large. Therefore, when the operation rate of the compressor 4 is high, the standard regeneration air amount Am1 is reduced, and the supply of the compressed dry air to the air pressure system is preferentially performed. The standard regeneration air amount Am1 increases as the operation rate of the compressor 4 decreases. When the work rate is low, it is estimated that the consumption amount of compressed dry air consumed by an air pressure system such as a brake system is small. Therefore, when the operation rate of the compressor 4 is low, the standard regeneration air amount Am1 is increased, and the purifying effect of the filter 17 per regeneration operation is improved.

Fig. 3B is a map 101 showing the relationship between the corrected unit air amount Am2 and the limit ventilation amount according to the cut-out pressure. The map 101 is stored in the storage unit 80A. The horizontal axis represents the limit ventilation, and the vertical axis represents the correction unit air amount Am2. In the figure, the unit is volume (liter), but may be the unit is mass. As with the standard regeneration air amount Am1, the correction unit air amount Am2 becomes smaller as the limit ventilation amount becomes larger, while the correction unit air amount Am2 becomes larger as the cut-out pressure becomes higher and becomes smaller as the cut-out pressure becomes lower when the limit ventilation amount is set to be fixed.

The surplus-shortage coefficient α (regeneration surplus-shortage coefficient) is a coefficient multiplied by the correction unit air amount Am, and is set to a negative value, a positive value, or "0". The excess/deficiency coefficient α is set based on the tendency of the wet state of the compressed dry air stored in the air tank 30. The excess or shortage of the regeneration operation can be determined from the amount of moisture captured by the filter 17, but the amount of moisture contained in the compressed air varies depending on the temperature and humidity of the air, so 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 passing through the filter 17. In addition, it is also difficult to directly measure the amount of moisture captured by the filter 17. As in the present embodiment, by determining the excess and shortage of the regeneration operation based on the wet state of the compressed dry air in the reservoir, the excess and shortage of the regeneration operation can be appropriately determined even in an indirect manner.

The tendency of the wet state, which is the basis of the excess/deficiency coefficient α, is determined for a period from the previous regeneration operation to the next regeneration operation. In the present embodiment, the saturation of the moisture content (hereinafter, moisture content) in the compressed dry air in the air tank 30 is calculated, and the saturation of the moisture content at the time of the end of the previous regenerating operation is subtracted from the saturation of the moisture content at the time of the end of the previous regenerating operation. When the saturation level of the moisture content at the end of the current regeneration is higher than that at the end of the previous regeneration, that is, when the wet state of the compressed dry air tends to be higher, it is determined that the moisture content captured by the filter 17 tends to be higher. Therefore, in the above formula (1), the excess/deficiency coefficient α is set to a negative value smaller than "0". When the excess/deficiency coefficient α is a negative value, the regeneration air amount is corrected to be larger than the standard regeneration air amount.

On the other hand, when the saturation level of the moisture content at the end of the current regeneration is lower than the saturation level at the end of the previous regeneration, that is, when the wet state of the compressed dry air tends to be lowered, it is determined that the moisture content captured by the filter 17 tends to be reduced. Therefore, the excess and deficiency coefficient α is set to a positive value greater than "0", thereby correcting the regeneration air amount to be smaller than the standard regeneration air amount. When it is determined that the wet state of the compressed dry air is in an appropriate state, the excess/deficiency coefficient is set to "0", so that the regeneration air amount Am is not corrected based on the standard regeneration air amount Am 1.

Fig. 4 shows the excess/deficiency coefficient information 200 that represents an example of the excess/deficiency coefficient α. The excess/deficiency coefficient information 200 is stored in the storage unit 80A. The excess/deficiency coefficient information 200 includes an excess/deficiency condition 200A and an excess/deficiency coefficient 200C. The state 200B conveniently represents the state shown by the excess-deficiency condition 200A and may be omitted. The range of regeneration surplus and shortage is set for the surplus and shortage condition 200A. The regeneration surplus shortage is an index indicating whether the saturation of the moisture contained in the compressed dry air in the air tank 30 is in a tendency of increasing or a tendency of decreasing.

The excess/deficiency coefficient 200C is a coefficient obtained by multiplying the regeneration excess/deficiency by a weighting coefficient. The excess/deficiency coefficient 103 corresponds to the excess/deficiency condition 200A, which is a range of the regeneration excess/deficiency degree. In fig. 4, the weighting coefficient is a positive integer, but may not be a positive integer.

In the excess/deficiency coefficient information 200, when the amount of regenerated air is significantly insufficient, that is, when the amount of water contained is large, the regeneration excess/deficiency is, for example, equal to or less than "-1", and is negative and has a large absolute value. In this case, a relatively large value such as "2" is set for the weighting coefficient. In addition, when the regeneration air amount is insufficient although not "greatly insufficient", the regeneration surplus shortage is, for example, in a range of more than "-1" and less than "-0.5", and the absolute value is smaller than that of "greatly insufficient". In addition, a value smaller than "greatly insufficient", for example, "1", or the like is set for the value of the weighting coefficient.

When the regeneration air amount is greatly excessive, that is, when the water content is small, the regeneration excess deficiency is, for example, "1" or more, and the absolute value is large. In this case, a relatively large value such as "2" is set for the weighting coefficient. In the case where the regeneration air amount is excessive although not "greatly excessive", the regeneration excess deficiency is, for example, in a range of "0.5" or more and less than "1", and the absolute value is smaller than that of "greatly excessive". In addition, a value smaller than "large excess", for example, "1", or the like is set for the value of the weighting coefficient.

When the regeneration surplus and shortage is in a range of, for example, "-0.5" or more and less than "0.5", the surplus and shortage coefficient is set to "0".

The following description will be given for the case where the regenerated air amount Am calculated using these standard regenerated air amounts, corrected unit air amounts, and excess/deficiency coefficients is divided into: the operation rate of the compressor 4 is low and high, and the wet state in the gas tank 30 is low and high. The precondition is that the limit ventilation is fixed.

(A) The operating rate of the compressor 4: low, wet state within the gas tank 30: high height

When the operating rate of the compressor 4 is low, the cut-out pressure is set low. This increases the execution frequency of the regeneration operation and the purge operation. In addition, the standard regeneration air amount Am1 becomes large by setting the cut-out pressure low.

The corrected unit air amount Am2 is reduced by setting the cut-out pressure to be low. Further, since the wet state in the gas tank 30 is high, the state becomes "greatly insufficient" or "insufficient", and the excess/deficiency coefficient α becomes a negative value. Therefore, a correction value of a positive value is added to the standard regeneration air amount, thereby making the regeneration air amount Am large. In addition, the "greatly insufficient" state increases the regeneration air amount Am as compared with the "insufficient" state.

(B) The operating rate of the compressor 4: low, wet state within the gas tank 30: low and low

The standard regeneration air amount Am1 and the corrected unit air amount Am2 are the same as in the state (a) described above. On the other hand, the wet state in the tank 30 is low, and thus the state becomes "greatly excessive" or "excessive", and the excess/deficiency coefficient α is a positive value. Therefore, the correction value is subtracted from the standard regeneration air amount, and the regeneration air amount Am becomes smaller than the regeneration air amount Am in the state (a).

(C) The operating rate of the compressor 4: high, wet state within the gas tank 30: high height

When the operating rate of the compressor 4 is high, the cut-out pressure is set high. Thereby, the execution frequency of the regeneration operation and the purge operation is reduced. In addition, the standard regeneration air amount Am1 is reduced by setting the cut-out pressure to be high.

The corrected unit air amount Am2 is increased by setting the cut-out pressure to be high. Further, the wet state in the gas tank 30 is high, and thus becomes a "greatly deficient" or "deficient" state, and the excess deficiency coefficient α is a negative value. Therefore, the correction value of the positive value is added to the standard regeneration air amount, and the regeneration air amount Am becomes smaller than the regeneration air amount Am in the state (a). The regeneration air amount Am in the state (C) may be smaller than the regeneration air amount Am in the state (B) or larger than the regeneration air amount Am in the state (B). The regeneration air amount Am in the state (B) and the regeneration air amount Am in the state (C) may be the same.

(D) The operating rate of the compressor 4: high, wet state within the gas tank 30: low and low

The standard regeneration air amount Am1 and the corrected unit air amount Am2 are the same as in the above-described state (C). On the other hand, the wet state in the gas tank 30 is low, and thus the state becomes "greatly excessive" or "excessive", and the excess/deficiency coefficient α is a positive value. Therefore, the correction value is subtracted from the standard regeneration air amount, and the regeneration air amount Am becomes smaller than the regeneration air amount Am in the state (C). That is, although depending also on the set value of the excess-deficiency coefficient α, the regeneration air amount Am is basically maximum in the case of the state (a) and minimum in the case of the state (D).

(Control of air drying Loop 11)

Next, a process in which the ECU 80 controls the air drying circuit 11 will be described with reference to fig. 5 to 7.

Referring to fig. 5, the process of overall control is described. The ECU 80 performs an air supply process of supplying the compressed air output from the compressor 4 to the supply circuit 12 (step S1). The air supply process is started under predetermined conditions such as when the engine is driven. The air supply process may be started when the pressure of the air tank 30 reaches a predetermined pressure such as a cut-in pressure as a lower limit value. In the air supply step, the air drying circuit 11 is in the first operation mode, and the dehumidification operation is performed.

When the air supply process is started, ECU 80 determines whether or not to stop the supply of air (step S2). Specifically, the ECU 80 acquires the pressure in the gas tank 30 detected by the pressure sensor 53, and determines whether the pressure reaches the cut-out pressure. When the ECU 80 determines that the pressure in the air tank 30 has not reached the cut-out pressure (step S2: NO), it returns the process to the air supply step (step S1).

When the ECU 80 determines that the pressure in the gas tank 30 has reached the cut-out pressure (yes in step S2), it ends the air supply process, turns the compressor 4 into a non-operating state, and executes the purge process (step S3). In the purge step, the ECU 80 determines whether or not the regeneration operation and the purge operation are required according to preset conditions, and executes the regeneration operation when it is determined that the regeneration operation is required and executes the purge operation when it is determined that the purge operation is required.

When the purge process is completed (step S3), the ECU 80 performs an air non-supply process (step S4). In the air non-supply step, when the compressor 4 is in a non-operating state, pressure adjustment of the air drying circuit 11 such as adjustment of the back pressure of the upstream check valve 15 is performed. For example, in the air non-supply step, at least one of the second operation mode, the fifth operation mode, and the sixth operation mode is executed one or more times to adjust the air pressure of the air drying circuit 11. When the pressure adjustment is ended, the ECU 80 determines whether to end the air supply based on the vehicle state (step S5). The end of the air supply is determined based on a vehicle state such as an engine stop of the vehicle.

If it is determined that the air supply is not completed (step S5: NO), the ECU 80 returns the process to step S1 to execute the process after the air supply step (step S1). On the other hand, when it is determined that the air supply is completed (yes in step S5), the air supply is stopped.

Next, a process of controlling the regenerating operation will be described with reference to fig. 6. The ECU 80 determines whether or not a regeneration operation is required, according to predetermined conditions (step S100). At this time, the ECU 80 determines whether or not the regenerating operation is necessary based on the wet state of the compressed dry air in the air tank 30. For example, ECU 80 calculates the moisture content (tank-containing moisture content) of the compressed dry air in air tank 30, determines that the regeneration operation is necessary when the tank-containing moisture content is equal to or higher than a predetermined value, and determines that the regeneration operation is necessary when the tank-containing moisture content is lower than the predetermined value.

When the ECU 80 determines that the regeneration operation is not necessary (step S100: NO), the process ends. On the other hand, when the ECU 80 determines that the regenerating operation is required (step S100: yes), it 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 air amount consumed in the regeneration operation, and the regeneration operation may be ended when the converted air amount reaches the regeneration air amount. Alternatively, the air drying circuit 11 may be switched to the third operation mode only at the regeneration time corresponding to the regeneration air amount, and the regeneration operation may be performed. The regeneration time may be calculated using a map that correlates the regeneration air amount with the regeneration time, or using a conversion equation on the premise that the air amount per unit time passing through the filter 17 at the time of regeneration is fixed. When the regenerating operation is completed, the purging step (step S3) is completed, and the process proceeds to the next step.

Next, a process for determining the regeneration air amount will be described with reference to fig. 7. The ECU 80 defines a cycle from the end of the regeneration operation to the start of the next regeneration operation. Then, the regeneration air amount is updated at a predetermined timing in one cycle. The regeneration air amount update timing 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 for each predetermined period, for example, a period shorter than the average time of one cycle.

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 of a new cycle is reached. When the ECU 80 determines that the predetermined timing has not been reached (step S110: NO), the process ends.

When the ECU 80 determines that the regeneration air amount is updated (step S110: YES), it calculates the regeneration surplus and shortage (step S111). As described above, the regeneration surplus and shortage degree may be calculated based on the change in the tank air moisture saturation degree. The tank air moisture saturation can be calculated from the humidity detected by the humidity sensor 51, the temperature detected by the temperature sensor 52, and the like.

When calculating the regeneration surplus and shortage degree, the ECU 80 acquires the surplus and shortage coefficient using the surplus and shortage coefficient information 200 (step S112). Then, ECU 80 acquires the cut-out pressure as the start pressure of the regeneration operation (step S113). In addition, the ECU 80 acquires the standard regeneration air amount using the map 100 based on the acquired cut-out pressure (step S114), and acquires the correction unit air amount using the map 101 (step S115). Then, the ECU 80 calculates the regeneration air amount according to the above formula (1) using the standard regeneration air amount, the corrected unit air amount, and the excess/deficiency coefficient (step S116). The regeneration air amount calculated here is used in step S101 of fig. 6. The ECU 80 performs a regenerating operation using the regeneration air amount calculated here.

As described above, according to the first embodiment, the following effects can be obtained.

(1) The ECU 80 sets the amount of regeneration air consumed in the regeneration operation based on the operation state of the compressor 4. The compressor 4 is driven in accordance with the state of supplying the compressed dry air to the air pressure system other than the air drying circuit 11, and therefore, by changing the regeneration air amount, it is possible to preferentially perform one of the supply of the compressed dry air from the air tank 30 to the other air pressure system and the purification of the filter 17.

(2) When the operation rate of the compressor 4 is high and the degree of supply of the compressed dry air from the air tank 30 to the air pressure system is large, the consumption of the compressed dry air stored in the air tank 30 can be suppressed by reducing the regeneration air amount, and the supply of the compressed dry air to the air pressure system can be preferentially performed. In addition, when the operation rate of the compressor 4 is low and the degree of supply of compressed dry air from the air tank 30 to the air pressure system is small, the purification of the filter 17 can be performed preferentially.

(3) When the wet state of the compressed dry air in the air tank 30 is high, the filter 17 can be preferentially purified by increasing the regeneration air amount. In addition, when the wet state of the compressed dry air is low, the compressed dry air can be preferentially supplied to the air pressure system by suppressing the consumption of the compressed dry air stored in the air tank 30.

(4) The cut-out pressure, which is the upper limit pressure for starting the regeneration operation, is set according to the operation state of the compressor 4, and the regeneration air amount is determined according to the cut-out pressure. When the operating rate of the compressor 4 is high, the cut-out pressure is set high and the regeneration air amount is reduced, so that the execution frequency of the regeneration operation is reduced and the consumption of the compressed dry air stored in the air tank 30 is suppressed, and the supply of the compressed dry air to the air pressure system can be preferentially performed. In addition, when the operating rate of the compressor 4 is low, the cut-out pressure is set low and the regeneration air amount is increased, so that the execution frequency of the regeneration operation can be increased to enhance the effect of the purification filter 17.

(Second embodiment)

A second embodiment is described with reference to fig. 8A-8B and fig. 9. The second embodiment shares the common points with the first embodiment: the standard regeneration air amount and the corrected unit air amount are changed according to the state of the air drying circuit 11, and the regeneration air amount is calculated. In the first embodiment, the standard regeneration air amount and the correction unit air amount are changed according to the cut-out pressure, but in the second embodiment, the standard regeneration air amount and the correction unit air amount are changed according to the temperature of the compressed dry air, which is different from the first embodiment in this point. Therefore, the following mainly describes the structure different from the first embodiment in detail, and for convenience of description, the detailed description of the same structure is omitted.

Fig. 8A is a map 110 in which the standard regeneration air amount Am1 is set according to the limit ventilation amount and the temperature, and the map 110 is stored in the storage unit 80A. The map 100 (see fig. 3) of the first embodiment is different in that the standard regeneration air amount is determined based on the cut-out pressure, whereas the map 110 is determined based on the temperature. The value detected by the temperature sensor 52 can be used for the temperature. Alternatively, a temperature sensor may be provided on the inlet side of the air drying circuit 11 and on the upstream side of the filter 17, so that the temperature detected by the temperature sensor is used. When the limit ventilation is set to be fixed, the standard regeneration air amount Am1 becomes smaller as the temperature decreases and becomes larger as the temperature increases. That is, when the temperature is high, the saturated water vapor amount (saturated water vapor pressure) of air increases, and therefore the water content in the compressed air tends to increase. Accordingly, it is assumed that the amount of moisture trapped by the filter 17 increases, and therefore the standard regeneration air amount Am1 increases, thereby improving the effect of removing moisture from the filter 17 in one regeneration operation. In addition, when the temperature is low, the saturated water vapor amount (saturated water vapor pressure) of the air becomes small, and thus the amount of water contained in the compressed air tends to be small. Accordingly, it is assumed that the amount of moisture trapped by the filter 17 also decreases, and therefore the standard regeneration air amount Am1 is reduced, thereby reducing the amount of compressed dry air consumed by one regeneration operation.

Fig. 8B is a map 111 in which the correction unit air amount Am2 is set according to the limit ventilation amount and the temperature, and the map 111 is stored in the storage unit 80A. Since the corrected unit air amount Am2 is a value subtracted from the standard regenerated air amount Am1, the corrected unit air amount Am2 becomes smaller as the limit ventilation amount becomes larger, as in the standard regenerated air amount Am1, while the corrected unit air amount Am2 becomes smaller as the temperature becomes higher and becomes larger as the temperature becomes lower, when the limit ventilation amount is set to be fixed.

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

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 uses the acquired temperature and map 110 to acquire a standard regeneration air amount (step S114). The ECU 80 also uses the acquired temperature and map 111 to acquire the corrected unit air amount (step S115). Then, the ECU 80 calculates the regeneration air amount using the standard regeneration air amount, the correction unit air amount, and the excess/deficiency coefficient (step S116).

In the second embodiment, the following effects can be obtained.

(5) The ECU 80 sets the amount of regeneration air consumed in the regeneration operation based on the temperature of the compressed air or the temperature of the compressed dry air. When the temperature of the compressed air or the temperature of the compressed dry air increases, the amount of moisture contained in the air increases, and therefore, by changing the amount of the regeneration air according to the amount of moisture contained in the air, it is possible to preferentially perform either one of the supply of the compressed dry air from the air tank 30 to the air pressure system and the purification of the filter 17.

(6) When the temperature of the air is low and the saturated water vapor amount is small, the consumption of the compressed dry air stored in the air tank 30 is suppressed by reducing the regeneration air amount, and the compressed dry air can be preferentially supplied to the air pressure system. In addition, when the temperature of the air is high and the saturated water vapor amount is large, the regeneration air amount can be increased, and the purification of the filter 17 can be performed preferentially.

The above embodiments can be modified and implemented as follows. The above embodiments and the following modifications can be combined and implemented within a range that is not technically contradictory.

In the first embodiment, the regeneration air amount is determined based on the regeneration excess and shortage degree, but the regeneration time may be determined based on the regeneration excess and shortage degree. In this case, the correction regeneration time is calculated by multiplying the correction unit time by the excess and shortage coefficient, and the correction regeneration time is added to the regeneration time as a standard.

In the first embodiment, the regeneration surplus and shortage degree is multiplied by the weighting coefficient to calculate the surplus and shortage coefficient α, but the regeneration surplus and shortage degree itself may be used as the surplus and shortage coefficient α. In this case, the regeneration air amount can be increased or decreased according to the excess or deficiency of the regeneration.

In the first embodiment, the regeneration surplus shortage is an index indicating whether the saturation of the moisture contained in the compressed dry air in the air tank 30 is increasing or decreasing, but instead of the regeneration surplus shortage, humidity may be used as an index. In addition, instead of the regeneration surplus and shortage, a tank containing a moisture amount may be used as an index.

The regeneration surplus and shortage degree of the first embodiment may be an average value obtained by using a plurality of cycles. If the average value is negative, it is estimated that the amount of water in the gas tank 30 is rising, and therefore it is determined that the regeneration air amount is insufficient.

In the first embodiment, the cut-out pressure is set according to the operation rate of the compressor 4, and the standard regeneration air amount and the corrected unit air amount constituting the regeneration air amount are set according to the cut-out pressure. In addition to this, the standard regeneration air amount and the corrected unit air amount may be set using a map or the like that correlates the operation rate of the compressor 4 with the standard regeneration air amount and the corrected unit air amount.

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

In each of the above embodiments, when the wet state of the compressed dry air in the air tank 30 is high, the excess/deficiency coefficient is set to a negative value to increase the regeneration air amount, and when the wet state of the compressed dry air in the air tank 30 is low, the excess/deficiency coefficient is set to a positive value to decrease the regeneration air amount. In addition to this, the amount of regeneration air may be changed by using the wet state of the compressed dry air sent from the compressor 4 and the wet state of the external air.

The regeneration air amount may be determined based on the cut-out pressure and the temperature of the compressed air or the compressed dry air. In this embodiment, a map obtained by correlating the cut-out pressure and temperature with the standard regeneration air amount, a map obtained by correlating the cut-out pressure and temperature with the correction unit air amount, and the like are used.

In each of the above embodiments, the standard regeneration air amount is corrected by the correction amount obtained by multiplying the correction unit air amount by the excess/deficiency coefficient, and the regeneration air amount is calculated. In this case, the map may be a map obtained by correlating the cut-out pressure (or temperature), an index indicating the wet state of the compressed dry air, and the regeneration air amount.

In the above embodiments, the filter 17 includes the oil capturing portion, but the oil capturing portion may be omitted from the filter 17.

The air drying circuit is not limited to the above-described structure. In short, the air drying circuit may be configured to perform the dehumidifying operation and the regenerating operation. Therefore, the air drying circuit is not configured to perform the second operation mode, the fourth operation mode, and the sixth operation mode as necessary.

In the above embodiments, the air supply system 10 was described as a system mounted on a vehicle such as a truck, a bus, or a construction machine. In addition to this, the air supply system 10 may be mounted on another moving body such as a passenger car or a railway vehicle.

The ECU 80 is not limited to software processing for all the processes executed by itself. For example, the ECU 80 may be provided with a dedicated hardware circuit (for example, an application specific integrated circuit: ASIC) that performs hardware processing on at least a part of the processing executed by itself. That is, the ECU 80 may be configured to include the following circuits (circuits): 1) 1 or more processors that operate in accordance with a computer program (software), 2) 1 or more dedicated hardware circuits that perform at least some of the various processes, or 3) combinations thereof. The processor includes a CPU, and memories such as a RAM and a ROM, which store program codes or instructions configured to cause the CPU to execute processing. Memory, i.e., computer-readable media, includes all available media that can be accessed by a general purpose or special purpose computer.

Description of the reference numerals

4: A compressor; 10: an air supply system; 11: an air drying loop; 12: a supply circuit; 15: an upstream one-way valve; 16: a branching path; 17: a filter; 18: an air supply passage; 19: a downstream one-way valve; 20: a bypass flow path; 21: a regeneration control valve; 22: an orifice; 25: a liquid discharge valve; 26A: a regulator; 26B: an unloading control valve; 27: a liquid discharge outlet as an outlet; 30: a gas tank as a reservoir; 50: a pressure sensor; 51: a humidity sensor; 52: a temperature sensor; 53: a pressure sensor; 80: an ECU;80A: a storage unit; e61 to E67: and (5) wiring.

Claims

1. An air supply system is provided with:

An air drying circuit provided between a compressor that sends out compressed air and a storage unit that stores compressed dry air, the air drying circuit having a filter that captures moisture; and

A control device which controls the air drying loop,

Wherein the control device is configured to:

The air drying circuit is controlled to perform a dehumidifying operation of supplying the compressed air sent from the compressor to the reservoir through the filter in a forward direction,

Controlling the air drying circuit to perform a regenerating operation of passing the compressed dry air stored in the storage unit through the filter in a reverse direction to discharge the fluid having passed through the filter from a discharge port,

The amount of regeneration air consumed in one of the regeneration operations is set in accordance with the operation state of the compressor.

2. An air supply system according to claim 1, wherein,

The control device is configured to:

The regeneration air amount is decreased when the operation rate of the compressor is high during a fixed period, and is increased when the operation rate of the compressor is low.

3. An air supply system according to claim 1 or 2, characterized in that,

The control device is configured to:

The regeneration air amount is increased when an index indicating a wet state of the compressed dry air in the storage unit is high, and the regeneration air amount is decreased when an index indicating a wet state of the compressed dry air in the storage unit is low.

4. An air supply system according to claim 1 or 2, characterized in that,

The control device is configured to:

Setting an upper limit pressure for starting the regenerating operation as the pressure of the reservoir to be high when the operation rate of the compressor is high, setting the upper limit pressure to be low when the operation rate of the compressor is low,

The regeneration air amount is decreased when the upper limit pressure is high, and the regeneration air amount is increased when the upper limit pressure is low.

5. An air supply system is provided with:

A control device which controls the air drying loop,

Wherein the control device is configured to:

The amount of regeneration air consumed in one regeneration operation is set according to the temperature of the compressed air or the compressed dry air.

6. An air supply system according to claim 5, wherein,

The control device is configured to:

The regeneration air amount is decreased when the temperature is low, and the regeneration air amount is increased when the temperature is high.

7. A control method for an air supply system is provided with: an air drying circuit provided between a compressor that sends out compressed air and a storage unit that stores compressed dry air, the air drying circuit having a filter that captures moisture; and a control device which controls the air drying circuit,

In the control method of the air supply system,

The control device performs the following processing:

8. A control method for an air supply system is provided with: an air drying circuit provided between a compressor that sends out compressed air and a storage unit that stores compressed dry air, the air drying circuit having a filter that captures moisture; and a control device which controls the air drying circuit,

In the control method of the air supply system,

The control device performs the following processing:

The amount of regeneration air consumed in one regeneration operation is set according to the temperature of the compressed air or the temperature of the compressed dry air.

9. A computer program product comprising a control program for an air supply system, the air supply system comprising: an air drying circuit provided between a compressor that sends out compressed air and a storage unit that stores compressed dry air, the air drying circuit having a filter that captures moisture; and a control device which controls the air drying circuit,

The control program of the air supply system causes the control device to function as:

a dehumidification operation execution unit that controls the air drying circuit to execute a dehumidification operation of supplying the compressed air sent from the compressor to the storage unit by passing the compressed air in a forward direction through the filter;

A regeneration operation execution unit that controls the air drying circuit to execute a regeneration operation of causing the compressed dry air stored in the storage unit to pass through the filter in a reverse direction and discharging the fluid having passed through the filter from a discharge port; and

And a setting unit that sets the amount of regeneration air consumed in one regeneration operation, based on the operation state of the compressor.

10. A computer storage medium storing a control program for an air supply system, the air supply system comprising: an air drying circuit provided between a compressor that sends out compressed air and a storage unit that stores compressed dry air, the air drying circuit having a filter that captures moisture; and a control device which controls the air drying circuit,

11. A computer program product comprising a control program for an air supply system, the air supply system comprising: an air drying circuit provided between a compressor that sends out compressed air and a storage unit that stores compressed dry air, the air drying circuit having a filter that captures moisture; and a control device which controls the air drying circuit,

And a setting unit that sets the amount of regeneration air consumed in one regeneration operation, based on the temperature of the compressed air or the temperature of the compressed dry air.

12. A computer storage medium storing a control program for an air supply system, the air supply system comprising: an air drying circuit provided between a compressor that sends out compressed air and a storage unit that stores compressed dry air, the air drying circuit having a filter that captures moisture; and a control device which controls the air drying circuit,