JP7263049B2 - AIR SUPPLY SYSTEM AND METHOD OF CONTROLLING AIR SUPPLY SYSTEM - Google Patents

Description

The present invention relates to an air supply system and a control method for an air supply system.

2. Description of the Related Art In vehicles such as trucks, buses, and construction machines, pneumatic systems such as brake systems and suspension systems are controlled using compressed air sent from compressors. This compressed air contains liquid impurities such as moisture contained in the atmosphere and oil that lubricates the inside of the compressor. If compressed air containing a large amount of water or oil enters the pneumatic system, it may cause rust and swelling of rubber members, resulting in malfunction. For this reason, a compressed air drying device for removing impurities such as moisture and oil from the compressed air is provided downstream of the compressor.

Compressed air dryers are equipped with desiccants and various valves. The compressed air dryer performs load operation (dehumidification operation) to remove moisture and the like. Compressed dry air generated by the dehumidifying operation is stored in the reservoir. In addition, the cleaning function of the compressed air drying device deteriorates according to the amount of compressed dry air passing through it. For this reason, the compressed air drying device performs an unloading operation (regenerating operation) in which the oil and moisture absorbed by the desiccant is removed and the removed oil and moisture is discharged as drain (see, for example, Patent Document 1).

Japanese Unexamined Patent Application Publication No. 2010-201323

By the way, the compressed air drying device switches between the dehumidifying operation and the regeneration operation based on the pressure in the reservoir, but there is a possibility that different pressure values may be detected in the pneumatic system in which a plurality of pressure sensors are arranged. Therefore, optimum control using a plurality of detected pressures is desired.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and an object of the present invention is to provide an air supply system and a method of controlling the air supply system that are capable of optimal control using a plurality of detected pressures.

An air supply system for solving the above problems includes an air drying circuit having a filter containing a desiccant that captures moisture and provided between a compressor that delivers compressed air and an air tank that stores compressed dry air, and the air drying circuit. The control device includes a supply operation in which the compressor is driven to send the compressed air to the filter and is supplied to the air tank, and pressure values obtained from a plurality of pressure sensors The supply operation is executed when the minimum pressure value among them reaches the cut-in pressure for performing the supply operation.

The cut-in pressure at which the supply operation is performed indicates that the compressed dry air in the air tank is low. Therefore, according to the above configuration, control is performed with the minimum pressure value among the pressure values obtained from the plurality of pressure sensors. Therefore, the supply operation can be started earlier than when the higher pressure value among the plurality of pressure values is used, and the supply of compressed dry air to the air tank can be started earlier. Therefore, optimum control using a plurality of detected pressures is possible.

For the above air supply system, the controller comprises a regeneration operation of passing the compressed dry air through the filter in a reverse direction and discharging the fluid that has passed through the filter through an outlet, wherein the minimum pressure value reaches the regeneration Preferably, said regeneration action is performed when a cut-out pressure for action is reached.

The cutout pressure at which the regenerative action takes place is an indication that the air tank is full of compressed dry air. Therefore, according to the above configuration, control is performed with the minimum pressure value among the pressure values obtained from the plurality of pressure sensors. Therefore, it is possible to start the regeneration operation later than using the higher pressure value among the plurality of pressure values, in other words, it is possible to secure a longer supply time. Therefore, optimum control using a plurality of detected pressures is possible.

Preferably, for the air supply system, the controller performs the regeneration operation when the minimum pressure value reaches the cutout pressure and the dryness of the compressed dry air does not meet a predetermined value.

If the compressed dry air is supplied and consumed and the cutout pressure is not reached and the compressed dry air continues to be supplied, the drying capacity of the filter is reduced. Therefore, according to the above configuration, when the cutout pressure is not reached and the dryness of the compressed dry air does not satisfy the predetermined value, the regeneration operation is performed to regenerate the desiccant and restore the dryness of the compressed dry air. can be maintained.

In the above air supply system, the control device includes a purge operation of causing the compressed dry air of the air drying circuit to pass through the filter in the reverse direction and discharging the fluid that has passed through the filter from the discharge port, Preferably, the purge operation is performed when the minimum pressure value reaches the cutout pressure and the dryness of the compressed dry air satisfies a predetermined value.

According to the above configuration, when the dry state of the compressed dry air satisfies the predetermined value, the compressed dry air in the air drying circuit is passed through the filter in the reverse direction instead of the regeneration operation in which the compressed dry air in the air tank passes through the filter in the reverse direction. Perform a purge operation to pass. Therefore, consumption of compressed dry air in the air tank can be suppressed.

In the above air supply system, a discharge valve that communicates a branch passage connected to the air drying circuit with a discharge port, and a forward flow from the filter toward the air tank and a reverse flow from the air tank toward the filter. and a regeneration control valve for switching between and, wherein the control device preferably controls the discharge valve and the regeneration control valve. According to the above configuration, the supply operation and the regeneration operation can be performed by the controller controlling the discharge valve and the regeneration control valve.

A method of controlling an air supply system for solving the above problems includes an air drying circuit having a filter containing a desiccant that captures moisture and provided between a compressor that delivers compressed air and an air tank that stores compressed dry air; and a control device for controlling an air drying circuit, wherein the control device performs a supply operation in which the compressor is driven so that the compressed air is delivered to the filter and supplied to the air tank. Sometimes, the dry state of the compressed dry air stored in the air tank is determined from the water content, the compressed dry air is passed through the filter in the reverse direction, and the fluid that has passed through the filter is discharged from the discharge port. Decide whether to perform the action.

According to the above method, during the supply operation, the dry state of the compressed dry air is determined from the water content to determine whether or not to perform the regeneration operation. Therefore, the regeneration operation is performed when the desiccant regeneration is insufficient due to the supply operation being performed. Therefore, the dry state of the compressed dry air can be maintained.

According to the present invention, drying of compressed air can be accurately controlled by pressure.

1 is a configuration diagram showing a schematic configuration of an embodiment of an air supply system; FIG. FIG. 4 is a diagram showing operation modes of the air drying circuit of the same embodiment, wherein (a) is a diagram showing the first operation mode and the seventh operation mode, (b) is a diagram showing the second operation mode, and (c) is a diagram showing the second operation mode. FIG. 11 shows a third operation mode and an eighth operation mode, (d) shows a fourth operation mode, (e) shows a fifth operation mode, and (f) shows a sixth operation mode. The transition diagram which shows the transition of the operation|movement of the air drying circuit of the same embodiment. 4 is a flowchart showing transition from the first operation mode of the air drying circuit of the same embodiment; 4 is a flowchart showing transitions from the second operation mode and the third operation mode of the air drying circuit of the same embodiment; 4 is a flowchart showing transition from the fifth operation mode of the air drying circuit of the same embodiment; 4 is a flowchart showing transition from the seventh operation mode of the air drying circuit of the same embodiment; 4 is a flowchart showing transition from the eighth operation mode of the air drying circuit of the same embodiment;

One embodiment of an air supply system will be described with reference to FIGS. 1-8. Air supply systems are mounted on vehicles such as trucks, buses, and construction machines. Compressed dry air supplied by an air supply system is used in pneumatic equipment such as a brake system mounted on a vehicle.

<Configuration of Air Supply System 10>
The configuration of the air supply system 10 will be described with reference to FIG. The air supply system 10 includes a compressor 4, an air drying circuit 11, and an ECU (Electronic Control Unit) 80 as a controller.

In the air supply system 10, the ECU 80 is connected to a plurality of wirings E61 to E66. The ECU 80 includes an arithmetic section, a communication interface section, a volatile storage section, and a nonvolatile storage section. The calculation unit is a computer processor, and controls the air drying circuit 11 according to an air supply program stored in a nonvolatile storage unit (storage medium). The arithmetic unit may realize at least a part of the processing that it executes by a circuit such as an ASIC. The air supply program may be executed by one computer processor or may be executed by a plurality of computer processors. The ECU 80 also includes a storage section 80A that stores the operation results of the air drying circuit 11 . The storage unit 80A is a non-volatile storage unit or a volatile storage unit, and may be the same as or different from the storage unit storing the control program.

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

The compressor 4 is switched between an operating state (load operation) in which air is compressed and delivered, and a non-operating state (idle operation) in which air is not compressed, based on a command value from the ECU 80 . The compressor 4 operates 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 during load operation. The air drying circuit 11 delivers 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 . The supply circuit 12 branches into a first supply circuit 12A and a second supply circuit 12B. A first air tank 30A for the front brake is connected to the first supply circuit 12A, and a second air tank 30B for the rear brake is connected to the second supply circuit 12B.

The compressed dry air stored in the air tank 30 is supplied to pneumatic equipment such as a brake system mounted on the vehicle. For example, when the brakes are operated frequently, such as when the vehicle is traveling on a downhill road or in an urban area, the amount of compressed dry air stored in the air tank 30 is increased. Conversely, when the frequency of brake operation is low, the amount of compressed dry air stored in the air tank 30 is reduced.

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.

<Configuration of air drying circuit 11>
The air drying circuit 11 has a filter 17 inside 11A (see FIG. 2) such as a case. Filter 17 is provided in the middle of air supply passage 18 connecting compressor 4 and supply circuit 12 . Note that the filter 17 contains a desiccant. In addition, the filter 17 may include an oil-capturing portion that captures oil separately from the desiccant. The oil-capturing part may be a foam such as urethane foam, a metal material having a large number of air holes, a glass fiber filter, etc., as long as it can capture oil while allowing air to pass through.

The filter 17 allows the compressed air sent from the compressor 4 to pass through a desiccant to remove moisture contained in the compressed air and dry it. In addition, the desiccant or the oil trapping part traps the oil contained in the air and cleans it. The air that has passed through the filter 17 is supplied to the supply circuit 12 side via a downstream check valve 19 as a check valve that allows only the flow of air downstream from the filter 17 . In other words, the downstream check valve 19 allows air to flow only from the upstream side to the downstream side when the filter 17 side is the upstream side and the supply circuit 12 side is the downstream side. Since the downstream check valve 19 has a predetermined valve opening pressure (sealing pressure), when compressed air flows, the upstream pressure is higher than the downstream pressure by the valve opening pressure.

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

The regeneration control valve 21 is an electromagnetic valve whose operation is switched by power on/off (drive/non-drive) from the ECU 80 via the wiring E64. The regeneration control valve 21 is closed to seal the bypass channel 20 when the power is off, and is opened to communicate the bypass channel 20 when the power is on. 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.

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 while the flow rate is regulated by the orifice 22 . The compressed dry air sent to the filter 17 flows back through the filter 17 from the downstream side to the upstream side of the filter 17 . Such processing is an operation for regenerating the filter 17, and is called a regeneration operation of the dryer. At this time, the compressed dry air sent to the filter 17 is dried and cleaned air supplied to the supply circuit 12 from the air supply passage 18 through the filter 17 and the like. and oil is 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 in the air tank 30 reaches the lower limit (cut-in pressure), the open regeneration control valve 21 is closed.

A branch passage 16 connected to a drain discharge valve 25 is provided between the compressor 4 and the filter 17 . A drain outlet 27 is provided at the end of the branch passage 16 .
The drain containing 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 a pneumatically driven valve, and is provided between the filter 17 and the drain discharge port 27 in the branch passage 16 of the air supply passage 18 . The drain discharge valve 25 is a two-port, two-position valve that changes positions between a closed position and an open position. The drain discharge valve 25 sends the drain to the drain discharge port 27 in the open position. The drain discharged from the drain outlet 27 may be collected by an oil separator (not shown). Note that the drain corresponds to the fluid that has passed through the filter 17 in the reverse direction.

Drain discharge valve 25 is controlled by governor 26A. The governor 26A is an electromagnetic valve whose operation is switched by turning on/off (driving/non-driving) the power from the ECU 80 via the wiring E63. When the power is turned on, the governor 26A opens the drain discharge valve 25 by inputting an air pressure signal to the drain discharge valve 25 . Further, when the power is turned off, the governor 26A closes the drain valve 25 by setting the pressure to the atmospheric pressure without inputting the air pressure signal to the drain valve 25 .

The drain discharge valve 25 is maintained at the closed position when no pneumatic signal is input from the governor 26A, and becomes the open position when the pneumatic signal is input from the governor 26A. Further, when the input port of the drain discharge valve 25 on the compressor 4 side exceeds the upper limit value and becomes high pressure, the drain discharge valve 25 is forcibly switched to the open 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 . The upstream check valve 15 allows air to flow only from upstream to downstream when the compressor 4 side is upstream and the filter 17 side is downstream. Since the upstream check valve 15 has a predetermined valve opening pressure (sealing pressure), when compressed air flows, the upstream pressure is higher than the downstream pressure by the valve opening pressure. A reed valve at the outlet of the compressor 4 is provided upstream of the upstream check valve 15, and a branch passage 16 and a filter 17 are provided downstream thereof.

<Compressor 4>
The compressor 4 is controlled by an unload control valve 26B. The unload control valve 26B is a solenoid valve, and is operated in response to turning on/off (driving/non-driving) the power from the ECU 80 via the wiring E62. When the power is turned off, the unload control valve 26B is in the open position to open the flow path between the compressor 4 to the atmosphere. Also, when the power is turned on, the unload control valve 26B is in the supply position and sends an air pressure signal consisting of compressed air to the compressor 4 .

The compressor 4 enters a non-operating state (idle operation) when an air pressure signal is input from the unload control valve 26B. For example, when the pressure in the supply circuit 12 reaches the cutout pressure, no supply of compressed dry air is required. The unload control valve 26B becomes the supply position when the pressure on the supply circuit 12 side reaches the cutout pressure and the power is turned on (driven) from the ECU 80 . As a result, an air pressure signal is supplied from the unload control valve 26B to the compressor 4, and the compressor 4 is put into a non-operating state.

<Sensor>
A pressure sensor 50 is provided between the compressor 4 and the upstream check valve 15 . The pressure sensor 50 measures the air pressure of the connected air supply passage 18 and transmits the measured result to the ECU 80 via the wiring 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 measures the humidity of the compressed dry air downstream of the filter 17 and outputs the measured result to the ECU 80 via the wiring E65. The temperature sensor 52 measures the temperature of the compressed dry air downstream of the filter 17 and outputs the measured result to the ECU 80 via the line E66. The ECU 80 determines the dryness of the compressed dry air based on the input humidity and temperature of the compressed dry air.

The ECU 80 calculates the amount of water contained in the supplied air from the humidity and temperature when the compressed dry air is supplied to the air tank 30, and calculates the reference amount of water contained in the tank air from the humidity and temperature at the time of regeneration in which the compressed dry air flows back from the air tank 30. Calculate The water content in the tank air is determined by equation (1). The amount of water contained in the supplied air is the amount of water supplied to the air tank 30 at the time of supply, and can be calculated from humidity, temperature, and the amount of supplied air between supply cycles. The tank air moisture content reference amount is the amount of moisture present in the air tank 30 when the moisture content is updated, and can be calculated from the humidity and temperature at the time of regeneration or the tank air moisture content. The amount of water contained in the consumed air is the amount of water delivered from the air tank 30 due to consumption, and can be calculated from the amount of water contained in the tank air and the amount of air consumed between consumption cycles.

(Water content in tank air) = (standard water content in tank air) + (variation in water content in tank air) (1)
(Moisture content change in tank air) = (Water content in supplied air) - (Water content in consumed air)

A first pressure sensor 53 , a second pressure sensor 54 and a third pressure sensor 55 are provided between the downstream check valve 19 and the supply circuit 12 . The first pressure sensor 53 is provided so as to be able to detect the air pressure in the unbranched portion of the supply circuit 12, and is connected to the ECU 80 via the wiring E67. The second pressure sensor 54 is provided so as to detect the air pressure of the branched first supply circuit 12A, and is connected to the ECU 80 via the wiring E68. The third pressure sensor 55 is provided so as to detect the air pressure of the branched second supply circuit 12B, and is connected to the ECU 80 via the wiring E69. The detection result of the second pressure sensor 54 can be used as the pressure inside the first air tank 30A, and the detection result of the third pressure sensor 55 can be used as the pressure inside the second air tank 30B.

The ECU 80 acquires the pressure values detected by the first pressure sensor 53, the second pressure sensor 54, and the third pressure sensor 55, and controls the air drying circuit 11 using the minimum pressure value among the acquired pressure values. I do.

<Description of the operation of the air drying circuit 11>
As shown in FIG. 2, the operation modes of the air drying circuit 11 include eight operation modes, first to eighth.

(First operation mode)
As shown in FIG. 2(a), the first operation mode is a mode in which a "supply" operation for normal dehumidification (loading) is performed. This first operation mode is a mode in which the regeneration control valve 21, the governor 26A, and the unload control valve 26B are each closed (denoted 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 port of the compressor 4 and the port of the drain discharge valve 25, which are connected downstream thereof, to the atmosphere. In the first operation mode, when compressed air is being supplied from the compressor 4 (denoted as "ON" in the figure), the filter 17 removes moisture and the like, and the compressed air is supplied to the supply circuit 12. FIG.

(Second operation mode)
As shown in FIG. 2(b), the second operation mode is a mode in which the compressed dry air in the air drying circuit 11 is passed through the filter 17 to purify the filter 17 in a "purge" operation. In this second operation mode, the regeneration control valve 21 is closed, and the governor 26A and the unload control valve 26B are opened (denoted as "OPEN" in the figure). At this time, power is supplied to the governor 26A and the unload control valve 26B, respectively, and the port of the compressor 4 and the port of the drain discharge valve 25, which are connected downstream thereof, are directed upstream (to the supply circuit 12 side). Connecting. As a result, the compressor 4 is put into a non-operating state (denoted as "OFF" in the drawing), 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 a direction opposite to the air flow in the first mode of operation (supply) (counterflow), causing the moisture trapped by the filter 17 to etc. are discharged from the drain outlet 27 as drain. Also, the air pressure in the filter 17 and the air supply passage 18 is set to the atmospheric pressure.

(Third operation mode)
As shown in FIG. 2(c), the third operation mode is a mode in which a "regeneration" operation for regenerating the filter 17 is performed. In this third operation mode, the regeneration control valve 21, the governor 26A, and the unload control valve 26B are each opened. At this time, power is also supplied to the regeneration control valve 21 . In the third operation mode, the compressor 4 is put into a non-operating state, and the compressed dry air stored in the supply circuit 12 or the air tank 30 is reversed to the filter 17 and discharged from the drain outlet 27 to be captured by the filter 17. remove any moisture, etc. Both the second operation mode and the third operation mode are modes for cleaning the filter 17, but the third operation mode differs from the second operation mode in that at least the regeneration control valve 21 is opened. Accordingly, in the third operation mode, the compressed dry air in the air tank 30 can be passed through the filter 17 via the supply circuit 12 and the bypass flow path 20, so that the effect of purifying the filter 17 is higher. . Also in the third operation mode, the air pressure in the filter 17 and the air supply passage 18 is set to the atmospheric pressure.

(Fourth operation mode)
As shown in FIG. 2(d), the fourth operation mode is a mode in which an "oil cut" operation is performed in which the compressed air supplied from the compressor 4 is discharged while the compressor 4 is being operated. When the compressor 4 is in a non-operating state, oil may accumulate in the compression chamber. If the compressor 4 is switched to the operating state with oil remaining in the compression chamber, the amount of oil contained in the compressed air sent from the compression chamber may increase. The oil cut operation is performed for the purpose of discharging this excessively oily compressed air through the drain discharge valve 25 in order to reduce the load on the filter 17 . In this fourth operation mode, the regeneration control valve 21 and the unload control valve 26B are closed, and the governor 26A is closed after being opened for a certain period of time. The fourth operation mode causes the compressed air supplied by the compressor 4 to be discharged from the drain outlet 27 for a certain period of time when the compressor 4 is in operation. Therefore, it is possible to suppress an increase in the amount of water captured and the amount of oil captured by the filter 17 immediately after the compressor 4 is switched from the non-operating state to the operating state. When the number of engine revolutions increases during operation, or when the amount of oil from the compressor 4 increases due to a high load on the engine, etc., an oil cut operation can be performed.

(Fifth operation mode)
As shown in FIG. 2(e), the fifth operation mode is a mode in which a "purgeless supply stop" operation is performed to stop the compressor 4 without purging. In this fifth operation mode, the regeneration control valve 21 and the governor 26A are each closed, and the unload control valve 26B is opened. In the fifth operation mode, when the compressor 4 is not in operation, the compressed air or compressed dry air remaining in the desiccant in the air supply passage 18 or the filter 17 is not discharged from the drain outlet 27 to maintain the air pressure. .

(Sixth operation mode)
As shown in FIG. 2(f), the sixth operation mode is a mode in which a "compressor assist" operation for pressurization is performed. In this sixth operation mode, the regeneration control valve 21 and the unload control valve 26B are each opened, and the governor 26A is closed. In the sixth operation mode, when the compressor 4 is not in operation, the compressed air in the supply circuit 12 is supplied (reversely flows) into the desiccant in the air supply passage 18 and the filter 17 to make the pressure higher than the atmospheric pressure. , to maintain the back pressure (air pressure) of the upstream check valve 15 at a pressure higher than the atmospheric pressure. Therefore, it is possible to suppress the generation of negative pressure in the cylinder and to reduce the operating load of the compressor 4 which is idle. Specifically, when the compressor 4 is running idle, the drain discharge valve 25 is closed, and the compressed air supplied by the compressor 4 reduces the air pressure in the desiccant in the filter 17 and in the air supply passage 18 to atmospheric pressure. Maintain higher pressure.

(Seventh operation mode)
As shown in FIG. 2(a), the seventh operation mode is a mode in which a "regenerative supply" operation is performed in which dehumidification (loading) is performed during regeneration when the compressor 4 is driven while the engine is in an unloaded state. The seventh operation mode is a mode in which the regeneration control valve 21, the governor 26A, and the unload control valve 26B are each closed (denoted as "CLOSE" in the figure), similarly to the first operation mode.

(Eighth operation mode)
As shown in FIG. 2(c), the eighth operation mode is a mode in which a "forced regeneration" operation for forcibly regenerating the filter 17 is performed. In this eighth operation mode, the regeneration control valve 21, the governor 26A, and the unload control valve 26B are each opened as in the third operation mode.

(Transition of operation mode)
As shown in FIG. 3, the eight operation modes of the air drying circuit 11 are changed based on each determination made by the ECU 80. FIG.

Transition from each operation mode will be described with reference to FIGS. 4 to 8. FIG.
The ECU 80 performs a supply step of supplying the compressed air output from the compressor 4 to the supply circuit 12 . The supply process is initiated under conditions such as when the engine is started. In the supply step, the air drying circuit 11 is in supply (first operation) mode M1.

As shown in FIG. 4, in the supply (first operation) mode M1, the ECU 80 determines whether or not the pressure in the supply circuit 12 is higher than the cutout pressure (step S11). That is, the ECU 80 acquires pressure values detected by the first pressure sensor 53, the second pressure sensor 54, and the third pressure sensor 55, and determines whether or not the minimum pressure value has reached the cutout pressure.

Then, when the ECU 80 determines that the pressure in the supply circuit 12 has reached the cutout pressure (step S11: YES), it determines whether the water content in the air tank 30 is large (step S12). That is, the ECU 80 determines the moisture content of the air tank 30 because it is necessary to regenerate the desiccant in the filter 17 when the moisture content of the air tank 30 is equal to or greater than a predetermined value.

Then, when the ECU 80 determines that the amount of moisture in the air tank 30 is equal to or greater than the predetermined value (step S12: YES), the regeneration (regenerating (regenerating) for regenerating the desiccant in the filter 17 by passing the compressed dry air stored in the air tank 30 through the filter 17) is performed. Third operation) Transition to mode M3.

Further, when the ECU 80 determines that the amount of moisture in the air tank 30 is less than the predetermined value (step S12: NO), the compressed dry air between the downstream check valve 19 and the filter 17 is allowed to pass through the filter 17 and captured by the filter 17. In this mode, a purge (second operation) mode M2 is entered in which the water and the like that have been removed are discharged from the drain outlet 27 as drain.

On the other hand, when the ECU 80 determines that the pressure in the supply circuit 12 has not reached the cutout pressure (step S11: NO), it determines whether or not the conditions for shifting to the oil cut (fourth operation) mode M4 are satisfied. Determine (step S13). That is, the ECU 80 determines whether all of the following conditions for shifting to the oil cut (fourth operation) mode M4: elapse of a predetermined period of time, less than a specified number of oil cuts, and a low operating rate of the compressor 4 are satisfied. determine whether or not When the ECU 80 determines that the condition for shifting to the oil cut (fourth operation) mode M4 is not satisfied (step S13: NO), the process shifts to step S11.

On the other hand, when the ECU 80 determines that the conditions for shifting to the oil cut (fourth operation) mode M4 are satisfied (step S13: YES), the compressor 4 is operated and the compressed air supplied from the compressor 4 is discharged. It shifts to the oil cut (fourth operation) mode M4.

In the oil cut (fourth operation) mode M4, the ECU 80 determines whether or not a predetermined time has passed (step S14). That is, the ECU 80 performs the oil cut (fourth operation) mode M4 for a predetermined time. When the ECU 80 determines that the predetermined time has elapsed (step S14: YES), the ECU 80 shifts to the supply (first operation) mode M1.

As shown in FIG. 5, in the purge (second operation) mode M2 and the regeneration (third operation) mode M3, the ECU 80 determines whether or not a predetermined time has passed (step S21). That is, the ECU 80 performs the purge (second operation) mode M2 and the regeneration (third operation) mode M3 for a predetermined time.

When the ECU 80 determines that the predetermined time has not elapsed (step S21: NO), it determines whether the pressure in the supply circuit 12 is lower than the cut-in pressure (step S24). That is, the ECU 80 acquires the pressure values detected by the first pressure sensor 53, the second pressure sensor 54, and the third pressure sensor 55, and determines whether or not the minimum pressure value has reached the cut-in pressure.

When the ECU 80 determines that the pressure in the supply circuit 12 has reached the cut-in pressure (step S24: YES), the supply (first operation) mode M1 is entered because the compressed dry air is insufficient. On the other hand, when the ECU 80 determines that the pressure in the supply circuit 12 has not reached the cut-in pressure (step S24: NO), the process proceeds to step S21.

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

When the ECU 80 determines that the compressor assist (sixth operation) process is disabled (step S22: NO), the ECU 80 shifts to a purgeless supply stop (fifth operation) mode M5 in which the compressor 4 is stopped without purging.

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

In the compressor assist (sixth operation) mode M6, the ECU 80 determines whether or not a predetermined time has passed (step S23). That is, the ECU 80 performs the compressor assist (sixth operation) mode M6 for a predetermined time. When the ECU 80 determines that the predetermined time has elapsed (step S23: YES), the ECU 80 shifts to the purgeless supply stop (fifth operation) mode M5.

As shown in FIG. 6, in the purgeless supply stop (fifth operation) mode M5, the ECU 80 determines whether or not the pressure in the supply circuit 12 is lower than the cut-in pressure (step S31). That is, the ECU 80 acquires the pressure values detected by the first pressure sensor 53, the second pressure sensor 54, and the third pressure sensor 55, and determines whether or not the minimum pressure value has reached the cut-in pressure.

When the ECU 80 determines that the pressure in the supply circuit 12 has reached the cut-in pressure (step S31: YES), the supply (first operation) mode M1 is entered because the compressed dry air is insufficient.

On the other hand, when the ECU 80 determines that the pressure in the supply circuit 12 has not reached the cut-in pressure (step S31: NO), it determines whether or not the condition for shifting to the regenerative supply (seventh operation) mode M7 is satisfied. (step S32). That is, the ECU 80 determines whether or not the vehicle is running, there is no fuel consumption, and the pressure in the supply circuit 12 is less than the threshold as conditions for shifting to the regenerative supply (seventh operation) mode M7. judge. When the ECU 80 determines that the conditions for shifting to the regenerative supply (seventh operation) mode M7 are not satisfied (step S32: NO), the ECU 80 shifts to step S31.

On the other hand, when the ECU 80 determines that the condition for shifting to the regenerative supply (seventh operation) mode M7 is satisfied (step S32: YES), the regenerative supply (seventh operation) mode M7 performs dehumidification (loading) during regeneration. transition to

As shown in FIG. 7, in the regenerative supply (seventh operation) mode M7, the ECU 80 determines whether or not conditions for transition to the purgeless supply stop (fifth operation) mode M5 are satisfied (step S41). That is, the ECU 80 sets at least one of the following conditions for shifting to the purgeless supply stop (fifth operation) mode M5: the pressure in the supply circuit 12 is higher than the cutout pressure, the predetermined time has passed, and the fuel consumption of the engine is high. It is determined whether or not one is established. When the ECU 80 determines that the conditions for shifting to the purgeless supply stop (fifth operation) mode M5 are satisfied (step S41: YES), the ECU 80 shifts to the purgeless supply stop (fifth operation) mode M5.

On the other hand, when the ECU 80 determines that the condition for shifting to the purgeless supply stop (fifth operation) mode M5 is not satisfied (step S41: NO), it determines whether the pressure in the supply circuit 12 is lower than the cut-in pressure. Determine (step S42). That is, the ECU 80 acquires the pressure values detected by the first pressure sensor 53, the second pressure sensor 54, and the third pressure sensor 55, and determines whether or not the minimum pressure value has reached the cut-in pressure.

When the ECU 80 determines that the pressure in the supply circuit 12 has reached the cut-in pressure (step S42: YES), the supply (first operation) mode M1 is entered because the compressed dry air is insufficient.

On the other hand, when the ECU 80 determines that the pressure in the supply circuit 12 has not reached the cut-in pressure (step S42: NO), it determines whether or not the conditions for shifting to the forced regeneration (eighth operation) mode M8 are satisfied. Determine (step S43). That is, the ECU 80 determines whether all of the conditions for shifting to the forced regeneration (eighth operation) mode M8, that is, the pressure in the supply circuit 12 is higher than the threshold value and the water content in the air tank 30 is large, are satisfied. do. In the regenerative supply (seventh operation) mode M7, the ECU 80 determines the dryness of the compressed dry air based on the amount of water contained in the tank air in the air tank 30 . The ECU 80 determines that the water content in the air tank 30 is high when the water content in the tank air is equal to or greater than a predetermined value, and determines that the water content in the air tank 30 is low when the water content in the tank air is less than the predetermined value. When the ECU 80 determines that the conditions for shifting to the forced regeneration (eighth operation) mode M8 are not satisfied (step S43: NO), the process proceeds to step S42.

On the other hand, when the ECU 80 determines that the conditions for shifting to the forced regeneration (eighth operation) mode M8 are satisfied (step S43: YES), the ECU 80 enters the forced regeneration (eighth operation) mode M8 in which the filter 17 is forcibly regenerated. transition to The ECU 80 executes a forced regeneration (eighth operation) mode M8 in which compressed dry air flows in the reverse direction when the determination result that the water content is high and other conditions are satisfied.

As shown in FIG. 8, in the forced regeneration (eighth operation) mode M8, the ECU 80 determines whether or not a predetermined time has passed (step S51). That is, the ECU 80 performs the forced regeneration (eighth operation) mode M8 for a predetermined time.

When the ECU 80 determines that the predetermined time has not elapsed (step S51: NO), it determines whether the pressure in the supply circuit 12 is lower than the cut-in pressure (step S55). That is, the ECU 80 acquires the pressure values detected by the first pressure sensor 53, the second pressure sensor 54, and the third pressure sensor 55, and determines whether or not the minimum pressure value has reached the cut-in pressure.

When the ECU 80 determines that the pressure in the supply circuit 12 has reached the cut-in pressure (step S55: YES), the supply (first operation) mode M1 is entered because the compressed dry air is insufficient. On the other hand, when the ECU 80 determines that the pressure in the supply circuit 12 has not reached the cut-in pressure (step S55: NO), the process proceeds to step S51.

On the other hand, when the ECU 80 determines that the predetermined time has passed (step S51: YES), it determines whether the operating rate of the compressor 4 is high (step S52). That is, the ECU 80 determines whether or not the load when the compressor 4 is driven is high by checking the operation rate of the compressor 4 .

Then, when the ECU 80 determines that the operating rate of the compressor 4 is high (step S52: YES), the compressor assist (sixth operation) is unnecessary, so the mode shifts to the supply (first operation) mode M1.

On the other hand, when the ECU 80 determines that the operating rate of the compressor 4 is low (step S52: NO), it determines whether or not the compressor assist (sixth operation) process is enabled in order to perform the compressor assist (sixth operation). (Step S53).

When the ECU 80 determines that the compressor assist (sixth operation) process is disabled (step S53: NO), the ECU 80 shifts to the purgeless supply stop (fifth operation) mode M5. When the ECU 80 determines that the compressor assist (sixth operation) process is enabled (step S53: YES), the ECU 80 shifts to the compressor assist (sixth operation) mode M6.

In the compressor assist (sixth operation) mode M6, the ECU 80 determines whether or not a predetermined time has passed (step S54). That is, the ECU 80 performs the compressor assist (sixth operation) mode M6 for a predetermined time. When the ECU 80 determines that the predetermined time has elapsed (step S54: YES), the ECU 80 shifts to the purgeless supply stop (fifth operation) mode M5.

Next, the effects of this embodiment will be described.
(1) Control is performed with the minimum pressure value among the pressure values acquired from the first pressure sensor 53, the second pressure sensor 54, and the third pressure sensor 55; Therefore, the supply (first operation) can be started earlier than when the higher pressure value among the plurality of pressure values is used, and the compressed dry air can be started to be supplied to the air tank 30 earlier. Therefore, optimum control using a plurality of detected pressures is possible.

(2) Control with the minimum pressure value among the pressure values acquired from the first pressure sensor 53, the second pressure sensor 54, and the third pressure sensor 55; Therefore, the regeneration (third operation) can be started later than when the higher pressure value among the plurality of pressure values is used, in other words, a longer supply time can be ensured. Therefore, optimum control using a plurality of detected pressures is possible.

(3) When the cutout pressure is not reached and the dry state of the compressed dry air does not satisfy a predetermined value, regeneration (third operation) is performed to regenerate the desiccant and maintain the dry state of the compressed dry air. can do.

(4) When the dry state of the compressed dry air satisfies a predetermined value, the compressed dry air in the air drying circuit 11 is filtered instead of the regeneration (third operation) in which the compressed dry air in the air tank 30 is passed through the filter 17 in the reverse direction. 17 in the opposite direction to purge (second operation). Therefore, consumption of compressed dry air in the air tank 30 can be suppressed.

(5) By controlling the drain discharge valve 25 and the regeneration control valve 21 by the ECU 80, supply (first operation), purge (second operation), and regeneration (third operation) can be performed.
(Other embodiments)

The above embodiment can be implemented with the following modifications. The above embodiments and the following modifications can be combined with each other within a technically consistent range.
- In the above embodiment, the supply circuit 12 may be further provided with another pressure sensor, and the minimum pressure value may be used for determination.

- In the above-described embodiment, the first pressure sensor 53, the second pressure sensor 54, and the third pressure sensor 55 are provided, and the minimum value of these detected pressures is used for determination. However, only any two sensors may be provided and a low pressure value may be used for determination.

In the above embodiment, the water content in the tank air is calculated from the reference water content in the tank air, the amount of change in the water content in the tank air, and the like. However, the dryness of the compressed dry air may be determined by estimating the water content in the tank air from the humidity and temperature of the compressed dry air in the air tank 30 .

・In the above embodiment, purge (second operation) mode M2, regeneration (third operation) mode M3, oil cut (fourth operation) mode M4, compressor assist (sixth operation) mode M6, regenerative supply (seventh operation) ) Mode M7 and forced regeneration (eighth operation) mode M8 are performed for a predetermined time. However, the predetermined time in each mode may be set arbitrarily.

In step S13 of the above embodiment, the transition to the oil cut (fourth operation) mode M4 is made when all the conditions for transition to the oil cut (fourth operation) mode M4 are satisfied, but even if the transition is made when at least one of the transition conditions is satisfied, good. That is, in step S13, the ECU 80 sets at least one of the elapse of a predetermined time period, the number of oil cuts performed less than a specified number, and the low operating rate of the compressor 4 as conditions for shifting to the oil cut (fourth operation) mode M4. It is determined whether or not one is established.

In step S32 of the above embodiment, the transition to the regenerative supply (seventh operation) mode M7 occurs when all the conditions for transitioning to the mode M7 are satisfied. good. That is, in step S32, the ECU 80 determines that at least one of the vehicle is running, the fuel is not consumed, and the pressure of the supply circuit 12 is less than the threshold value is satisfied as a transition condition to the regenerative supply (seventh operation) mode M7. determine whether or not

In step S42 of the above-described embodiment, the transition to the forced regeneration (eighth operation) mode M8 was made when all the conditions for transition were satisfied, but at least the moisture content of the air tank 30 is large, but the transition condition is satisfied. May migrate at times. That is, in step S42, the ECU 80 determines whether or not the water content in the air tank 30 is large as a condition for shifting to the forced regeneration (eighth operation) mode M8.

- In the above-described embodiment, the filter 17 is configured to include an oil trapping portion, but this may be omitted.
- In the above embodiment, the air drying circuit is not limited to the configuration described above. The air drying circuit may be configured so as to be capable of executing supply (first operation) mode M1, purge (second operation) mode M2, and regeneration (third operation) mode M3. Therefore, the air drying circuit operates in oil cut (fourth operation) mode M4, purgeless supply stop (fifth operation) mode M5, compressor assist (sixth operation) mode M6, regenerative supply (seventh operation) mode M7, and forced regeneration. (Eighth operation) Mode M8 is not an essential operation.

- In the above embodiment, the purge (second operation) mode M2 may be omitted.
- In the above-described embodiment, the air supply system 10 is described as being mounted on a vehicle such as a truck, a bus, or a construction machine. Alternatively, the air supply system may be installed in other vehicles such as passenger cars and railroad vehicles.

4 Compressor 10 Air supply system 11 Air drying circuit 12 Supply circuit 15 Upstream check valve 16 Branch passage 17 Filter 18 Air supply passage 19 Downstream check valve 20 Bypass flow path 21 Regeneration control valve 22 Orifice 25 Drain discharge valve 26A Governor 26B Unload control valve 27 Drain discharge port as a discharge port 30 Air tank 50 Pressure sensor 51 -- Humidity sensor, 52 -- Temperature sensor, 53 -- Pressure sensor, 80 -- ECU, 80A -- Storage unit, E61 to E67 -- Wiring.

Claims (6)

an air drying circuit having a filter that contains a desiccant that traps moisture and is provided between a compressor that delivers compressed air and an air tank that stores compressed dry air;
A control device that controls the air drying circuit,
The control device has a supply operation in which the compressor is driven to send the compressed air to the filter and is supplied to the air tank. An air supply system that performs the supply operation when the minimum pressure value among the pressure values acquired from the pressure sensor reaches a cut-in pressure for performing the supply operation. The control device comprises a regeneration operation in which the compressed dry air is passed through the filter in a reverse direction and the fluid that has passed through the filter is discharged through an outlet, and the minimum pressure value is a cutout pressure at which the regeneration operation is performed. 2. The air supply system of claim 1, wherein the regenerating action is performed when a is reached. 3. The air supply system of claim 2, wherein the controller performs the regeneration action when the minimum pressure value reaches the cutout pressure and the dryness of the compressed dry air does not meet a predetermined value. The control device has a purge operation for passing the compressed dry air of the air drying circuit through the filter in the reverse direction and discharging the fluid that has passed through the filter from the discharge port, and the minimum pressure value is the 4. The air supply system of claim 3, wherein said purge operation is performed when a cutout pressure is reached and the dryness of said compressed dry air meets a predetermined value. a discharge valve communicating between a branch passage connected to the air drying circuit and a discharge port;
a regeneration control valve that switches between a forward flow from the filter to the air tank and a reverse flow from the air tank to the filter;
The air supply system according to any one of claims 1 to 4, wherein the controller controls the exhaust valve and the regeneration control valve. an air drying circuit having a filter that contains a desiccant that traps moisture and is provided between a compressor that delivers compressed air and an air tank that stores compressed dry air;
A control method for an air supply system comprising a control device for controlling the air drying circuit,
The control device has a supply operation in which the compressor is driven to send the compressed air to the filter and is supplied to the air tank. When the minimum pressure value among the pressure values obtained from the pressure sensor reaches the cut-in pressure for performing the supply operation, the supply operation is performed.
How to control the air supply system.

Images