阅读说明：本技术 空气供给系统 (Air supply system ) 是由 杉尾卓也 于 2019-12-27 设计创作，主要内容包括：提供一种能够抑制空气干燥器的性能下降的空气供给系统。空气供给系统进行使从压缩机(4)供给的压缩空气经由具有过滤器(17)和单向阀(19)的空气干燥器(11)从上游流向下游的供给动作。空气供给系统具备ECU(80),ECU(80)对以检测空气压力在供给开始值以下为必要条件来使供给动作开始的供给动作、以及不向单向阀(19)的上流供给压缩空气的非供给动作进行切换,在非供给动作中进行使过滤器(17)再生的再生动作。ECU(80)还具备非供给持续条件,非供给持续条件用于尽管检测空气压力成为供给开始值以下但是只要在再生动作的中途就不进行供给动作。(Provided is an air supply system capable of suppressing a performance degradation of an air dryer. The air supply system performs a supply operation of flowing compressed air supplied from a compressor (4) from upstream to downstream via an air dryer (11) having a filter (17) and a check valve (19). The air supply system is provided with an ECU (80), and the ECU (80) switches between a supply operation for starting the supply operation and a non-supply operation for not supplying compressed air to the upstream of the check valve (19) on the condition that the detected air pressure is less than or equal to a supply start value, and performs a regeneration operation for regenerating the filter (17) during the non-supply operation. The ECU (80) is also provided with a non-supply continuation condition for not performing the supply operation as long as the regeneration operation is in the middle of the regeneration operation although the detected air pressure is equal to or lower than the supply start value.)

1. An air supply system for performing a supply operation of flowing compressed air supplied from a compressor from upstream to downstream through an air dryer having a filter and a check valve, the air supply system comprising:

a pressure sensor that detects an air pressure downstream of the check valve; and

a control device that switches between the supply operation and a non-supply operation and performs a regeneration operation for regenerating the filter during the non-supply operation,

wherein the control device is provided with a supply start value for starting the supply operation on condition that the detected air pressure detected by the pressure sensor is equal to or less than the supply start value,

the control device further includes a non-supply continuation condition for not performing the supply operation as long as the supply operation is in the middle of the regeneration operation although the detected air pressure is equal to or lower than the supply start value.

2. The air supply system according to claim 1,

the control device further includes a non-supply cancellation condition for starting the supply operation when the non-supply continuation condition is satisfied, based on the detected air pressure being equal to or lower than a predetermined pressure value that is lower than the supply start value.

3. The air supply system according to claim 2,

the predetermined pressure value is set to a value that can ensure a time required for the regeneration operation.

4. The air supply system according to any one of claims 1 to 3,

the non-supply continuation condition includes a running state in which a consumption amount of the compressed air is large.

5. The air supply system according to claim 4,

the control device determines that the running state is a running state in which the consumption amount of the compressed air is large, based on a large amount of decrease per unit time of the detected air pressure.

6. The air supply system according to claim 4,

the control device determines that the running state is a running state in which the consumption amount of the compressed air is large, based on a signal transmitted from a control device of the vehicle.

Technical Field

The present invention relates to an air supply system for supplying compressed air to an apparatus.

Background

In vehicles such as trucks, buses, construction machines, etc., compressed air delivered from a compressor is used to control air pressure systems including brakes, suspensions, etc. The compressed air contains water 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, swelling of the rubber member, and the like are caused, which causes a malfunction. Therefore, an air dryer for removing impurities such as moisture and oil in the compressed air is provided downstream of the compressor.

The air dryer performs a dehumidifying operation for removing oil and moisture from the compressed air, and a regenerating operation for removing the oil and moisture adsorbed on the drying agent from the drying agent and discharging the oil and moisture as a drain. For example, patent document 1 describes a technique for performing a regeneration operation in an air dryer.

The air supply system described in patent document 1 stores air compressed by an air compressor in a tank. When the air pressure in the air tank is equal to or lower than the first pressure, the air supply system drives the air compressor to supply compressed air to the air tank until the air pressure rises to reach the second pressure. When the air pressure reaches the second pressure, the air supply system stops the supply of compressed air from the air compressor to the air tank, and opens the discharge valve (purge valve). Then, the air supply system performs the following regeneration operation until the air pressure drops to a third pressure: by maintaining the valve-open state, the compressed air in the air tank passes through the air dryer and is discharged to the atmosphere. When the air pressure in the air tank reaches the third pressure, the air supply system closes the discharge valve.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2015-229127

Disclosure of Invention

Problems to be solved by the invention

However, there is a risk that: in a running state where the consumption amount of compressed air is large, when rapid consumption of compressed air by a brake or the like and consumption of compressed air by a regeneration operation of an air dryer overlap, the air pressure in the air tank reaches a supply start value at which supply of compressed air from the compressor is started. At this time, in the air supply system, the regeneration operation of the air dryer is interrupted, and the supply operation by the compressor is started. This avoids a shortage of compressed air, while the regeneration operation is interrupted, thereby reducing the regeneration amount of the air dryer. Therefore, there is a risk that the performance of the air dryer is maintained in a degraded state.

The invention aims to provide an air supply system capable of inhibiting the performance reduction of an air dryer.

Means for solving the problems

An air supply system for achieving the above object performs a supply operation of supplying compressed air supplied from a compressor from an upstream to a downstream via an air dryer having a filter and a check valve, the air supply system including: a pressure sensor that detects an air pressure downstream of the check valve; and a control device that switches between the supply operation and a non-supply operation in which a regeneration operation for regenerating the filter is performed, wherein the control device includes a supply start value for starting the supply operation on condition that a detected air pressure detected by the pressure sensor is equal to or less than the supply start value, and further includes a non-supply continuation condition for not performing the supply operation as long as the supply operation is in the middle of the regeneration operation although the detected air pressure is equal to or less than the supply start value.

In this case, even when the timing of the consumption of the compressed air by the brake or the like overlaps with the timing of the consumption of the compressed air by the regeneration operation of the air dryer, the consumption of the compressed air by the brake or the like can be continued and the regeneration operation of the air dryer can be continued without interruption. This can suppress a decrease in performance of the air dryer.

In one embodiment, the control device may further include a non-supply cancellation condition for starting the supply operation when the non-supply continuation condition is satisfied, based on the detected air pressure being equal to or lower than a predetermined pressure value lower than the supply start value.

In this case, the regeneration operation of the air dryer can be continued as much as possible, and the shortage of the compressed air can be prevented.

In one embodiment, the predetermined pressure value may be set to a value that can ensure a time required for the regeneration operation.

In this case, the regeneration operation of the air dryer can be performed more reliably.

In one embodiment, the non-supply continuation condition may include a running state in which a running state is a running state in which the consumption amount of the compressed air is large.

In this case, it is possible to reduce the risk of the regeneration operation of the air dryer being interrupted in the running state in which the consumption amount of the compressed air is large.

In one embodiment, the control device may determine that the running state is a running state in which the consumption amount of the compressed air is large, based on a large amount of decrease per unit time of the detected air pressure.

In this case, the running state can be determined from the amount of decrease in the air pressure per unit time.

In one embodiment, the control device may determine that the running state is a running state in which the consumption amount of the compressed air is large, based on a signal transmitted from a control device of a vehicle.

In this case, the running state can be determined based on a signal transmitted from the vehicle.

Drawings

Fig. 1 is a block diagram showing a schematic configuration of an embodiment of an air supply system used in an air pressure system.

Fig. 2 is a schematic configuration diagram showing the configuration of the air supply system according to the embodiment.

Fig. 3 is a diagram showing an operation pattern of the air dryer according to the embodiment, where (a) is a diagram showing a supply operation, (b) is a diagram showing a purge operation, and (c) is a diagram showing a regeneration operation.

Fig. 4 is a graph showing the air supply state of the embodiment by the air pressure.

Detailed Description

An embodiment of an air supply system included in an air pressure system will be described with reference to fig. 1 to 4. The air supply system is mounted on a vehicle such as a truck, a bus, or a construction machine.

An outline of the air pressure system is explained with reference to fig. 1.

In the air pressure system, a compressor 4, an air dryer 11, a protection valve 12, an air tank 13, a brake valve 14, and a brake chamber 15 are connected in order via air supply paths 4E, 11E, 12E, 13E, 14E. The compressor 4, the air dryer 11, and the protection valve 12 constitute an air supply system 10.

The compressor 4 is driven by power of an engine (not shown) of the automobile, compresses air, and supplies the compressed air to the air supply system 10. The compressor 4 is connected to the air dryer 11 via an air supply path 4E.

In the air dryer 11, the compressed air sent from the compressor 4 is passed through a filter 17 (see fig. 2), whereby impurities in the air are captured and the compressed air is purified. The compressed air thus purified is supplied from the air dryer 11 to the air tank 13 via the air supply path 11E, the protection valve 12, and the air supply path 12E.

The air tank 13 is connected to a brake valve 14 operated by the driver via an air supply path 13E. The brake valve 14 is connected to the brake chamber 15 via an air supply path 14E. Therefore, in response to the operation of the brake valve 14, compressed air is supplied to the brake chamber 15, whereby the service brake is operated.

The air supply system 10 further includes an ECU 80 as a control device. The ECU 80 is electrically connected to the air dryer 11 via wirings E62, E63. Further, the ECU 80 is electrically connected to the pressure sensor 65 via a wiring E65. The pressure sensor 65 detects the air pressure of the protection valve 12, and outputs the air pressure to the ECU 80. The ECU 80 acquires a detected air pressure corresponding to the air pressure of the gas tank 13 based on the detection signal of the pressure sensor 65. The ECU 80 is electrically connected to the temperature/humidity sensor 66 via a wiring E66. The temperature/humidity sensor 66 detects the humidity of the compressed air of the air tank 13, and outputs the humidity to the ECU 80. The ECU 80 is electrically connected to the vehicle ECU100 so as to be able to acquire various signals of the vehicle on which the air supply system 10 is mounted.

The ECU 80 includes a not-shown arithmetic unit, a volatile memory unit, and a nonvolatile memory unit, and supplies signals for specifying various operations to the air dryer 11 in accordance with a program stored in the nonvolatile memory unit. The ECU 80 also has a timer for measuring a period relating to the regeneration operation.

The air supply system 10 is explained with reference to fig. 2.

The air dryer 11 has a maintenance port P12. The maintenance port P12 is a port for supplying compressed air to the upstream side of the filter 17 of the air dryer 11 during maintenance.

The ECU 80 is electrically connected to the regeneration control valve 21 of the air dryer 11 via a wiring E63, and is electrically connected to the regulator 26 of the air dryer 11 via a wiring E62.

When referring to fig. 3, the inner space 11A of the air dryer 11 is provided with a filter 17. The filter 17 is provided in the middle of the air supply passage 18, and the air supply passage 18 connects the air supply passage 4E from the upstream compressor 4 to the air supply passage 11E connected to the downstream protection valve 12.

The filter 17 contains a desiccant and is provided with a filter unit. The filter 17 passes the compressed air through a desiccant, thereby removing moisture contained in the compressed air from the compressed air to dry the compressed air, and also removes oil contained in the compressed air from the compressed air through a filter portion to purify the compressed air. The compressed air having passed through the filter 17 is supplied to the protection valve 12 via a check valve 19 as a check valve that allows only the compressed air to flow downstream of the filter 17. That is, when the filter 17 is set upstream and the protection valve 12 is set downstream, the check valve 19 allows only the compressed air to flow from the upstream to the downstream.

Referring back to fig. 2, a bypass flow path 20 that bypasses (bypasses) the check valve 19 is provided in the check valve 19 so as to be parallel to the check valve 19. The regeneration control valve 21 is connected to the bypass passage 20.

The regeneration control valve 21 is an electromagnetic 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 E63, thereby switching the operation of the regeneration control valve 21. The regeneration control valve 21 closes the bypass passage 20 when the power supply is off, and opens the bypass passage 20 when the power supply is on. For example, the regeneration control valve 21 is driven when the value of the detected air pressure exceeds the supply stop value.

An orifice 22 is provided in the bypass passage 20 at a portion between the regeneration control valve 21 and the filter 17. When the regeneration control valve 21 is energized, the compressed air of the air tank 13 passes through the protection valve 12 and 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 air sent to the filter 17 is reversed in the filter 17 from downstream toward upstream. Such a process is a process of regenerating the filter 17, and is referred to as a regeneration process of the air dryer. At this time, the dried and purified compressed air in the gas tank 13 flows in reverse through the filter 17, thereby removing the moisture and oil captured by the filter 17 from the filter 17. For example, the regeneration control valve 21 is controlled to open for a predetermined period. The predetermined period is a period during which the filter 17 can be regenerated, and is set theoretically, experimentally, or empirically.

A 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 valve 25, and a drain outlet 27 is connected to the end of the branch passage 16.

The drain liquid containing the moisture and oil removed from the filter 17 is sent to the drain liquid discharge valve 25 together with the compressed air. The drain valve 25 is an air pressure-driven valve driven by air pressure, and is provided in the branch passage 16 between the filter 17 and the drain port 27. The drain discharge valve 25 is a two-position, two-way valve that changes its position between a closed valve position and an open valve position. When the drain discharge valve 25 is in the open valve 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 valve 25 is controlled by a regulator 26. The regulator 26 is a solenoid valve controlled by the ECU 80. The ECU 80 controls on/off (driving/non-driving) of the power supply of the regulator 26 via the wiring E62, thereby switching the operation of the regulator 26. When the power is turned on, the regulator 26 opens the drain valve 25 by inputting an unload signal of a predetermined air pressure to the drain valve 25. When the power supply is turned off, the regulator 26 opens the port of the drain valve 25 to the atmospheric pressure without inputting an unload signal to the drain valve 25, thereby closing the drain valve 25.

The drain valve 25 is maintained at the valve-closed position in a state where the unload signal is not input from the regulator 26, and is switched to the valve-open position when the unload signal is input from the regulator 26. Further, when the input port of the drain valve 25 connected to the compressor 4 exceeds the upper limit value and becomes high pressure, the drain valve 25 is forcibly switched to the valve-open position.

The compressor 4 performs a load operation in which compressed air is supplied and a no-load operation in which compressed air is not supplied. The regulator 26 controls switching between the load operation and the no-load operation of the compressor 4. When the power is turned on, the regulator 26 sends an unload signal to the compressor 4, thereby causing the compressor 4 to operate without load. When the power supply is turned off, the regulator 26 does not input the unload signal to the compressor 4, and opens the port of the compressor 4 to the atmosphere, thereby turning the compressor 4 on.

The ECU 80 turns on (drives) the power supply of the regulator 26 based on the detected air pressure of the pressure sensor 65, thereby switching the regulator 26 to the supply position that outputs the unload signal. In addition, the ECU 80 cuts off (does not drive) the power supply to the regulator 26 based on the detected air pressure of the pressure sensor 65, thereby switching the regulator 26 to the non-supply position where the unload signal is not output.

The supply operation, purge operation, and regeneration operation of the air dryer 11 will be described with reference to fig. 3 again. The supply operation shown in fig. 3 (a) is an operation of supplying compressed air to the air tank 13. The purge operation shown in fig. 3 (b) is an operation of stopping the compressor to perform a purge process or the like. The regeneration operation shown in fig. 3 (c) is an operation of causing the filter 17 to perform a regeneration process. The regeneration operation and the purge operation constitute a non-supply operation.

Referring to fig. 3 (a), during the supply operation, the ECU 80 CLOSEs the regeneration control valve 21 and the regulator 26 (shown as "CLOSE"). At this time, the drive signal (power supply) from the ECU 80 is not supplied to each of the regeneration control valve 21 and the regulator 26. Therefore, the regulator 26 opens the port of the compressor 4 and the port of the drain valve 25 connected downstream to the atmosphere. In the supply operation, the compressor 4 supplies compressed air (shown as "ON" in the figure). The compressed air (IN the drawing) supplied to the air dryer 11 is supplied to the air tank 13 (OUT IN the drawing) through the protection valve 12 after moisture and oil are removed by the filter 17.

Referring to fig. 3 (b), during the purge operation, the ECU 80 closes the regeneration control valve 21 and OPENs the regulator 26 (shown as "OPEN"). At this time, the regulator 26 is opened by a drive signal (power supply) supplied from the ECU 80, and the port of the compressor 4 and the port of the drain valve 25 connected to the downstream are connected to the upstream (protection valve 12), respectively. In the purge operation, the compressor 4 is in a no-load operation state (shown as "OFF" in the figure) by the unload signal (shown as "CONT") from the regulator 26, and the compressed air in the filter 17 and the air supply passage 18 is discharged from the drain outlet 27 together with moisture, oil, and the like.

Referring to fig. 3 (c), during the regeneration operation, the ECU 80 opens the regeneration control valve 21 and the regulator 26, respectively. At this time, a drive signal (power supply) from the ECU 80 is supplied to the regeneration control valve 21 and the regulator 26. During the regeneration operation, the compressor 4 is in the no-load operation state by the unload signal from the regulator 26. In the regeneration operation, the regeneration control valve 21 and the drain valve 25 are opened, and thus the compressed air on the protection valve 12 side with respect to the filter 17 flows backward through the filter 17 (the desiccant stored therein) from the downstream side to the upstream side, and the regeneration process of the filter 17 is performed.

The operation of the air supply system 10 will be described with reference to fig. 4.

The ECU 80 is provided with a supply start value CI1 and a supply stop value CO, the supply start value CI1 being a value corresponding to the air pressure that is a requirement for starting the supply of the compressed air by the compressor 4, and the supply stop value CO being a value corresponding to the air pressure that stops the supply of the compressed air by the compressor 4. The ECU 80 is provided with a non-supply cancellation value CI3 that is a predetermined pressure value lower than the supply start value CI 1. For example, the supply stop value CO, the supply start value CI1, and the non-supply cancellation value CI3 may be stored in a nonvolatile storage unit or the like of the ECU 80.

The ECU 80 compares the air pressure detected by the pressure sensor 65, that is, the detected air pressure with the supply start value CI 1. When the detected air pressure becomes equal to or less than the supply start value CI1 (time t11 at the end of the section UL 11), the ECU 80 switches the air dryer 11 (compressor 4) to the supply operation to supply the compressed air to the air tank 13. Thereby, the regulator 26 of the air dryer 11 is closed and the output of the unload signal is stopped. The compressor 4 is in load operation in response to the stop of the unload signal. The detected air pressure with respect to the air tank 13 rises due to the supply operation of the continuous air dryer 11 (compressor 4) (interval LD11 from time t11 to time t 12).

When the detected air pressure becomes equal to or higher than the supply stop value CO by supplying the compressed air (time t12), the ECU 80 switches the air dryer 11 to the regeneration operation. In this way, the regulator 26 opens and outputs an unload signal in the air dryer 11. The compressor 4 is operated without load in response to the input of the unload signal. In addition, the regulator 26 outputs an unload signal to the drain valve 25 in the air dryer 11. The drain valve 25 is opened in response to the input of the unload signal, and the compressed air in the filter 17 of the air dryer 11 flows in the regeneration direction. The regeneration direction is a direction from downstream to upstream, and is a direction opposite to the supply direction of the flow of the compressed air when the compressed air is purified. As a result, the impurities trapped in the filter 17 are discharged as a drain from the drain discharge valve 25 together with the compressed air flowing in the regeneration direction, and the filter 17 is regenerated (time t12 to time t 13). The period from time t12 to time t13 is a period required for regeneration of the filter 17. As long as the consumption amount of the compressed air due to the brake chamber 15 and the like is normal, this period ends before the detected air pressure falls below the supply start value CI 1.

Normally, the ECU 80 starts the supply operation as indicated by the broken line L1 (time t22 to time t23) in response to the detected air pressure becoming equal to or less than the supply start value CI1 (time t22) which is a requirement for starting the supply operation.

However, there is also a risk of: when the timing of the large consumption of the compressed air due to the brake chamber 15 or the like overlaps with the timing of the consumption of the compressed air due to the regeneration operation of the air dryer 11, the detected air pressure becomes equal to or lower than the supply start value CI1 before the period required for the regeneration of the filter 17 elapses, that is, during the regeneration operation (time t 22). At this time, if the ECU 80 starts the supply operation in response to the detected air pressure becoming equal to or lower than the supply start value CI1 as usual, the regeneration of the filter 17 is interrupted or the regeneration performance is degraded. For example, if the regeneration operation of the air dryer 11 is interrupted or the like until the period required for regeneration (time t12 to time t13) elapses (time t22), the regeneration amount corresponding to the period lost due to the interruption or the like (time t22 to time t13) becomes insufficient with respect to the original regeneration amount. Moreover, there is a risk that: when the regeneration amount of the filter 17 is insufficient due to interruption of the regeneration operation of the air dryer 11 or the like, the purification performance of the air dryer 11 is maintained in a state of being lowered.

Therefore, in the present embodiment, as shown by the solid line L2, even if the detected air pressure becomes the supply start value CI1 or less (time t22) during the regeneration operation of the air dryer 11, the ECU 80 does not start the supply operation and continues the regeneration operation of the air dryer 11 (after time t 22). Then, the ECU 80 starts the supply operation based on the detected air pressure reaching the non-supply cancellation value CI3 where the supply amount of the compressed air is not insufficient. That is, since the air pressure difference Δ GP2 from the supply stop value CO to the non-supply release value CI3 can be ensured to be greater than the air pressure difference Δ GP1 from the normal supply start value CI1 to the supply stop value CO, the period UL12 (time t12 to time t14) longer than the period required for regeneration can be ensured. That is, the non-supply cancellation value CI3 is set to ensure the time required for the regeneration operation of the air dryer 11 even when the amount of compressed air consumed is large. This can continue the consumption of the compressed air by the brake chamber 15 and the regeneration operation of the air dryer 11. Therefore, the performance of the air dryer 11 can be suppressed from being lowered.

Then, the ECU 80 switches the air dryer 11 (compressor 4) to the supply operation to supply the compressed air to the air tank 13 in response to the detected air pressure becoming the non-supply-cancellation value CI3 or less (time t 14). The detection air pressure becomes the non-supply cancellation value CI3 or less, and constitutes a non-supply cancellation condition. Accordingly, the load operation of the compressor 4 is started, and the detected air pressure of the air tank 13 rises due to the continued supply operation of the air dryer 11 (compressor 4) (the interval LD12 from time t14 to time t 15).

Even if the regeneration operation of the air dryer 11 is being executed, the ECU 80 interrupts the regeneration operation of the air dryer 11 when the detected air pressure reaches the non-supply-cancellation value CI 3. This can continue the consumption of the compressed air by the brake chamber 15, and can ensure a longer duration of the regeneration operation of the air dryer 11. Therefore, the performance of the air dryer 11 can be suppressed from being lowered.

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

(1) Even when the timing of the consumption of the compressed air by the brake or the like overlaps with the timing of the consumption of the compressed air by the regeneration operation of the air dryer 11, the consumption of the compressed air by the brake or the like can be continued and the regeneration operation of the air dryer 11 can be continued without interruption. This can suppress a decrease in performance of the air dryer.

(2) The supply operation by the compressor 4 is started based on the detected air pressure being equal to or lower than a predetermined pressure value lower than the normal supply start value, whereby the regeneration operation of the air dryer 11 can be continued as much as possible while preventing the compressed air from being insufficient.

(3) The non-supply cancellation value CI3 is set to ensure the time required for the regeneration operation of the air dryer 11, and thus the regeneration operation of the air dryer 11 can be performed more reliably.

The present embodiment can be modified and implemented as follows. The present embodiment and the following modifications can be combined and implemented within a range not technically contradictory to each other.

The air tank 13 may supply compressed air to a device other than the brake valve 14 that consumes compressed air, for example, a parking brake.

The pressure sensor 65 may detect the air pressure at any position downstream of the check valve 19 as long as it can detect the air pressure corresponding to the air pressure of the gas tank 13. For example, a pressure sensor may also detect the air pressure in the air tank 13. Thus, the ECU 80 may control the supply operation, the non-supply operation, and the regeneration operation based on the detected air pressure in the air tank 13.

ECU 80 may determine that the running state is a running state in which the amount of compressed air consumed is large, based on a signal transmitted from vehicle ECU100 as a control device of the vehicle. Thus, the running state in which the amount of compressed air consumed is large can be determined based on the signal transmitted from the vehicle.

The ECU 80 may determine that the running state is a running state in which the consumption amount of compressed air is large, based on the large amount of decrease per unit time in the detected air pressure. Thus, the travel state can be determined from the amount of decrease per unit time in the detected air pressure.

The non-supply continuation condition may include a running state in which the running state is a running state in which the consumption amount of compressed air is large. In the running state where the consumption amount of the compressed air is large, even if the air pressure reaches the supply start value CI1, the period required for regeneration is likely not to elapse. Therefore, the regeneration operation of the air dryer 11 can be performed in advance until the non-supply-operation continuation condition is satisfied and the air pressure becomes the non-supply-cancellation value CI 3. The risk of interruption of the regeneration operation of the air dryer 11 in a running state in which the consumption of compressed air is high can be reduced.

In the above embodiment, the filter 17 has both the desiccant and the filter unit, but the filter 17 may have only one of them.

In the above embodiment, the case where the filter 17 is provided is exemplified, but the present invention is not limited thereto, and an oil mist separator may be provided upstream of the filter 17.

The oil mist separator is provided with a filter for performing gas-liquid separation by colliding with the compressed air, and captures oil contained in the compressed air sent from the compressor 4. The filter may be obtained by compression molding a metal material, or may be a porous material such as a sponge. By providing this oil mist separator, the purification performance of the compressed air can be further improved.

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. As another embodiment, the air supply system may be mounted on another vehicle such as a car or a railway vehicle.

Description of the reference numerals

4: a compressor; 10: an air supply system; 11: an air dryer; 11A: an interior space; 12: a protection valve; 13: a gas tank; 14: a brake valve; 4E, 11E, 12E, 13E, 14E: an air supply path; 15: a brake chamber; 16: a branch passage; 17: a filter; 18: an air supply passage; 19: a one-way valve; 20: a bypass flow path; 21: a regeneration control valve; 22: an orifice; 25: a liquid discharge valve; 26: a regulator; 27: a liquid discharge outlet; 65: a pressure sensor; 66: a temperature and humidity sensor; 80: an ECU; 100: a vehicle ECU; e62, E63, E65, E66: wiring; p12: a maintenance port.