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)和止回阀(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)在供给动作与不向止回阀(19)的上游供给压缩空气的非供给动作之间进行切换,在非供给动作中进行使过滤器(17)再生的再生动作。ECU(80)具备用于使供给动作开始的供给开始值、以及即使在检测空气压力比供给开始值高时也开始供给动作的供给开始条件。(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 and a non-supply operation in which compressed air is not supplied upstream of the check valve (19), and performs a regeneration operation in which the filter (17) is regenerated during the non-supply operation. The ECU (80) is provided with a supply start value for starting the supply operation, and a supply start condition for starting the supply operation even when the detected air pressure is higher 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 based on a comparison between the supply start value and a detected air pressure detected by the pressure sensor,

the control device further includes a supply start condition for starting the supply operation even when the detected air pressure is higher than the supply start value.

2. The air supply system according to claim 1,

the supply start condition includes that the duration of the non-supply operation is longer than a predetermined period.

3. The air supply system according to claim 2,

the supply start condition further includes that the detected air pressure is higher than the supply start value and lower than a supply stop value, wherein the supply stop value is higher than the supply start value, and the supply stop value is used to start the non-supply operation based on a comparison of the supply stop value and the detected air pressure.

4. The air supply system according to claim 1,

the supply start condition includes: the running state is a running state in which the amount of air consumption is small, and the detected air pressure is equal to or lower than a predetermined air pressure that is higher than the supply start value.

5. The air supply system according to claim 4,

the control device determines that the running state is a running state in which the air consumption amount is small, based on a small amount of decrease per unit time in 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 air consumption amount is small, based on a signal transmitted from a control device of a vehicle.

7. The air supply system according to any one of claims 1 to 6,

an air tank is provided downstream of the check valve,

the detected air pressure is an air pressure in the air tank.

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

The air supply system described in patent document 1 performs a regeneration operation after increasing the air pressure to a second pressure higher than a third pressure suitable for equipment supply. Therefore, in this air supply system, the compressor continues to operate until the air pressure in the air tank reaches a second pressure, which is a supply stop pressure higher than the third pressure, after exceeding the third pressure, which is the maximum pressure in use. There is a risk of: the ventilation amount of the air dryer is increased according to the continuous operation of the compressor until the third pressure is changed to the second pressure, and thus the dehumidification performance of the air dryer and the like are degraded.

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 and performs a regeneration operation for regenerating the filter during the non-supply operation, wherein the control device includes a supply start value for starting the supply operation based on a comparison between the supply start value and a detected air pressure detected by the pressure sensor, and the control device further includes a supply start condition for starting the supply operation even when the detected air pressure is higher than the supply start value.

In this case, since the supply operation is started before the detected air pressure reaches the supply start value, the amount of air passing through the filter is reduced, and therefore the amount of oil and moisture accumulated in the filter can be reduced. Further, by performing the regeneration operation while the accumulation of oil and water is small, the filter can be regenerated at a high level. Further, by performing the regeneration operation while the accumulation of oil and water is small, the oil and water can be prevented from being stuck to the filter. Therefore, the performance degradation of the air dryer is suppressed.

Further, since the supply operation is performed even at the detection air pressure higher than the supply start value without changing the supply stop value, the regeneration capability at the time of the regeneration operation, which is somewhat affected by the air pressure, is exhibited as usual.

In one embodiment, the feeding start condition may include that the duration of the non-feeding action is longer than a prescribed period.

In this case, the regeneration operation is periodically performed even in a situation where the amount of compressed air used is small.

In one embodiment, the supply start condition may further include that the detected air pressure is higher than the supply start value and lower than a supply stop value, the supply stop value being higher than the supply start value, the supply stop value being used to start the non-supply operation based on a comparison of the supply stop value and the detected air pressure.

In this case, it is possible to prevent the compressed air from being supplied when the compressed air is not consumed.

In one embodiment, the supply start condition may include a running state in which a running state is a running state in which an amount of air consumption is small, and the detected air pressure being a predetermined air pressure or less higher than the supply start value.

In this case, the performance degradation of the filter according to the running state is suppressed.

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

In this case, the travel state can be determined based on the amount of decrease per unit time in the detected air pressure.

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

In this case, the running state in which the amount of decrease in the air pressure is small can be determined based on the signal transmitted from the vehicle.

In one embodiment, a gas tank may be provided downstream of the check valve, and the detected air pressure may be an air pressure in the gas tank.

In this case, the supply operation, the non-supply operation, and the regeneration operation can be controlled based on the air pressure in the air tank.

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 air sent from the compressor 4 is passed through a filter 17 (see fig. 2), whereby impurities in the air are captured and the air is purified. The 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. Accordingly, in response to the operation of the brake valve 14, 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 ECU 80 detects the air pressure of the protection valve 12 through the pressure sensor 65. The detected air pressure corresponding to the air pressure of the gas tank 13 is obtained from the detection signal of the pressure sensor 65. The ECU 80 is connected to the temperature/humidity sensor 66 via a wiring E66. The ECU 80 detects the humidity of the compressed air in the air tank 13 by the temperature/humidity sensor 66. The ECU 80 is electrically connected to the vehicle ECU 100 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 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 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 air through the desiccant, thereby removing moisture contained in the air from the air to dry the air, and also removes oil contained in the air from the air through the filter portion to purify the air. The 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 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 air to flow only from upstream to 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 is an operation of supplying compressed air to the air tank 13. The purge operation is an operation of stopping the compressor to perform a purge process or the like. The regeneration operation is an operation for 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 at which the air supply by the compressor 4 is started, and the supply stop value CO being a value corresponding to the air pressure at which the air supply by the compressor 4 is stopped. The ECU 80 is provided with an auxiliary supply start value CI2, and the auxiliary supply start value CI2 is a value that is smaller than the supply stop value CO and is higher than the supply start value CI 1. For example, the supply stop value CO, the supply start value CI1, and the auxiliary supply start value CI2 may be stored in a nonvolatile storage portion 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 lower than the supply start value CI1 (the left end of L11A in the graph), the ECU 80 switches the air dryer 11 to the supply operation to supply 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 as the supply operation of the air dryer 11 continues (L11A in the graph).

When the detected air pressure becomes equal to or higher than the supply stop value CO (the right end of L11A in the graph) due to the supply of the compressed air, the ECU 80 switches the air dryer 11 to the regeneration operation. Thus, the regeneration control valve 21 is opened in the air dryer 11, and the compressed air can flow back from the protection valve 12. In the air dryer 11, the regulator 26 is opened to output an unload signal. 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 air in the filter 17 of the air dryer 11 flows in the regeneration direction by the compressed air flowing in reverse through the regeneration control valve 21. The regeneration direction is a direction from downstream to upstream, and is a direction opposite to the supply direction of the air flow when the air is purified. As a result, the impurities caught by the filter 17 are discharged as a drain from the drain discharge valve 25 together with the air flowing in the regeneration direction, and the filter 17 is regenerated (in the graph, the left end portions of L11B and L21B).

In addition, since the compressor 4 performs the no-load operation in response to the input of the unload signal when the filter 17 is regenerated in this manner, the compressed air is not consumed uselessly.

After that, when the regeneration process is ended, the ECU 80 switches the air dryer 11 to the purge operation. Thereby, the compressed air from the air tank 13 is stopped and the compressed air does not circulate through the filter 17. In addition, the air pressure of the air tanks 13 decreases (L11B, L21B, etc. in the graph) as the compressed air of the air tanks 13 is consumed by the brake chamber 15.

First, a normal operation in which the supply operation is started when the compressed air is consumed to the supply start value CI1 will be described.

The ECU 80 switches the air dryer 11 to the supply operation again and stops the unloading signal of the compressor 4 to supply air (L12A in the graph) in response to the determination that the detected air pressure is equal to or lower than the supply start value CI1 (L11B in the graph). After that, when the detected air pressure is equal to or higher than the supply stop value CO (the right end of L12A in the graph), the ECU 80 switches the air dryer 11 from the supply operation to the non-supply operation. Therefore, the air pressure falls (in the graph, L12B). However, it is assumed that a predetermined period UL11 is required for detecting the decrease in air pressure from the supply stop value CO to the supply start value CI1 in L11B in the graph. That is, the duration of the non-supply operation is a predetermined period UL 11. The predetermined period UL11 is a period required for the air pressure to fall from the supply stop value CO to the supply start value CI1, and includes most of the periods during which air is consumed in the vehicle. For example, the majority means a portion of 95% or more.

Next, the operation of starting the supply operation when the compressed air is consumed to the auxiliary supply start value CI2 will be described. Further, the regeneration process of the filter 17 is performed at a high level in this action, and thus this action is described as an action for high regeneration.

In the present embodiment, even when the detected air pressure is higher than the supply start value CI1, the ECU 80 switches the air dryer 11 to the supply operation in response to the satisfaction of the supply start condition, stops the unload signal from the compressor 4, and supplies air.

As shown in L21B in the graph, the first supply start condition is lower in air pressure consumption than L11B in the graph indicating the normal air consumption. For example, in the case where the period UL21, which is the duration of the non-supply operation from the supply stop value CO, is longer than, for example, the predetermined period UL11 (i.e., the period required for the air pressure to fall from the supply stop value CO to the supply start value CI 1) in the vehicle, the ECU 80 determines that the consumption of the air pressure is small, and the first supply start condition is established at this time. The high regeneration operation is started in response to the satisfaction of the first supply start condition. That is, the ECU 80 switches the air dryer 11 to the supply operation in order to supply the compressed air to the air tank 13.

That is, as shown by L21B in the graph, when the period UL21 from the supply stop value CO is longer than the predetermined period UL11 (the right end of L21B in the graph), the ECU 80 switches the air dryer 11 to the supply operation again, stops the unload signal to the compressor 4, and supplies the compressed air (L22A in the graph). When the air pressure detected by the pressure sensor 65 becomes equal to or higher than the supply stop value CO (the right end of L22A in the graph), the ECU 80 switches the air dryer 11 to the non-supply operation. Therefore, the air pressure falls (in the graph, L22B).

Thus, even when the consumption amount of compressed air is small, the air supply and the regeneration process are performed in groups every time the predetermined period UL11 elapses, and the filter 17 is subjected to the regeneration process. An amount of compressed air corresponding to the pressure difference Δ GP2 passes through the filter 17. The pressure difference Δ GP2 is less than the normal pressure difference Δ GP1, and the amount of compressed air corresponding to the pressure difference Δ GP2 is less than the amount of compressed air corresponding to the pressure difference Δ GP 1. Therefore, since the filter 17 is subjected to the regeneration process for the oil and the moisture while the amount of the deposited oil is small, the filter 17 is regenerated at a higher level. Further, the pressure difference in the gas tank 13 is suppressed to the pressure difference Δ GP2 smaller than the normal pressure difference Δ GP1, and the amount of compressed air corresponding to the pressure difference Δ GP2 is smaller than the amount of compressed air corresponding to the pressure difference Δ GP1, so the load required for the supply of compressed air by the compressor 4 is suppressed. Further, the predetermined period UL11 is preferably set to a period sufficient to ensure that the moving interval of the compressor 4 does not load the compressor 4. Since the supply stop value CO is the same as that in the case of the normal operation, the regeneration capability in the regeneration operation, which is somewhat affected by the air pressure, is exhibited as in the normal operation.

The second supply start condition may be an air pressure equal to or lower than the auxiliary supply start value CI2, the auxiliary supply start value CI2 may be a value corresponding to an air pressure higher than the supply start value CI1 and lower than the supply stop value CO, and the air may be supplied in accordance with both the first supply start condition and the second supply start condition. Thus, when the consumption amount of the compressed air is extremely small, the execution time of the air supply and the regeneration process is suppressed, and therefore the load on the compressor 4 is suppressed. Further, it is preferable that the pressure difference Δ GP2 be set so that the load of the compressor 4 does not increase due to the short-time driving.

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

(1) Since the supply operation is started before the detected air pressure reaches the supply start value CI1, the amount of air passing through the filter 17 is small, and therefore the amount of oil and moisture accumulated in the filter 17 can be small. By performing the regeneration operation while the accumulation of oil and water is small, the filter 17 can be regenerated at a high level. Further, by performing the regeneration operation while the accumulation of oil and water is small, the oil and water can be prevented from being stuck to the filter 17. Therefore, the performance degradation of the air dryer 11 can be suppressed.

The supply operation is performed even at a detected air pressure higher than the supply start value CI1 without changing the supply stop value CO. Therefore, the regeneration capability at the time of the regeneration operation, which is somewhat affected by the air pressure, is exhibited as usual.

(2) The regeneration operation of the filter 17 is periodically performed even in a situation where the amount of compressed air used is small.

(3) It is possible to prevent the compressed air from being supplied when the compressed air is not consumed.

(4) By adopting, as the supply start condition, a running state in which the running state is a running state in which the air consumption amount is small (that is, the vehicle is in a running state in which the air consumption amount is small) and an auxiliary supply start value CI2 or less that is a value higher than the supply start value CI1, the performance degradation of the air dryer 11 according to the running state is suppressed.

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 within the air tank. Thus, the supply operation, the non-supply operation, and the regeneration operation may be controlled based on the detected air pressure in the air tank.

ECU 80 may determine the running state with a low air consumption amount based on a signal transmitted from vehicle ECU 100 as a control device of the vehicle. Thus, the running state in which the amount of decrease in the air pressure is small can be determined based on the signal transmitted from the vehicle.

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

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.