阅读说明：本技术 空气供给系统 (Air supply system ) 是由 板谷将治 田中克典 于 2019-06-06 设计创作，主要内容包括：空气供给系统具备：压缩机,其具有负荷运转模式和空运转模式；干燥剂,其构成为去除压缩机送出的压缩空气中的水分；第一电磁阀,其构成为将压缩机在负荷运转模式与空运转模式之间选择性地进行切换；排水排出阀,其连接于从连接通路分支出的分支通路,排水排出阀构成为响应于第二电磁阀被驱动而将分支通路开通,并且构成为响应于第二电磁阀不被驱动而将分支通路封闭；以及控制装置,其构成为对第一电磁阀和第二电磁阀进行控制。(The air supply system includes: a compressor having a load operation mode and an idle operation mode; a desiccant configured to remove moisture from compressed air sent from the compressor; a first solenoid valve configured to selectively switch the compressor between a load operation mode and an idle operation mode; a drain discharge valve connected to a branch passage branching from the connection passage, the drain discharge valve being configured to open the branch passage in response to the second solenoid valve being driven and configured to close the branch passage in response to the second solenoid valve not being driven; and a control device configured to control the first solenoid valve and the second solenoid valve.)

1. An air supply system is provided with:

a compressor having a load operation mode in which the compressor sends compressed air and an idle operation mode in which the compressor does not send the compressed air;

a desiccant configured to remove moisture from the compressed air sent by the compressor;

a connection passage connecting the compressor and the desiccant, the connection passage being for allowing circulation of the compressed air;

a first solenoid valve configured to selectively switch the compressor between the load operation mode and the idle operation mode, the compressor being configured to switch to the idle operation mode in response to the first solenoid valve being driven, and the compressor being configured to switch to the load operation mode in response to the first solenoid valve not being driven;

a drain discharge valve connected to a branch passage that branches from the connection passage, the drain discharge valve being configured to open the branch passage in response to a second solenoid valve being driven, and configured to close the branch passage in response to the second solenoid valve not being driven; and

and a control device configured to switch between driving and non-driving of the first solenoid valve and between driving and non-driving of the second solenoid valve.

2. The air supply system according to claim 1,

the control device is configured to: the second solenoid valve is controlled such that the second solenoid valve operates the drain discharge valve to close the branch passage during at least a part of a period in which the first solenoid valve is driven.

3. The air supply system according to claim 1 or 2,

the air supply system further includes an upstream check valve provided at a position on the connection passage between the compressor and the branch passage,

the upstream check valve allows air to be supplied from the compressor.

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

a downstream check valve that allows air to flow from the desiccant to a side opposite the compressor; and

a regeneration control valve provided in the middle of a passage connected in parallel to the passage in which the downstream check valve is provided,

the control device is configured to switch the regeneration control valve between an open state and a closed state,

the control device is further configured to: when the first solenoid valve is driven and the second solenoid valve operates the drain/discharge valve to close the branch passage, the regeneration control valve is opened for a predetermined period.

5. The air supply system according to claim 4,

the air supply system further includes a pressure sensor provided in the connection passage and configured to detect an air pressure,

the control device is configured to determine the predetermined period based on the air pressure detected by the pressure sensor.

6. The air supply system according to claim 3, further comprising:

a downstream check valve that allows air to flow from the desiccant to a side opposite the compressor;

a regeneration control valve provided in the middle of a passage connected in parallel to the passage in which the downstream check valve is provided; and

a pressure sensor provided in the connection passage and configured to detect air pressure, the pressure sensor being provided between the compressor and the upstream check valve,

the control device is configured to switch the regeneration control valve between an open state and a closed state,

the control device is configured to: when the first solenoid valve is driven and the second solenoid valve operates the drain/discharge valve to close the branch passage, the regeneration control valve is opened for a predetermined period of time,

the control device is configured to determine the predetermined period based on the air pressure detected by the pressure sensor.

7. The air supply system according to any one of claims 4 to 6,

the control device is configured to: when the first solenoid valve is driven, a purge-free process, a purge process, a regeneration process, and a pressurization process are performed,

the non-purification treatment comprises the following steps: the second solenoid valve operates the drain discharge valve to close the branch passage; and closing the regeneration control valve,

the purification treatment comprises the following steps: the second solenoid valve operates the drain discharge valve to open the branch passage; and closing the regeneration control valve,

the regeneration treatment includes: the second solenoid valve operates the drain discharge valve to open the branch passage; and opening the regeneration control valve,

the pressure treatment comprises: the second solenoid valve operates the drain discharge valve to close the branch passage; and opening the regeneration control valve.

8. The air supply system according to claim 7,

the control device is configured to perform an adjustment step of selecting any one of the purge-free process, the purge process, and the pressurization process and executing the selected process so as to maintain the air pressure in the connection passage at a predetermined value.

9. The air supply system according to claim 8,

the control device is configured to execute the regeneration process and the pressurization process in this order before the adjustment process.

10. The air supply system according to claim 1, further comprising:

a check valve that allows air to flow from the desiccant to a side opposite the compressor; and

a humidity measuring unit configured to measure a humidity of the compressed air having passed through the check valve,

the control device is configured to: and switching between driving and non-driving of the second solenoid valve based at least in part on the humidity measured by the humidity measuring unit.

11. The air supply system according to claim 10,

the control device is configured to: when the first solenoid valve is driven, the drain/drain valve is operated by the second solenoid valve to open the branch passage on the condition that the measured humidity is equal to or higher than a humidity threshold value,

the control device is configured to: when the first solenoid valve is driven, the drain/drain valve is operated by the second solenoid valve to close the branch passage, on the condition that the measured humidity is less than the humidity threshold value.

12. The air supply system according to claim 10 or 11,

the air supply system further includes a regeneration control valve provided in a midway of a bypass passage connected in parallel with a passage in which the check valve is provided,

the regeneration control valve is configured to close the bypass passage by closing the valve and to allow the air flow in the bypass passage by opening the valve.

13. The air supply system according to claim 12,

the control device is configured to: when the drain discharge valve is operated by the second solenoid valve to open the branch passage, the regeneration control valve is opened for a predetermined period.

14. The air supply system according to claim 12 or 13,

the control device is configured to: after the branch passage is opened by operating the drain/discharge valve with the second solenoid valve, the branch passage is closed by operating the drain/discharge valve with the second solenoid valve in a state where the regeneration control valve is opened.

15. The air supply system according to claim 12 or 13,

the control device is configured to: the regeneration control valve is opened after the drain discharge valve is operated to open the branch passage by the second solenoid valve and then the drain discharge valve is operated to close the branch passage.

16. The air supply system according to claim 15,

the control device is configured to: when the first solenoid valve is switched to be not driven, the branch passage is opened by operating the drain valve with the second solenoid valve, and after a predetermined period of time has elapsed, the branch passage is closed by operating the drain valve with the second solenoid valve.

Technical Field

The present disclosure relates to an air supply system that supplies compressed air to an apparatus.

Background

In vehicles such as trucks, buses, and construction machines, air pressure systems such as brakes and suspensions are controlled by compressed air supplied from a compressor. The compressed air contains liquid impurities such as moisture contained in the atmosphere and oil used for lubricating the inside of the compressor. When compressed air containing a large amount of moisture and oil enters the air pressure system, rust, swelling of the rubber member, and the like are caused, which causes a malfunction. Therefore, a compressed air drying device for removing impurities such as moisture and oil in the compressed air is provided downstream of the compressor.

The compressed air drying device performs a loading operation (dehumidifying operation) for removing oil-containing moisture and an unloading operation (regenerating operation) for removing oil-containing moisture adsorbed to the drying agent and discharging the oil-containing moisture as drain water. In addition, the air dryer discharges the drain water discharged from the air dryer to the oil separator in order to prevent the drain water from being discharged onto the road surface. In the oil separator, air containing oil and water is collided with a collision member to perform gas-liquid separation, thereby recovering oil and discharging clean air (see, for example, patent document 1).

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2013-234632

Disclosure of Invention

Problems to be solved by the invention

Since the purge operation and the regeneration operation consume a certain amount of compressed air, the operation load of the compressor is increased even in the purge operation and the regeneration operation required for discharging clean air. Therefore, an increase in the operating load of the compressor that generates compressed air by the rotational force transmitted from the rotational drive source such as the engine increases the load on the rotational drive source, and increases the amount of energy consumption such as fuel.

An object of the present disclosure is to provide an air supply system capable of achieving a reduction in load on a compressor.

In order to continuously supply clean air from the air dryer, in which the cleaning function is reduced according to the supply amount of the compressed air, it is necessary to perform a regeneration operation and a purge operation for returning the cleaning function of the air dryer by reversing the compressed air. For example, the purge operation is executed every time the unload operation is performed, and the regeneration operation is executed according to the unload count and the elapsed time. Since the compressed air is consumed in the purge operation and the regeneration operation, the engine load is increased to some extent. In recent years, since it has been required to increase the fuel consumption rate of a vehicle, there is room for improvement in order to maintain the function of the air dryer while suppressing the consumption of compressed air by optimizing the execution conditions rather than mechanically performing the purge operation and the regeneration operation.

An object of the present disclosure is to provide an air supply system capable of suppressing the consumption of compressed air.

Means for solving the problems

According to one aspect of the present disclosure, an air supply system includes: a compressor having a load operation mode in which the compressor sends compressed air and an idle operation mode in which the compressor does not send the compressed air; a desiccant configured to remove moisture from the compressed air sent by the compressor; a connection passage connecting the compressor and the desiccant, the connection passage being for allowing circulation of the compressed air; a first solenoid valve configured to selectively switch the compressor between the load operation mode and the idle operation mode, the compressor being configured to switch to the idle operation mode in response to the first solenoid valve being driven, and the compressor being configured to switch to the load operation mode in response to the first solenoid valve not being driven; a drain discharge valve connected to a branch passage that branches from the connection passage, the drain discharge valve being configured to open the branch passage in response to a second solenoid valve being driven, and configured to close the branch passage in response to the second solenoid valve not being driven; and a control device configured to switch between driving and non-driving of the first solenoid valve and between driving and non-driving of the second solenoid valve.

Drawings

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

Fig. 2 (a) is a diagram showing a first operation mode in the operation modes of the air dryer of the first embodiment, (b) is a diagram showing a second operation mode in the operation modes of the air dryer of the first embodiment, (c) is a diagram showing a third operation mode in the operation modes of the air dryer of the first embodiment, (d) is a diagram showing a fourth operation mode in the operation modes of the air dryer of the first embodiment, (e) is a diagram showing a fifth operation mode in the operation modes of the air dryer of the first embodiment, and (f) is a diagram showing a sixth operation mode in the operation modes of the air dryer of the first embodiment.

Fig. 3 is a flowchart illustrating an example of a process of supplying compressed air in the first embodiment.

Fig. 4 is a flowchart showing an example of the procedure of the air dryer and the regeneration process in the first embodiment.

Fig. 5 is a flowchart illustrating an example of a process of idling the compressor in the first embodiment.

Fig. 6 is a flowchart illustrating an example of a process of adjusting the pressure of the connection passage in the first embodiment.

Fig. 7 is a flowchart illustrating an example of a process of adjusting the pressure of the connection passage in the second embodiment of the air supply system.

Fig. 8 is a flowchart illustrating an example of a process of adjusting the pressure of the connection passage in the third embodiment of the air supply system.

Fig. 9 is a flowchart showing an example of a process of adjusting the pressure of the connection passage in the fourth embodiment of the air supply system.

Fig. 10 is a flowchart showing an example of a process of adjusting the pressure of the connection passage in the fifth embodiment of the air supply system.

Fig. 11 is a flowchart showing an example of a procedure for performing the degreasing operation in the fifth embodiment.

Fig. 12 is a flowchart showing an example of a process of performing a regeneration operation based on humidity in the sixth embodiment of the air supply system.

Fig. 13 is a flowchart showing an example of a process of supplying compressed air in the seventh embodiment.

Fig. 14 is a flowchart showing an example of the procedure of the air drying and regeneration process in the seventh embodiment.

Fig. 15 is a flowchart illustrating an example of a process of idling the compressor in the seventh embodiment.

Fig. 16 is a flowchart illustrating an example of a process of adjusting the pressure of the connection passage in the seventh embodiment.

Detailed Description

(first embodiment)

A first embodiment of the air supply system will be described with reference to fig. 1 to 6. Air supply systems are mounted in automobiles such as trucks, buses, and construction machines.

< construction of air supply System 10 >

The structure of the air supply system 10 is explained with reference to fig. 1. The air supply system 10 includes a compressor 4, an air drying circuit 11, and an ECU80 as a control device. The control device or the components of the control device may be configured to include 1) 1 or more processors operating according to a computer program (software), 2) 1 or more dedicated hardware circuits such as Application Specific Integrated Circuits (ASICs) that execute at least a part of various processes, or 3) a circuit (circuit) that is a combination of these circuits. The processor includes a CPU, and memories such as a RAM and a ROM, and the memories store program codes and instructions configured to cause the CPU to execute processing. Memory, or computer-readable media, includes all available media that can be accessed by a general purpose or special purpose computer.

The air supply system 10 connects a plurality of wires E61 to E66 to the ECU 80. The ECU80 includes a calculation unit, a volatile storage unit, and a nonvolatile storage unit, and supplies the instruction value to the air drying circuit 11 in accordance with a program stored in the nonvolatile storage unit.

The compressor 4 is selectively switched between an operating state (load operation mode) in which air is compressed and supplied and a non-operating state (idle operation mode) in which air is not compressed, based on a command value of the ECU 80. That is, the compressor 4 has a load operation mode in which the compressor 4 sends out compressed air and an idle operation mode in which the compressor 4 does not send out compressed air.

The air drying circuit 11 is a so-called air dryer. The air drying circuit 11 is connected to the ECU80, and dries the compressed air sent from the compressor 4 in the load operation. The air drying circuit 11 sends the dried compressed air to the supply circuit 12.

The supply circuit 12 stores the compressed air sent from the air drying circuit 11 in an air tank, not shown, mounted on the vehicle, and supplies the compressed air to each load, not shown.

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.

< Structure of air dryer Circuit 11 >

The air drying circuit 11 includes a filter 17 in an interior 11A (see fig. 2 a to 2 f). In the first embodiment, the filter 17 is provided in the middle of the air supply passage 18 connecting the compressor 4 and the supply circuit 12. The filter 17 corresponds to a desiccant. The air supply passage 18 corresponds to a connection passage.

The filter 17 dries air by removing moisture contained in the air by passing the air through a desiccant, and cleans the air by removing oil contained in the air using a filter portion. The air having passed through the filter 17 is supplied to the supply circuit 12 via a downstream check valve 19 as a check valve that allows only the air to flow to the downstream side as viewed from the filter 17. That is, the downstream check valve 19 allows air to flow only from the upstream side where the filter 17 is located to the downstream side where the supply circuit 12 is located. Since the downstream check valve 19 has a predetermined valve opening pressure (closing pressure), the upstream pressure is higher than the downstream pressure by a pressure corresponding to the valve opening pressure when the compressed air flows.

Further, a bypass flow path 20, which is a bypass passage bypassing the downstream check valve 19, is provided downstream of the filter 17 in parallel with the downstream check valve 19. The bypass passage 20 is provided with a regeneration control valve 21. That is, the regeneration control valve 21 is provided in the middle of a passage connected in parallel to the passage in which the downstream check valve 19 is provided.

The regeneration control valve 21 is an electromagnetic valve that switches its operation in response to turning on/off (driving/non-driving) of the power supply from the ECU80 via the wiring E64. 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. The ECU80 receives, for example, the value of the air pressure in the tank, and operates the regeneration control valve 21 when the value of the air pressure is out of a predetermined range.

An orifice 22 is provided in the bypass passage 20 at a position between the regeneration control valve 21 and the filter 17. When the regeneration control valve 21 is energized, the compressed air on the supply circuit 12 side is delivered to the filter 17 via the bypass flow path 20 in a state where the flow rate is restricted by the orifice 22. The air sent to the filter 17 passes through the filter 17 in a reverse flow from the downstream side to the upstream side of the filter 17. Such a process is a process of regenerating the filter 17, and is referred to as a regeneration process of the dryer. The compressed air sent to the filter 17 at this time is air dried and cleaned, which is supplied to the supply circuit 12 after passing through the filter 17 from the air supply passage 18, and therefore moisture and oil captured by the filter 17 are removed from the filter 17. Therefore, the ECU80 opens the regeneration control valve 21 for a predetermined period. The predetermined period is set based on theory, experiment, or experience, and the period during which the filter 17 can be regenerated is set.

A branch passage 16 connected to a drain/discharge valve 25 is provided between the compressor 4 and the filter 17. That is, the branch passage 16 branches from the air supply passage 18. A drain outlet 27 is provided at the end of the branch passage 16.

The drain water containing the moisture and the oil removed from the filter 17 is sent to the drain valve 25 together with the compressed air. The drain/discharge valve 25 is an air pressure driven valve driven by air pressure, and is provided at a position 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 2-port 2-position valve that changes its position between a closed valve position and an open valve position. The drain discharge valve 25 feeds drain to the drain outlet 27 at the valve open position. The drain discharged from the drain outlet 27 may be recovered by an oil separator not shown.

The drain discharge valve 25 is controlled by a governor 26A. The governor 26A is an electromagnetic valve, and the governor 26A is operated by turning on/off (driving/non-driving) the power supply from the ECU80 via a wiring E63. When the power supply is turned on, the governor 26A opens the drain valve 25 by inputting an air pressure signal to the drain valve 25. When the power supply is turned off, the governor 26A closes the drain valve 25 by setting the pressure to atmospheric pressure without inputting an air pressure signal to the drain valve 25. The governor 26A corresponds to a second electromagnetic valve.

The drain discharge valve 25 is maintained at the closed valve position in a state where no air pressure signal is input from the governor 26A, and is changed to the open valve position when an air pressure 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 valve-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. When the compressor 4 side is set upstream and the filter 17 side is set downstream, the upstream check valve 15 allows air to flow only from upstream to downstream. Since the upstream check valve 15 has a predetermined valve opening pressure (closing pressure), the upstream pressure is higher than the downstream pressure by a pressure corresponding to the valve opening pressure when the compressed air flows. Further, 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 of the upstream check valve 15.

< compressor 4>

The compressor 4 is controlled by the unloading control valve 26B. The unloading control valve 26B is an electromagnetic valve that operates in response to an on/off (driving/non-driving) operation of the power supply from the ECU80 via the wiring E62. The unloading control valve 26B is in an open position when the power supply is turned off, and opens the flow path with the compressor 4 to the atmosphere. In addition, the unloading control valve 26B is in the supply position when the power is turned on, and supplies an air pressure signal formed of compressed air to the compressor 4. The unload control valve 26B and governor 26A are controlled separately. The unload control valve 26B corresponds to a first solenoid valve.

When the air pressure signal is input from the unloading control valve 26B, the compressor 4 is in a non-operating state (idle operation). For example, when the pressure of the supply circuit 12 reaches the upper limit pressure, the supply of dry compressed air is not necessary. The pressure of the supply circuit 12 is measured by a pressure sensor, not shown, and is input to the ECU 80. When the ECU80 turns on (drives) the power supply based on the measurement result of the pressure sensor, the unload control valve 26B is in the supply position. Thereby, an air pressure signal is supplied from the unloading control valve 26B to the compressor 4.

< 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 ECU80 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 and the temperature sensor 52 measure the humidity of the compressed air and the temperature of the air downstream of the filter 17, respectively, and output the measured results to the ECU80 via the wirings E65 and E66, respectively. The ECU80 calculates the dew point based on the input humidity of the compressed air and the temperature of the compressed air. The humidity measuring portion may be constituted by the humidity sensor 51, the temperature sensor 52, and the ECU 80. For example, assuming that the humidity of the compressed air output from the compressor 4 is approximately 100%, the amount of moisture removed by the filter 17 can be calculated based on the difference between 100% and the measured humidity and the saturated water vapor amount at temperature.

< description of operation of air drying circuit 11 >

As shown in fig. 2 (a) to 2 (f), the air drying circuit 11 has 6 operation modes, i.e., a first operation mode to a sixth operation mode.

As shown in fig. 2 (a), the first operation mode is a mode in which a normal loading operation is performed for the supply process, and the regeneration control valve 21, the governor 26A, and the unloading control valve 26B are each closed. That is, the regeneration control valve 21, the governor 26A, and the unloading control valve 26B are each "CLOSE". At this time, the regeneration control valve 21, the governor 26A, and the unloading control valve 26B do not receive the supply of power. Further, the governor 26A and the unloading control valve 26B open a port of the compressor 4 and a port of the drain discharge valve 25 connected downstream thereof to the atmosphere, respectively. In the first operation mode, when compressed air is supplied from the compressor 4, moisture and oil are removed by the desiccant, and the compressed air is supplied to the supply circuit 12. That is, the compressor 4 is "ON".

As shown in fig. 2B, the second operation mode is a mode in which the compressor is stopped (purge process is present) for the purge process, and is a mode in which the regeneration control valve 21 is closed and the governor 26A and the unloading control valve 26B are opened. That is, the regeneration control valve 21 is "CLOSE", and the governor 26A and the unloading control valve 26B are each "OPEN". At this time, the governor 26A and the unloading control valve 26B receive the supply of the power source, and connect the port of the compressor 4 and the port of the drain/discharge valve 25 connected downstream of the governor and the unloading control valve to the upstream side (the supply circuit 12), respectively. In the second operation mode, when the compressor 4 is in the non-operating state, the compressed air in the drying agent of the filter 17 or in the air supply passage 18 is discharged from the drain outlet 27 together with moisture, oil, or the like, and the air pressure in the drying agent of the filter 17 or in the air supply passage 18 is set to the atmospheric pressure. That is, the compressor 4 is "OFF".

As shown in fig. 2 (c), the third operation mode is a mode in which a regeneration operation for a regeneration process is performed, and is a mode in which the regeneration control valve 21, the governor 26A, and the unloading control valve 26B are opened. At this time, power is also supplied to the regeneration control valve 21. In the third operation mode, the compressor 4 is set to the non-operating state, and the compressed air supplied to the circuit 12 is caused to flow backward to the filter 17 (in the desiccant) and discharged from the drain outlet 27, thereby removing the moisture in the desiccant in the filter 17.

As shown in fig. 2 (d), the fourth operation mode is a mode in which the degreasing operation is performed, and is a mode in which the regeneration control valve 21 and the unloading control valve 26B are closed, respectively, and the governor 26A is closed after being opened for a certain period of time. In the fourth operation mode, when the compressor 4 is in the operating state, the compressed air supplied from the compressor 4 is discharged from the drain outlet 27 for a certain period of time, and for example, immediately after switching from the non-operating state to the operating state, the compressed air containing a relatively large amount of oil is discharged from the drain outlet 27, whereby deterioration of the filter 17 can be reduced. The oil removing operation can be performed when the oil from the compressor 4 increases, such as when the engine speed increases or when the load on the engine increases in the operating state.

As shown in fig. 2 (e), the fifth operation mode is a mode in which the compressor stop operation (no purge process) is performed, and is a mode in which the regeneration control valve 21 and the speed governor 26A are closed and the unloading control valve 26B is opened, respectively. In the fifth operation mode, when the compressor 4 is in the non-operating state, the compressed air remaining in the air supply passage 18 or the desiccant in the filter 17 is not discharged from the drain outlet 27, and the air pressure is maintained.

As shown in fig. 2 (f), the sixth operation mode is a mode in which the assist operation is performed for the pressurization process, and is a mode in which the regeneration control valve 21 and the unload control valve 26B are opened and the governor 26A is closed, respectively. In the sixth operation mode, when the compressor 4 is in the non-operating state, the compressed air from the supply circuit 12 is supplied (or is reversely flowed) to the air supply passage 18 or the drying agent of the filter 17 to be a pressure higher than the atmospheric pressure, and the back pressure (air pressure) of the upstream check valve 15 is maintained to be a pressure higher than the atmospheric pressure.

< compressor assist action >

The compressor assist operation will be described with reference to fig. 3 to 6.

When the piston descends during the idle operation, the compressor 4 generates a negative pressure in the cylinder according to the increase in the volume, and this negative pressure increases the operation load. Therefore, the increase in the operation load due to the negative pressure is reduced by the compressor assist. Specifically, in the compressor assist, when the piston of the compressor 4 is lowered during the idle operation, the desiccant in the filter 17 or the air supply passage 18 is maintained at a pressure higher than the atmospheric pressure, so that the reed valve at the outlet of the compressor 4 is closed, and the cylinder interior is maintained at a pressure generated when the piston is raised to some extent, thereby suppressing the generation of negative pressure in the cylinder. This can reduce the operating load of the compressor 4 that performs the idle operation. Specifically, when the compressor 4 is in the idling operation, the drain discharge valve 25 is closed, and the compressed air supplied from the compressor 4 maintains the pressure of the air in the drying agent in the filter 17 or in the air supply passage 18 at a pressure higher than the atmospheric pressure.

When the air supply system 10 starts to supply the compressed air, an air supply step of supplying the compressed air output from the compressor 4 to the supply circuit 12 is performed (step S10 in fig. 3). In the air supply step, the air drying circuit 11 is in the first operation mode, and the compressed air supplied from the compressor 4 is output to the supply circuit 12 after the moisture and oil are removed. In the air supply step, the air pressure supplied to the circuit 12, for example, the air pressure in the air tank, is terminated when it exceeds the upper limit value.

When the air supply operation is completed in the air supply step (step S10 in fig. 3), the air supply system 10 deactivates the compressor 4 and performs the dryer regeneration step (step S11 in fig. 3). In the dryer regeneration step, a dryer regeneration process for regenerating the filter 17 is performed.

As shown in fig. 4, in the dryer regeneration process, the ECU80 performs a humidity measurement process (step S20 of fig. 4). In the humidity measurement step, the humidity of the compressed air is measured based on the humidity measured by the humidity sensor 51 and the temperature measured by the temperature sensor 52.

Next, the ECU80 determines whether or not "purging" of the filter 17 is necessary (step S21 of fig. 4). The ECU80 determines that "purge" is necessary when the humidity of the compressed air is equal to or higher than the first humidity threshold value, and determines that "purge" is unnecessary when the humidity of the compressed air is lower than the first humidity threshold value. Whether or not "purging" is necessary can also be determined based on "the amount of ventilation to the filter" and "the amount of oil to the filter".

If it is determined that "purge" is necessary (step S21: "yes" in fig. 4), the ECU80 sets the air drying circuit 11 to the second operation mode and performs the compressor stop operation (purge process is present) (step S22 in fig. 4), and then determines whether or not the "regeneration process" of the filter 17 is necessary (step S24 in fig. 4). The ECU80 determines that the "regeneration process" is necessary when the humidity of the compressed air is equal to or higher than the second humidity threshold value, and determines that the "regeneration process" is unnecessary when the humidity of the compressed air is lower than the second humidity threshold value.

If it is determined that the "regeneration process" is necessary (step S24: "yes" in fig. 4), ECU80 sets air drying circuit 11 to the third operation mode and performs the regeneration operation (step S25 in fig. 4). When the regeneration process is completed, the ECU80 then terminates the dryer regeneration process (step S11 in fig. 3) and advances the process to the next step.

On the other hand, if it is determined that the "regeneration process" is not necessary (step S24: "NO" in FIG. 4), the ECU80 ends the dryer regeneration process (step S11 in FIG. 3) and proceeds to the next step.

On the other hand, when it is determined that "purge" is not necessary (step S21 in FIG. 4: NO), ECU80 sets air drying circuit 11 to the fifth operation mode and performs the compressor stop operation (no purge process) (step S23 in FIG. 4). By performing the compressor stop operation (no purge process), the desiccant in the filter 17 or the air supply passage 18 is not opened to the atmosphere after the compressor 4 is stopped, and therefore the back pressure of the upstream check valve 15 can be maintained higher than the atmospheric pressure. Therefore, the compressor assist can be performed. Accordingly, the dryer regeneration step (step S11 in fig. 3) is also completed, and the process proceeds to the next step.

Next, as shown in fig. 3, the air supply system 10 performs an air non-supply step (step S12 in fig. 3). In the air non-supply step, the ECU80 performs an air non-supply process to maintain the back pressure of the upstream check valve 15 high during the compressor stop operation.

Specifically, as shown in fig. 5, in the air non-supply process, it is determined by the ECU80 whether or not the air pressure in the desiccant in the filter 17 or in the air supply passage 18 is high (step S30 in fig. 5). The ECU80 compares the measurement value of the pressure sensor 50 with a high pressure threshold value, and determines that the air pressure is high if the measurement value is equal to or higher than the high pressure threshold value, and determines that the air pressure is low if the measurement value is lower than the high pressure threshold value.

If it is determined that the air pressure in the desiccant in the filter 17 or in the air supply passage 18 is high (step S30: "yes" in fig. 5), the ECU80 sets the air drying circuit 11 to the fifth operation mode and performs the compressor stop operation (no purge processing) (step S32 in fig. 5). On the other hand, when it is determined that the air pressure in the desiccant in the filter 17 or in the air supply passage 18 is low (step S30: "NO" in FIG. 5), the ECU80 performs the assist operation (step S31 in FIG. 5). In the assist operation, the air drying circuit 11 is set to the sixth operation mode, and the air pressure in the drying agent in the filter 17 or in the air supply passage 18 is increased. Then, the air drying circuit 11 is set to the fifth operation mode, and the compressor stop operation (no purge process) is performed (step S32 in fig. 5). Therefore, the back pressure of the upstream check valve 15 is maintained higher than the atmospheric pressure, and the compressor assist is possible.

Next, the ECU80 performs a pressure adjustment process (step S33 of fig. 5). In the pressure adjustment step, the ECU80 performs a pressure adjustment process.

As shown in fig. 6, the ECU80 determines whether or not the air pressure in the desiccant in the filter 17 or in the air supply passage 18 is low in the pressure adjustment process (step S40 in fig. 6). The ECU80 determines that the air pressure is low if the measurement value of the pressure sensor 50 is equal to or less than the low pressure threshold value, and determines that the air pressure is not low if the measurement value of the pressure sensor 50 is greater than the low pressure threshold value. In the first embodiment, since the upstream check valve 15 is provided on the downstream side of the pressure sensor 50, the value of the pressure sensor 50 is stable, and the number of times of the assist operation and the purge operation can be suppressed to be small.

If it is determined that the air pressure is low (step S40: "yes" in fig. 6), the ECU80 sets the air drying circuit 11 to the sixth operation mode to perform the assist operation (step S41 in fig. 6), and then sets the air drying circuit 11 to the fifth operation mode to perform the compressor stop operation (no purge process) (step S42 in fig. 6). On the other hand, if it is determined that the air pressure is not low (step S40: "NO" in FIG. 6), the ECU80 sets the air drying circuit 11 to the fifth operation mode and performs the compressor stop operation (no purge processing) (step S42 in FIG. 6).

In addition, the ECU80 determines whether the air pressure is high (step S43 of fig. 6). The ECU80 determines that the air pressure is high if the measurement value of the pressure sensor 50 is equal to or higher than the high pressure threshold, and determines that the air pressure is not high if the measurement value of the pressure sensor 50 is smaller than the high pressure threshold.

If it is determined that the air pressure is high (step S43: "yes" in fig. 6), the ECU80 sets the air drying circuit 11 to the second operation mode to perform the compressor stop operation (purge process) (step S44 in fig. 6), and sets the air drying circuit 11 to the fifth operation mode to perform the compressor stop operation (purge process not) (step S45 in fig. 6). On the other hand, if it is determined that the air pressure is not high (step S43 in FIG. 6: NO), the ECU80 sets the air drying circuit 11 to the fifth operation mode and performs the compressor stop operation (no purge process) (step S45 in FIG. 6). This maintains the back pressure of the upstream check valve 15 higher than the atmospheric pressure, and enables compressor assist. That is, the high and low of the air pressure have the relationship "atmospheric pressure < low pressure threshold value < high pressure threshold value". Next, the ECU80 performs an air pressure determination process (step S46 of fig. 6). In the air pressure determination process, if the measurement value of the pressure sensor 50 is less than the high pressure threshold value and not less than the low pressure threshold value, it is determined that the air pressure is "appropriate", and if it is not less than the high pressure threshold value or less than the low pressure threshold value, it is determined that the air pressure is "inappropriate".

Then, as shown in fig. 5, when the pressure adjustment process is finished, the pressure adjustment process (step S33 in fig. 5) is finished, and the process proceeds to the next step.

Next, it is determined whether or not the air non-supply process is ended (step S34 in fig. 5). The ECU80 determines that the air non-supply process is to be ended when the compressor 4 needs to be subjected to the load operation, and determines that the air non-supply process is not to be ended when the compressor 4 does not need to be subjected to the load operation.

That is, if it is determined that the air non-supply process is not to be ended (step S34: "NO" in FIG. 5), the ECU80 continues the pressure adjustment process (step S33 in FIG. 5). On the other hand, if it is determined that the air non-supply process is to be ended (step S34: "YES" in FIG. 5), the air non-supply process is ended (step S13 in FIG. 3), and the process proceeds to the next step.

Then, as shown in fig. 3, it is determined whether or not to end the air supply (step S13 of fig. 3). The air supply is determined to be terminated based on, for example, stopping of the engine of the vehicle, and is determined not to be terminated based on continuation of the engine rotation of the vehicle.

If it is determined that the air supply is not to be ended (step S13: "no" in fig. 3), the ECU80 returns the process to step S10, and executes the processes after the air supply process (step S10 in fig. 3). On the other hand, if it is determined that the air supply is ended (step S13: "YES" of FIG. 3), the air supply is stopped.

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

(1) When the solenoid valve for idling (unloading) the compressor 4 is the same as the solenoid valve for switching the drain valve 25, the air pressure in the air supply passage 18 or the desiccant becomes atmospheric pressure while the compressor 4 is idling. Therefore, the compressor 4 cannot suck air from the reed valve closed when the piston descends during the idle operation, and the cylinder becomes a negative pressure, which increases the operation load. According to the above configuration, the compressor 4 is switched between the load operation and the idle operation by the unload control valve 26B, and the drain discharge valve 25 is switched between the closed state and the open state by the governor 26A. That is, the unload control valve 26B and the governor 26A are controlled individually. Therefore, when the compressor 4 is in the idle operation, the discharge valve 25 can be closed in advance. For example, if the drain discharge valve 25 is closed in advance, the air pressure in the air supply passage 18 or the air pressure in the desiccant in the filter 17 can be maintained at a pressure higher than the atmospheric pressure to some extent by the air pressure supplied from the compressor 4. Therefore, the pressure in the cylinder of the compressor 4 is also maintained at a high pressure by the rise of the piston, and therefore the negative pressure generated in the cylinder when the piston is lowered is suppressed by the maintained pressure. This can reduce the load on the compressor 4.

(2) During at least a part of the period in which the compressor 4 is idling, the branch passage 16 is closed, and therefore the air pressure in the air supply passage 18 to which the reed valve of the compressor 4 is connected or the air pressure in the desiccant of the filter 17 is maintained high. In particular, even when the compressor 4 is switched from the load operation to the idle operation, the closing of the drain valve 25 is maintained in advance, and thereby the decrease in the air pressure in the air supply passage 18 or in the desiccant in the filter 17 is suppressed.

(3) In the air supply passage 18, the air pressure from the reed valve on the outlet side of the compressor 4 to the upstream check valve 15 can be maintained by the closing pressure of the upstream check valve 15.

(4) When the branch passage 16 is closed by the drain/discharge valve 25, the regeneration control valve 21 is opened to supply the compressed air downstream of the downstream check valve 19, thereby increasing the air pressure in the air supply passage 18 or the desiccant in the filter 17.

(5) By controlling the open/close valve of the regeneration control valve 21 based on the air pressure in the air supply passage 18 or in the desiccant in the filter 17 with reference to the measurement result of the pressure sensor 50, the air pressure in the air supply passage 18 or in the desiccant in the filter 17 can be adjusted to a pressure higher than the atmospheric pressure.

(6) The pressure sensor 50 can measure the air pressure in the air supply passage 18 connected to the reed valve on the outlet side of the compressor 4 or in the desiccant in the filter 17, and the open/close valve of the regeneration control valve 21 can be adjusted by the measured residual pressure.

(7) When the unload control valve 26B is driven (unloaded), the purge-less process, the purge process, the regeneration process, and the pressurization process can be performed in time.

(8) The air pressure in the air supply passage 18 or in the desiccant in the filter 17 can be maintained at a predetermined value higher than the atmospheric pressure. Further, if the value of the pressure sensor 50 is observed and feedback processing is performed, the air pressure can be maintained at a predetermined value with higher accuracy.

(9) The air pressure in the air supply passage 18 or the drying agent in the filter 17, which is reduced to the atmospheric pressure during the regeneration process, can be set to a pressure higher than the atmospheric pressure.

(second embodiment)

A second embodiment of the air supply system is explained with reference to fig. 7. The second embodiment is different from the first embodiment in that the upstream check valve 15 is not provided in the air supply passage 18. That is, the second embodiment has a structure in which the upstream check valve 15 is not provided in fig. 1 of the first embodiment.

In the second embodiment, by performing the compressor assist operation, the ECU80 performs the pressure adjustment process as shown in fig. 5 of the first embodiment (step S33 of fig. 5). In the pressure adjustment step, the ECU80 performs a pressure adjustment process.

As shown in fig. 7, the ECU80 determines whether or not the air pressure in the desiccant of the filter 17 or the air pressure in the air supply passage 18 is low in the pressure adjustment process (step S50 in fig. 7). In the second embodiment, the pressure sensor 50 is provided between the compressor 4 and the filter 17, but an upstream check valve is not provided. Therefore, although the value of the pressure sensor 50 may be somewhat unstable compared to the configuration of the first embodiment, the pressure adjustment process can be preferably performed by relatively increasing the number of times of the assist operation and the purge operation.

If it is determined that the air pressure is low (step S50: "yes" in fig. 7), the ECU80 performs an assist operation (step S51 in fig. 7). On the other hand, if it is determined that the air pressure is not low (step S50: "NO" in FIG. 7), or if the assist operation of step S51 is ended, the ECU80 performs the compressor stop operation (no purge processing) (step S52 in FIG. 7).

Next, the ECU80 determines whether the air pressure is high (step S53 of fig. 7).

If it is determined that the air pressure is high (step S53: "yes" in fig. 7), the ECU80 performs the compressor stop operation (presence of purge processing) (step S54 in fig. 7). On the other hand, if it is determined that the air pressure is not high (step S53: "NO" in FIG. 7), or if the purge operation of step S54 is ended, the ECU80 performs the compressor stop operation (no purge process) (step S55 in FIG. 7). Accordingly, the air pressure in the desiccant in the filter 17 or in the air supply passage 18 located upstream of the downstream check valve 19 is maintained higher than the atmospheric pressure, and the compressor assist can be performed. Further, the ECU80 performs the following air pressure determination process (step S56 of fig. 7): if the air pressure is less than the high pressure threshold value and equal to or greater than the low pressure threshold value, the air pressure is determined to be "appropriate", and if the air pressure is not equal to or greater than the low pressure threshold value, the air pressure is determined to be "inappropriate".

As described above, according to the second embodiment, the following effects can be obtained in addition to the effects (1), (2), (4), (5), (7) to (9) described in the first embodiment.

(10) Even if the upstream check valve 15 is not provided, the drain/discharge valve 25 is closed in advance when the compressor 4 is in the idle operation, and the air pressure in the desiccant in the filter 17 or the air pressure in the air supply passage 18 is maintained at a pressure higher than the atmospheric pressure to some extent. This can reduce the load on the compressor 4.

(third embodiment)

A third embodiment of the air supply system is explained with reference to fig. 8. The third embodiment is different from the first embodiment in that the pressure sensor 50 is not provided in the air supply passage 18. That is, the third embodiment has a structure in which the pressure sensor 50 is not provided in fig. 1 of the first embodiment.

In the third embodiment, by performing the compressor assist operation, the ECU80 performs the pressure adjustment process as shown in fig. 5 of the first embodiment (step S33 of fig. 5). In the pressure adjustment step, the ECU80 performs a pressure adjustment process.

As shown in fig. 8, the ECU80 determines whether or not to perform the assist in the pressure adjustment process (step S60 of fig. 8). In the third embodiment, since the upstream check valve 15 is provided, the ECU80 determines that the assist is not necessary when the compressor stop operation (no purge process) is continued after the compressor stop or when the previous operation is the assist operation. Further, the ECU80 determines that the assist is necessary when the previous operation is the compressor stop operation (there is the purge process) or the regeneration operation.

If it is determined that assistance is necessary (step S60: "yes" in fig. 8), the ECU80 performs an assist operation (step S61 in fig. 8). On the other hand, when it is determined that the assist is not necessary (step S60: "NO" in FIG. 8), or when the assist operation of step S61 is ended, the ECU80 determines whether or not the assist operation is ended (step S62 in FIG. 8). For example, when the condition for causing the compressor 4 to perform the load operation is satisfied, it is determined that the assist is ended.

If it is determined that the assist is not to be ended (no in step S62 of fig. 8), the ECU80 returns the process to step S60 to continue the operation corresponding to the determination of whether the assist operation is necessary. On the other hand, when it is determined that the assist is to be ended (step S62: "YES" of FIG. 8), ECU80 performs the compressor stop operation (no purge processing) (step S63 of FIG. 8). Then, the process returns to the pressure adjustment step, and the process proceeds to the next step of the pressure adjustment step.

As described above, according to the third embodiment, the following effects can be obtained in addition to the effects (1) to (4), (6) to (9) described in the first embodiment.

(11) Even if the pressure sensor 50 is not provided, the drain/discharge valve 25 is closed in advance when the compressor 4 is in the idling operation, and the air pressure in the air supply passage 18 or the desiccant in the filter 17 is maintained at a pressure higher than the atmospheric pressure to some extent by the closing pressure of the upstream check valve 15. This can reduce the load on the compressor 4.

(fourth embodiment)

A fourth embodiment of the air supply system is explained with reference to fig. 9. The fourth embodiment is different from the first embodiment in that the pressure sensor 50 and the upstream check valve 15 are not provided in the air supply passage 18. That is, the fourth embodiment has a structure in which the pressure sensor 50 and the upstream check valve 15 are not provided in fig. 1 of the first embodiment.

In the fourth embodiment, by performing the compressor assist operation, the ECU80 performs the pressure adjustment process as shown in fig. 5 of the first embodiment (step S33 of fig. 5). In the pressure adjustment step, the ECU80 performs a pressure adjustment process. Further, in the fourth embodiment, since the upstream check valve is not provided, the air pressure may become somewhat unstable as compared with the structure of the first embodiment. Further, since no pressure sensor is provided, feedback control based on the air pressure cannot be performed. Therefore, the control for the pressure adjustment process is performed based on the predetermined condition.

As shown in fig. 9, the ECU80 determines whether or not to perform the assist in the pressure adjustment process (step S70 of fig. 9). In the fourth embodiment, since the pressure sensor 50 and the upstream check valve 15 are not provided, the ECU80 determines that the assist is not necessary when the compressor is stopped and then continues to operate for stopping the compressor (no purge process) or when the previous operation is the assist operation. The ECU80 determines that the assist is necessary when the compressor stopping operation (purge process is present) or the regeneration operation is performed.

If it is determined that assistance is necessary (step S70: "yes" in fig. 9), the ECU80 performs an assist operation (step S71 in fig. 9). On the other hand, when it is determined that the assist is not necessary (step S70: "NO" in FIG. 9) or when the assist operation of step S71 is ended, the ECU80 determines whether or not the assist operation is ended (step S72 in FIG. 9). For example, when the condition for causing the compressor 4 to perform the load operation is satisfied, it is determined that the assist is ended.

If it is determined that the assist operation is not to be ended (no in step S72 in fig. 9), the ECU80 returns the process to step S70 to perform an operation corresponding to the determination of whether the assist operation is necessary. On the other hand, when it is determined that the assist is to be ended (step S72: "YES" of FIG. 9), ECU80 performs a compressor stop operation (no purge process) (step S73 of FIG. 9). Then, the process returns to the pressure adjustment step, and the process proceeds to the next step of the pressure adjustment step.

As described above, according to the fourth embodiment, the following effects can be obtained in addition to the effects (1), (2), (4), (7) to (9) described in the first embodiment.

(12) Even if the pressure sensor 50 and the upstream check valve 15 are not provided, the drain/discharge valve 25 is closed in advance when the compressor 4 is in the idling operation, and the air pressure in the air supply passage 18 or the desiccant in the filter 17 is maintained at a pressure higher than the atmospheric pressure to some extent. This can reduce the load on the compressor 4.

(fifth embodiment)

A fifth embodiment of the air supply system will be described with reference to fig. 10 and 11. The fifth embodiment is different from the first embodiment in that the degreasing treatment is performed in the normal load operation. Here, an example in which the degreasing treatment is performed at the start of the load operation will be described.

As shown in fig. 10, when the air supply system 10 starts supplying air, the degreasing process is first performed in the degreasing process (step S83 in fig. 10).

As shown in fig. 11, in the deoiling process, the ECU80 determines whether or not to perform the deoiling (step S90 of fig. 11). If it is determined that the oil removal is necessary (step S90: "yes" in fig. 11), the ECU80 sets the air drying circuit 11 to the fourth operation mode (see fig. 2 (d)) and performs the oil removal operation (step S91 in fig. 11). On the other hand, if it is determined that the degreasing is not necessary (step S90: "NO" in FIG. 11), or if the degreasing operation in step S91 is completed, the ECU80 ends the degreasing process (step S83 in FIG. 10).

Next, the same process as that in the first embodiment is performed when air starts to be supplied. That is, the air supply system 10 sequentially performs an air supply step (step S80 in fig. 10) of supplying the compressed air output from the compressor 4 to the supply circuit 12, a dryer regeneration step (step S81 in fig. 10), and an air non-supply step (step S82 in fig. 10).

Then, it is determined by the ECU80 whether or not to end the air supply (step S84 of fig. 10).

If it is determined that the air supply is not to be ended (step S84: "no" in fig. 10), ECU80 returns the process to step S83 to continue the air supply process. On the other hand, if it is determined that the air supply process is ended (step S84: "YES" of FIG. 10), the supply of air is stopped.

As described above, according to the fifth embodiment, in addition to the effects (1) to (12) described in the first to fourth embodiments, the following effect can be obtained.

(13) The compressed air containing relatively much oil is discharged from the discharge port 27, and deterioration of the filter 17 due to oil-containing moisture can be reduced. For example, it is preferably performed immediately after the compressor 4 is switched from the non-operating state to the operating state.

(sixth embodiment)

A sixth embodiment of the air supply system is explained with reference to fig. 12. The sixth embodiment is different from the first embodiment in that the forced regeneration process is performed during the load operation of the compressor 4. In the sixth embodiment, when the compressor 4 is in the load operation, the humidity of the compressed air is measured, and the forced regeneration process is performed based on the measured humidity.

As shown in fig. 12, when the supply of air is started, the ECU80 performs an air supply operation of supplying the compressed air output from the compressor 4 to the supply circuit 12 (step S100 in fig. 12). The ECU80 also performs a humidity measurement step of measuring the humidity of the compressed air supplied to the supply circuit 12 (step S101 in fig. 12).

Then, the ECU80 determines whether or not the "regeneration process" needs to be performed (step S102 of fig. 12).

If it is determined that the "regeneration process" is necessary (step S102: "yes" in fig. 12), ECU80 sets air drying circuit 11 to the third operation mode (see fig. 2 (c)) and forcibly performs the regeneration operation (step S103 in fig. 12). On the other hand, when it is determined that the "regeneration process" is not necessary (step S102 in FIG. 12: NO), the ECU80 keeps the compressor 4 in the load operation (first operation mode) and determines whether or not to end the air supply (step S104 in FIG. 12).

If it is determined that the air supply is not to be ended (no in step S104 in fig. 12), the ECU80 returns the process to step S100 in fig. 12 and continues the air supply process. On the other hand, if it is determined that the air supply process is ended (step S104: "YES" of FIG. 12), the supply of air is stopped.

As described above, according to the sixth embodiment, in addition to the effects (1) to (13) described in the first embodiment, the following effect can be obtained.

(14) Since the regeneration process can be performed even during the air supply, the deterioration of the filter 17 can be suppressed.

(seventh embodiment)

A seventh embodiment of the air supply system will be described with reference to fig. 13 to 16. The seventh embodiment is different from the first embodiment in that a compressed air usage amount adjustment operation is performed instead of the compressor assist operation.

< compressed air usage amount adjustment action >

The operation of optimizing the amount of compressed air used will be described with reference to fig. 13 to 16.

Since the regeneration operation and the purge operation for recovering the dehumidification performance of the filter 17 consume a certain amount of compressed air, the operation load of the compressor 4 is increased to supply the consumed compressed air. More specifically, an increase in the operating load of the compressor 4 for generating compressed air by the rotational force transmitted from the rotational drive source such as an engine increases the load on the rotational drive source, and increases the amount of energy consumed by fuel or the like. Therefore, by setting the execution conditions of the regeneration operation and the purge operation to realize the optimization of the number of times of performing the regeneration operation and the purge operation, the usage amount of the compressed air can be optimized, and the load of the compressor 4 can be reduced.

In the case where the regeneration operation or the purge operation is not performed, the drain/discharge valve 25 is closed during the idling operation of the compressor 4, and the pressure of the air in the drying agent of the filter 17 or in the air supply passage 18 can be maintained at a pressure higher than the atmospheric pressure by the compressed air supplied from the compressor 4. This can provide an effect equivalent to the compressor assist, and can reduce the operation load of the compressor 4 that performs the idle operation.

As shown in fig. 13, when the air supply system 10 starts to supply the compressed air, an air supply step of supplying the compressed air output from the compressor 4 to the supply circuit 12 is performed (step S110 in fig. 13). In the air supply step, the air drying circuit 11 is set to the first operation mode, and the compressed air supplied from the compressor 4 is supplied to the supply circuit 12 after moisture and oil are removed therefrom. When the air pressure supplied to the circuit 12, for example, the air pressure in the air tank exceeds the upper limit value, the air supply process is terminated.

When the air supply operation is completed in the air supply step (step S110 in fig. 13), the air supply system 10 deactivates the compressor 4 and performs the dryer regeneration step (step S111 in fig. 13). In the dryer regeneration step, a dryer regeneration process for regenerating the filter 17 is performed.

As shown in fig. 14, in the dryer regeneration process, the ECU80 performs a humidity measurement process (step S120 in fig. 14). In the humidity measurement step, the ECU80 measures the humidity of the compressed air based on the humidity measured by the humidity sensor 51 and the temperature measured by the temperature sensor 52. The humidity sensor 51 corresponds to a humidity measuring unit.

Next, the ECU80 determines whether or not the humidity is at or above the "medium" level (step S121 in fig. 14). The ECU80 determines that the humidity is equal to or higher than the "intermediate" level when the humidity of the compressed air is equal to or higher than the low humidity threshold value, and determines that the humidity is not equal to or higher than the "intermediate" level when the humidity of the compressed air is lower than the low humidity threshold value.

If it is determined that the humidity is at or above the "medium" level (step S121 in fig. 14: yes), ECU80 sets air drying circuit 11 to the second operation mode and performs the compressor stop operation (purge process) (step S122 in fig. 14), and then determines whether or not the humidity is at or above the "high" level (step S124 in fig. 14). The ECU80 determines that the humidity is at least the "high" level when the humidity of the compressed air is at least the high humidity threshold value, and determines that the humidity is not at least the "high" level when the humidity of the compressed air is less than the high humidity threshold value.

If it is determined that the humidity is at or above the "high" level (step S124 in fig. 14: yes), the ECU80 sets the air drying circuit 11 to the third operation mode and performs the regeneration operation (step S125 in fig. 14). When the regeneration process is completed, the ECU80 then terminates the dryer regeneration process (step S111 in fig. 13) and advances the process to the next step.

On the other hand, if it is determined that the humidity is less than the "high" level (step S124 in FIG. 14: NO), the ECU80 ends the dryer regeneration step (step S111 in FIG. 13) and advances the process to the next step.

On the other hand, when it is determined that the humidity is less than the "middle" level (step S121 in FIG. 14: NO), the ECU80 sets the air drying circuit 11 to the fifth operation mode and performs the compressor stop operation (no purge processing) (step S123 in FIG. 14). By performing the compressor stop operation (no purge process), the desiccant in the filter 17 or the air supply passage 18 is not opened to the atmosphere after the compressor 4 is stopped, and therefore, the effect of compressor assist can be expected. Accordingly, the dryer regeneration step (step S111 in fig. 13) is also completed, and the process proceeds to the next step.

Thus, if the humidity of the compressed air supplied from the compressor 4 is high and the moisture absorption amount of the desiccant is large when the compressor 4 is in the idle operation, the oil-containing moisture is discharged together with the air from the air supply passage 18 communicating with the drain discharge valve or the desiccant in the filter 17, so that the air cleanliness can be maintained (steps S122 and S25). At this time, if the humidity is at or above the "high" level, the regeneration operation using the compressed air flowing backward from the supply circuit 12 is performed (step S125), and if the humidity is at or above the "medium" level, the purge operation using the compressed air remaining in the air drying circuit 11 is performed (step S122). On the other hand, if the humidity of the compressed air supplied from the compressor 4 is low, the moisture absorption amount of the desiccant is small, and the amount of oil discharged from the compressor 4 together with the compressed air is small, the air is not discharged from the desiccant in the air supply passage 18 or the filter 17, and therefore the consumption of the compressed air is suppressed (step S123).

Next, as shown in fig. 13, the air supply system 10 performs an air non-supply step (step S112 in fig. 13). In the air non-supply step, the ECU80 performs an air non-supply process to maintain the back pressure of the upstream check valve 15 high during the compressor stop operation.

Specifically, as shown in fig. 15, in the air non-supply process, the ECU80 operates during non-supply (step S130 in fig. 15). During the non-supply time operation, the ECU80 performs a pressure adjustment process based on the measurement value of the pressure sensor 50 (fig. 16). In the pressure adjustment step, the ECU80 performs a pressure adjustment process. For example, in the pressure adjustment process, the air pressure in the desiccant of the filter 17 or in the air supply passage 18 is adjusted as necessary.

As shown in fig. 16, the ECU80 determines whether or not the air pressure in the desiccant in the filter 17 or in the air supply passage 18 is low in the pressure adjustment process (step S140 in fig. 16). The ECU80 determines that the air pressure is low if the measurement value of the pressure sensor 50 is equal to or less than the low pressure threshold value, and determines that the air pressure is not low if the measurement value of the pressure sensor 50 is greater than the low pressure threshold value. In addition, in the seventh embodiment, since the upstream check valve 15 is provided on the downstream side of the pressure sensor 50, the value of the pressure sensor 50 is stable, and the number of times of the assist operation and the purge operation can be suppressed to be small.

If it is determined that the air pressure is low (step S140: "yes" in fig. 16), the ECU80 sets the air drying circuit 11 to the sixth operation mode to perform the assist operation (step S141 in fig. 16), and then sets the air drying circuit 11 to the fifth operation mode to perform the compressor stop operation (no purge process) (step S142 in fig. 16). On the other hand, if it is determined that the air pressure is not low (no in step S140 in fig. 16), the ECU80 sets the air drying circuit 11 to the fifth operation mode and performs the compressor stop operation (no purge processing) (step S142 in fig. 16).

Further, the ECU80 determines whether the air pressure is high (step S143 of fig. 16). The ECU80 determines that the air pressure is high if the measurement value of the pressure sensor 50 is equal to or higher than the high pressure threshold, and determines that the air pressure is not high if the measurement value of the pressure sensor 50 is smaller than the high pressure threshold.

If it is determined that the air pressure is high (step S143: "yes" in fig. 16), ECU80 sets air drying circuit 11 to the second operation mode to perform the compressor stop operation (purge process) (step S144 in fig. 16), and sets air drying circuit 11 to the fifth operation mode to perform the compressor stop operation (purge process not) (step S145 in fig. 16). On the other hand, if it is determined that the air pressure is not high (step S143 in FIG. 16: NO), the ECU80 sets the air drying circuit 11 to the fifth operation mode and performs the compressor stop operation (no purge processing) (step S145 in FIG. 16). This maintains the back pressure of the upstream check valve 15 higher than the atmospheric pressure, and enables compressor assist. That is, the high and low of the air pressure have the relationship "atmospheric pressure < low pressure threshold value < high pressure threshold value". Next, the ECU80 performs an air pressure determination process (step S146 in fig. 16). In the air pressure determination process, if the measurement value of the pressure sensor 50 is less than the high pressure threshold value and not less than the low pressure threshold value, it is determined that the air pressure is "appropriate", and if it is not less than the high pressure threshold value or less than the low pressure threshold value, it is determined that the air pressure is "inappropriate".

When the pressure adjustment processing is completed, as shown in fig. 15, the non-supply-time operation (step S130 in fig. 15) is completed, and the process proceeds to the next step.

Next, it is determined whether or not the air non-supply process is ended (step S131 in fig. 15). The ECU80 determines that the air non-supply process is to be ended when the compressor 4 needs to be subjected to the load operation, and determines that the air non-supply process is not to be ended when the compressor 4 does not need to be subjected to the load operation.

That is, if it is determined that the air non-supply process is not to be ended (step S131 in FIG. 15: NO), the ECU80 continues the non-supply operation (step S130 in FIG. 15). On the other hand, if it is determined that the air non-supply process is to be ended (step S131 in FIG. 15: YES), the air non-supply process is ended (step S113 in FIG. 13), and the process proceeds to the next step.

Then, as shown in fig. 13, it is determined whether or not to end the air supply (step S113 in fig. 13). The air supply is determined to be terminated based on, for example, stopping of the engine of the vehicle, and is determined not to be terminated based on continuation of the engine rotation of the vehicle.

If it is determined that the air supply is not to be ended (no in step S113 in fig. 13), the ECU80 returns the process to step S110, and executes the processes after the air supply step (step S110 in fig. 13). On the other hand, if it is determined that the air supply is ended (step S113 in FIG. 13: YES), the air supply is stopped.

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

(15) When the solenoid valve for idling (unloading) the compressor 4 is the same as the solenoid valve for switching the drain valve 25, the air in the connection passage or the desiccant is released to the atmosphere in accordance with the idling of the compressor 4. Therefore, a part of the compressed air supplied from the compressor 4 is discharged in an unused state, and accordingly, the compressed air is consumed. According to the above configuration, the compressor 4 is switched between the load operation and the idle operation by the unload control valve 26B, and the drain discharge valve 25 is switched between the closed state and the open state by the governor 26A based on the humidity measured by the humidity measuring unit. Therefore, when the compressor 4 is in the idle operation, the discharge valve 25 can be closed in advance. For example, if the drain valve 25 is closed in advance when the air is dried, the air pressure in the air supply passage 18 or the air pressure in the desiccant in the filter 17 of the dryer can be maintained at a pressure higher than the atmospheric pressure by the air pressure supplied from the compressor 4. This can suppress the consumption of compressed air.

(16) When the compressor 4 is in the idle operation, if the humidity of the supplied compressed air is high, the moisture absorption amount of the desiccant of the filter 17 is large, and therefore, the oil-containing moisture is discharged together with the air from the air supply passage 18 communicating with the drain discharge valve 25 or the desiccant of the filter 17, and the air cleanliness can be maintained. On the other hand, if the humidity of the supplied compressed air is low, the amount of moisture absorbed by the desiccant in the filter 17 is small, and therefore the air pressure in the air supply passage 18 or the desiccant in the filter 17 is maintained, and therefore the consumption of the compressed air can be suppressed.

(17) Since the dried compressed air can be caused to flow back from the air tank, for example, by opening the regeneration control valve 21, the regeneration process of the drying agent in the filter 17 can be performed by the dry air flowing back, for example.

(18) Since the regeneration control valve can be controlled to be opened for a predetermined period of time, the regeneration process can be performed for a predetermined period of time.

(19) By the pressure adjustment process, even after the regeneration process is performed, the air pressure in the air supply passage 18 or the air pressure in the desiccant in the filter 17 can be maintained in a high state. For example, compressor assist is possible.

(other embodiments)

The above embodiments can be implemented as follows.

The above embodiments may be combined within a range not inconsistent with each other. For example, at least one of the fifth embodiment and the sixth embodiment may be combined with each of the first to fourth embodiments. At least one of the fifth embodiment and the sixth embodiment can be combined with the seventh embodiment.

In the first embodiment, the case where the pressure sensor 50 is provided on the upstream side of the upstream check valve 15 is exemplified. However, the present invention is not limited to this, and the pressure sensor may be provided on the downstream side of the upstream check valve. This allows the air pressure in the branch passage to be directly detected.

In each of the above embodiments, the filter 17 has a configuration including a desiccant and a filter unit, but may have a configuration including either one of the desiccant and the filter unit.

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

The oil mist separator includes a filter for performing gas-liquid separation by colliding with the compressed air, and traps 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 cleanliness of the compressed air can be further improved.

After the air drying circuit 11 is subjected to the regeneration process in the third operation mode, the ECU80 may close the drain discharge valve 25 without driving the governor 26A via the fifth operation mode or the second operation mode, and may perform the compressor assist after the sixth operation mode is set. This makes it possible to quickly maintain a state in which the air pressure in the connection passage or in the desiccant is high even after the regeneration process is performed. So-called compressor assist can be performed.

In each of the above embodiments, the humidity measuring unit is constituted by the humidity sensor 51, the temperature sensor 52, and the ECU 80. However, the humidity measuring unit is not limited to this, and may be configured by a device including a sensor as long as the humidity can be measured. For example, the calculation may not be performed by the ECU.

In the above embodiments, the air supply system 10 is mounted on a vehicle such as a truck, a bus, or a construction machine. As another embodiment, the air supply system may be mounted in another vehicle such as a car or a railway vehicle.