JP7343673B2 - air supply system - Google Patents

Description

The present invention relates to an air supply system that supplies compressed air to equipment.

In vehicles such as trucks, buses, and construction equipment, pneumatic systems such as brakes and suspensions are controlled using compressed air sent from a compressor. This compressed air contains liquid impurities such as moisture contained in the atmosphere and oil that lubricates the inside of the compressor. If compressed air containing a large amount of water or oil enters a pneumatic system, it may cause rust or swelling of rubber members, leading to malfunction. For this reason, a compressed air drying device is provided downstream of the compressor to remove impurities such as moisture and oil from the compressed air.

The compressed air drying device performs a loading operation (dehumidifying operation) for removing oil and moisture, and an unloading operation (regeneration operation) for removing oil and moisture adsorbed by a desiccant and releasing the oil and moisture as drain. Further, the air dryer discharges the drain discharged from the air dryer to the oil separator in order to prevent the drain from being discharged onto the road surface. In an oil separator, air containing oil and moisture collides with a collision material to perform gas-liquid separation, thereby recovering oil and discharging clean air (see, for example, Patent Document 1).

Japanese Patent Application Publication No. 2013-234632

In order to continuously supply clean air from an air dryer whose cleaning function decreases depending on the amount of compressed air supplied, it is necessary to perform a regeneration operation or a purge operation to restore the cleaning function of the air dryer by causing the compressed air to flow backwards. For example, the purge operation is performed every unload operation, and the regeneration operation is performed according to the number of unloads or elapsed time. Since these purge operations and regeneration operations consume compressed air, they increase the engine load to some extent. Incidentally, in recent years, there has been a demand for improved fuel efficiency of vehicles.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an air supply system that can improve the fuel efficiency of a vehicle .

The air supply system that achieves the above purpose includes a compressor that can switch between a load operation in which compressed air is sent out and an idle operation in which the compressed air is not sent out, and a dryer that removes moisture from the compressed air sent out by the compressor. a connecting passage connecting the compressor and the desiccant so that the compressed air can flow therethrough; a check valve that allows air to flow from the desiccant in a direction opposite to the compressor; a humidity measuring unit that measures the humidity of the compressed air that has passed through the valve; and a first electromagnetic valve that switches between the load operation and the idle operation of the compressor, the first electromagnetic valve being driven to switch the compressor between the load operation and the idle operation. the first electromagnetic valve that causes the compressor to be switched to the load operation when it is not driven; and the drain discharge valve that is connected to the branch passage of the connection passage; the drain discharge valve that seals or communicates the branch passage depending on whether the valve is driven/non-driven; switching the first electromagnetic valve between driving/non-driving; and driving/non-driving the second electromagnetic valve. and a control device that can switch between driving and non-driving the second electromagnetic valve, and the control device switches between driving and non-driving the second electromagnetic valve in consideration of the humidity measured by the humidity measuring section.

If the solenoid valve that runs the compressor dry (unloads) is the same as the solenoid valve that switches the drain discharge valve, the air in the communication passage and in the desiccant is released to the atmosphere in response to the dry run of the compressor. For this reason, a portion of the compressed air supplied by the compressor is discharged unused, and that amount of compressed air is consumed. According to such a configuration, the first solenoid valve switches the compressor between load operation and idle operation, and the second solenoid valve switches between sealing and drying the drain discharge valve depending on the humidity measured by the humidity measuring section. Communication can be switched. Therefore, when the compressor is in idle operation, the drain discharge valve can be kept sealed. For example, if the drain discharge valve is sealed when the air is dry, the air pressure in the connecting passage and the air pressure in the desiccant can be maintained at a pressure higher than atmospheric pressure by the air pressure supplied by the compressor. Thereby, the amount of compressed air consumed can be suppressed.

In a preferred configuration, when the first electromagnetic valve is driven, the control device operates the drain discharge valve with the second electromagnetic valve on the condition that the measured humidity is equal to or higher than a humidity threshold. The second electromagnetic valve operates the drain discharge valve to seal the branch passage under the condition that the humidity is less than the humidity threshold.

According to such a configuration, when the compressor is in idle operation, if the humidity of the supplied compressed air is high, the amount of water absorbed by the desiccant is large, so the connection passage communicating with the drain discharge valve and the desiccant are The cleanliness of the air is maintained by expelling oil and water from inside along with the air. On the other hand, if the humidity of the supplied compressed air is low, the amount of water absorbed by the desiccant is small, so purge or regeneration processing is not performed, and the air pressure in the connecting passage and desiccant is maintained, reducing the consumption of compressed air. is suppressed.

As a preferable configuration, the regeneration control valve is provided in the middle of a bypass passage parallel to the check valve, and the regeneration control valve seals the bypass passage when the valve is closed, and communicates the bypass passage when the valve is opened. Be prepared for more.

According to such a configuration, by opening the regeneration control valve, dry compressed air can be caused to flow back from the air tank, so that the desiccant can be regenerated using the backflowed dry air.

Preferably, the control device opens the regeneration control valve for a predetermined period when the second electromagnetic valve operates the drain discharge valve to communicate the branch passage.
According to such a configuration, the regeneration control valve can be controlled to open only for a predetermined period of time, so that regeneration processing can be performed for a predetermined period of time.

In a preferred configuration, the control device operates the drain discharge valve with the second solenoid valve to connect the branch passage, and then operates the second solenoid valve with the regeneration control valve opened. The drain discharge valve is operated to seal the branch passage.

According to such a configuration, even after the regeneration process is performed, the air pressure in the connecting passage and in the desiccant is quickly maintained at a high state. So-called compressor assist becomes possible.

As a preferable configuration, the control device operates the drain discharge valve with the second electromagnetic valve to connect the branch passage, operates the drain discharge valve to seal the branch passage, and then operates the drain discharge valve to open the branch passage. Open the regeneration control valve.

According to such a configuration, even after the purge process is performed, the air pressure in the connecting passage and in the desiccant is maintained at a high state. So-called compressor assist becomes possible.
As a preferable configuration, when the first electromagnetic valve is switched to non-drive, the control device operates the drain discharge valve with the second electromagnetic valve to communicate the branch passage, and when a predetermined period of time has elapsed. After that, the second electromagnetic valve operates the drain discharge valve to seal the branch passage.

According to such a configuration, compressed air supplied to the compressor for a predetermined period is discharged through the drain discharge valve. Thereby, oil and moisture that may be contained in the compressed air during load operation can be discharged. For example, immediately after switching from idle operation to loaded operation.

According to the present invention, consumption of compressed air can be suppressed.

FIG. 1 is a configuration diagram showing a schematic configuration of a first embodiment of an air supply system. FIG. 3 is a diagram showing operation modes of the air dryer of the same embodiment, in which (a) is a diagram showing a first operation mode, (b) is a diagram showing a second operation mode, and (c) is a diagram showing a third operation mode. , (d) is a diagram showing the fourth operation mode, (e) is a diagram showing the fifth operation mode, and (f) is a diagram showing the sixth operation mode. 5 is a flowchart showing an example of a procedure for supplying compressed air in the same embodiment. 2 is a flowchart illustrating an example of an air dryer and a regeneration process procedure in the same embodiment. 1 is a flowchart illustrating an example of a procedure for causing a compressor to run idly in the same embodiment. 5 is a flowchart illustrating an example of a procedure for adjusting the pressure of a connection passage in the same embodiment. 7 is a flowchart illustrating an example of a procedure with an oil cut in the second embodiment of the air supply system. 5 is a flowchart showing an example of a procedure for performing an oil cut operation in the same embodiment. 7 is a flowchart illustrating an example of a procedure for performing a regeneration operation based on humidity in a third embodiment of the air supply system.

(First embodiment)
A first embodiment of the air supply system will be described with reference to FIGS. 1 to 6. Air supply systems are installed in vehicles such as trucks, buses, and construction machines.

<Configuration of air supply system 10>
The configuration of the air supply system 10 will be described with reference to FIG. 1. The air supply system 10 includes a compressor 4, an air drying circuit 11, and an ECU 80 as a control device.

In the air supply system 10, a plurality of wires E61 to E66 are connected to the ECU 80. The ECU 80 includes a calculation section, a volatile storage section, and a nonvolatile storage section, and is configured to give a command value to the air drying circuit 11 according to a program stored in the nonvolatile storage section.

The compressor 4 is switched between an operating state (load operation) in which air is compressed and supplied, and a non-operating state (idle operation) in which air is not compressed, based on a command value from the ECU 80.
The air drying circuit 11 is a so-called air dryer. The air drying circuit 11 is connected to the ECU 80 and dries the compressed air sent from the compressor 4 during load operation. The air drying circuit 11 sends 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 it 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.

<Configuration of air drying circuit 11>
The air drying circuit 11 includes a filter 17 inside 11A (see FIG. 2). In this embodiment, the filter 17 is provided in the middle of an air supply passage 18 that connects the compressor 4 and the supply circuit 12. Note that the filter 17 corresponds to a desiccant. Note that the air supply passage 18 functions as a connection passage.

The filter 17 dries the air by removing moisture contained in the air by passing the air through a desiccant, and also cleans the air by removing oil contained in the air through a filtration section. The air that has passed through the filter 17 is supplied to the supply circuit 12 through a downstream check valve 19 that is a check valve that only allows air to flow downstream when viewed from the filter 17 . That is, the downstream check valve 19 allows air to flow only from upstream to downstream when the filter 17 side is upstream and the supply circuit 12 side is downstream. Note that the downstream check valve 19 has a predetermined valve opening pressure (sealing pressure), so when compressed air flows, the upstream pressure is higher than the downstream pressure by the valve opening pressure.

Furthermore, downstream of the filter 17 , a bypass passage 20 serving as a detour that bypasses the downstream check valve 19 is provided in parallel with the downstream check valve 19 . A regeneration control valve 21 is connected to the bypass passage 20 .

The regeneration control valve 21 is an electromagnetic valve whose operation is switched by turning on and off (driving/non-driving) the power from the ECU 80 via the wiring E64. The regeneration control valve 21 closes to seal the bypass passage when the power is turned off, and opens when the power is turned on to communicate the bypass circuit. For example, the ECU 80 receives the value of the air pressure in the air tank and operates the regeneration control valve 21 when the value of the air pressure exceeds a predetermined range.

An orifice 22 is provided in the bypass passage 20 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 sent to the filter 17 via the bypass passage 20 with the flow rate regulated by the orifice 22. The air sent to the filter 17 flows backward through the filter 17 from the downstream side to the upstream side of the filter 17. Such processing is processing for regenerating the filter 17, and is referred to as dryer regeneration processing. At this time, the compressed air sent to the filter 17 is dried and purified air that has passed through the filter 17 from the air supply passage 18 and is supplied to the supply circuit 12, so the moisture and oil trapped in the filter 17 are removed. removed from the filter 17. Therefore, the regeneration control valve 21 is opened only for a predetermined period by the ECU 80. The predetermined period is a period in which the filter 17 can be regenerated, and is set based on logic, experimentation, or experience.

A branch passage 16 connected to a drain discharge valve 25 is provided between the compressor 4 and the filter 17. A drain outlet 27 is provided at the end of the branch passage 16.
Drain containing water and oil removed from the filter 17 is sent to the drain discharge valve 25 together with compressed air. The drain discharge valve 25 is a pneumatically driven valve that is driven by air pressure, and is provided between the filter 17 and the drain discharge port 27 in the branch passage 16 of the air supply passage 18 . The drain discharge valve 25 is a two-port, two-position valve that changes position between a closed position and an open position. The drain discharge valve 25 sends drain to the drain outlet 27 in the open position. Drain discharged from the drain outlet 27 may be collected by an oil separator (not shown).

Drain discharge valve 25 is controlled by governor 26A. The governor 26A is a solenoid valve, and is activated by turning on/off (driving/non-driving) the power from the ECU 80 via the wiring E63. When the power is turned on, the governor 26A inputs a pneumatic signal to the drain discharge valve 25 to open the drain discharge valve 25. Further, when the power is turned off, the governor 26A closes the drain discharge valve 25 by setting it to atmospheric pressure without inputting an air pressure signal to the drain discharge valve 25. Note that the governor 26A functions as a second solenoid valve.

The drain discharge valve 25 is maintained at a closed position when no pneumatic signal is input from the governor 26A, and becomes an open position when a pneumatic signal is input from the governor 26A. Further, when the input port of the drain discharge valve 25 on the compressor 4 side becomes high pressure exceeding the upper limit value, the drain discharge valve 25 is forcibly switched to the open position.

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

<Compressor 4>
Compressor 4 is controlled by unload control valve 26B. The unload control valve 26B is a solenoid valve, and is activated in response to the power being turned on and off (driving/non-driving) from the ECU 80 via the wiring E62. When the power is turned off, the unload control valve 26B becomes an open position and opens the flow path between the unload control valve 26B and the compressor 4 to the atmosphere. Furthermore, when the power is turned on, the unload control valve 26B goes to the supply position and sends a pneumatic signal consisting of compressed air to the compressor 4. Note that the unload control valve 26B functions as a first electromagnetic valve.

When a pneumatic signal is input from the unload control valve 26B, the compressor 4 enters a non-operating state (idle operation). For example, when the pressure in the supply circuit 12 reaches the upper limit pressure, there is no need to supply dry compressed air. The pressure in the supply circuit 12 is measured by a pressure sensor (not shown) and input to the ECU 80. The unload control valve 26B enters the supply position when the ECU 80 turns on (drives) the power based on the measurement result of the pressure sensor. As a result, a pneumatic signal is supplied to the compressor 4 from the unload control valve 26B.

<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 in the connected air supply passage 18 and transmits the measured result to the ECU 80 via the wiring E61.

A humidity sensor 51 and a temperature sensor 52 are provided between the downstream check valve 19 and the supply circuit 12. The humidity sensor 51 and the temperature sensor 52 respectively measure the humidity of compressed air downstream of the filter 17 and the temperature of the air, and output the measured results to the ECU 80 via wiring E65 and E66. The ECU 80 calculates the dew point based on the input compressed air humidity and compressed air temperature. The humidity sensor 51, the temperature sensor 52, and the ECU 80 constitute a humidity measuring section. For example, if the humidity of the compressed air output from the compressor 4 is approximately 100%, the amount of water removed by the filter 17 is calculated based on the difference between 100% and the measured humidity and the saturated amount of water vapor at the temperature. can.

<Operation explanation of air drying circuit 11>
As shown in FIG. 2, the air drying circuit 11 has six operating modes: a first operating mode to a sixth operating mode.

As shown in FIG. 2(a), the first operation mode is a mode in which a normal loading operation is performed for supply processing, and the regeneration control valve 21, governor 26A, and unloading control valve 26B are respectively placed on the upstream side ( This is a mode in which the supply circuit 12 side) is closed (indicated as "CLOSE" in the figure). At this time, power is not supplied to the regeneration control valve 21, governor 26A, and unload control valve 26B, respectively. Further, the governor 26A and the unload control valve 26B open the port of the compressor 4 and the port of the drain discharge valve 25, which are connected downstream thereof, to the atmosphere, respectively. In the first operation mode, when compressed air is being supplied from the compressor 4 (denoted as "ON" in the figure), moisture and oil are removed using a desiccant, and the compressed air is supplied to the supply circuit 12.

As shown in FIG. 2(b), the second operation mode is a mode in which the compressor is stopped for purge processing (with purge), the regeneration control valve 21 is closed, and the governor 26A and unload control are performed. This is a mode in which each valve 26B is opened (denoted as "OPEN" in the figure). At this time, power is supplied to the governor 26A and the unload control valve 26B, and the port of the compressor 4 and the port of the drain discharge valve 25, which are connected downstream thereof, are respectively placed on the upstream side (the supply circuit 12 side). Connecting. In the second operation mode, when the compressor 4 is in a non-operating state (indicated as "OFF" in the figure), the compressed air in the desiccant of the filter 17 and the air supply passage 18 is drained from the drain outlet 27 to remove moisture and oil. The air pressure in the desiccant in the filter 17 and in the air supply passage 18 is brought to atmospheric pressure.

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

As shown in FIG. 2(d), the fourth operation mode is a mode for performing an oil cut operation, in which the regeneration control valve 21 and the unload control valve 26B are closed, and the governor 26A is opened for a certain period of time. In this mode, the valve is closed after the valve is closed. The fourth operation mode is to discharge the compressed air supplied by the compressor 4 from the drain outlet 27 for a certain period of time when the compressor 4 is in the operating state, for example, immediately after switching from the non-operating state to the operating state. As a result, compressed air containing a relatively large amount of oil is discharged from the drain outlet 27, and deterioration of the filter 17 can be reduced. An oil cut operation can also be performed when the oil from the compressor 4 increases when the engine speed increases during operation or when the engine is under high load.

As shown in FIG. 2(e), the fifth operation mode is a mode in which the compressor is stopped (no purge), and the regeneration control valve 21 and governor 26A are closed, and the unload control valve 26B is closed. This is the mode to open the valve. In the fifth operation mode, when the compressor 4 is not in operation, compressed air remaining in the desiccant in the air supply passage 18 and the filter 17 is not discharged from the drain outlet 27 to maintain air pressure.

As shown in FIG. 2(f), the sixth operation mode is a mode in which an assist operation is performed for pressurization processing, in which the regeneration control valve 21 and the unload control valve 26B are opened, and the governor 26A is opened. This mode closes the valve. In the sixth operation mode, when the compressor 4 is not in operation, the compressed air from the supply circuit 12 is supplied (backflow) into the desiccant in the air supply passage 18 and the filter 17 to create a pressure higher than atmospheric pressure. , the back pressure (air pressure) of the upstream check valve 15 is maintained at a pressure higher than atmospheric pressure.

<Compressed air usage optimization operation>
The compressed air usage optimization operation will be described with reference to FIGS. 3 to 6.
Since the regeneration operation and the purge operation for restoring the dehumidifying performance of the filter 17 consume some compressed air, the operating load of the compressor 4 is increased in order to supply the consumed compressed air. Specifically, an increase in the operating load of the compressor 4, which generates compressed air using rotational force transmitted from a rotational drive source such as an engine, increases the load on the rotational drive source and increases the consumption of energy such as fuel. let Therefore, by setting the execution conditions for the regeneration operation and purge operation to optimize the number of times the regeneration operation and purge operation are performed, the amount of compressed air used can be optimized, and the load on the compressor 4 can be reduced. That's what I do.

In addition, when the regeneration operation or the purge operation is not executed and the compressor 4 is running idly, the drain discharge valve 25 is sealed and the compressed air supplied by the compressor 4 is used to fill the desiccant of the filter 17 and the air supply. Air pressure within passageway 18 is maintained at a pressure above atmospheric pressure. As a result, an effect equivalent to compressor assist can be obtained, and the operating load on the compressor 4 that is running idly can be reduced.

As shown in FIG. 3, when the air supply system 10 starts supplying compressed air, it performs an air supply process of supplying the compressed air output from the compressor 4 to the supply circuit 12 (step S10 in FIG. 3). In the air supply process, the air drying circuit 11 is in the first operation mode, removes moisture and oil from the compressed air supplied from the compressor 4, and outputs the compressed air to the supply circuit 12. Note that the air supply process ends when the air pressure in the supply circuit 12, for example, the air pressure in the air tank, exceeds an 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 puts the compressor 4 into a non-operating state and performs a dryer regeneration step (step S11 in FIG. 3). In the dryer regeneration process, a dryer regeneration process for regenerating the filter 17 is performed.

As shown in FIG. 4, in the dryer regeneration process, the ECU 80 performs a humidity measurement process (step S20 in FIG. 4). In the humidity measurement step, the ECU 80 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.

Subsequently, the ECU 80 determines whether the humidity is at or above "medium" level (step S21 in FIG. 4). When the humidity of the compressed air is equal to or higher than the low humidity threshold, the ECU 80 determines that the humidity is "medium" or higher, and when the humidity of the compressed air is lower than the low humidity threshold, the ECU 80 determines that the humidity is "moderate" or higher. It is determined that there is no.

Then, if it is determined that the humidity is above "medium" level (YES in step S21 in FIG. 4), the ECU 80 sets the air drying circuit 11 to the second operation mode and performs a compressor stop operation (with purge). From step S22) in FIG. 4, it is determined whether the humidity is higher than "high" level (step S24 in FIG. 4). When the humidity of the compressed air is equal to or higher than the high humidity threshold, the ECU 80 determines that the humidity is at or above the "high" level, and when the humidity of the compressed air is less than the high humidity threshold, the ECU 80 determines that the humidity is at or above the "high" level. It is determined that there is.

If it is determined that the humidity is higher than "high" (YES in step S24 of FIG. 4), the ECU 80 sets the air drying circuit 11 to the third operation mode and performs a regeneration operation (step S25 of FIG. 4). When the regeneration process is completed, the ECU 80 ends 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 humidity is less than "high" (NO in step S24 in FIG. 4), the ECU 80 ends 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 humidity is less than "medium" (NO in step S21 in FIG. 4), the ECU 80 sets the air drying circuit 11 to the fifth operation mode and performs a compressor stop operation (no purge) (FIG. 4). 4 step S23). By performing the compressor stop operation (without purging), the desiccant in the filter 17 and the air supply passage 18 are not exposed to the atmosphere after the compressor 4 is stopped, so that a compressor assist effect can be expected. This also ends the dryer regeneration process (step S11 in FIG. 3), and the process proceeds to the next step.

As a result, when the compressor 4 is in idle operation, if the humidity of the compressed air supplied by the compressor 4 is high and the amount of moisture absorbed by the desiccant is large, the air supply passage 18 and filter 17 connected to the drain discharge valve Since the oil and moisture are discharged together with the air from the desiccant, the cleanliness of the air is maintained (steps S22 and S25). At this time, if the humidity is above the "high" level, a regeneration operation using the compressed air reversely flowed from the supply circuit 12 is performed (step S25), and if the humidity is above the "medium" level, the air drying circuit A purge operation using the compressed air remaining in the air conditioner 11 is performed (step S22). Conversely, if the humidity of the compressed air supplied by the compressor 4 is low, the amount of moisture absorbed by the desiccant is small, and the amount of oil discharged from the compressor 4 together with the compressed air is small, the air supply passage 18 and filter 17 Since air is not discharged from the desiccant, consumption of compressed air is suppressed (step S23).

Subsequently, as shown in FIG. 3, the air supply system 10 performs an air non-supply process (step S12 in FIG. 3). In the air non-supply process, the ECU 80 performs air non-supply processing so that the back pressure of the upstream check valve 15 is maintained high during the compressor stop operation.

More specifically, as shown in FIG. 5, in the air non-supply process, the ECU 80 performs a non-supply operation (step S30 in FIG. 5). In the non-supply operation, the ECU 80 performs a pressure adjustment process based on the measured value of the pressure sensor 50 (FIG. 6). In the pressure adjustment step, the ECU 80 performs pressure adjustment processing. For example, the pressure adjustment process adjusts the air pressure in the desiccant of the filter 17 and the air supply passage 18 as necessary.

As shown in FIG. 6, in the pressure adjustment process, the ECU 80 determines whether the air pressure in the desiccant of the filter 17 or in the air supply passage 18 is low (step S40 in FIG. 6). The ECU 80 determines that the air pressure is low if the measured value of the pressure sensor 50 is less than or equal to the low pressure threshold, and determines that the air pressure is not low if the measured value of the pressure sensor 50 is greater than the low pressure threshold. In this embodiment, since the upstream check valve 15 is provided downstream of the pressure sensor 50, the value of the pressure sensor 50 is stabilized, and the number of assist operations and purge operations can be kept small.

If it is determined that the air pressure is low (YES in step S40 in FIG. 6), the ECU 80 sets the air drying circuit 11 to the sixth operation mode to perform an assist operation (step S41 in FIG. 6), and then switches the air drying circuit 11 into the sixth operation mode. As the fifth operation mode, a compressor stop operation (without purge) is performed (step S42 in FIG. 6). On the other hand, if it is determined that the air pressure is not low (NO in step S40 in FIG. 6), the ECU 80 sets the air drying circuit 11 to the fifth operation mode and performs a compressor stop operation (no purge) (step S42 in FIG. 6). .

The ECU 80 also determines whether the air pressure is high (step S43 in FIG. 6). The ECU 80 determines that the air pressure is high if the measured value of the pressure sensor 50 is greater than or equal to the high pressure threshold, and determines that the air pressure is not high if the measured value of the pressure sensor 50 is less than the low pressure threshold.

If it is determined that the air pressure is high (YES in step S43 in FIG. 6), the ECU 80 sets the air drying circuit 11 to the second operation mode, performs a compressor stop operation (with purge) (step S44 in FIG. 6), and also The drying circuit 11 is set to the fifth operation mode, and the compressor is stopped (without purging) (step S45 in FIG. 6). On the other hand, if it is determined that the air pressure is not high (NO in step S43 in FIG. 6), the ECU 80 sets the air drying circuit 11 to the fifth operation mode and performs a compressor stop operation (no purge) (step S45 in FIG. 6). . Thereby, the back pressure of the upstream check valve 15 is maintained higher than atmospheric pressure, and compressor assist becomes possible. That is, the height of the air pressure has a relationship of "atmospheric pressure<low pressure threshold<high pressure threshold". Next, the ECU 80 performs air pressure determination processing (step S46 in FIG. 6). In the air pressure determination process, the air pressure is determined to be "appropriate" if the measured value of the pressure sensor 50 is less than the high pressure threshold and more than the low pressure threshold, and the air pressure is determined to be "appropriate" if it is more than the high pressure threshold or less than the constant pressure threshold. It is judged to be "inappropriate".

Then, as shown in FIG. 5, when the pressure adjustment process ends, the non-supply operation (step S30 in FIG. 5) ends, and the process proceeds to the next step.
Subsequently, it is determined whether or not to end the air non-supply process (step S31 in FIG. 5). If the compressor 4 needs to be operated under load, the ECU 80 determines to end the air non-supply process, whereas if the compressor 4 does not need to be operated under load, the ECU 80 determines not to end the air non-supply process.

That is, if it is determined that the air non-supply process is not to be ended (NO in step S31 in FIG. 5), the ECU 80 continues to perform the non-supply operation (step S30 in FIG. 5). On the other hand, if it is determined that the air non-supply process is to be ended (YES in step S31 in FIG. 5), the air non-supply process (step S13 in FIG. 3) is ended 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 in FIG. 3). For example, it is determined that the air supply is to be terminated based on, for example, the engine of the vehicle being stopped, and it is determined that the air supply is not to be terminated based on, for example, that the engine of the vehicle continues to rotate.

If it is determined that the air supply is not to be ended (NO in step S13 in FIG. 3), the ECU 80 returns the process to step S10 and executes the air supply process (step S10 in FIG. 3) and subsequent processes. On the other hand, if it is determined that the air supply is to be ended (YES in step S13 in FIG. 3), the air supply is stopped.

As explained above, according to this embodiment, the following effects can be obtained.
(1) The unload control valve 26B switches the compressor 4 between load operation and idle operation, and the governor 26A switches the drain discharge valve 25 between sealing and communication according to the humidity measured by the humidity measuring section. Therefore, when the compressor 4 is in idle operation, the drain discharge valve 25 can be kept sealed. For example, if the drain discharge valve 25 is sealed when the air is dry, the air pressure supplied by the compressor 4 will reduce the air pressure in the air supply passage 18 and the air pressure in the desiccant in the dryer filter 17 to atmospheric pressure. Can maintain higher pressure. Thereby, the amount of compressed air consumed can be suppressed.

(2) When the compressor 4 is in idle operation, if the humidity of the supplied compressed air is high, the amount of water absorbed by the desiccant in the filter 17 is large, so the air supply passage 18 communicating with the drain discharge valve 25 Since oil and water are discharged from the desiccant of the filter 17 along with the air, the cleanliness of the air can be maintained. Conversely, if the humidity of the supplied compressed air is low, the amount of moisture absorbed by the desiccant in the filter 17 is small, so the air pressure in the air supply passage 18 and the desiccant in the filter 17 is maintained, reducing the consumption of compressed air. can be suppressed.

(3) By opening the regeneration control valve 21, it becomes possible to cause dry compressed air to flow back from, for example, an air tank, so it becomes possible, for example, to regenerate the desiccant in the filter 17 using the backflow dry air. .

(4) Since the regeneration control valve can be controlled to open only for a predetermined period, regeneration processing can be performed for a predetermined period.
(5) The pressure adjustment process maintains the air pressure in the air supply passage 18 and the air pressure in the desiccant of the filter 17 at a high level even after the regeneration process has been performed. For example, compressor assist becomes possible.

(Second embodiment)
A second embodiment of the air supply system will be described with reference to FIGS. 7 and 8. This embodiment differs from the first embodiment in that oil cut processing is performed during normal load operation. Here, an example will be described in which oil cut processing is performed when load operation is started.

As shown in FIG. 7, when air supply is started, the air supply system 10 first performs an oil cut process in an oil cut process (step S83 in FIG. 7).
As shown in FIG. 8, in the oil cut process, the ECU 80 determines whether or not to perform an oil cut (step S90 in FIG. 8). If it is determined that oil cut is necessary (YES in step S90 of FIG. 8), the ECU 80 puts the air drying circuit 11 into the fourth operation mode (see FIG. 2(d)) and performs the oil cut operation (see FIG. 8 step S91). On the other hand, if it is determined that oil cut is not necessary (NO in step S90 in FIG. 8), or if the oil cut operation in step S91 is completed, the ECU 80 ends the oil cut process (step S83 in FIG. 7). do.

Subsequently, the same process as when air supply is started in the first embodiment is performed. In other words, the air supply system 10 performs an air supply process (step S80 in FIG. 7) in which compressed air output from the compressor 4 is supplied to the supply circuit 12, a dryer regeneration process (step S81 in FIG. 7), and an air non-supply process. (Step S82 in FIG. 7) is performed sequentially.

Then, the ECU 80 determines whether or not to end the air supply (step S84 in FIG. 7).
If it is determined that the air supply is not to be ended (NO in step S84 in FIG. 7), the ECU 80 returns the process to step S83 and continues the air supply process. On the other hand, if it is determined that the air supply process is to be completed (YES in step S84 in FIG. 7), the supply of air is stopped.

As explained above, according to this embodiment, in addition to the effects (1) to (5) described in the first embodiment, the following effects can be obtained.
(6) Since compressed air containing a relatively large amount of oil is discharged from the drain outlet 27, it is possible to reduce the possibility that the filter 17 will deteriorate due to oil and moisture. For example, it may be carried out immediately after the compressor 4 is switched from a non-operating state to an operating state.

(Third embodiment)
A third embodiment of the air supply system will be described with reference to FIG. This embodiment differs from the first embodiment in that forced regeneration processing is performed while the compressor 4 is operating under load. In this embodiment, when the compressor 4 is operating under load, the humidity of compressed air is measured, and forced regeneration processing is performed based on the measured humidity.

As shown in FIG. 9, when air supply is started, the ECU 80 performs an air supply operation to supply compressed air output from the compressor 4 to the supply circuit 12 (step S100 in FIG. 9). Further, the ECU 80 performs a humidity measurement step of measuring the humidity of the compressed air supplied to the supply circuit 12 (step S101 in FIG. 9).

Then, the ECU 80 determines whether "regeneration processing" is necessary (step S102 in FIG. 9).
If it is determined that "regeneration processing" is necessary (YES in step S102 of FIG. 9), the ECU 80 sets the air drying circuit 11 to the third operation mode (see FIG. 2(c)) and forces the regeneration operation. (Step S103 in FIG. 9). On the other hand, if it is determined that the "regeneration process" is not necessary (NO in step S102 in FIG. 9), the ECU 80 determines whether to terminate the air supply while maintaining the compressor 4's load operation (first operation mode). (Step S104 in FIG. 9).

If it is determined that the air supply is not to be ended (NO in step S104 in FIG. 9), the ECU 80 returns the process to step S100 in FIG. 9 and continues the air supply process. On the other hand, if it is determined that the air supply process is to be completed (YES in step S104 in FIG. 9), the supply of air is stopped.

As explained above, according to this embodiment, in addition to the effects (1) to (6) described in the first and second embodiments, the following effects can be obtained.
(7) Since the regeneration process can be performed even while air is being supplied, deterioration of the filter 17 can be suppressed.

(Other embodiments)
Note that each of the embodiments described above can also be implemented in the following forms.
- The above embodiments may be combined to the extent that no contradiction occurs. For example, the first embodiment may be combined with at least one of the second and third embodiments.

- In each of the above embodiments, the case where the pressure sensor 50 is provided upstream of the upstream check valve 15 is illustrated. However, the present invention is not limited to this, and the pressure sensor may be provided downstream of the upstream check valve. Thereby, the air pressure in the branch passage can be directly detected.

- In each of the above embodiments, the filter 17 has a desiccant and a filtration section, but it may have either one of them.
- In each of the above embodiments, the case where the filter 17 is provided is illustrated, 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 that performs gas-liquid separation by collision with compressed air, and captures oil contained in the compressed air sent from the compressor 4. The filter may be made of a compression molded metal material or may be made of a porous material such as a sponge. By providing this oil mist separator, the cleanliness of compressed air can be further improved.

- After regenerating the air drying circuit 11 in the third operation mode, the ECU 80 deactivates the governor 26A and closes the drain discharge valve 25 without going through the fifth operation mode or the second operation mode. The sixth operation mode may be set to perform compressor assist. As a result, even after the regeneration process is performed, the air pressure in the connecting passage and in the desiccant is quickly maintained at a high state. So-called compressor assist becomes possible.

- In each of the above embodiments, the humidity sensor 51, the temperature sensor 52, and the ECU 80 constitute the humidity measuring section. However, the present invention is not limited to this, and the humidity measuring section may be configured with a device including a sensor as long as it can measure humidity. For example, it is not necessary to perform calculations using the ECU.

- In each of the above embodiments, the air supply system 10 has been described as being mounted on a vehicle such as a truck, bus, or construction machine. In other embodiments, the air supply system may be mounted on other vehicles such as passenger cars and railway vehicles.

4... Compressor, 10... Air supply system, 11... Air drying circuit, 11A... Internal, 12... Supply circuit, 15... Upstream check valve, 16... Branch passage, 17... Filter, 18... Air supply passage, 19... Downstream check Valve, 20... Bypass passage, 21... Regeneration control valve, 22... Orifice, 25... Drain discharge valve, 26A... Governor, 26B... Unload control valve, 27... Drain discharge port, 50... Pressure sensor, 51... Humidity sensor , 52...Temperature sensor, 80...ECU, E61-E66...Wiring, P12...Maintenance port.

Claims (7)

a compressor capable of switching between a load operation in which compressed air is sent out and an idle operation in which the compressed air is not sent out;
a desiccant that removes moisture from the compressed air sent out by the compressor;
a connection passage connecting the compressor and the desiccant so that the compressed air can flow;
a check valve that allows air to flow from the desiccant in a direction opposite to the compressor;
A first electromagnetic valve that switches the compressor between the load operation and the idle operation, the first electromagnetic valve switching the compressor between the load operation and the idle operation when driven, and the first solenoid valve that switches the compressor between the load operation and the idle operation when not being driven. the first solenoid valve to be switched into operation ;
A drain discharge valve connected to a branch passage of the connection passage closes when no pneumatic signal is input because the second solenoid valve is not driven, and the second solenoid valve closes when no air pressure signal is input. the drain discharge valve that opens when a pneumatic signal is input by being driven ;
a control device capable of switching driving/non-driving of the first electromagnetic valve and switching driving/non-driving of the second electromagnetic valve;
a regeneration control valve provided in the middle of a bypass passage parallel to the check valve, the regeneration control valve sealing the bypass passage by closing the valve and communicating the bypass passage by opening the valve;
The control device drives the first electromagnetic valve to open the regeneration control valve when the compressor is in a non-operating state, and also causes the second electromagnetic valve to be non-driven to open the drain discharge valve. Air supply system that performs compressor assist operation to close the valve. a compressor capable of switching between a load operation in which compressed air is sent out and an idle operation in which the compressed air is not sent out;
a desiccant that removes moisture from the compressed air sent out by the compressor;
a connection passage connecting the compressor and the desiccant so that the compressed air can flow therethrough;
a check valve that allows air to flow from the desiccant in a direction opposite to the compressor;
a humidity measuring unit that measures the humidity of the compressed air that has passed through the check valve;
A first electromagnetic valve that switches the compressor between the load operation and the idle operation, the first electromagnetic valve switching the compressor between the load operation and the idle operation when driven, and the first solenoid valve that switches the compressor between the load operation and the idle operation when not being driven. the first solenoid valve for switching to operation;
A drain discharge valve connected to a branch passage of the connection passage closes when no pneumatic signal is input because the second solenoid valve is not driven, and the second solenoid valve closes when no air pressure signal is input. the drain discharge valve that opens when a pneumatic signal is input by being driven ;
a control device capable of switching driving/non-driving of the first electromagnetic valve and switching driving/non-driving of the second electromagnetic valve;
a regeneration control valve provided in the middle of a bypass passage parallel to the check valve, the regeneration control valve sealing the bypass passage by closing the valve and communicating the bypass passage by opening the valve;
The control device switches the second electromagnetic valve between driving and non-driving in consideration of the humidity measured by the humidity measuring unit, and drives the first electromagnetic valve when the compressor is in a non-operating state. , an air supply system that performs a compressor assist operation in which the regeneration control valve is opened, the second electromagnetic valve is not driven, and the drain discharge valve is closed. The air supply system according to claim 1 or 2, wherein the control device performs the compressor assist operation when the air pressure in the connection passage is lower than a low pressure threshold. After the compressor assist operation, the control device closes the regeneration control valve and the second solenoid valve, and performs a compressor stop operation without purge that opens the first solenoid valve. The air supply system according to any one of items 1 to 3. The control device opens the regeneration control valve, the second solenoid valve, and the first solenoid valve to perform a regeneration operation of causing compressed air to flow back into the desiccant, and then controls the compressor assist. The air supply system according to any one of claims 1 to 4, wherein the air supply system performs an operation. The air supply system according to any one of claims 1 to 4, wherein the first solenoid valve and the second solenoid valve are not driven and connect to the atmosphere. The air supply system according to any one of claims 1 to 6, wherein the drain discharge valve opens the branch passage to the atmosphere by deactivating the second electromagnetic valve.

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