WO2020066515A1

WO2020066515A1 - Air suspension device

Info

Publication number: WO2020066515A1
Application number: PCT/JP2019/034808
Authority: WO
Inventors: 小林　寛; 勉伊藤
Original assignee: 日立オートモティブシステムズ株式会社
Priority date: 2018-09-25
Filing date: 2019-09-04
Publication date: 2020-04-02

Abstract

This air suspension device is provided with: a compressor 2 configured to compress air supplied from a tank 12 by way of an intake pipeline 13 (first passage); an air suspension 1 connected to a discharge side 2B of the compressor 2 by way of an air dryer 6; a return solenoid valve 16 configured to return compressed air in the air suspension 1 to the tank 12 by way of a tank pipeline 15 (second passage); a venting solenoid valve 17 which opens in accordance with the pressure in the tank 12, and which is provided in a bypass pipeline 8 (third passage) in order to vent compressed air inside the air suspension 1 by way of the air dryer 6; and an intake valve 18 comprising a check valve configured to take in air from the atmosphere if the pressure of air between an intake side 2A of the compressor 2 and the tank 12 is equal to or less than atmospheric pressure.

Description

Air suspension device

The present invention relates to an air suspension device mounted on a vehicle such as a four-wheel vehicle.

車両 Some vehicles such as four-wheeled vehicles are equipped with an air suspension device for adjusting the vehicle height. This type of air suspension device includes an open type and a closed type. The open type has the advantages that the system configuration is simple and the number of components can be reduced. However, since the air is compressed from the atmospheric pressure state, it takes time to increase the pressure of the compressed air to a desired pressure. On the other hand, a closed-type air suspension device (for example, see Patent Literature 1) has an advantage that the pressure of the suction air can be made higher than the atmospheric pressure, so that the pressure of the compressed air can be increased to a desired pressure in a short time. .

JP-T-2012-516256A

However, the closed-type air suspension device described in Patent Literature 1 uses high-pressure air in the tank to regenerate the desiccant (moisture adsorbent) of the air dryer, so that the regeneration efficiency of the air dryer is reduced. There is. Furthermore, since an expensive three-way solenoid valve is used, there is a problem that the manufacturing cost increases.

The present invention has been made in consideration of the above-described problems of the related art, and an object of the present invention is to provide an air suspension device capable of efficiently regenerating an air dryer.

In order to solve the above-mentioned problem, the present invention relates to an air suspension device, comprising: a tank configured to store air, and configured to compress air supplied from the tank through a first passage. Compressed air, an air suspension connected to the discharge side of the compressor via an air dryer, and compressed air in the air suspension via a second passage provided to branch off from between the air dryer and the air suspension. A return valve configured to return to the tank by an exhaust valve provided in a third passage that opens according to the pressure in the tank and exhausts the compressed air in the air suspension through the air dryer. When the pressure of the air between the suction side of the compressor and the tank is equal to or lower than the atmospheric pressure, the air is sucked from the atmosphere. It is characterized in that it comprises a an intake valve is configured check valve.

According to the present invention, the air dryer can be efficiently regenerated by discharging the compressed air in the air suspension to the outside air through the exhaust valve.

FIG. 1 is a circuit diagram illustrating an overall configuration of an air suspension device according to a first embodiment of the present invention. FIG. 3 is a control block diagram of an air suspension device including a controller. 5 is a flowchart illustrating a control process when the controller increases the vehicle height. 5 is a flowchart showing a control process when the controller lowers the vehicle height. FIG. 5 is a characteristic diagram illustrating a relationship between a pressure difference between an air suspension and a tank and a vehicle height descending speed. It is a flowchart which shows the control processing at the time of lowering | hanging a vehicle height by 2nd Embodiment.

Hereinafter, an air suspension device according to an embodiment of the present invention will be described in detail with reference to FIGS. 1 to 6 of the accompanying drawings, taking an example in which the air suspension device is applied to a vehicle such as a four-wheeled vehicle.

FIGS. 1 to 5 show a first embodiment. In the figure, a total of four air suspensions 1 are provided on a left front wheel (FL), a right front wheel (FR), a left rear wheel (RL), and a right rear wheel (RR) side of the vehicle. (Neither is shown). These air suspensions 1 adjust the vehicle height in accordance with expansion and contraction of the air chamber 1C by supplying and discharging compressed air into an air chamber 1C described later.

Each of the air suspensions 1 includes, for example, a cylinder 1A mounted on the axle side of the vehicle, a piston rod 1B protruding from the inside of the cylinder 1A so as to be able to expand and contract in the axial direction, and a protruding end side mounted on the vehicle body side; And an air chamber 1C which is provided so as to be extendable and contractable between the protruding end of the cylinder and the cylinder 1A and operates as an air spring. The air chamber 1C of each air suspension 1 is expanded and contracted in the axial direction by supplying and discharging compressed air from a branch pipe 10A described later. At this time, each air suspension 1 adjusts the height (vehicle height) of the vehicle in accordance with the supply and discharge amount of the compressed air by the piston rod 1B extending and contracting in the axial direction from inside the cylinder 1A.

The compressor 2 generates compressed air while sucking air from the suction side 2A (hereinafter referred to as the suction side 2A), and is constituted by, for example, a reciprocating compressor or a scroll compressor. The compressed air generated from the compressor 2 is supplied to an air chamber 1C of an air suspension 1 which is a pneumatic device. The compressor 2 is rotationally driven by an electric motor 3 as a drive source. The drive and stop of the electric motor 3 are controlled by a controller 20 (see FIG. 2) described later.

(4) The intake / exhaust pipe 4 is connected to the intake side 2A of the compressor 2, and the supply / discharge pipe 5 is connected to the discharge side 2B of the compressor 2. One end of the supply / discharge conduit 5 is connected to the discharge side 2B of the compressor 2, and the other end is connected to an air conduit 10 described later. An air dryer 6 and a slow return valve 7 are provided at an intermediate position of the supply / discharge conduit 5.

The intake / exhaust line 4 constitutes an intake passage of the compressor 2, and a tank-side intake line 13, which will be described later, is connected to the connection point 4A. The supply / discharge conduit 5 constitutes a supply / discharge passage for supplying / discharging the compressed air generated from the compressor 2 to / from the air chamber 1 C of the air suspension 1. The compressed air supplied to the air chamber 1C of the air suspension 1 is discharged from the air chamber 1C through the supply / discharge pipe 5 so as to flow back through the air dryer 6, for example, when the vehicle height is lowered, or the compressed air is supplied to a tank 12 described later. It is discharged so as to escape inside.

バイパス Further, a bypass pipe 8 is provided between the intake side 2A and the discharge side 2B of the compressor 2 as a third passage which bypasses (bypasses) the compressor 2 and connects the two. The bypass conduit 8 is connected to the supply / discharge conduit 5 so that one end branches off from the supply / discharge conduit 5 at the position of the connection point 5A, and the other end of the bypass conduit 8 is connected to the suction / drain at the position of the connection point 4B. It is connected to the intake / exhaust line 4 so as to branch off from the exhaust line 4. That is, the connection point 4B connects the intake / exhaust line 4 to the bypass line 8 at a position between the intake / exhaust port 9 and the intake valve 18 described later. The connection point 5A connects the supply / discharge pipe line 5 to the bypass pipe line 8 at a position between the discharge side 2B of the compressor 2 and the air dryer 6. An exhaust solenoid valve 17 described later is provided in the middle of the bypass pipe 8.

One end of the intake / exhaust line 4 of the compressor 2 is a suction / exhaust port 9 which opens to the outside of the compressor 2. The intake / exhaust port 9 is provided with a filter (not shown) for removing dust and the like in the air. ing. The other end of the intake / exhaust line 4 is connected to the intake side 2 A of the compressor 2, and an intake valve 18 described later is provided in the intake / exhaust line 4. The suction / discharge port 9 is a port for sucking outside air into the intake side 2A when the compressor 2 is driven, and for discharging compressed air to the outside when the exhaust solenoid valve 17 is opened.

The air dryer 6 constitutes an air drying means provided in the middle of the supply / discharge pipeline 5. The air dryer 6 contains a moisture adsorbent (not shown) such as silica gel, for example, and is disposed between the discharge side 2B of the compressor 2 and the slow return valve 7. The slow return valve 7 is configured by a parallel circuit of a throttle 7A and a check valve 7B, and does not throttle the flow rate of compressed air by opening the check valve 7B for a forward flow described later. However, the check valve 7B closes against the flow in the reverse direction, and the flow rate of the compressed air at this time is reduced by the throttle 7A, so that the compressed air flows backward in the air dryer 6 slowly with a small flow rate.

The air dryer 6 contacts the compressed air with the internal moisture adsorbent when the high-pressure compressed air generated by the compressor 2 flows through the supply / discharge pipe 5 in the forward direction toward the air suspension 1. Moisture is adsorbed and dried compressed air is supplied to the air chamber 1C. On the other hand, when the compressed air (exhaust) discharged from the air suspension 1 (air chamber 1C) flows in the air dryer 6 (supply / discharge conduit 5) in the opposite direction, the dried air flows back through the air dryer 6. The moisture of the moisture adsorbent in the air dryer 6 is desorbed by the dry air. As a result, the moisture adsorbent of the air dryer 6 is regenerated and returned to a state where moisture can be adsorbed again.

The air chamber 1 C of the air suspension 1 is connected to a supply / discharge pipe line 5 of the compressor 2 via an air conduit 10. Here, the air conduit 10 is provided with a plurality (for example, four) of branch pipes 10A that are branched from each other. The distal end side of each branch pipe 10A is detachably connected to the air chamber 1C of the air suspension 1.

The compressed air supply / exhaust valve 11 is provided in the middle of each branch pipe 10A for controlling the supply / discharge of compressed air to / from the air chamber 1C of the air suspension 1. The supply / exhaust valve 11 is constituted by, for example, an electromagnetic switching valve (solenoid valve) having two ports and two positions. The supply / exhaust valve 11 is normally in the valve closing position (a), and is switched from the valve closing position (a) to the valve opening position (b) when excited by a control signal from the controller 20 described later.

The air supply / exhaust valve 11 may be provided so as to be connected between the air chamber 1C of the air suspension 1 and the branch pipe 10A. The supply / exhaust valve 11 has a function as a relief valve (safety valve). For this reason, when the pressure in the air chamber 1C exceeds the relief set pressure, the air supply / exhaust valve 11 is temporarily switched from the valve closing position (a) to the valve opening position (b) as a relief valve even if the air supply / exhaust valve 11 remains demagnetized. The excess pressure at this time can be released into the air conduit 10.

The tank 12 for storing compressed air has a connection pipe 12A made of, for example, a flexible hose. One end of the connection pipe 12A is detachably connected to the tank 12, and the other end is connected to a tank-side suction pipe 13 and a tank pipe 15 described later. The connection pipe 12A of the tank 12 is connected to the intake side 2A of the compressor 2 via a tank-side suction pipe 13 as a first passage. One end of the tank side suction pipe 13 is connected to the tank 12 (connection pipe 12A), and the other end is connected to the suction / exhaust pipe 4 at a connection point 4A. That is, the connection point 4A connects the intake / exhaust pipe 4 to the tank-side suction pipe 13 at a position between the intake side 2A of the compressor 2 and the intake valve 18. In other words, the tank side suction pipe 13 branches off from the suction / exhaust pipe 4 at the position of the connection point 4A.

The tank-side suction pipe 13 is provided with an intake solenoid valve 14 (ie, an intake switching valve) for supplying and stopping the compressed air in the tank 12 to the intake side 2A of the compressor 2. The intake electromagnetic valve 14 is constituted by, for example, an electromagnetic switching valve (solenoid valve) having two ports and two positions. The intake solenoid valve 14 is normally in the valve closing position (c), and is switched from the valve closing position (c) to the valve opening position (d) when excited by a control signal from the controller 20. Further, the intake solenoid valve 14 has a function as a relief valve (safety valve), similarly to the supply / exhaust valve 11 described above.

The intake solenoid valve 14 is an on / off type solenoid valve having a valve closing position (c) and a valve opening position (d). A highly versatile electromagnetic switching valve can be employed. For example, a three-way solenoid valve is used. Such an expensive valve as described above can be eliminated. It should be noted that also for the return solenoid valve 16 and the exhaust solenoid valve 17 to be described later, similarly to the intake solenoid valve 14, a highly versatile electromagnetic switching valve can be adopted.

The connection pipe 12A of the tank 12 is connected to the discharge side 2B of the compressor 2 via a tank pipe 15 as a second passage. One end of the tank pipe 15 is connected to the tank 12 (connection pipe 12A), and the other end is connected to the supply / discharge pipe 5 at a connection point 5B. That is, the connection point 5B connects the supply / discharge conduit 5 to the tank conduit 15 at a position between the air dryer 6 and the air suspension 1 (that is, between the slow return valve 7 and the air conduit 10). ing. In other words, the tank pipe 15 branches off from the supply / discharge pipe 5 at the position of the connection point 5B.

The tank line 15 is provided with a return solenoid valve 16 serving as a return valve for supplying and stopping compressed air in the tank 12 to return to the supply / discharge line 5. The return solenoid valve 16 is configured to return the compressed air in the air suspension 1 to the tank 12 via a second passage (tank pipe 15) provided to be branched from between the air dryer 6 and the air suspension 1. This is the return valve that was set. The return solenoid valve 16 is constituted by, for example, an electromagnetic switching valve (solenoid valve) having two ports and two positions. The return solenoid valve 16 is normally at the valve closing position (e), and is switched from the valve closing position (e) to the valve opening position (f) when excited by a control signal from the controller 20. When the return solenoid valve 16 is opened, for example, the compressed air in the air suspension 1 can be accumulated so as to return to the inside of the tank 12 through the tank pipe 15. Further, the return solenoid valve 16 has a function as a relief valve (safety valve), similarly to the supply / exhaust valve 11 described above.

排気 The exhaust solenoid valve 17 as an exhaust valve is provided in the bypass pipe 8 as the third passage. The exhaust solenoid valve 17 is constituted by, for example, an electromagnetic switching valve (solenoid valve) having two ports and two positions. The exhaust solenoid valve 17 is normally in the closed position (g), and is switched from the closed position (g) to the open position (h) when excited by a control signal from the controller 20. When the exhaust solenoid valve 17 is opened, the compressed air in the tank 12 is exhausted to the outside via the air dryer 6 and the bypass pipe 8, or the compressed air in the air suspension 1 is discharged to the air dryer 6 and the bypass pipe 8. And can be exhausted to the outside. Further, the exhaust electromagnetic valve 17 has a function as a relief valve (safety valve), similarly to the supply / exhaust valve 11 described above. When the pressure difference ΔP between the tank pressure Pt in the tank 12 and the suspension pressure Ps in the air suspension 1 is equal to or less than a predetermined value (low-pressure threshold P0), the exhaust solenoid valve 17 is slow in decreasing the vehicle height. The valve is opened. In other words, the opening and closing of the exhaust electromagnetic valve 17 is controlled depending on whether the speed of decreasing the vehicle height is slow or fast.

(4) The intake valve 18 is provided in the middle of the intake / exhaust pipe 4 and between the connection points 4A and 4B. The intake valve 18 is a check valve configured to intake air from the atmosphere via the intake / discharge port 9. That is, when the pressure of the air between the intake side 2A of the compressor 2 and the tank 12 becomes equal to or lower than the atmospheric pressure at the position of the connection point 4A, the intake valve 18 constituted by the check valve is connected to the atmosphere via the intake / discharge port 9. It is constituted so that air may be taken in from.

The intake valve 18 functions as a so-called intake valve, and allows air to flow from the intake / exhaust port 9 to the inside of the intake / exhaust line 4 (that is, to the connection point 4A side of the intake / exhaust line 4). , And a check valve for preventing reverse flow. Therefore, when the pressure in the intake / exhaust pipe 4 (that is, the connection point 4A side of the intake / exhaust pipe 4) is higher than the atmospheric pressure (positive pressure), the intake valve 18 is closed, and Compressed air from the tank 12 is supplied (sucked) to the intake side 2A of the compressor 2 via the tank-side suction pipe 13 and the intake solenoid valve 14.

Further, a pressure detector 19 is provided in the supply / discharge conduit 5, for example, at the position of the connection point 5B. The pressure detector 19 moves, for example, the return electromagnetic valve 16 from the closed position (e) to the open position (f) in a state where all the supply / exhaust valves 11, the intake electromagnetic valve 14, and the exhaust electromagnetic valve 17 are closed. Upon switching, the pressure in the tank 12 is detected via the tank line 15. When at least one of the supply / exhaust valve 11 is opened in a state where the intake electromagnetic valve 14, the return electromagnetic valve 16 and the exhaust electromagnetic valve 17 are closed, the pressure in the air chamber 1C of the corresponding air suspension 1 is increased. Can be detected by the pressure detector 19. When all the supply / exhaust valves 11 are opened, the air chambers 1C of all the air suspensions 1 communicate with each other, and the pressure in the air chamber 1C in this state can be detected by the pressure detector 19.

The controller 20 as a control device is constituted by, for example, a microcomputer or the like. The input side of the controller 20 is connected to a pressure detector 19, a plurality of vehicle height sensors 21 (that is, the FL, FR, RL, and RR vehicle height sensors 21), a selection switch 22, and the like. The FL, FR, RL, and RR side vehicle height sensors 21 are provided on each of the air suspensions 1 on the left front wheel (FL), right front wheel (FR), left rear wheel (RL), and right rear wheel (RR) sides. The vehicle height is detected individually. The selection switch 22 is, for example, an operation switch for switching between an automatic mode for adjusting the vehicle height and a selection mode for arbitrarily changing the vehicle height according to the driver's preference.

Here, when the selection switch 22 is operated to select the vehicle height adjustment in the automatic mode, the controller 20 detects the vehicle height detected by the FL, FR, RL, and RR vehicle height sensors 21. Based on the signal, it is compared (determined) whether the vehicle height of each air suspension 1 is higher or lower than the target vehicle height (that is, the set height). Based on the comparison (judgment) result, the controller 20 controls each air suspension on the left front wheel (FL), right front wheel (FR), left rear wheel (RL) and right rear wheel (RR) sides of the vehicle. 1 is performed individually.

The output side of the controller 20 is connected to the electric motor 3 of the compressor 2, the supply / exhaust valves 11 on the FL side, the FR side, the RL side, and the RR side, the intake solenoid valve 14, the return solenoid valve 16, the exhaust solenoid valve 17, and the like. It is connected. Further, the controller 20 has a memory 20A including a ROM, a RAM, a nonvolatile memory, and the like. In this memory 20A, for example, a program for a control process at the time of raising the vehicle height shown in FIG. 3, a program for a control process at the time of vehicle height reduction shown in FIG. Have been.

The controller 20 controls the driving of the electric motor 3 based on signals from the respective vehicle height sensors 21 and the selection switch 22, and also controls the supply / exhaust valve 11, the intake solenoid valve 14, the return solenoid valve 16, and the exhaust solenoid valve. A control signal is output to the control valve 17 and the like, and these

valves

11, 14, 16, and 17 (specifically, each solenoid) are individually excited or demagnetized. As a result, the supply / exhaust valve 11 is switched between the closed position (a) and the open position (b) shown in the drawing, and the intake solenoid valve 14, the return solenoid valve 16 and the exhaust solenoid valve 17 are each switched. It can be switched to that position.

The air suspension device according to the first embodiment has the above-described configuration, and its operation will be described with reference to an example in which the selection switch 22 is operated to perform the vehicle height adjustment in the automatic mode.

When the load on the vehicle increases (for example, when the number of occupants of the vehicle including the driver increases, or when luggage or the like is loaded), the air chamber 1C of the air suspension 1 shrinks as the vehicle weight increases. Therefore, the vehicle height is lower than the set height (target vehicle height). Therefore, in such a case, in order to raise the vehicle height to the target vehicle height (set height), the controller 20 executes a vehicle height raising control process as shown in FIG.

3. That is, when the processing operation of FIG. 3 starts, in step 1, the pressure in the tank 12 detected by the pressure detector 19 (that is, the tank pressure Pt) is read. By switching the return solenoid valve 16 from the valve closing position (e) to the valve opening position (f) while each of the supply / exhaust valves 11 shown in FIG. 1 is held at the valve closing position (a), the pressure detector 19 The pressure in the tank 12 can be detected. After detecting the pressure in the tank 12 (tank pressure Pt), control is performed to return the return solenoid valve 16 from the open position (f) to the closed position (e).

In the next step 2, it is determined whether or not the tank pressure Pt is equal to or higher than the high pressure threshold Pm. The high pressure threshold value Pm is set to a pressure value high enough to operate the air suspension 1 in the vehicle height increasing direction by the compressed air in the tank 12 without using the compressor 2. When it is determined “YES” in step 2, it can be determined that the pressure of the tank 12 (tank pressure Pt) is a sufficiently high pressure state.

Therefore, in the next step 3, the return solenoid valve 16 is switched from the closed position (e) to the open position (f) to open the valve, and in the next step 4, the supply / exhaust valve 11 of the air suspension 1 is opened. Switch to position (b). Thereby, the compressed air in the tank 12 can be directly supplied into the air chamber 1C of the air suspension 1, and the air suspension 1 can be operated in the vehicle height increasing direction while the compressor 2 is stopped. .

At this time, in step 5, the vehicle height is read based on the detection signal from the vehicle height sensor 21. In the next step 6, it is determined whether or not the vehicle height is lower than the target vehicle height (set height). Then, if "YES" is determined in step 6, the vehicle height is lower than the set height and has not reached the target vehicle height, so the flow returns to step 3 and the subsequent processing is continued.

On the other hand, if "NO" is determined in step 6, it can be determined that the vehicle height has become equal to or higher than the set height and the vehicle height has been increased until the vehicle height reaches the target vehicle height. Therefore, in the next step 7, the vehicle height raising operation by the air suspension 1 is stopped. That is, in the process of step 7, when the vehicle height has reached the target vehicle height, the return solenoid valve is kept in the closed position (a) while the intake / exhaust valve 11 is in the closed position (a) and the intake electromagnetic valve 14 is also in the closed position (c). Control is performed to return the valve 16 to the valve closing position (e). Then, the process returns in the next step 8.

On the other hand, when the determination in step 2 is “NO”, it can be determined that the tank pressure Pt of the tank 12 is not in a high pressure state (a high pressure state in which compressed air can be supplied from the tank 12 to the air suspension 1). Therefore, in the next step 9, the intake electromagnetic valve 14 is switched from the valve closing position (e) to the valve opening position (d), and the tank 12 is communicated with the intake / exhaust line 4 via the tank side intake line 13. . In step 9, the return solenoid valve 16 has already been returned to the valve closing position (e), and the tank 12 is shut off from the supply / discharge conduit 5.

In the next step 10, the compressor 2 is driven by the electric motor 3, and in the step 11, the supply / exhaust valve 11 of the air suspension 1 is switched to the valve opening position (b). As a result, the compressed air (relatively low-pressure compressed air) in the tank 12 is sucked in from the intake side 2A with the operation of the compressor 2, and the compressed air is sent from the discharge side 2B to the air dryer 6 and the slow return valve 7. The air is supplied to the air chamber 1C of the air suspension 1 via the air suspension 1 so that the vehicle height can be increased. As described above, when the vehicle height increases, the air compressed by the compressor 2 is dried by passing through the air dryer 6, and the compressed air in a dry state is supplied into the air chamber 1 C of the air suspension 1.

In this case, the compressor 2 can generate compressed air having a higher pressure on the discharge side 2B while sucking the compressed air stored in the tank 12 from the intake side 2A. Can be supplied quickly. In other words, the compressor 2 can generate compressed air at a higher pressure by sucking the compressed air in the tank 12 that has been compressed beforehand, instead of the air at the atmospheric pressure, so that the pressurizing time of the compressed air can be shortened. Thus, the air chamber 1C of the air suspension 1 can be extended (elevated) at an early stage.

During this time, the compressed air in the tank 12 is sucked into the intake side 2A of the compressor 2, so that the pressure in the tank 12 gradually decreases. However, if the internal pressure of the tank 12 becomes negative in this state, the intake valve 18 (check valve) is automatically opened. That is, by setting the intake valve 18 to open when, for example, the connection point 4A side becomes lower than the atmospheric pressure, the compressor 2 sucks air insufficient for compression from the suction / discharge port 9 to secure a necessary suction air amount. can do.

For this reason, the compressor 2 draws compressed air from the outside air through the intake / exhaust port 9 and the intake / exhaust line 4, and sends compressed air through the supply / exhaust line 5, the air dryer 6 and the slow return valve 7. To the air chamber 1C. In this case also, in step 12, the vehicle height is read based on the detection signal from the vehicle height sensor 21. In the next step 13, it is determined whether or not the vehicle height is lower than the target vehicle height (set height). If "YES" is determined in the step 13, the vehicle height is lower than the set height and has not reached the target vehicle height, so the flow returns to the step 9 and the subsequent processing is continued.

On the other hand, if "NO" is determined in the step 13, it can be determined that the vehicle height has become higher than the set height and the vehicle height has been increased until the vehicle height reaches the target vehicle height. Therefore, in order to end the vehicle height raising processing, the processing of step 7 is executed, and the intake electromagnetic valve is kept in the closed position (e) with the supply / exhaust valve 11 in the closed position (a) and the intake electromagnetic valve 16 in the closed position (e). The valve 14 is controlled to return to the valve closing position (c). Then, the process returns in the next step 8. At this time, the drive of the electric motor 3 of the compressor 2 can be stopped to interrupt the compression operation.

Next, when the load of the vehicle decreases (for example, when the number of occupants of the vehicle decreases or the load of luggage or the like decreases), the air chamber 1C of the air suspension 1 expands as the vehicle weight decreases. Therefore, the vehicle height becomes higher than the set height (target vehicle height). Therefore, in such a case, in order to lower the vehicle height to the target vehicle height (set height), the controller 20 executes a vehicle height reduction control process as shown in FIG.

4. That is, when the processing operation of FIG. 4 starts, in step 21, the pressure in the air chamber 1C of the air suspension 1 detected by the pressure detector 19 (that is, the suspension pressure Ps) is read. In this case, the air chamber 1C of the air suspension 1 is switched by switching the supply / exhaust valve 11 from the closed position (a) to the open position (b) while the return electromagnetic valve 16 is returned to the closed position (e). The suspension pressure Ps is detected by the pressure detector 19 in this state. After the detection of the suspension pressure Ps, control is performed to return the supply / exhaust valve 11 from the valve opening position (b) to the valve closing position (a).

In the next step 22, the pressure in the tank 12 detected by the pressure detector 19, that is, the tank pressure Pt is read. In this case, the pressure detection is performed by switching the return solenoid valve 16 from the closed position (e) to the open position (f) while each of the supply / exhaust valves 11 shown in FIG. 1 is held at the closed position (a). The device 19 can detect the pressure in the tank 12. After the detection of the tank pressure Pt, control is performed to return the return solenoid valve 16 from the open position (f) to the closed position (e).

In the next step 23, the suspension pressure Ps is compared with the tank pressure Pt to determine whether or not the suspension pressure Ps is lower than the tank pressure Pt (Ps <Pt). If "YES" is determined in step 23, since the tank pressure Pt is higher than the suspension pressure Ps, the compressed air in the air suspension 1 (air chamber 1C) is directly discharged to the outside air to reduce the vehicle height. There is a need to.

Then, in step 24, the supply / exhaust valve 11 of the air suspension 1 is switched to the open position (b), and in the next step 25, the exhaust electromagnetic valve 17 is switched from the closed position (g) to the open position (h). I do. As a result, the compressed air is directly discharged from the air chamber 1C of the air suspension 1 to the outside air via the supply / discharge line 5, the bypass line 8, and the exhaust solenoid valve 17.

Therefore, the vehicle height descending speed when the vehicle height is reduced by reducing the air chamber 1C of the air suspension 1 can be increased. Also, at this time, the compressed air discharged from the air suspension 1 (air chamber 1C) flows back through the air dryer 6 via the supply / discharge conduit 5, so that the moisture adsorbent of the air dryer 6 causes the air suspension 1 to dry. The air dryer 6 is regenerated by passing the supplied air, and the air dryer 6 can be efficiently regenerated.

In the next step 26, the vehicle height is read based on the detection signal from the vehicle height sensor 21. Then, in a step 27, it is determined whether or not the vehicle height is higher than a target vehicle height (set height). If "YES" is determined in the step 27, the vehicle height is higher than the set height, and the vehicle height has not been lowered to the target vehicle height. Therefore, the process returns to the step 24 and the subsequent processes are continued.

On the other hand, if "NO" is determined in the step 27, it can be determined that the vehicle height has become equal to or less than the set height and the vehicle height has been lowered until reaching the target vehicle height. Therefore, in the next step 28, the vehicle height lowering operation by the air suspension 1 is stopped. That is, in the process of step 28, when the vehicle height has reached the target vehicle height, the exhaust electromagnetic valve is kept in the closed position (a) while the return solenoid valve 16 is kept in the closed position (e). The valve 17 is controlled to return to the valve closing position (c). Then, the process returns in the next step 29.

When the determination in step 23 is "NO", the suspension pressure Ps is equal to or higher than the tank pressure Pt, and in the next step 30, the return solenoid valve 16 is moved from the closed position (e) to the open position (f). ) To open the valve. In the next step 31, the pressure difference ΔP between the suspension pressure Ps and the tank pressure Pt is calculated as “ΔP = Ps−Pt”.

では In the next step 32, it is determined as “ΔP ≦ P0” whether or not the pressure difference ΔP is smaller than a low pressure threshold value P0 as a predetermined value. The low pressure threshold value P0 serves as a criterion for determining whether the compressed air in the air chamber 1C is released into the tank 12 or directly discharged to the outside air when the air suspension 1 is operated in the vehicle height lowering direction. Pressure.

That is, the speed at which the vehicle height is reduced by reducing the air chamber 1C of the air suspension 1 by releasing the compressed air in the air suspension 1 (air chamber 1C) into the tank 12 (that is, the vehicle height descending speed V). When the pressure difference ΔP between the air suspension 1 and the tank 12 becomes smaller than the low pressure threshold value P0, it becomes too slow.

The characteristic line 23 shown in FIG. 5 is a characteristic obtained by mapping the relationship between the pressure difference ΔP between the suspension pressure Ps and the tank pressure Pt and the vehicle height descending speed V based on test data and the like. When the pressure difference ΔP is equal to or less than the low pressure threshold value P0, the vehicle height descending speed V is larger than zero and equal to or less than the speed threshold value V0 (0 <V ≦ V0). That is, since the lowering speed of the vehicle height (vehicle lowering speed V) is reduced to the speed threshold value V0, extra time is required for the control process of lowering the vehicle height, and the workability at the time of adjusting the vehicle height is reduced.

Therefore, if "YES" is determined in step 32, it can be determined that the pressure difference ΔP becomes smaller than the low pressure threshold value P0 and the vehicle height descending speed V becomes slower. Therefore, in the next step 33, the return solenoid valve 16 is switched to the valve closing position (e), and the tank 12 is shut off from the supply / discharge pipe line 5. Thereafter, the processing of steps 24 to 27 is executed, and the compressed air is directly discharged from the air chamber 1C of the air suspension 1 to the outside air via the supply / discharge line 5, the bypass line 8, and the exhaust solenoid valve 17. I do.

This makes it possible to increase the vehicle height lowering speed when reducing the vehicle height by reducing the air chamber 1C of the air suspension 1. In this case as well, the compressed air discharged from the air suspension 1 (air chamber 1C) flows back through the air dryer 6 through the supply / discharge conduit 5, so that the moisture adsorbent of the air dryer 6 is It is regenerated by passing the dried air, and the air dryer 6 can be efficiently regenerated.

On the other hand, when "NO" is determined in the step 32, it can be determined that the pressure difference ΔP is larger than the low pressure threshold value P0 and the speed of lowering the vehicle height (vehicle height lowering speed V) can be faster than the speed threshold value V0. Therefore, in the next step 34, the supply / exhaust valve 11 of the air suspension 1 is switched to the valve opening position (b). In this case, since the return solenoid valve 16 is opened in the step 30, the compressed air in the air suspension 1 (air chamber 1C) is discharged so as to escape into the tank 12, and the air chamber 1C of the air suspension 1 is discharged. The height can be reduced by reducing the size.

In the next step 35, the vehicle height is read based on the detection signal from the vehicle height sensor 21. Then, in step 36, it is determined whether or not the vehicle height is higher than the target vehicle height (set height). If "YES" is determined in the step 27, the vehicle height is higher than the set height, and the vehicle height has not been lowered to the target vehicle height. Therefore, the process returns to the step 30, and the subsequent processing is continued.

On the other hand, if "NO" is determined in the step 36, it can be determined that the vehicle height has become lower than the set height and the vehicle height has been lowered until reaching the target vehicle height. For this reason, the vehicle height lowering operation by the air suspension 1 is stopped by the process of step 28. That is, in the process of step 28, the supply / exhaust valve 11 is set to the closed position (a) and the return solenoid valve 16 is set to the closed position in order to end the vehicle height reduction process when the vehicle height has reached the target vehicle height. Control is performed such that the exhaust electromagnetic valve 17 is returned to the valve closing position (c) while keeping the state (e). Then, the process returns in the next step 29.

In other words, when the controller 20 determines that the target vehicle height has been reached based on the detection signal from the vehicle height sensor 21, the controller 20 performs control to demagnetize the solenoid of the supply / exhaust valve 11 to end the vehicle height lowering operation. A signal is output to return the supply / exhaust valve 11 to the valve closing position (a). As a result, the supply / discharge pipe line 5 of the compressor 2 is shut off from the air chamber 1C of the air suspension 1, so that the air suspension 1 operates as an air spring so as to maintain the target vehicle height, and Thus, the vehicle height can be kept low.

Thus, according to the first embodiment, the compressor 2 configured to compress the air supplied from the tank 12 through the tank-side suction pipe 13 (first passage), and the discharge of the compressor 2 An air suspension 1 connected to the side 2B via an air dryer 6 and a structure in which compressed air in the air suspension 1 (air chamber 1C) is returned to the tank 12 via a tank pipe 15 (second passage). The bypass line 8 (third passage) for opening the valve in accordance with the returned solenoid valve 16 and the pressure in the tank 12 to exhaust the compressed air in the air suspension 1 (air chamber 1C) through the air dryer 6. The check is configured to take in air from the atmosphere when the pressure of the air between the exhaust solenoid valve 17 provided at the intake side 2A of the compressor 2 and the tank 12 is lower than the atmospheric pressure. And a suction valve 18 is.

For this reason, at the time of vehicle height raising control by the controller 20, the compressor 2 is driven by the electric motor 3, so that the compressed air in the tank 12 is sucked in from the intake side 2A of the compressor 2 and the compressed air from the discharge side 2B is air-dried. 6. It can be supplied to the air suspension 1 via the slow return valve 7 and can drive the vehicle height in the ascending direction. When the vehicle height rises, the air compressed by the compressor 2 is dried by the air dryer 6, and the dry compressed air can be supplied into the air chamber 1 C of the air suspension 1.

In this case, the compressor 2 can supply compressed air having a higher pressure from the discharge side 2B into the air chamber 1C of the air suspension 1 while sucking the compressed air previously stored in the tank 12 from the intake side 2A. it can. Therefore, high-pressure compressed air can be quickly supplied into the air chamber 1C of the air suspension 1 in a short time, and the air suspension 1 can be quickly extended to increase the vehicle height. Therefore, the vehicle height can be quickly and efficiently increased as compared with a conventional open type (for example, a type in which air is compressed from atmospheric pressure by a compressor).

On the other hand, in this state, if the internal pressure of the tank 12 becomes negative, the intake valve 18 (check valve) is automatically opened. For this reason, the compressor 2 draws compressed air from the outside air through the intake / exhaust port 9 and the intake / exhaust line 4, and sends compressed air through the supply / exhaust line 5, the air dryer 6 and the slow return valve 7. To the air chamber 1C.

After the vehicle height raising control is completed, the control for driving the compressor 2 with the supply / exhaust valve 11 on each air suspension 1 side closed and the return solenoid valve 16 opened can be performed. Thus, the compressed air generated by the compressor 2 can be stored in the tank 12, and the amount of compressed air stored in the tank 12 can be adjusted by the control of the controller 20.

In this case, by setting the intake solenoid valve 14 to the open position (d), the intake side 2A of the compressor 2 can be set to a pressure equivalent to that of the tank 12. When the intake solenoid valve 14 is returned from the open position (d) to the closed position (c) and closed, the intake side 2A of the compressor 2 is set to a pressure close to the atmospheric pressure, and the outside air is compressed. 2 can inhale.

Further, at the time of vehicle height reduction control by the controller 20, when the pressure difference ΔP between the pressure in the tank 12 and the pressure in the air suspension 1 (air chamber 1C) is larger than a low pressure threshold value P0 as a predetermined value (that is, the vehicle). When the high reduction speed V is higher than the speed threshold value V0), the compressed air in the air suspension 1 (air chamber 1C) is removed from the tank while the exhaust solenoid valve 17 is closed and the return solenoid valve 16 is opened. The compressed air can be discharged into the air suspension 12 and the compressed air can be circulated between the air suspension 1 and the tank 12 to lower the vehicle height.

On the other hand, when the pressure difference ΔP between the tank 12 and the air suspension 1 (air chamber 1C) is equal to or less than the low pressure threshold value P0 (that is, when the vehicle height reduction speed V is reduced to the speed threshold value V0 or less), the return electromagnetic force is reduced. Control is performed to close the valve 16 and open the exhaust electromagnetic valve 17. Thereby, compressed air can be directly discharged from the air chamber 1C of the air suspension 1 to the outside air via the supply / discharge line 5, the bypass line 8, and the exhaust solenoid valve 17, and the air room 1C of the air suspension 1 is reduced. As a result, the vehicle height lowering speed when the vehicle height is lowered can be increased. In this case, the compressed air discharged from the air suspension 1 (air chamber 1C) flows back through the air dryer 6 through the supply / discharge conduit 5, so that the moisture adsorbent of the air dryer 6 is discharged from the air suspension 1. Regeneration can be performed with dry air, and regeneration of the air dryer 6 can be performed efficiently.

As described above, according to the first embodiment, in order to open the exhaust solenoid valve 17 according to the pressure in the tank 12, for example, the pressure difference ΔP between the air suspension 1 and the tank 12 becomes a predetermined value (low pressure threshold value). When it becomes smaller than P0), the compressed air in the air suspension 1 can be discharged to the outside air via the exhaust solenoid valve 17. Therefore, the air dryer 6 can be efficiently regenerated.

An intake solenoid valve 14 (intake switching valve) is provided in the tank-side intake pipe 13 (first passage) between the intake side 2A of the compressor 2 and the tank 12. Is configured to switch between a valve closing position (c) and a valve opening position (d). Thus, if both the intake solenoid valve 14 and the return solenoid valve 16 are closed, the compressed air in the tank 12 can be prevented from leaking out of the tank, and the airtightness of the tank 12 can be improved. .

Further, the controller 20 as a control device is configured to control the operation and stop of the compressor 2 and the opening and closing of the return solenoid valve 16, the exhaust solenoid valve 17 and / or the intake solenoid valve 14. The controller 20 controls the operation and stop of the compressor 2 and the opening and closing of the return solenoid valve 16, the exhaust solenoid valve 17 and / or the intake solenoid valve 14, as shown in FIG. Can be executed, and the vehicle height reduction control processing can be executed as shown in FIG.

Moreover, the air suspension device according to the first embodiment can store the compressed and dry compressed air in the tank 12, and the compressed air stored in the tank 12 is further compressed by the compressor 2. In addition, a closed circuit (closed type) that can be supplied to the air suspension 1 can be realized. Further, the compressed air discharged from the air chamber 1C of the air suspension 1 can be returned to the tank 12 using the return solenoid valve 16 without being released into the atmosphere, and the compressed air in a dry state is wasted. It can be used effectively without exhausting.

Further, in the air suspension device according to the first embodiment, since the compressor 2 sucks and compresses the compressed air in the tank 12, the frequency of sucking air from the outside atmosphere (ie, the frequency of opening the intake valve 18) is reduced. This can greatly reduce the frequency of occurrence of problems caused by inhaling dust and moisture in the atmosphere. In addition, it is not necessary to perform pressure control using a pressure detector (pressure sensor) or the like as compared with the conventional closed type, and there is no need to perform complicated control, and the overall configuration is simplified. can do.

Therefore, according to the first embodiment, since the adsorption and regeneration of moisture by the air dryer 6 are appropriately performed, the saturation of the adsorbent can be prevented. Further, a closed-type system that does not require complicated control by the controller 20 can be provided. Moreover, unlike the related art (Patent Document 1), a low-cost system can be provided without requiring a three-way solenoid valve. As the supply / exhaust valve 11, the intake solenoid valve 14, the return solenoid valve 16, and the exhaust solenoid valve 17, an on / off type versatile electromagnetic switching valve can be adopted, and the number thereof can be minimized.

In addition, in the first embodiment, since the normal use range as the air suspension device is established by the closed system, the vehicle height rising time at the time of frequent use can be reduced. Then, only when the vehicle height adjustment range becomes larger than the normal use range, the air is taken in (opening the intake valve 18) or the compressed air is released into the atmosphere (the exhaust solenoid valve 17 is opened) as necessary. Or open the valve).

FIG. 6 shows a second embodiment. Note that, in the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. However, the feature of the second embodiment is that, in the vehicle height lowering process for lowering the vehicle height to the target vehicle height (set height), the controller 20 uses the signal from the vehicle height sensor 21 to control the vehicle height reduction speed. Calculate Vd. The controller 20 compares the vehicle height reduction speed Vd with a predetermined speed threshold value V0 to determine whether the vehicle height reduction speed Vd is slow or fast, and performs the opening and closing control of the exhaust electromagnetic valve 17. It has a configuration.

Here, the vehicle height lowering processing program shown in FIG. 6 is stored together with the speed threshold value V0 and the like in the memory 20A of the controller 20 shown in FIG. 2, for example. When the processing operation of FIG. 6 starts, the controller 20 performs the processing of steps 41 to 50 in the same manner as in steps 21 to 30 shown in the first embodiment (FIG. 4). Then, in step 51 shown in FIG. 6, the supply / exhaust valve 11 of the air suspension 1 is switched from the valve closing position (a) to the valve opening position (b) and opened. At this time, since the return solenoid valve 16 has been opened in step 50, the compressed air in the air suspension 1 (air chamber 1C) is discharged so as to escape into the tank 12, and the air chamber 1C of the air suspension 1 is discharged. Reduce the vehicle height by reducing it.

In the next step 52, the vehicle height is read based on the signal (vehicle height detection value) from the vehicle height sensor 21. Then, in the next step 53, the vehicle height reduction speed (that is, vehicle height reduction speed Vd) is calculated based on the signal from the vehicle height sensor 21. The vehicle height lowering speed Vd can be obtained, for example, by dividing the change in the vehicle height detection value for each program cycle by the time of the program cycle (that is, the read repetition time). The vehicle height lowering speed Vd may be calculated by differentiating the vehicle height detection value from the vehicle height sensor 21.

In the next step 54, it is determined as "Vd≤V0" whether or not the vehicle height lowering speed Vd has decreased to or below the low speed threshold V0 as a predetermined value and the vehicle height lowering speed Vd has decreased. The low speed threshold value V0 is a criterion for determining whether the compressed air in the air chamber 1C is released into the tank 12 or discharged directly to the outside air when the air suspension 1 is operated in the vehicle height lowering direction. Is a predetermined vehicle height lowering speed (lowering speed).

Here, when “YES” is determined in step 54, the vehicle height reduction speed Vd has decreased to the low speed threshold value V0 and has become slow. Therefore, in the next step 55, the return solenoid valve 16 is switched to the valve closing position (e), and the tank 12 is shut off from the supply / discharge pipe line 5. Thereafter, the processing of steps 44 to 47 is executed to directly supply the compressed air from the air chamber 1C of the air suspension 1 to the outside air via the supply / discharge line 5, the bypass line 8, and the exhaust solenoid valve 17. To be discharged.

On the other hand, when the determination in step 54 is “NO”, it can be determined that the vehicle height reduction speed Vd is faster than the speed threshold value V0 and it is not necessary to open the exhaust electromagnetic valve 17. Therefore, in the next step 56, it is determined whether or not the vehicle height is higher than the target vehicle height (set height). If "YES" is determined in the step 46, the vehicle height is higher than the set height, and the vehicle height has not been lowered to the target vehicle height. Therefore, the process returns to the step 50 and the subsequent processes are continued.

If it is determined "NO" in step 56, it can be determined that the vehicle height has fallen below the set height and the vehicle height has been lowered until it reaches the target vehicle height. Therefore, in this case, the vehicle height lowering operation by the air suspension 1 is stopped by the processing of step 48. That is, in step 48, when the vehicle height has reached the target vehicle height, the supply / exhaust valve 11 is set to the closed position (a) and the return solenoid valve 16 is set to the closed position (e) in order to end the vehicle height lowering process. ), The exhaust electromagnetic valve 17 is controlled to return to the valve closing position (c). Then, the process returns in the next step 49.

Thus, also in the second embodiment configured as described above, the exhaust valve (the exhaust electromagnetic valve 17) is opened or closed depending on whether the vehicle height reduction speed Vd is slower or faster than the speed threshold value V0. Therefore, the same effect as that of the first embodiment can be obtained (ie, the effect that the extra time is not required for the control process for lowering the vehicle height and the workability at the time of adjusting the vehicle height can be improved). To play. In particular, in the second embodiment, the vehicle height reduction speed Vd is calculated and obtained based on the signal from the vehicle height sensor 21. Therefore, it is possible to more stably determine whether to open the exhaust valve (the exhaust electromagnetic valve 17).

That is, it is assumed that while the vehicle height is being lowered by the air suspension 1, the load on the vehicle body fluctuates due to the occupant getting off, and the suspension pressure Ps becomes lower than the tank pressure Pt. In such a case as well, in the second embodiment, whether or not the compressed air is directly discharged from the air suspension 1 to the outside air depends on whether or not the vehicle height reduction speed Vd is equal to or lower than the speed threshold value V0. And the opening / closing control of the exhaust electromagnetic valve 17 can be quickly performed.

In each of the above embodiments, an example has been described in which the intake solenoid valve 14, the return solenoid valve 16, and the exhaust solenoid valve 17 are configured to have a function as a relief valve (safety valve). However, the intake solenoid valve 14, the return solenoid valve 16 and / or the exhaust solenoid valve 17 do not necessarily need to operate as a relief valve, and the exhaust valve may be configured using an electromagnetic switching valve having no relief function. Good.

In each of the above embodiments, the case where the intake side 2A of the compressor 2 is connected to the intake / discharge port 9 via the intake / exhaust line 4 has been described as an example. However, the present invention is not limited to this, and the intake / exhaust passages may be configured by two separate passages (pipelines) of an intake passage and an exhaust passage. In other words, the intake side 2A of the compressor 2 is configured to communicate with the outside air via the intake passage. Apart from this, a third passage is provided as an exhaust passage which can communicate with the outside air. 17 may be provided. In this case, the third passage may be connected to the connection point 5A of the supply / discharge line 5 instead of the bypass line 8.

Next, the invention included in the above embodiment will be described. That is, as a first aspect of the present invention, there is provided an air suspension device which is configured to store air and configured to compress air supplied from the tank via a first passage. Compressed air, an air suspension connected to a discharge side of the compressor via an air dryer, and compressed air in the air suspension via a second passage provided to be branched from between the air dryer and the air suspension. A return valve configured to return to the tank by an exhaust valve provided in a third passage that opens according to the pressure in the tank and exhausts the compressed air in the air suspension through the air dryer. When the pressure of the air between the suction side of the compressor and the tank is equal to or lower than the atmospheric pressure, the air is sucked from the atmosphere. An intake valve is a check valve which comprises a.

As a second aspect, in the first aspect, the air suspension adjusts the vehicle height by supplying and discharging compressed air, and the exhaust valve determines whether the vehicle height decreasing speed is low, It is characterized by opening and closing control depending on whether it is fast. As a third aspect, in the second aspect, the exhaust valve is configured to reduce the vehicle height decreasing speed when a pressure difference between a pressure in the tank and a pressure in the air suspension is equal to or less than a predetermined value. It is characterized by being opened as late. On the other hand, as a fourth aspect, in the second aspect, the exhaust valve is closed when the vehicle height reduction speed is faster than a predetermined speed threshold, and is opened when the vehicle height reduction speed is slower than the speed threshold. It is characterized by being valved.

In a fifth aspect, in the first aspect, an intake switching valve is provided in the first passage between the intake side of the compressor and the tank. According to a sixth aspect, in the fifth aspect, the intake switching valve is a 2-port 2-position solenoid valve. According to a seventh aspect, in the first aspect, the return valve is a 2-port 2-position solenoid valve.

According to an eighth aspect, in any one of the first to fourth or seventh aspects, the control device controls the operation and stop of the compressor and the opening and closing of the return valve and / or the exhaust valve. It is characterized by having. As a ninth aspect, in the fifth or sixth aspect, there is provided a control device for controlling the operation and stop of the compressor and the opening and closing of the return valve, the exhaust valve and / or the intake switching valve. It is characterized by having.

DESCRIPTION OF SYMBOLS 1 Air suspension 2 Compressor 3 Electric motor 4 Intake / exhaust line 5 Supply / exhaust line 6 Air dryer 8 Bypass line (third passage)
9 suction / discharge port 10 air conduit 11 supply / exhaust valve 12 tank 13 tank side suction pipe (first passage)
14. Intake solenoid valve (intake switching valve)
15 Pipe for tank (second passage)
16 Return solenoid valve (return valve)
17 Exhaust solenoid valve (exhaust valve)
18 Intake valve 19 Pressure detector 20 Controller (control device)
21 Vehicle height sensor P0 Low pressure threshold (predetermined value)
ΔP Pressure difference V0 Speed threshold (predetermined value)
Vd Vehicle height reduction speed

Claims

An air suspension device,
A tank configured to store air;
A compressor configured to compress air supplied from the tank via the first passage;
An air suspension connected to a discharge side of the compressor via an air dryer,
A return valve configured to return the compressed air in the air suspension to the tank via a second passage branched from the air dryer and the air suspension;
An exhaust valve provided in a third passage that opens in accordance with the pressure in the tank and exhausts the compressed air in the air suspension through the air dryer;
When the pressure of air between the intake side of the compressor and the tank is equal to or lower than the atmospheric pressure, an intake valve that is a check valve configured to intake air from the atmosphere,
An air suspension device comprising:
The air suspension adjusts the vehicle height by supplying and discharging compressed air,
2. The air suspension device according to claim 1, wherein the exhaust valve is controlled to open and close depending on whether the speed of decreasing the vehicle height is slow or fast.
3. The exhaust valve according to claim 2, wherein when the pressure difference between the pressure in the tank and the pressure in the air suspension is equal to or less than a predetermined value, the speed of decreasing the vehicle height is slow, and the exhaust valve is opened. The air suspension device according to claim 1.
3. The air suspension according to claim 2, wherein the exhaust valve is closed when the speed of decreasing the vehicle height is faster than a predetermined speed threshold, and is opened when the speed is slower than the speed threshold. 4. apparatus.
The air suspension device according to claim 1, wherein an intake switching valve is provided in the first passage between the intake side of the compressor and the tank.
The air suspension device according to claim 5, wherein the intake switching valve is a 2-port 2-position solenoid valve.
The air suspension device according to claim 1, wherein the return valve is a two-port two-position solenoid valve.
The control device according to any one of claims 1 to 4, wherein a control device for controlling operation and stop of the compressor and opening and closing of the return valve and / or the exhaust valve is provided. An air suspension device as described.
7. The air suspension according to claim 5, further comprising a control device for controlling operation and stop of the compressor and opening and closing the return valve, the exhaust valve and / or the intake switching valve. apparatus.