Air suspension system

An air suspension system includes a tank, a tank-side open/close valve, an air suspension-side open/close valve, a system portion, and the like. The system portion includes a compressor, an air drier, and a first passage and a second passage provided between the tank-side open/close valve and the air suspension-side open/close valve in parallel, a discharge valve, a tank-side control valve, an air suspension-side control valve, and the like. Due to this configuration, the air suspension system regenerates the air drier by opening the discharge valve to thus cause the air in the second passage to flow from an opposite side toward one side of the air drier when no power is supplied to the tank-side control valve and the air suspension-side control valve.

TECHNICAL FIELD

The present invention relates to an air suspension system mounted on a vehicle, such as a four-wheeled automobile.

BACKGROUND ART

Some of vehicles such as four-wheeled automobiles are equipped with a closed air suspension system for adjusting a vehicle height (for example, refer to PTL 1). The air suspension system according to this kind of related technique includes an air suspension disposed between a vehicle body and an axle and configured to adjust the vehicle height according to supply/discharge of air, a compressor configured to compress the air, a tank storing the air compressed by this compressor, and an air drier configured to dry the compressed air.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

Then, in the closed air suspension system according to the related technique, the compressor is disposed between the air suspension and the tank, and they are connected to each other via passages formed by pipes and the like. The compressed air in these pipes should be dried via the air drier. However, the air drier may cause the compressed air containing moisture to remain in the pipes unless being subjected to efficient regeneration processing, which leads to a desire for realization of an efficient air purge in the pipes and the air drier.

The present invention has been made inconsideration of the drawback of the above-described related technique, and an object of the present invention is to provide an air suspension system capable of efficiently purging the air in the pipes and the air drier and allowing the compressed air in the pipes to be kept in a dried state.

Solution to Problem

According to one aspect of the present invention, an air suspension system includes an air suspension disposed between a vehicle body and an axle and configured to adjust a vehicle height according to supply and discharge of air, a system portion including a compressor configured to compress the air, a tank configured to store the air compressed by the compressor, a first open/close valve provided between the system portion and the tank and configured to permit and prohibit a flow of the air between them, and a second open/close valve provided between the system portion and the air suspension and configured to permit and prohibit a flow of the air between them. The system portion includes a first passage connecting the first open/close valve side and the second open/close valve side therebetween and connected to an intake side of the compressor, a second passage connecting the first open/close valve side and the second open/close valve side therebetween, provided in parallel with the first passage, and connected to a discharge side of the compressor, an air drier having one side connected to the discharge side of the compressor and an opposite side connected to the second passage, a discharge valve provided between the discharge side of the compressor and one side of the air drier and capable of emitting the air out of the system portion, a first control valve disposed between the first and second passage and the first open/close valve. The first control valve is configured to bring the first passage out of communication with the first open/close valve and also bring the second passage into communication with the first open/close valve when no power is supplied, and bring the first passage into communication with the first open/close valve and also bring the second passage out of communication with the first open/close valve when power is supplied. The system portion further includes a second control valve disposed between the first and second passage and the second open/close valve. The second control valve is configured to bring the first passage out of communication with the second open/close valve and also bring the second passage into communication with the second open/close valve when no power is supplied, and bring the first passage into communication with the second open/close valve and also bring the second passage out of communication with the second open/close valve when power is supplied. The air suspension system regenerates the air drier by opening the discharge valve to thus cause the air in the second passage to flow from an opposite side toward the one side of the air drier when no power is supplied to the first and second control valves.

According to the one aspect of the present invention, the air suspension system can efficiently purge the air in the second passage (the pipe) and the air drier, thereby keeping the compressed air in the second passage in the dried state.

DESCRIPTION OF EMBODIMENTS

In the following description, a closed air suspension system according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings, based on an example in which this air suspension system is mounted on a vehicle such as a four-wheeled automobile.

FIGS. 1 to 8illustrate the embodiment of the present invention. InFIG. 1, an air suspension system1intended to be mounted on a vehicle includes an air suspension2, a tank5, a system portion11, and the like.

The air suspension2is provided so as to be positioned on each of a front wheel side and a rear wheel side of the vehicle and disposed between a vehicle body side and an axle side of the vehicle (both are not illustrated). More specifically, four air suspensions2are provided so as to correspond to a left wheel and a right wheel on the front side and a left wheel and a right wheel on the rear side, respectively (only one of them is illustrated). The air suspension2functions to, when compressed air is supplied or discharged, adjust a vehicle height of the vehicle by extending or compressing vertically according to a supplied or discharged amount of air (a compressed air amount) at this time. The air suspension2is connected to the system portion11via a supply/discharge path3.

Now, a proximal end of the supply/discharge path3is connected to an air suspension-side control valve33of the system portion11, which will be described below, and a distal end of the supply/discharge path3is connected to the air suspension2. A pressure sensor9and an air suspension-side open/close valve8, which will be described below, are provided at intermediate positions of the supply/discharge path3. Now, a supply/discharge path4branches off from the supply/discharge path3, and is connected to each of the other not-illustrated air suspensions.

The tank5is provided so as to be connected to a tank conduit6. This tank5functions to store (reserve) compressed air pressurized by a compressor14, which will be described below. Due to this configuration, the air suspension system1can allow the compressed air stored in the tank5to flow to an intake side of the compressor14, thereby reducing a time taken to supply high-pressure compressed air to the air suspension2, when supplying the compressed air to the air suspension2.

The tank conduit6is provided so as to be positioned between the tank5and a tank-side control valve22of the system portion11. More specifically, a distal end of the tank conduit6is connected to the tank5, and a proximal end of the tank conduit6is connected to the tank-side control valve22of the system portion11.

A tank-side open/close valve7is positioned between the tank5and the tank-side control valve22of the system portion11, and is provided at an intermediate position of the tank conduit6. This tank-side open/close valve7is formed by a two-port two-position electromagnetic valve equipped with a solenoid (coil)7A, and switching thereof is controlled by a controller44, which will be described below. The tank-side open/close valve7is selectively switched to an open position (a) and a close position (b) due to power supply from the controller44to the solenoid7A. At the open position (a), the tank-side open/close valve7opens the tank conduit6, thereby permitting supply and discharge of the compressed air to and from the tank5. At the close position (b), the tank-side open/close valve7closes the tank conduit6, thereby blocking the supply and the discharge of the compressed air to and from the tank5. In other words, the tank-side open/close valve7forms a first open/close valve that permits and blocks a flow of the air between the tank5and the system portion11.

The open/close valve8on the air suspension side (hereinafter referred to as the air suspension-side open/close valve8) is positioned between the air suspension2and the control valve33on the air suspension side (hereinafter referred to as the air suspension-side control valve33) of the system portion11, and is provided at the intermediate position of the supply/discharge path3. This air suspension-side open/close valve8is formed by a two-port two-position electromagnetic valve equipped with a solenoid (coil)8A, and switching thereof is controlled by the controller44. The air suspension-side open/close valve8is selectively switched to an open position (c) and a close position (d) due to power supply from the controller44to the solenoid8A. At the open position (c), the air suspension-side open/close valve8opens the supply/discharge path3, thereby permitting supply and discharge of the compressed air to and from the air suspension2. At the close position (d), the air suspension-side open/close valve8closes the supply/discharge path3, thereby blocking the supply and the discharge of the compressed air to and from the air suspension2. In other words, the air suspension-side open/close valve8forms a second open/close valve that permits and blocks a flow of the air between the air suspension2and the system portion11.

The pressure sensor9is positioned between the air suspension-side open/close valve8and the air suspension-side control valve33, and is provided at the intermediate position of the supply/discharge passage3. This pressure sensor9can also detect pressures of the compressed air in the air suspension2and the tank5by detecting pressures in the supply/discharge passages3and4.

The system portion11is provided so as to be positioned between the air suspension2and the tank5. More specifically, a tank-side end portion of the system portion11is connected to the tank conduit6via a connection point11A, and an air suspension-side end portion of the system portion11is connected to the supply/discharge passage3via a connection point11B. As illustrated inFIG. 1, this system portion11includes an intake conduit12, a main conduit13, the compressor14, an electric motor15, an air dryer16, a slow return valve17, a discharge conduit18, a discharge valve19, first and second passages20and21, the tank-side control valve22as a first control valve, the air suspension-side control valve33as a second control valve, and the like. The system portion11forms a pneumatic source that supplies the compressed air to the air suspension2.

The intake conduit12is provided so as to be positioned at an intake side14A of the compressor14. More specifically, one end of the intake conduit12is in communication with outside via an intake filter12A, and an opposite end of the intake conduit12is connected to the first passage20. This intake conduit12functions to allow outside air or the atmosphere introduced from the intake filter12A due to actuation of the compressor14to flow toward the compressor14. An intake valve12B is provided in the intake conduit12. The intake valve12B is formed by a check valve that prevents a reverse flow of the air introduced from the intake filter12A.

The main conduit13connects the first passage20and the second passage21, which will be described below, to each other therebetween. More specifically, an end portion of the main conduit13on an upstream side is connected to a connection point20C of the first passage20, and an end portion of the main conduit13on a downstream side is connected to a connection point21C of the second passage21. The main conduit13forms a supply/discharge conduit that supplies and discharges the compressed air to and from the air suspension2. The compressor14, the air drier16, and the slow return valve17are provided in the main conduit13.

The compressor14is positioned in the main conduit13, and is formed by, for example, a reciprocating compressor, a scroll compressor, or the like. The compressor14is drive by the electric motor15serving as a driving source, such as a linear motor, a direct-current motor, or an alternating-current motor, and generates the compressed air by compressing the air introduced from the first passage20side or the intake conduit12side. Then, the compressor14discharges and thus supplies the compressed air toward the air drier16. In this case, the intake side14A of the compressor14is connected to the first passage20via the main conduit13, and the discharge side14B of the compressor14is connected to the air drier16via the main conduit13.

The air drier16is provided so as to be positioned at an intermediate position of the main conduit13. One side of the air drier16is connected to the discharge side14B of the compressor14, and an opposite side of the air drier16is connected to the second passage21via the slow return valve17. This air drier16includes a moisture absorbent or the like (not illustrated) therein, and absorbs moisture by the internal moisture absorbent when the compressed air supplied from the compressor14flows in a forward direction toward the slow return valve17. Then, the air drier16supplies the dried compressed air (the dry air) toward the air suspension2or the tank5. On the other hand, the compressed air (the discharged air) flowing in a backward direction from the air suspension2toward the discharge conduit18, which will be described below, flows backward in the air drier16, thereby capturing the moisture absorbed by the moisture absorbent and thus regenerating this moisture absorbent.

The slow return valve17is located at an intermediate position of the main conduit13, and is provided between the air drier16and the second passage21. This slow return valve17is formed by a parallel circuit including an orifice17A and a check valve17B, and does not reduce a flow rate of the compressed air with respect to the flow in the forward direction as the check valve17B is opened therefor. However, the check valve17B is closed for the flow in the backward direction, and the compressed air at this time is subjected to a reduction in the flow rate thereof due to the orifice17A and therefore flows backward slowly at a small flow rate inside the air drier16.

The discharge conduit18is provided by branching off from a connection point13A of the main conduit13between the discharge side14B of the compressor14and the one side of the air drier16. More specifically, one end of the discharge conduit18is connected to the main conduit13via the connection point13A, and the opposite end of the discharge conduit18is in communication with outside via a discharge port18A. This discharge conduit18is a conduit for discharging the compressed air in the air suspension2to the external atmosphere. The discharge valve19is provided at an intermediate position of the discharge conduit18.

The discharge valve19is a valve that brings the discharge conduit18connected to the main conduit13into and out of communication with the atmosphere. This discharge valve19is formed by a two-port two-position electromagnetic valve equipped with a solenoid (coil)19A, and switching thereof is controlled by the controller44. The discharge valve19is selectively switched to an open position (e) and a close position (f) due to power supply from the controller44to the solenoid19A. At the open position (e), the discharge valve19opens the discharge conduit18, thereby permitting the discharge of the compressed air from the discharge port18A. At the close position (f), the discharge valve19closes the discharge conduit18, thereby blocking the discharge of the compressed air from the discharge port18A. In other words, the discharge valve19is normally closed to bring the discharge conduit18out of communication with the discharge port18A. Then, when being opened, the discharge valve19brings the discharge conduit18into communication with the discharge port18A, thereby permitting the discharge (release) of the compressed air in the discharge conduit18to the atmosphere outside the system portion11.

The first passage20is positioned between the air suspension2and the tank5, and is formed by a pipe connecting the tank-side open/close valve7side and the air suspension-side open/close valve8side to each other therebetween. More specifically, a tank-side end portion of the first passage20is connected to the tank-side control valve22, and an air suspension-side end portion of the first passage20is connected to the air suspension-side control valve33. This first passage20connects the supply/discharge passage3and the tank conduit6to each other therebetween, and a portion at an intermediate position of the first passage20is connected to the intake side14A of the compressor14(the upstream side of the main conduit13). In this case, the first passage20includes a tank-side first passage20A and a first passage20B on the air suspension side (hereinafter referred to as the air suspension-side first passage20B). The tank-side first passage20A connects the tank-side control valve22and the connection point20C of the main conduit13to each other therebetween. The air suspension-side first passage20B connects the connection point20C of the main conduit13and the air suspension-side control valve33to each other therebetween.

On the other hand, the second passage21is formed by a pipe positioned between the air suspension2and the tank5, connecting the tank-side open/close valve7side and the air suspension-side open/close valve8side to each other therebetween, and provided in parallel with the first passage20. More specifically, a tank-side end portion of the second passage21is connected to the tank-side control valve22, and an air suspension-side end portion of the second passage21is connected to the air suspension-side control valve33. This second passage21extends over the discharge side14B of the compressor14, thereby serving to connect the tank-side control valve22and the air suspension-side control valve33to each other therebetween. In this case, the second passage21includes a tank-side second passage21A and a second passage21B on the air suspension side (hereinafter referred to as the air suspension-side second passage21B). The tank-side second passage21A connects the tank-side control valve22and the connection point21C of the main conduit13to each other therebetween. The air suspension-side second passage21B connects the connection point21C of the main conduit13and the air suspension-side control valve33to each other therebetween.

The tank-side control valve22is disposed between the first passage20and the second passage21, and the tank-side open/close valve7as the first control valve. This tank-side control valve22is formed by, for example, a three-port two-position three-way electromagnetic valve and is controlled by the controller44to be switched to either a power supply position (g) and a non-power supply position (h) to selectively connect the tank conduit6to the first passage20or the second passage21. As illustrated inFIG. 2, the tank-side control valve22includes a valve cylinder case23, a valve holding cylinder25, a coil26, a first valve body27, a core28, a spring member29, a first communication path30, an opposite-side chamber32as a first pilot chamber, and the like.

In this case, the tank-side control valve22is selectively switched to the power supply position (g) and the non-power supply position (h) due to power supply from the controller44thereto. More specifically, the tank-side control valve22is placed at the power supply position (g) when power is supplied thereto, where the tank-side control valve22brings the first passage20into communication with the tank-side open/close valve7and also brings the second passage21out of communication with the tank-side open/close valve7. On the other side, the tank-side control valve22is placed at the non-power supply position (h) when no power is supplied thereto, where the tank-side control valve22brings the first passage20out of communication with the tank-side open/close valve7and also brings the second passage21into communication with the tank-side open/close valve7.

As illustrated inFIG. 2, the tank-side control valve22is formed as a cylindrical body with use of the valve cylinder case23serving as an outer shell thereof. The valve cylinder case23includes a one-side connection portion24A on the first passage20side thereof and an opposite-side connection portion24B on the second passage21side thereof. The one-side connection portion24A is in communication with the first passage20. The opposite-side connection portion24B is in communication with the second passage21. The valve holding cylinder25is arranged inside the coil26in the valve cylinder case23. In this case, a one-side passage24A1and a common passage24A2are pierced in the one-side connection portion24A. The one-side passage24A1is in communication with the first passage20and a first one-side port25B, which will be described below. The common passage24A2is in communication with the tank conduit6and a first common port25C, which will be described below. Further, an opposite-side passage24B1is pierced in the opposite-side connection portion24B. The opposite-side passage24B1is in communication with the second passage21and an air vent path28C, which will be described below.

The valve holding cylinder25is provided inside the valve cylinder case23and the coil26, which will be described below. A one-side valve seat25A, the first one-side port25B, and the first common port25C are provided on the first passage20side of the valve holding cylinder25. The first valve body27is seated on and separated from the one-side valve seat25A. The first one-side port25B is brought out of communication with the second passage21by the first valve body27, and is brought into communication with the first passage20via the one-side passage24A1. The first common port25C is in communication with the tank conduit6via the common passage24A2. The coil26is wound on an outer peripheral side of the valve holding cylinder25at a position between this outer peripheral side and the valve cylinder case23.

The first valve body27is arranged so as to axially face the core28in the valve holding cylinder25, and is formed as a stepped cylindrical poppet valve. This first valve body27is slidably fittedly inserted in the valve holding cylinder25at a position between the one-side valve seat25A of the valve holding cylinder25and the core28. The first valve body27is formed with use of a magnetic material, and is driven as if being attracted to the core28side when the coil26is excited. A one-side valve portion27A, which is seated on and separated from the one-side valve seat25A, is provided on the first passage20side of the first valve body27. An opposite-side valve portion27B, which is seated on and separated from an opposite-side valve seat28A of the core28, is provided on the second passage21side of the first valve body27. An outer diameter dimension of the first valve body27is formed so as to be sufficiently larger than hole diameters A1and A2of the first one-side port25B and the first opposite-side port28B, which will be described below.

In this case, the first valve body27functions selectively bring any one of the first passage20and the second passage21out of communication with the port of the tank-side open/close valve7, and selectively bring the other of them into communication with the port of the tank-side open/close valve7. More specifically, the first valve body27brings the second passage21out of communication with the port of the tank-side open/close valve7and brings the first passage20into communication with the port of the tank-side open/close valve7when power is supplied thereto. On the other hand, the first valve body27brings the first passage20out of communication with the port of the tank-side open/close valve7and brings the second passage21into communication with the port of the tank-side open/close valve7when no power is supplied thereto.

The core28is provided at a position between the opposite-side connection portion24B and the first valve body27. This core28is formed cylindrically with use of a magnetic material. The opposite-side valve seat28A and a first opposite-side port28B are provided on one side of the core28. The opposite-side valve portion27B of the first valve body27is seated on and separated from the opposite-side valve seat28A. The first opposite-side port28B brings the second passage21and the opposite-side chamber32into communication with each other therebetween. Further, the small-diameter air vent path28C is axially pierced on a central side of the core28. The air vent path28C connects the opposite-side passage24B1and the first opposite-side port28B to each other.

Then, the hole diameter A2of the first opposite-side port28B (for example, 2.2 mm) is formed so as to be smaller than the hole diameter A1of the first one-side port25B (for example, 3.0 mm). More specifically, a pressure-receiving area over which the first valve body27bears the pressure of the compressed air flowing into the first one-side port25B is determined based on the hole diameter A1when the first one-side port25B is closed. Further, a pressure-receiving area over which the first valve body27bears the pressure of the compressed air flowing into the first opposite-side port28B is determined based on the hole diameter A2when the first opposite-side port28B is closed. In this case, the pressure-receiving area based on the first opposite-side port28B is smaller than or falls below the pressure-receiving area based on the first one-side port25B.

Then, the spring member29is arranged between the first valve body27and the core28, and this spring member29constantly biases the first valve body27toward the one-side valve seat25A side of the valve holding cylinder25. In other words, the spring member29constantly biases the first valve body27downward (i.e., in a direction for causing the first valve body27to close the first one-side port25B). Further, the first communication path30is formed on an outer peripheral side of the first valve body27. The first communication path30includes a plurality of vertical grooves extending in an axial direction of the first valve body27at a position between the outer peripheral side of the first valve body27and the valve holding cylinder25. This first communication path30is constantly in communication with the first common port25C and the common passage24A2at a position located on an outer peripheral side of the one-side valve portion27A, and is constantly in communication with the opposite-side chamber32at a position located on an outer peripheral side of the opposite-side valve portion27B. In other words, the first communication path30brings the opposite-side chamber32and the tank-side open/close valve7side into communication with each other therebetween.

A one-side chamber31of the tank-side control valve22is provided between the first valve body27and one side of the valve holding cylinder25. More specifically, when power is supplied to the tank-side control valve22, the first valve body27is separated from the one-side valve seat25A of the valve holding cylinder25against the spring member29and the one-side valve portion27A opens the first one-side port25B, by which the one-side chamber31is formed.

On the other hand, the opposite-side chamber32of the tank-side control valve22is positioned on an axially opposite side of the first valve body27from the one-side chamber31, and is provided between the first valve body27and the core28. More specifically, when no power is supplied to the tank-side control valve22(i.e., when the tank-side control valve22is in a state illustrated inFIG. 2), the first valve body27is separated from the opposite-side valve seat28A of the core28and the opposite-side valve portion27B opens the first opposite-side port28B, by which this opposite-side chamber32is formed. At this time, the opposite-side chamber32is placed into a state in communication with the second passage21. The opposite-side chamber32forms the first pilot chamber that biases the first valve body27with use of the pressure of the compressed air in the second passage21in a direction for causing the one-side valve portion27A to close the one-side valve seat25A.

The air suspension-side control valve33is disposed between the first passage20and the second passage21, and the air suspension-side open/close valve8as the second control valve. This air suspension-side control valve33is formed by, for example, a three-port two-position three-way electromagnetic valve and is controlled by the controller44to be switched to either a power supply position (i) and a non-power supply position (j) to selectively connect the supply/discharge path3to the first passage20or the second passage21. As illustrated inFIG. 3, the air suspension-side control valve33includes a valve cylinder case34, a valve holding cylinder36, a coil37, a second valve body38, a core39, a spring member40, a second communication path41, an opposite-side chamber43as a second pilot chamber, and the like.

In this case, the air suspension-side control valve33is selectively switched to the power supply position (i) and the non-power supply position (j) due to power supply from the controller44thereto. More specifically, the air suspension-side control valve33is placed at the power supply position (i) when power is supplied thereto, where the air suspension-side control valve33brings the first passage20into communication with the air suspension-side open/close valve8and also brings the second passage21out of communication with the air suspension-side open/close valve8. On the other side, the air suspension-side control valve33is placed at the non-power supply position (j) when no power is supplied thereto, where the air suspension-side control valve33brings the first passage20out of communication with the air suspension-side open/close valve8and also brings the second passage21into communication with the air suspension-side open/close valve8.

As illustrated inFIG. 3, the air suspension-side control valve33is formed as a cylindrical body with use of the valve cylinder case34serving as an outer shell thereof. The valve cylinder case34includes a one-side connection portion35A on the first passage20side thereof and an opposite-side connection portion35B on the second passage21side thereof. The one-side connection portion35A is in communication with the first passage20. The opposite-side connection portion35B is in communication with the second passage21. The valve holding cylinder36is arranged inside the coil37in the valve cylinder case34. In this case, a one-side passage35A1and a common passage35A2are pierced in the one-side connection portion35A. The one-side passage35A1is in communication with the first passage20and a second one-side port36B, which will be described below. The common passage35A2is in communication with the supply/discharge path3and a second common port36C, which will be described below. Further, an opposite-side passage35B1is pierced in the opposite-side connection portion35B. The opposite-side passage35B1is in communication with the second passage21and an air vent path39C, which will be described below.

The valve holding cylinder36is provided inside the valve cylinder case34and the coil37, which will be described below. A one-side valve seat36A, the second one-side port36B, and the second common port36C are provided on the first passage20side of the valve holding cylinder36. The second valve body38is seated on and separated from the one-side valve seat36A. The second one-side port36B is brought out of communication with the second passage21by the second valve body38, and is brought into communication with the first passage20via the one-side passage35A1. The second common port36C is in communication with the supply/discharge path3via the common passage35A2. The coil37is wound on an outer peripheral side of the valve holding cylinder36at a position between this outer peripheral side and the valve cylinder case34.

The second valve body38is arranged so as to axially face the core39in the valve holding cylinder36, and is formed as a stepped cylindrical poppet valve. This second valve body38is slidably fittedly inserted in the valve holding cylinder36at a position between the one-side valve seat36A of the valve holding cylinder36and the core39. The second valve body38is formed with use of a magnetic material, and is driven as if being attracted to the core39side when the coil37is excited. A one-side valve portion38A, which is seated on and separated from the one-side valve seat36A, is provided on the first passage20side of the second valve body38. An opposite-side valve portion38B, which is seated on and separated from an opposite-side valve seat39A of the core39, is provided on the second passage21side of the second valve body38. An outer diameter dimension of the second valve body38is formed so as to be sufficiently larger than hole diameters B1and B2of the second one-side port36B and the second opposite-side port39B, which will be described below.

In this case, the second valve body38functions to selectively bring any one of the first passage20and the second passage21out of communication with the port of the air suspension-side open/close valve8, and selectively bring the other of them into communication with the port of the air suspension-side open/close valve8. More specifically, the second valve body38brings the second passage21out of communication with the port of the air suspension-side open/close valve8and brings the first passage20into communication with the port of the air suspension-side open/close valve8when power is supplied thereto. On the other hand, the second valve body38brings the first passage20out of communication with the port of the air suspension-side open/close valve8and brings the second passage21into communication with the port of the air suspension-side open/close valve8when no power is supplied thereto.

The core39is provided at a position between the opposite-side connection portion35B and the second valve body38. This core39is formed cylindrically with use of a magnetic material. The opposite-side valve seat39A and a second opposite-side port39B are provided on one side of the core39. The opposite-side valve portion38B of the second valve body38is seated on and separated from the opposite-side valve seat39A. The second opposite-side port39B brings the second passage21and the opposite-side chamber43into communication with each other therebetween. Further, the small-diameter air vent path39C is axially pierced on a central side of the core39. The air vent path39C connects the opposite-side passage35B1and the second opposite-side port39B to each other.

Then, the hole diameter B2of the second opposite-side port39B (for example, 2.2 mm) is formed so as to be smaller than the hole diameter B1of the second one-side port36B (for example, 3.0 mm). More specifically, a pressure-receiving area over which the second valve body38bears the pressure of the compressed air flowing into the second one-side port36B is determined based on the hole diameter B1when the second one-side port36B is closed. Further, a pressure-receiving area over which the second valve body38bears the pressure of the compressed air flowing into the second opposite-side port39B is determined based on the hole diameter B2when the second opposite-side port39B is closed. In this case, the pressure-receiving area based on the second opposite-side port39B falls below the pressure-receiving area based on the second one-side port36B.

Then, the spring member40is arranged between the second valve body38and the core39, and this spring member40constantly biases the second valve body38toward the one-side valve seat36A side of the valve holding cylinder36. In other words, the spring member40constantly biases the second valve body38downward (i.e., in a direction for causing the second valve body38to close the second one-side port36B). Further, the second communication path41is formed on an outer peripheral side of the second valve body38. The second communication path41includes a plurality of vertical grooves extending in an axial direction of the second valve body38at a position between the outer peripheral side of the second valve body38and the valve holding cylinder36. This second communication path41is constantly in communication with the second common port36C and the common passage35A2at a position located on an outer peripheral side of the one-side valve portion38A, and is constantly in communication with the opposite-side chamber43at a position located on an outer peripheral side of the opposite-side valve portion38B. In other words, the second communication path41brings the opposite-side chamber43and the air suspension-side open/close valve8side into communication with each other therebetween.

A one-side chamber42of the air suspension-side control valve33is provided between the second valve body38and the one side of the valve holding cylinder36. More specifically, when power is supplied to the air suspension-side control valve33, the second valve body38is separated from the one-side valve seat36A of the valve holding cylinder36against the spring member40and the one-side valve portion38A opens the second one-side port36B, by which the one-side chamber42is formed.

On the other hand, the opposite-side chamber43of the air suspension-side control valve33is positioned on an axially opposite side of the second valve body38from the one-side chamber42, and is provided between the second valve body38and the core39. More specifically, when no power is supplied to the air suspension-side control valve33(i.e., when the air suspension-side control valve33is in a state illustrated inFIG. 3), the second valve body38is separated from the opposite-side valve seat39A of the core39and the opposite-side valve portion38B opens the second opposite-side port39B, by which this opposite-side chamber43is formed. At this time, the opposite-side chamber43is placed into a state in communication with the second passage21. The opposite-side chamber43forms the second pilot chamber that biases the second valve body38with use of the pressure of the compressed air in the second passage21in a direction for causing the one-side valve portion38A to close the one-side valve seat36A.

The controller44is formed by a microcomputer or the like as a control device that controls the supply and the discharge of the compressed air to and from the air suspension2. As illustrated inFIG. 1, an input side of this controller44is connected to the pressure sensor9and the like, and an output side of the controller44is connected to the electric motor15, the solenoid7A of the tank-side open/close valve7, the solenoid8A of the air suspension-side open/close valve8, the solenoid19A of the discharge valve19, the coil26of the tank-side control valve22, the coil37of the air suspension-side control valve33, and the like.

The controller44controls driving and stop of the electric motor15, and controls opening and closing of the tank-side open/close valve7, the air suspension-side open/close valve8, the discharge valve19, the tank-side control valve22, and the air suspension-side control valve33. More specifically, the controller44stores, for example, a map corresponding to a timing chart illustrated inFIG. 4, and controls the tank-side open/close valve7, the air suspension-side open/close valve8, the discharge valve19, the tank-side control valve22, and the air suspension-side control valve33, thereby controlling the air suspension2serving as a vehicle height adjustment mechanism and thus adjusting the vehicle height of the vehicle. The controller44controls the driving and the stop of the electric motor15and also controls currents to be supplied to the tank-side open/close valve7, the air suspension-side open/close valve8, the discharge valve19, the tank-side control valve22, and the air suspension-side control valve33based on a detection signal input from the pressure sensor9and the like.

The air suspension system1according to the present embodiment is configured in the above-described manner, and an operation thereof will be described next.

First, when the compressed air is not sufficiently stored in the tank5(i.e., the pressure in the tank5is lower than a reference set pressure), the tank-side open/close valve7is switched from the close position (b) to the open position (a), and the tank-side control valve22and the air suspension-side control valve33are held at the non-power supply positions (h) and (j), respectively. Further, the air suspension-side open/close valve8and the discharge valve19are held at the close positions (d) and (f), respectively. Then, the compressor14is actuated (i.e., is driven to start the compression operation) by the electric motor15.

Due to this operation, the compressor14introduces the atmosphere into the compressor14via the intake filter12A and the intake valve12B of the intake conduit12and the main conduit13, pressurizes (compresses) this air, and discharges the compressed air toward the air drier16. The compressed air discharged from the compressor14is dried by the air drier16, and, after that, is stored into the tank5via the slow return valve17, the tank-side second passage21A, the tank-side control valve22, the tank conduit6, and the tank-side open/close valve7. Then, for example, when the pressure in the tank5reaches the predetermined set pressure, the compressor14is stopped. Due to this operation, the inside of the tank5can be filled with a sufficient amount of the compressed air to store it. In this case, since the supply/discharge path3with the pressure sensor9provided therein is connected to the tank conduit6, the controller44can monitor the pressure in the tank5via the pressure sensor9. Further, the moisture absorbent in the air drier16is in a state containing moisture according to the introduction of the atmosphere into the compressor14.

Next, when the vehicle height is raised with the use of the supply of the air from the tank5into the air suspension2, the controller44controls the tank-side control valve22(the first control valve), the compressor14(the electric motor15), the tank-side open/close valve7(the first open/close valve), the air suspension-side open/close valve8(the second open/close valve), the discharge valve19, and the like according to the timing chart illustrated inFIG. 4.

First, as illustrated inFIGS. 4 and 5, at time t1, the controller44turns on the tank-side control valve22, thereby switching it from the non-power supply position (h) to the power supply position (g). Further, the controller44holds the tank-side open/close valve7, the air suspension-side open/close valve8, and the discharge valve19at the close positions (b), (d), and (f), respectively, and also holds the air suspension-side control valve33at the non-power supply position (j).

Then, at time t2, the controller44actuates the compressor14by the electric motor15, thereby introducing and compressing the atmosphere. The air compressed by the compressor14is dried by the air drier16, and, after that, is supplied to the opposite-side chamber43by a predetermined pressure via the slow return valve17, the air suspension-side second passage21B, the opposite-side passage35B1of the opposite-side connection portion35B, the air vent path39C of the core39, and the second opposite-side port39B. The compressed air supplied to the opposite-side chamber43biases the second valve body38of the air suspension-side control valve33in a direction for closing the second one-side port36B. In this case, the moisture absorbent in the air drier16is in a state containing moisture according to the introduction of the atmosphere into the compressor14.

Now, the “predetermined pressure” refers to such a pressure that the second one-side port36B is not opened by the pressure of the compressed air applied to the first passage20. In other words, the “predetermined pressure” corresponds to the pressure of the compressed air generated by actuating the compressor14from time t2to time t3.

Next, as illustrated inFIGS. 4 and 6, at time t3, the controller44turns on the tank-side open/close valve7and the air suspension-side open/close valve8, thereby switching them from the close positions (b) and (d) to the open positions (a) and (c), respectively. By this switching, the controller44brings the air suspension2and the tank5into communication with each other therebetween, thereby supplying the compressed air in the tank5toward the air suspension2via the tank conduit6, the tank-side control valve22, the tank-side first passage20A, the main conduit13, the air suspension-side second passage21B, the air suspension-side control valve33, and the supply/discharge path3. In this case, the compressor14introduces the dried air in the tank5, and therefore the moisture absorbent in the air drier16does not further absorb moisture from inside the compressed air.

In this case, the compressed air in the first passage20also applies the pressure to the second one-side port36B of the air suspension-side control valve33via the air suspension-side first passage20B of the first passage20. However, the second valve body38is biased by the compressed air supplied to the opposite-side chamber43and the spring member40in the direction for closing the second one-side port36B, so that the second one-side port36B can be prevented from being opened.

More specifically, the compressed air supplied to the opposite-side chamber43is the high-pressure compressed air pressurized by the compressor14, and therefore the compressed air supplied to the opposite-side chamber43has a higher pressure than the pressure of the compressed air supplied to the second one-side port36B. In addition, the pressure-receiving area of the second valve body38based on the compressed air supplied to the opposite-side chamber43extends over the entire outer diameter of the second valve body38, and therefore is larger than the pressure-receiving area of the second valve body38based on the compressed air supplied to the second one-side port36B. As a result, the air suspension-side control valve33is held at the non-power supply position (j) illustrated inFIGS. 1 and 3, and the second valve body38is kept in a valve-closed state closing the second one-side port36B even when the spring member40exerts only a weak biasing force. Therefore, the second valve body38is prevented from being inadvertently separated (opened) from the one-side valve seat36A.

On the other hand, the compressed air in the second passage21also applies the pressure to the first opposite-side port28B of the tank-side control valve22via the tank-side second passage21A of the second passage21. However, the first valve body27is biased in the direction for closing the first opposite-side port28B due to the power supply to the coil26, and therefore can be kept in the state closing the first opposite-side port28B. In this case, the pressure-receiving area of the first valve body27based on the compressed air supplied to the one-side chamber31extends over the entire outer diameter of the first valve body27, and therefore exceeds the pressure-receiving area of the first valve body27based on the compressed air supplied to the first opposite-side port28B. As a result, the first opposite-side port28B can be prevented from being inadvertently opened even when the coil26exerts only a weak excitation force (attraction force).

After completion of the operation for raising the vehicle height, at time t4, the controller44turns off the tank-side control valve22, the compressor14, the tank-side open/close valve7, and the air suspension-side open/close valve8, and turns on the discharge valve19, as illustrated inFIGS. 4 and 7. In other words, the controller44switches the tank-side open/close valve7and the air suspension-side open/close valve8from the open positions (a) and (c) to the close positions (b) and (d), thereby closing the supply/discharge path3and the tank conduit6, respectively. As a result, the controller44can stop the outflow (the transmission) of the compressed air from the tank5and the supply of the compressed air to the air suspension2, thereby keeping the air suspension2in the extension state and thus keeping the air suspension2in the state raising the vehicle height.

In the state illustrated inFIG. 7, to perform processing for regenerating the air drier16, the controller44switches the tank-side control valve22from the power supply position (g) to the non-power supply position (h) to thus set both the tank-side control valve22and the air suspension-side control valve33to the non-power supply positions (h) and (j), respectively, and also switches the discharge valve19from the close position (f) to the open position (e). As a result, a part of the compressed air remaining in the tank-side control valve22(the common passage24A2, the first common port25C, the first communication path30, the opposite-side chamber32, the first opposite-side port28B, the air vent path28C, and the opposite-side passage24B1), the air suspension-side control valve33(the common passage35A2, the second common port36C, the second communication path41, the opposite-side chamber43, the second opposite-side port39B, the air vent path39C, and the opposite-side passage35B1), and the second passage21can be directly discharged outward from the discharge port18A via the orifice17A of the slow return valve17, the air drier16, and the discharge conduit18.

In this case, the controller44turns on (opens) the discharge valve19from time t4to time t5, thereby causing the compressed air discharged from inside the second passage21to flow from the opposite side to the one side of the air drier16in the backward direction toward the discharge conduit18via the connection point13A of the main conduit13. This operation allows the moisture to be removed from the moisture absorbent (a drying agent) loaded in the air drier16, and leads to regeneration of the moisture absorbent. In other words, the controller44can perform the processing for regenerating the air drier16from time t4to time t5in consideration of a time period during which the air drier16has absorbed the atmosphere containing the moisture (for example, the time period during which the compressed air has been stored into the tank5and the time period from time t2to time t3in the operation of raising the vehicle height). Therefore, even when the compressed air is transmitted in the forward direction into the air drier16as will be described below, the compressed air can be prevented from becoming moist air containing moisture after passing through the air drier16. The timing at which the discharge valve19is turned on is not limited to exactly time t4and may be delayed from the timing at which the other devices (for example, the compressor14) are turned off.

Next, when lowering the vehicle height, the controller44switches the tank-side open/close valve7and the air suspension-side open/close valve8from the close positions (b) and (d) to the open positions (a) and (c), respectively, and also switches the discharge valve19from the open position (e) to the close position (f), as illustrated inFIG. 8. Further, the controller44turns on the air suspension-side control valve33, thereby switching it from the non-power supply position (i) to the power supply position (j).

When the compressor14is started to operate in this state, the compressed air in the air suspension2flows toward the intake side14A of the compressor14via the supply/discharge path3, the air suspension-side control valve33, the air suspension-side first passage20B, and the main conduit13. Then, the compressed air in the air suspension2is introduced by the compressor14to be transmitted toward the air drier16side, and this compressed air is supplied so as to be stored into the tank5via the main conduit13, the air drier16, the tank-side second passage21A, the tank-side control valve22, and the tank conduit6. As a result, the compressed air is discharged from the air suspension2and the air suspension2is displaced in a compression direction, by which the vehicle height can be lowered. In this case, the compressed air from the air suspension2passes through from the compressor14to the air drier16in the forward direction, but the moisture absorbent in the air drier16is already regenerated from time t4to time t5and therefore the compressed air flowing inside the air drier16in the forward direction is prevented from becoming moist air containing moisture.

When the vehicle height is lowered, the compressed air in the first passage20also applies the pressure to the first one-side port25B of the tank-side control valve22via the tank-side first passage20A of the first passage20as illustrated inFIG. 8in an opposite manner from when the vehicle height is raised. However, the first valve body27is biased by the compressed air supplied to the opposite-side chamber32and the spring member29in the direction for closing the first one-side port25B, and therefore the first valve body27can be prevented from performing an intended operation of incorrectly inadvertently opening the first one-side port25B.

More specifically, since the compressed air supplied to the opposite-side chamber32is the high-pressure compressed air pressurized by the compressor14, the compressed air supplied to the opposite-side chamber32has a higher pressure than the pressure of the compressed air supplied to the first one-side port25B. In addition, the pressure-receiving area of the first valve body27based on the compressed air supplied to the opposite-side chamber32extends over the entire outer diameter of the first valve body27, and therefore is larger than the pressure-receiving area of the first valve body27based on the compressed air supplied to the first one-side port25B. As a result, the first valve body27can be prevented from performing the intended operation of opening the first one-side port25B even when the spring member29exerts only a weak biasing force.

On the other hand, the compressed air in the second passage21applies the pressure to the second opposite-side port39B of the air suspension-side control valve33via the air suspension-side second passage21B of the second passage21. However, the second valve body38is biased in the direction for closing the second opposite-side port39B with power supplied to the coil37, and therefore inadvertent opening of the second opposite-side port39B can be prevented or reduced. In addition, the pressure-receiving area of the second valve body38based on the compressed air supplied to the one-side chamber42extends over the entire outer diameter of the second valve body38, and therefore exceeds the pressure-receiving area of the second valve body38based on the compressed air supplied to the second opposite-side port39B. As a result, the second opposite-side port39B can be prevented from being inadvertently opened even when the coil37exerts only a weak excitation force (attraction force).

In this manner, according to the air suspension system1of the embodiment, the system portion11includes the tank-side control valve22configured to bring the first passage20out of communication with the tank-side open/close valve7and also bring the second passage21into communication with the tank-side open/close valve7when no power is supplied while bringing the first passage20into communication with the tank-side open/close valve7and also bringing the second passage21out of communication with the tank-side open/close valve7when power is supplied, and the air suspension-side control valve33configured to bring the first passage20out of communication with the air suspension-side open/close valve8and also bring the second passage21into communication with the air suspension-side open/close valve8when no power is supplied while bringing the first passage20into communication with the air suspension-side open/close valve8and also bringing the second passage21out of communication with the air suspension-side open/close valve8when power is supplied.

Due to this configuration, the air suspension system1can regenerate the air drier16by opening the discharge valve19to thus cause the air in the second passage21to flow from the opposite side toward the one side of the air drier16in the backward direction when no power is supplied to the tank-side control valve22and the air suspension-side control valve33. As a result, the air suspension system1can efficiently purge the air in the second passage21and the air drier16when no power is supplied to the tank-side control valve22and the air suspension-side control valve33, thereby keeping the compressed air in the second passage21in the dried state.

Then, some air suspension system may be configured to omit the air purge in the second passage21and the air drier16after the completion of the operation of raising the vehicle height. However, in such a case, the air suspension system involves a problem of having difficulty in keeping the inside of the second passage21in the dried state when driving the compressor14to lower the vehicle height since not regenerating the air drier16. In other words, this configuration increases a possibility that the discharged air (the compressed air) from the air suspension2passes through inside the air drier16containing moisture when flowing through the compressor14and the air drier16in the forward direction.

On the other hand, the air suspension system1according to the present embodiment discharges the compressed air remaining in the tank-side control valve22, the air suspension-side control valve33, and the second passage21outward, thereby performing the processing for regenerating the air drier16, after completing the operation of raising the vehicle height. Due to this operation, the air suspension system1can keep the inside of the second passage21in the dried state. As a result, when the vehicle height is lowered, the compressed air in the air suspension2is supposed to pass through inside the air drier16processed by the regeneration processing in advance, and therefore the compressed air in the dried state can be supplied so as to be stored from the second passage21into the tank5.

Further, the tank-side control valve22includes the first valve body27configured to selectively bring any one of the first passage20and the second passage21out of communication with the tank-side open/close valve7and selectively bring the other of them into communication with the tank-side open/close valve7, the spring member29configured to constantly bias this first valve body27in the valve-closing direction, the opposite-side chamber32configured to be formed due to the movement of the first valve body27in the valve-closing direction and brought into communication with the second passage21when no power is supplied, and the first communication path30configured to bring this opposite-side chamber32and the tank-side open/close valve7side into communication with each other therebetween. The air suspension-side control valve33includes the second valve body38configured to selectively bring any one of the first passage20and the second passage21out of communication with the air suspension-side open/close valve8and selectively bring the other of them into communication with the air suspension-side open/close valve8, the spring member40configured to constantly bias this second valve body38in the valve-closing direction, the opposite-side chamber43configured to be formed due to the movement of the second valve body38in the valve-closing direction and brought into communication with the second passage21when no power is supplied, and the second communication path41configured to bring this opposite-side chamber43and the air suspension-side open/close valve8side into communication with each other therebetween.

Due to this configuration, the first valve body27can be pressed in the direction for closing the first one-side port25B due to the inflow of the compressed air into the opposite-side chamber32of the tank-side control valve22. Further, the second valve body38can be pressed in the direction for closing the second one-side port36B due to the inflow of the compressed air into the opposite-side chamber43of the air suspension-side control valve33. As a result, the air suspension system1can reduce the size of the spring member29, which biases the first valve body27in the direction for closing the first one-side port25B, and the size of the spring member40, which biases the second valve body38in the direction for closing the second one-side port36B, thereby reducing the sizes of the tank-side control valve22and the air suspension-side control valve33.

Further, due to the reduction in the size of the spring member29, the air suspension system1can reduce the force required to bias the first valve body27in the direction for closing the first opposite-side port28B when power is supplied to the tank-side control valve22. Due to this reduction, the air suspension system1can reduce the size of the coil26of the tank-side control valve22. Regarding the air suspension-side control valve33, the air suspension system1can also reduce the size of the coil37of the air suspension-side control valve33due to the reduction in the size of the spring member40.

In this case, the opposite-side chamber32in communication with the second passage21is formed by the spring member29when no power is supplied to the tank-side control valve22. Due to this configuration, the air suspension system1can discharge the air in the opposite-side chamber32outward via the second passage21, the air drier16, the discharge conduit18, and the like by opening the discharge valve19when no power is supplied to the tank-side control valve22. As a result, the air suspension system1can efficiently purge the air in the opposite-side chamber32when no power is supplied to the tank-side control valve22, thereby keeping the compressed air in the tank-side control valve22in the dried state.

Further, similarly regarding the air suspension-side control valve33, the air suspension system1can efficiently purge the air in the opposite-side chamber43when no power is supplied to the air suspension-side control valve33, thereby keeping the compressed air in the air suspension-side control valve33in the dried state.

More specifically, the air suspension system1can reduce the pressure applied from the second passage21side to the first valve body27of the tank-side control valve22and the second valve body38of the air suspension-side control valve33by discharging outward the compressed air remaining in the tank-side control valve22, the air suspension-side control valve33, and the second passage21. Due to this configuration, the air suspension system1can easily displace the first valve body27and the second valve body38toward the second passage21side when power is supplied to the tank-side control valve22and the air suspension-side control valve33, thereby achieving the reductions in the sizes of the coils26and37.

Further, the air suspension system1is configured to open the tank-side open/close valve7after the predetermined pressure of the compressed air is supplied to the opposite-side chamber43with power supplied to the tank-side control valve22, when supplying the compressed air from the tank5to the air suspension2. Due to this configuration, the air suspension system1can press the second valve body38of the air suspension-side control valve33by the compressed air in the opposite-side chamber43in the direction for closing the second one-side port36B, thereby preventing or reducing unintended actuation of the air suspension-side control valve33when raising the vehicle height. As a result, the air suspension system1can supply the predetermined compressed air to the air suspension2after this compressed air passes through the air drier16, thereby improving reliability of the air suspension system1.

Further, the tank-side control valve22is configured to be formed by the three-way electromagnetic valve including the first one-side port25B configured to be brought out of communication with the second passage21and into communication with the first passage20by the first valve body27, the first opposite-side port28B configured to bring the second passage21and the opposite-side chamber32into communication with each other therebetween, and the first common port25C configured to be brought into communication with the tank5. Further, the air suspension-side control valve33is configured to be formed by the three-way electromagnetic valve including the second one-side port36B configured to be brought out of communication with the second passage21and into communication with the first passage20by the second valve body38, the second opposite-side port39B configured to bring the second passage21and the opposite-side chamber43into communication with each other therebetween, and the second common port36C configured to be brought into communication with the air suspension2.

Due to this configuration, the air suspension system1can connect the first passage20and the second passage21and the tank conduit6with use of the tank-side control valve22, and connect the first passage20and the second passage21and the supply/discharge path3with use of the air suspension-side control valve33. As a result, the air suspension system1can reduce design cost of the entire air suspension system1.

Further, the air suspension system1is configured in such a manner that the hole diameter A2of the first opposite-side port28B is formed so as to be smaller than the hole diameter A1of the first one-side port25B. Due to this configuration, the air suspension system1allows the compressed air applied from the first opposite-side port28B side to the first valve body27when the first opposite-side port28B is closed to have a smaller pressure than the pressure of the compressed air applied from the first one-side port25B side to the first valve body27when the first one-side port25B is closed. As a result, the air suspension system1can press the first valve body27by the compressed air in the opposite-side chamber32in the direction closing the first one-side port25B, thereby preventing or reducing unintended actuation of the tank-side control valve22.

Further, the air suspension system1is configured in such a manner that the hole diameter B2of the second opposite-side port39B is formed so as to be smaller than the hole diameter B1of the second one-side port36B. Due to this configuration, the air suspension system1allows the compressed air applied from the second opposite-side port39B side to the second valve body38when the second opposite-side port39B is closed to have a smaller pressure than the pressure of the compressed air applied from the second one-side port36B side to the second valve body38when the second opposite-side port39B is closed. As a result, the air suspension system1can press the second valve body38by the compressed air in the opposite-side chamber43in the direction closing the second one-side port36B, thereby preventing or reducing unintended actuation of the air suspension-side control valve33.

Further, the tank-side control valve22and the air suspension-side control valve33are each configured to be formed by the poppet valve. Due to this configuration, the air suspension system1can use a simply structured poppet valve, thereby reducing manufacturing cost of the air suspension system1. Further, the poppet valve (the first valve body27and the second valve body38) operates with a short stroke and also lacks a slidable seal portion, and therefore the air suspension system1can prevent or reduce an air leak from the tank-side control valve22and the air suspension-side control valve33, thereby prolonging lifetimes of the tank-side control valve22and the air suspension-side control valve33.

Further, in the above-described embodiment, the air suspension system1is configured in such a manner that the hole diameter A2of the first opposite-side port28B is formed so as to be smaller than the hole diameter A1of the first one-side port25B, and the hole diameter B2of the second opposite-side port39B is formed so as to be smaller than the hole diameter B1of the second one-side port36B. However, the present invention is not limited thereto, and the hole diameter of the first opposite-side port may be equal to the hole diameter of the first one-side port. Further, the hole diameter of the second opposite-side port may be equal to the hole diameter of the second one-side port.

Further, in the above-described embodiment, the air suspension system1is configured to supply the compressed air from the air suspension2to the tank5via the air suspension-side first passage20B, the main conduit13, the compressor14, and the tank-side second passage21A when lowering the vehicle height. However, the present invention is not limited thereto, and may be configured to cause the compressed air to flow from the air suspension toward the tank directly without passing through the compressor when the pressure in the tank is lower than the pressure in the air suspension. In this case, the compressed air may be supplied directly to the tank via the first passage or may be supplied directly to the tank via the second passage.

Further, in the above-described embodiment, the air suspension system1is configured to open the discharge valve19to discharge the compressed air remaining in the second passage21outward after completing the operation for raising the vehicle height. However, the present invention is not limited thereto, and may be configured to open the discharge valve to discharge the compressed air remaining in the second passage outward immediately before adjusting the vehicle height next time.

Further, in the above-described embodiment, the air suspension system1is configured to include the four air suspensions2at the positions on the front wheel side and the rear wheel side of the vehicle. However, the present invention is not limited thereto, and may be configured to include the air suspensions on any one of the front wheel side and the rear wheel side of the vehicle. Further, the present invention may be applied to not only the four wheeled automobile but also another vehicle such as a two-wheeled vehicle.

Possible configurations as the air suspension system based on the above-described embodiment include the following examples.

According to a first configuration, an air suspension system includes an air suspension disposed between a vehicle body and an axle and configured to adjust a vehicle height according to supply and discharge of air, a system portion including a compressor configured to compress the air, a tank configured to store the air compressed by the compressor, a first open/close valve provided between the system portion and the tank and configured to permit and prohibit a flow of the air between them, and a second open/close valve provided between the system portion and the air suspension and configured to permit and prohibit a flow of the air between them. The system portion includes a first passage connecting the first open/close valve side and the second open/close valve side therebetween and connected to an intake side of the compressor, a second passage connecting the first open/close valve side and the second open/close valve side therebetween, provided in parallel with the first passage, and connected to a discharge side of the compressor, an air drier having one side connected to the discharge side of the compressor and an opposite side connected to the second passage, a discharge valve provided between the discharge side of the compressor and one side of the air drier and capable of emitting the air out of the system portion, a first control valve disposed between the first and second passage and the first open/close valve. The first control valve is configured to bring the first passage out of communication with the first open/close valve and also bring the second passage into communication with the first open/close valve when no power is supplied, and bring the first passage into communication with the first open/close valve and also bring the second passage out of communication with the first open/close valve when power is supplied. The system portion further includes a second control valve disposed between the first and second passage and the second open/close valve. The second control valve is configured to bring the first passage out of communication with the second open/close valve and also bring the second passage into communication with the second open/close valve when no power is supplied, and bring the first passage into communication with the second open/close valve and also bring the second passage out of communication with the second open/close valve when power is supplied. The air suspension system regenerates the air drier by opening the discharge valve to thus cause the air in the second passage to flow from an opposite side toward the one side of the air drier when no power is supplied to the first and second control valves. Due to this configuration, the air suspension system can efficiently purge the air in the second passage and the air drier.

As a second configuration, in the first configuration, the first control valve includes a first valve body configured to selectively bring any one of the first passage and the second passage out of communication with the first open/close valve and selectively bring the other of them into communication with the first open/close valve, a spring member configured to constantly bias this first valve body in a valve-closing direction, a first pilot chamber configured to be formed due to the movement of the first valve body in the valve-closing direction and brought into communication with the second passage when no power is supplied, and a first communication path configured to bring this first pilot chamber and the first open/close valve side into communication with each other therebetween. The second control valve includes a second valve body configured to selectively bring any one of the first passage and the second passage out of communication with the second open/close valve and selectively bring the other of them into communication with the second open/close valve, a spring member configured to constantly bias this second valve body in a valve-closing direction, a second pilot chamber configured to be formed due to the movement of the second valve body in the valve-closing direction and brought into communication with the second passage when no power is supplied, and a second communication path configured to bring this second pilot chamber and the second open/close valve side into communication with each other therebetween. Due to this configuration, due to this configuration, the air suspension system can efficiently purge the air in the first pilot chamber and the second pilot chamber.

As a third configuration, in the first or second configuration, the air suspension system introduces and compresses an atmosphere by driving the compressor with the first open/close valve closed and power supplied to the first control valve when supplying the air from the tank to the air suspension, and opens the first open/close valve after supplying a predetermined pressure of the compressed air to the second pilot chamber. Due to this configuration, the air suspension system can prevent or reduce unintended actuation of the second control valve when raising the vehicle height.

As a fourth configuration, in any of the first to third configurations, the first control valve includes a three-way electromagnetic valve. This three-way electromagnetic valve includes a first one-side port configured to be brought out of communication with the second passage and brought into communication with the first passage by the first valve body, a first opposite-side port configured to bring the second passage and the first pilot chamber into communication with each other therebetween, and a first common port configured to be brought into communication with the tank. The second control valve includes a three-way electromagnetic valve. This three-way electromagnetic valve includes a second one-side port configured to be brought out of communication with the second passage and brought into communication with the first passage by the second valve body, a second opposite-side port configured to bring the second passage and the second pilot chamber into communication with each other therebetween, and a second common port configured to be brought into communication with the air suspension. Due to this configuration, the air suspension system can reduce the number of control valves of the entire air suspension system, thereby reducing design cost of the entire air suspension system.

As a fifth configuration, in the fourth configuration, a hole diameter of the first opposite-side port is formed so as to be smaller than a hole diameter of the first one-side port. A hole diameter of the second opposite-side port is formed so as to be smaller than a hole diameter of the second one-side port. Due to this configuration, the air suspension system can facilitate opening and closing operations of the first valve body of the first control valve and the second valve body of the second control valve.

As a sixth configuration, in any of the first to fifth configurations, the first valve body of the first control valve and the second valve body of the second control valve are each formed as a poppet valve. Due to this configuration, the air suspension system can use a simply structured poppet valve, thereby reducing manufacturing cost of the air suspension system.

The present invention is not limited to the above-described embodiment, and includes various modifications. For example, the above-described embodiment has been described in detail to facilitate better understanding of the present invention, and the present invention is not necessarily limited to the configuration including all of the described features. Further, a part of the configuration of some embodiment can be replaced with the configuration of another embodiment, and some embodiment can also be implemented with a configuration of another embodiment added to the configuration of this embodiment. Further, each embodiment can also be implemented with another configuration added, deleted, or replaced with respect to a part of the configuration of this embodiment.

The present application claims priority under the Paris Convention to Japanese Patent Application No. 2016-188144 filed on Sep. 27, 2016. The entire disclosure of Japanese Patent Application No. 2016-188144 filed on Sep. 27, 2016 including the specification, the claims, the drawings, and the abstract is incorporated herein by reference in its entirety.

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