Air suspension installation, compressed air supply installation and pneumatic system

A pneumatic installation, especially an air suspension installation for a vehicle, operates in conjunction with a compressed air supply installation and comprises: a gallery line, at least one air spring having a pressure chamber, which can be pneumatically connected to the gallery line, an accumulator for compressed air, which is pneumatically connectable to the gallery line, and a compressed air port for pneumatic connection of the pneumatic installation and the compressed air supply installation. The pneumatic connection comprises a controllable shut-off valve system, which is formed by at least one directional valve and has first, second and third ports, the accumulator being pneumatically connected to the first port, the compressed air port being pneumatically connected to the second port, and the gallery line being pneumatically connected to the third port, the second port being switchable to a closed state in which the pneumatic connection is completely closed in both directions.

FIELD OF THE INVENTION

The invention generally relates to an air suspension installation having a pneumatic installation and a compressed air supply installation, and to a pneumatic system having the air suspension installation.

BACKGROUND OF THE INVENTION

A compressed air supply installation is used in vehicles of all types, in particular for supplying an air suspension installation of a vehicle with compressed air. Air suspension installations can also comprise level control devices, with which the distance between the vehicle axle and the vehicle body can be adjusted. An air suspension installation of a pneumatic system comprises a plurality of air bellows pneumatically connected to a common line (gallery), which can lift the vehicle body with increased filling and correspondingly lower the body with reduced filling. With increasing distance between the vehicle axle and the vehicle body or increasing ground clearance, the spring travels are longer and larger ground unevenness can also be overcome without this causing contact with the vehicle body. Such systems are increasingly used in off-road vehicles and Sport Utility Vehicles (SUV). In particular, with SUVs, it is desirable in the case of very powerful engines to provide the vehicle, on the one hand, with relatively small ground clearance for high speeds on the road and, on the other hand, with a relatively large ground clearance for off-road. It is also desirable to carry out a change of the ground clearance as rapidly as possible, which increases the requirements with regard to speed, flexibility and reliability of a compressed air supply installation.

In order to provide for long-term operation of the compressed air supply installation, a main pneumatic line comprises an air dryer, with which the compressed air is dried. Collection of moisture in the pneumatic system is thereby prevented.

At relatively low temperatures, moisture can lead to valve-damaging crystal formation and other unwanted effects in the compressed air supply installation and in the pneumatic installation. An air dryer comprises a drying means, normally a bed of pellets, through which the compressed air can flow, so that the bed of pellets can take up moisture contained in the compressed air by adsorption. If applicable, an air dryer can be designed as a regenerative air dryer. The bed of pellets carries a throughflow of the dried compressed air from the pneumatic installation, in particular an air suspension installation, for each venting cycle in a counter flow or a direct flow relative to the filling direction. A regeneration of the air dryer is essentially enabled by a pressure change at the air dryer, wherein a pressure during the regeneration is frequently low in comparison to the adsorption in order to enable the output of moisture from the granulate. For this purpose, the venting valve assembly can be opened, wherein the regenerative capacity of the air dryer is frequently dependent on the pressure conditions and the pressure change in the compressed air supply installation. It is also desirable for such a so-called pressure change adsorption to provide a compressed air supply installation that is both flexible and reliable. In particular, on the one hand, relatively rapid venting is desirable, and yet a sufficiently low air pressure is to be available for regeneration of the air dryer.

A level control device provided with air filters for vehicles is known from the applicant's DE 35 429 74 A1, by which, depending on the load on the vehicle, a specified distance of the vehicle cell from the vehicle axle can be adjusted by filling or emptying the air springs. The device has a safety valve that is controllable by the pressure in the air springs. Regeneration of the air dryer is possible for such an installation by means of a choke and a non-return valve to be opened against a filling direction.

DE 199 11 933 B4 discloses a compressed air supply installation having an air dryer with a first compressed air supply line, wherein the compressed air is passed through drying means of the air dryer, and a second compressed air supply line, which can carry a throughflow without the compressed air being passed through the drying means.

A variety of approaches are known for making a pneumatic connection between a compressed air feed and a pneumatic installation. These approaches take into account the basic functions of a compressed air supply installation during pressurization of the pneumatic installation and venting of the pneumatic installation. With respect to the requirement for relatively rapid venting with a sufficiently low air pressure for regeneration of the air dryer, there is, however, still room for improvement.

DE 102 23 405 B4 discloses an air suspension system of a motor vehicle with a compressed air supply installation having a pressure line for connecting a compressor to the air springs and a venting line, via which the pressure line can be connected to the atmosphere, the connection being able to be blocked by means of a switching valve. A section of the pressure line in the form of a pneumatic parallel circuit is provided between a dryer and level control valves of a gallery of the air suspension installation and comprises a choke disposed parallel to a non-return valve and parallel to another switching valve. The switching valve in the venting line and the switching valve in the section of the pressure line are connected via electrical control lines to the same final stage of a controller.

DE 101 21 582 C2 discloses an air supply unit for an air suspension installation, in which a venting valve is provided in a venting line, an air suspension valve is provided in the gallery of the air suspension installation and an air control valve is provided. All three valves are connected to an electronic control unit. In a section of a pressure line in the form of a pneumatic parallel circuit between the dryer and the spring valve, the air control valve is connected parallel to a non-return valve, so that air can be taken into the air suspension installation without hindrance, but can only be let out again under the control of the air control valve. All three valves are opened for blowing off compressed air from the air suspension installation.

U.S. Pat. No. 6,098,967 discloses a compressed air supply installation in which a section in the form of a pneumatic parallel circuit with two parallel connected branch lines is disposed in the main pneumatic line between the air dryer and the air suspension installation. A non-return valve that can conduct a flow to supply air is connected in a first branch line and a non-return valve that can conduct a flow for venting is connected in a second branch line in series with a choke and a switching valve.

EP 1 216 860 B1 discloses a level control installation for a motor vehicle with air springs and with a controller, which controls or regulates the filling and emptying functions depending on the level of the vehicle body. A controllable control valve of a compressed air supply installation and a controllable control valve upstream of a reservoir are connected to the controller. The controllable, and in the opened state only constantly choked, control valve of the compressed air supply installation is disposed in a parallel connection to a non-return valve.

The relatively complex or component-intensive connection of an air suspension installation to the compressed air supply installation, which is still capable of improvement, is problematic with all of the foregoing conventional compressed air supply installations. Because of the section that is frequently in the form of a parallel circuit in a main pneumatic line, this is open at least in a bypass line or, e.g., opens against a back pressure of a non-return valve.

EP 1 243 447 A2 discloses (in FIG. 9) a closed level control installation with a gallery line, to which a plurality of bellows are connected, each acting as a pressure chamber for an air spring, and a controllable isolating valve assembly of a pneumatic installation formed by a series arrangement of a first 2/2-way valve and of a second 2/2-way valve. The second control valve is disposed in the compressed air line between the first controllable control valve and the air springs. The gallery line is connected to the second control valve. The pneumatic installation can be filled and vented by the compressed air supply installation connected to the first control valve via the isolating valve assembly. A compressed air reservoir is connected via a separate control valve and a separate pneumatic line to the compressed air supply installation.

EP 1 380 453 B discloses a similar closed level control installation for vehicles, by means of which a vehicle body is sprung relative to at least one vehicle axle. The pneumatic installation can be filled and vented by a compressed air supply installation connected to a single 2/2-way valve. With this, the compressed air reservoir is connected via a separate control valve and a separate pneumatic line to the compressed air supply installation. The compressed air reservoir is isolated from the compressed air supply installation separately from an air suspension installation by a 4/4-way valve or two 2/2-way valves.

The pneumatic systems can also be improved further with a relatively complex connection of the pneumatic installation to the necessarily closed compressed air supply installation.

SUMMARY OF THE INVENTION

Generally speaking, it is an object of the present invention to provide an improved pneumatic installation and compressed air supply installation for the operation of a pneumatic installation that provide reliable and yet flexible, possibly rapid operation. That is, it is an object of the present invention to provide a pneumatic installation and a compressed air supply installation of relatively simple construction that enable relatively rapid venting with highly advantageous dryer regeneration and also improved acoustic characteristics.

It is a further object of the present invention to provide a pneumatic system having an improved pneumatic installation and an improved compressed air supply installation.

It is a still further object of the present invention to provide a vehicle system and/or a vehicle with an improved pneumatic system and a controller that has a control connection to the isolating valve assembly and/or to the venting valve. In particular, a common or respective separate control line can be provided for the isolating valve assembly and/or the venting valve.

A compressed air supply installation can be operated with compressed air in a pneumatic system with a pneumatic installation in an air suspension installation, e.g., in the context of a pressure level of 5 through 20 bar. The compressed air is provided to the compressed air supply installation from a compressed air feed. The compressed air can be generated for the compressed air feed by an air compressor disposed between the air feed and a compressed air supply connection. The compressed air feed is connected via a first pneumatic connection to a compressed air connection to the pneumatic installation for supplying the pneumatic installation. The pneumatic connection of the compressed air supply installation advantageously comprises a main pneumatic line. Moreover, the compressed air supply installation comprises a second pneumatic connection, advantageously a venting line, with a controllable venting valve, which is pneumatically connected to the main pneumatic line and to a venting connection to the surroundings. The compressed air feed is thereby pneumatically connected via the controllable venting valve to a venting connection to the surroundings. By means of the controllable venting valve, the compressed air supply installation can be vented to the venting connection by blowing off air, in particular to also vent the pneumatic installation. This is a so-called open compressed air supply installation, because it is directly vented to the surroundings or compressed air is taken in directly from the surroundings through the compressed air supply connection. The first and second pneumatic connections are preferably connections that are separately connected to a common compressed air supply connection; the first and second pneumatic connections, preferably in the form of the main pneumatic line and the venting line, can however also wholly or partly come together in a line, which can be used both for venting and also for filling the pneumatic installation.

The design of the pneumatic connection between the compressed air feed and a compressed air connection of the air suspension installation can represent a basis for improved dryer regeneration, in particular also flexible and potentially faster venting of the compressed air supply installation and/or the pneumatic installation or the pressurization thereof. The compressed air connection of the air suspension installation and/or a main pneumatic line of the compressed air supply installation can be relatively simply designed to represent the pneumatic connection. The pneumatic connection can be bidirectionally and fully closable. For this purpose, a controllable isolating valve assembly formed of at least one control valve can be provided in the pneumatic connection between the compressed air supply installation and the pneumatic installation.

The pneumatic installation can be filled and vented from the compressed air supply installation via the isolating valve assembly. The compressed air supply installation can, advantageously, be designed as open and above all to be simple to avoid the disadvantages of a closed compressed air supply installation; in particular, it can be operated at a lower pressure level and thus with lower energy costs.

An isolating valve and/or a venting valve are, advantageously, control valves. A controllable isolating valve of the isolating valve assembly can—in an isolation mode—be switched to a closed state, wherein in the closed state the pneumatic connection is bidirectionally and fully isolated, i.e., is closed. In other words, a pneumatic connection between the compressed air feed and the pneumatic installation is pneumatically tightly closed when the controllable isolating valve is in the closed state. This leads to decoupling of the compressed air supply installation and the pneumatic installation. The pneumatic connection is formed by means of the main pneumatic line of the compressed air supply installation and the pneumatic line of the pneumatic installation as well as a compressed air connection that connects the same. In an embodiment, the isolating valve assembly can be disposed in the main pneumatic line of the compressed air supply installation. In another embodiment, the isolating valve assembly can be disposed in the pneumatic line of the pneumatic installation. In principle, the isolating valve assembly can be disposed at any point in the pneumatic connection without an affiliation to the compressed air supply installation or pneumatic installation having to be specified. Advantageously, the main pneumatic line or pneumatic line is the only line of the pneumatic connection. Preferably, the isolating valve assembly is the only valve assembly in the pneumatic connection. The isolating valve assembly can be disposed with a restrictor in a series arrangement in the main pneumatic line or pneumatic line as a single pneumatic connection.

With a pneumatic connection that can be disconnected bidirectionally and completely, it is possible to achieve diverse operating states for the pneumatic installation, in particular an air suspension installation, without the compressed air supply installation being influenced thereby—potentially ineffective influence on the air dryer is thereby avoided. It is also advantageous to provide the main pneumatic line or the pneumatic line as a single line to represent the pneumatic connection between the compressed air feed and the compressed air connection. Thus, for a pneumatically fully and bidirectionally closed pneumatic connection in an air suspension installation connected to the compressed air connection, a pressure measurement can be taken in the reservoir or the bellows. Cross-switching of the reservoir and/or bellows can also take place via the gallery of the air suspension installation without the compressed air supply installation, in particular an air dryer, being adversely affected.

Conversely, the controllable isolating valve assembly can be set—in a throughflow mode—to an open state such that the series arrangement of the controllable isolating valve in the open state and the restrictor represents an optimized series arrangement for filling the pneumatic installation and venting the pneumatic installation. Using the series arrangement, dryer regeneration can be achieved or the requirements of a flexible and potentially rapidly operable compressed air supply installation and pneumatic installation can be fulfilled.

Because of the series arrangement of the restrictor and the isolating valve assembly, moreover, the pneumatic connection, in particular the compressed air connection and/or the main pneumatic line and/or the pneumatic line, can be simply and flexibly and yet reliably designed.

According to an embodiment of the present invention, for a controllable isolating valve assembly consisting of at least one control valve of the pneumatic installation or the compressed air supply installation, the isolating valve assembly comprises a first, second and third port, wherein the compressed air reservoir is pneumatically connected to the first port, the compressed air connection is pneumatically connected to the second port and the gallery of the air suspension installation is pneumatically connected to the third port. A pressure chamber of an air spring is advantageously in the form of a bellows.

Such a controllable isolating valve assembly consisting of at least one control valve having three ports can advantageously be provided in a compressed air supply installation or a pneumatic installation or can be disposed at any point in a pneumatic system. Here, the compressed air connection is pneumatically connected to the second port—on the side of the compressed air supply installation. The first port is provided for connecting a compressed air reservoir of the air suspension installation and the third port is provided for connecting a gallery of the air suspension installation. The isolating valve assembly serves, and thus switches, all connections, namely, for the reservoir, gallery and compressed air supply installation, at one point of the pneumatic system. This represents a considerable structural simplification of the conventional systems known from EPI 216 860B1 or EP 1 243 447A or EPI 380 453A1.

Accordingly, a pneumatic system can be provided, in which, according to an embodiment of the invention, a controllable isolating valve assembly consisting of at least one control valve is provided with at least three ports. Here, the compressed air reservoir of the air suspension installation is connected to the first port and the gallery of the air suspension installation is connected to the third port. In addition, the compressed air connection, i.e., the pneumatic connection between the compressed air supply installation and the air suspension installation, is pneumatically connected to the second port. In a closed state of the second port, the pneumatic connection is bidirectionally and fully closed.

According to another embodiment of the present invention, the isolating valve assembly is constructed to adopt at least three switch positions, wherein, in at least one of the switch positions, the second port of the isolating valve assembly can be switched into a closed state, in which the pneumatic line to the dryer is bidirectionally and fully closed.

Bidirectionally fully closed means that a pneumatic connection between the compressed air supply installation and the pneumatic installation is pneumatically tightly closed in a closed state of the second port. This also means that the pneumatic connection in the filling direction, i.e., in a direction from the compressed air supply installation to the pneumatic installation, is thus closed; this is even the case at higher pressures, which would open a non-return valve in the forward direction in prior art constructions. At the same time, the pneumatic connection is also pneumatically tightly closed in a venting direction, i.e., in a direction from the pneumatic installation to the compressed air supply installation. Such an effect is advantageously achieved by creation of the pneumatic connection with a single main pneumatic line and/or pneumatic line between the gallery and the dryer. In particular, a restrictor and the isolating valve assembly can, advantageously, be disposed in a series arrangement in the pneumatic connection. Conventionally, only parallel dispositions of an isolating valve—e.g., in parallel with a non-return valve or a restrictor—are known, so that a pneumatic connection between the compressed air supply installation and the pneumatic installation is pneumatically open at least in one direction, primarily in a filling direction from the compressed air supply installation to the pneumatic installation, by overcoming a switching pressure, e.g., of a non-return valve. It is advantageous to open a compressed air feed and/or a venting connection to the surroundings.

In other words, embodiments of the present invention include a bidirectionally and pneumatically fully closable pneumatic connection between the compressed air supply installation and the pneumatic installation in combination with an isolating valve assembly provided with three ports. This leads to a particularly flexible switching capability of the isolating valve assembly on the one hand, and, on the other hand, to a simply achievable, space-saving and component-saving solution to the decoupling of the pneumatic installation and the compressed air supply installation. For example, superfluous or relatively complex parallel circuits are substantially avoided. Moreover, with a three-port, controllable isolating valve assembly consisting of at least one control valve, at least three compressed air consumers and/or suppliers provided in a single isolating valve assembly can be switched. This relates to the operation of the isolating valve assembly both in throughflow mode and also in isolation mode.

The isolating valve assembly can be implemented simply within an isolating valve unit. This relates in particular to the specific design of the isolating valve assembly in the form of a 3/4-way valve or of a 3/3-way valve or in the form of a combination with two 2/2-way valves. For the latter case, the third port, for the gallery line, is connected between the first and second 2/2-way valves. This has the advantage that only one of the control valves has to be operated for pneumatic coupling or decoupling of the gallery to or from the compressed air supply installation; thus, a reduction in operating complexity is achieved.

In an embodiment, the isolating valve assembly is formed with at least three ports using a first and a second control valve. The first and second control valves of the isolating valve assembly are advantageously 2/2-way valves. Preferably, the first control valve—also referred to below as the primary valve—is implemented as a 2/2-way valve with the function of a level control valve for the compressed air reservoir, i.e., in a reservoir branch line. A reservoir branch line comprises a first control valve as a primary valve and the pneumatic connection, in particular the compressed air connection, comprises a second control valve as a secondary valve. Both control valves are advantageously implemented as 2/2-way valves. In the latter case, it is desirable that the first and second control valves are implemented in the form of a dual armature solenoid valve. This can be implemented relatively simply and in a compact construction. Overall, the first, second and third ports can be implemented relatively simply; namely as a first connection to the first control valve, in particular the primary valve, as a second connection to the second control valve, in particular the secondary valve, and as a third connection between the first and second control valves. The isolating valve assembly implemented in this way can be constructed with simple components, namely 2/2-way valves, at relatively low cost.

In other embodiments, the isolating valve assembly is formed with at least three ports, i.e., with a 3/4-way valve or a 3/3-way valve, which comprises the first, second and third ports. Such an arrangement is relatively compact and simple to control. In particular, a level control valve for a compressed air reservoir can be implemented within the isolating valve assembly in the form of a 3/4-way valve or a 3/3-way valve; and a level control valve for the compressed air reservoir can be omitted, in particular in a reservoir branch line. Finally, the implementation of the isolating valve assembly as a 3/4-way valve or a 3/3-way valve enables a level control valve for the compressed air reservoir to be saved.

In addition to the capability to regulate and/or to control a compressed air flow between the pneumatic installation and the compressed air supply installation by active intervention, inventive embodiments enable considerable energy savings and improved control performance for the compressed air supply installation and/or the pneumatic installation. In particular, the efficiency of regeneration of the air dryer is considerably improved, because this is not occupied with a regeneration operation during each operating function of the pneumatic installation, which may perhaps be incomplete or ineffective. This results in effective operation and overall lower loading of the air dryer and hence an extended operating life of the air dryer or an extended life of the dryer granulate in the air dryer. These and other advantages arise in particular for the case of the redistribution of compressed air in the pneumatic installation and in the case of measurements in the pneumatic installation and in the case of lifting or lowering processes, which can be carried out without a compressed air feed of the compressed air supply installation.

According to a preferred embodiment, the third port is designed as a normally open port. In a de-energized state of the controllable isolating valve assembly, consisting of at least one control valve, this results in a pneumatic connection between a compressed air feed of the compressed air supply installation and a gallery of the air suspension installation being pneumatically open.

The implementation of an isolating valve assembly and/or of a venting valve assembly with a single valve assembly, e.g., as a multi-armature or dual armature solenoid valve, is salutary. In particular, an isolating valve assembly can be implemented within a multi-armature or dual armature solenoid valve assembly. A venting valve assembly can be implemented in the context of a multi-armature solenoid valve or a dual armature solenoid valve assembly. Generally, a primary valve and a secondary valve can be in the form of one valve in a common housing, which comprises a primary armature supporting a first seal element of the primary valve and a secondary armature supporting a second seal element of the secondary valve, which are disposed in a common coil body. The coil body and the armature together form a coil within the magnetic part of the solenoid valve assembly. Advantageously, in a dual armature solenoid valve, the primary armature and the secondary armature pull in sequentially in time, e.g., with increasing control current. Additionally, a valve spring can be implemented for a primary valve or a secondary valve with a different respective spring force, so that the valves pull in time-sequentially, i.e., first the primary valve then the secondary valve. Using an adjustable control current, for which an armature pull-in force exceeds spring forces, the primary valve and the secondary valve can also be activated simultaneously.

For a vehicle system, the controller can be designed to match the control states of the isolating valve assembly and/or of a venting valve assembly to each other. For example, the second and/or third ports of the isolating valve assembly can be normally open. For this state, a venting valve of the venting valve assembly is normally closed. Moreover, the ports of the isolating valve assembly and venting valve assembly can be connected in a complementary manner in the de-energized position. The isolating valve assembly and the venting valve assembly can be controlled with respective separate control lines and with corresponding separate control signals that can be transmitted thereon. A control signal is preferably implemented in the form of a PWM control signal. The venting valve of the venting valve assembly and/or the isolating valve of the isolating valve assembly is/are advantageously implemented in the form of a solenoid valve. Nevertheless, a common controller suitable for both or a corresponding control module can be provided.

Preferably, flow rate can be regulated and/or controlled in throughflow mode at least for the controllable isolating valve assembly—possibly also for the controllable venting valve. The controllable isolating valve assembly can be controlled such that, for the series arrangement with the restrictor, a setting by the controller can be achieved that is advantageous for venting, pressurization and equally for dryer regeneration and the acoustics of the compressed air supply installation. A venting bang can be expected for a compressed air supply installation if an excessive compressed air volume is vented at too high a pressure in too short a time period. In particular, even for relatively rapid venting processes the controllable isolating valve can be regulated and/or controlled in throughflow mode with respect to a flow rate of a compressed air flow in order to achieve a preferred venting behavior.

Preferably, at least one isolating valve of the controllable isolating valve assembly can be switched to an open state for a throughflow mode. Advantageously, at least one isolating valve of the controllable isolating valve assembly can be switched to a closed state for an isolation mode. The pneumatic connection is bidirectionally and fully disconnected in the closed state enabling advantageous—pneumatically sealed—decoupling of the compressed air supply installation and the pneumatic installation for diverse operating modes of the pneumatic installation.

According to an embodiment of the present invention, at least one isolating valve of the controllable isolating valve assembly can be switched between a first control state and a second control state. Here, the first control state is assigned to a closed state of a controllable isolating valve and the second control state is assigned to an open state of a controllable isolating valve. The first and/or second control states can be specified at least for the controllable isolating valve by an electronic controller, e.g., using a suitable control signal conducted via a control line to the controllable isolating valve. The first control state can be designed so that the isolating valve changes fully to the closed state. The first control state can also be designed so that the isolating valve begins to change into the closed state at the start of the switching process without the closed state being reached. Analogously, the second control state can change the controllable isolating valve into the fully open state. The second control state can also be designed so that the controllable isolating valve is partly opened at the start of the switching process and, during the further course of the process, moves towards the fully opened state without the fully opened state being reached. For example, the first and second control states can be designed such that the controllable isolating valve moves dynamically and reciprocally between a fully closed and a fully opened state without becoming fully closed or fully opened. In particular, a control state change can also take place with a suitably selected clock rate.

Advantageously, in a throughflow mode to the second port, the isolating valve assembly can be switched between a first control state assigned to a closed state and a second control state assigned to an opened state, and, in a second control state assigned to an opened state, can be reciprocally switched with a clock rate of a control state change.

The design and matching of first and second control states is advantageous for the implementation of an effective nominal size of a series arrangement of an isolating valve assembly and a restrictor in the pneumatic connection. More specifically, the isolating valve assembly and a restrictor form a series arrangement in the pneumatic connection to the air dryer such that at least one controllable control valve of the isolating valve assembly can be switched into an open state in a throughflow mode and into a closed state in an isolation mode, wherein the first pneumatic connection is bidirectionally and fully closed in the closed state.

A restrictor is basically understood to mean a means of constricting the line cross section of the main pneumatic line. A preferred nominal dimension of the main pneumatic line is greater than 4 mm. The restrictor preferably has an actual nominal dimension greater than 0.6 mm determined by the smallest clear choke cross section. Depending on the line cross section of the main pneumatic line, a choke cross section can be up to 8 mm in size. Preferably, an actual nominal size of the restrictor is between 1 and 3 mm, in particular 2.5 mm. The effective nominal size of the series arrangement of the restrictor and the controllable isolating valve is preferably less than the specified actual nominal size of the restrictor.

Preferably, the restrictor is in the form of a choke that is separate from the isolating valve. In principle, this can be any type of variation of the line cross section of the main pneumatic line or a specially formed restrictor. A restrictor can also be formed in the isolating valve and/or in a further valve, e.g., by an opening of a valve seat of the isolating valve and/or the further valve or another cross-sectional constriction at a point in a pneumatic connection.

According to an embodiment of the present invention, the venting valve is a directly switched valve—part of a solenoid valve assembly for direct switching of a compressed air volume, wherein the solenoid valve assembly does not comprise a control valve. In other words, the solenoid valve assembly is used to implement a directly controlled venting solenoid valve assembly. By directly switching a compressed air volume, the switching time of the directly controlled venting solenoid valve assembly can be less than that of an indirectly controlled venting solenoid valve assembly; this is the case with venting cross-sections of equal size. This has advantages for the venting of the compressed air supply installation during regeneration of the air dryer.

In another embodiment, the venting valve forms an indirectly switched relay valve part of a solenoid valve assembly for indirect switching of a compressed air volume. The solenoid valve assembly then comprises a control valve for controlling the relay valve, the control valve being exposed to a pressure of the main pneumatic line. The pressure can be a total pressure in the main pneumatic line; it can also be a partial pressure of the main pneumatic line (that is, the solenoid valve assembly can be used to implement an indirectly controlled venting solenoid valve assembly). By indirectly switching a total compressed air volume, a control pressure can be kept relatively low. A relatively rapid switching operation of the venting valve can still be achieved by using a total pressure in the main pneumatic line for the control valve.

In one embodiment of the pneumatic installation, at least one air spring, in particular its bellows, is connected to the gallery via at least one bellows branch line. Additionally or alternatively, the compressed air reservoir is connected to the gallery via a reservoir branch line. A gallery is understood to be a gallery line or similar collecting line and/or distribution line, from which at least a bellows branch line branches off, or possibly even a different branch line, such as, e.g., to a pressure sensor or a reservoir; in other words, at least a plurality of bellows branch lines is combined in a collecting and/or distribution line of a gallery type. Moreover, a gallery can comprise a compressed air connection for a pneumatic connection of the air suspension installation to the compressed air supply installation. A gallery is thus a collecting and/or distribution line for the at least one bellows branch line and the compressed air connection.

Preferably, the bellows branch line comprises a level control valve. A level control valve in a branch line has the advantage that the pressure chamber of an air spring can be pneumatically disconnected from the gallery if the level control valve is in a closed state. In a similar function, a reservoir valve in a reservoir branch line can connect a compressed air reservoir. By opening one or a plurality of the level control valves or a reservoir valve, in individual cases—apart from level control—pressure equalization can be carried out between one or a plurality of pressure chambers of the air springs or the compressed air reservoir and the pressure chambers. In particular, redistribution of compressed air between the pressure chambers of the air springs and/or a compressed air reservoir can take place via the gallery. This is also referred to as “cross-linking” of the air springs and/or—more importantly—the compressed air reservoirs. This can present disadvantages in the event that an air dryer of the compressed air supply installation is not shut off from the gallery. This problem is avoided by the controllable isolating valve assembly provided according to embodiments of the present invention, which includes at least one control valve and which is disposed in the pneumatic connection of the air suspension installation to the compressed air supply installation. The pneumatic installation can, however, also be operated in any other operating state independently of the compressed air supply installation, e.g., by cross-linking, because the isolating valve assembly offers the option of decoupling the pneumatic installation and the compressed air supply installation from each other by bidirectional and full closure of the pneumatic connection.

A level control valve can be advantageously formed as a 2/2-way valve. Depending on the implementation of the controllable isolating valve assembly consisting of at least one control valve, a level control valve or reservoir valve in the form of a 2/2-way valve—whether it is for an air spring or for a compressed air reservoir—can also be implemented as part of the controllable isolating valve assembly.

A preferred embodiment of the compressed air supply installation provides the isolating valve assembly as the only valve assembly in the only main pneumatic line between the air dryer and the compressed air connection, in particular between the air dryer and the gallery line.

Preferably, in the compressed air supply installation and/or the pneumatic system:

(a) the isolating valve assembly is formed by means of a first control valve and a second control valve, wherein the third port is pneumatically connected between the first control valve and the second control valve, or

(b) the isolating valve assembly is formed by a 3/4-way valve, or

(c) the isolating valve assembly is formed by a 3/3-way valve.

In an embodiment of the compressed air supply installation, the venting valve is a directly switched valve part of a solenoid valve assembly for direct switching of a compressed air volume.

In another embodiment of the compressed air supply installation, the venting valve is an indirectly switched relay valve, part of a solenoid valve assembly for indirect switching of a compressed air volume, wherein the solenoid valve assembly comprises a control valve exposed to a pressure of the main pneumatic line and for controlling the relay valve.

Preferably, in the compressed air supply installation and/or the pneumatic system, it is also provided that the third and/or second port is/are connected in a pneumatically open connection in the de-energized state of the isolating valve assembly.

Also, it is preferable that, in a first operating mode, the pneumatic connection between the gallery line and the air dryer is bidirectionally and fully closed, wherein a pressure measurement and/or cross-linking of a reservoir and/or a bellows can be carried out in the pneumatic installation without the air dryer of the compressed air supply installation being exposed to compressed air.

The present invention accordingly comprises the features of construction, combination of elements, and arrangement of parts, all as exemplified in the constructions herein set forth, and the scope of the invention will be indicated in the claims.

In the drawing figures, the same reference characters are used for identical or similar parts or parts of identical or similar function, where suitable.

LIST OF REFERENCE CHARACTERS

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1shows a pneumatic system101with a compressed air supply installation11and a pneumatic installation901in the form of an air suspension installation. The air suspension installation comprises a number of bellows91, each of which is assigned to a wheel of a vehicle and forms an air spring of the vehicle. Moreover, the air suspension installation comprises a reservoir92for storing rapidly available compressed air for the bellows91. A solenoid valve93is disposed upstream of each bellows91in a bellows branch line90and each acts as a level control valve for opening or closing an air spring formed by a bellows91. The solenoid valves93in the bellows branch lines90are 2/2-way valves. A separate solenoid valve as a reservoir valve can be disposed upstream of the reservoir92in a reservoir branch line94, its function being undertaken in this case by an isolating valve assembly900. The solenoid valves93are connected by means of the bellows branch lines90to a gallery line95, which forms a common pneumatic collecting line. The gallery line95is pneumatically connected via a further pneumatic line96to form a pneumatic connection to a compressed air port2of the compressed air supply installation11. In the present case, the pneumatic installation901is provided with a pressure sensor98, which is connected via a further sensor branch line99to the gallery line95so that a pressure in the gallery line95of the pneumatic installation901can be measured by the pressure sensor98. A pressure sensor98can be attached to the gallery line95, as with the pneumatic installations901,903,904, or can even be attached to the reservoir92as with the pneumatic installation902. The solenoid valves93are disposed in a valve block97with five valves together with the single solenoid 3/4-way valve of the isolating valve assembly900. The solenoid valves93are shown inFIG. 1in a de-energized state—the solenoid valves93are formed as normally closed solenoid valves. Other modified embodiments can implement a different disposition of the solenoid valves93—for example, fewer solenoid valves can be used within the valve block97. The present, relatively compact, isolating valve assembly900disposed together with the solenoid valves93in the five-fold valve block97is part of the pneumatic installation901; an isolating valve can be designed differently within the scope of the invention, and can be disposed elsewhere in the pneumatic connection to the compressed air supply installation11.

The compressed air supply installation11is used to operate the pneumatic installation901. The compressed air supply installation11comprises a compressed air feed1and a compressed air port2to the pneumatic installation901. The compressed air feed1is formed here with an air feed0, an air compressor51and a compressed air supply connection52in the form of a suitable interface. The air feed0can be disposed upstream of a filter. The air compressor52is driven by a drive, in the present case in the form of a motor M. The pneumatic connection between the compressed air supply installation11and the pneumatic installation901is formed here by a single main pneumatic line60and a continuation pneumatic line96connected in series therewith; the pneumatic connection thus connects, on the one hand, to the compressed air supply connection52to the air feed1and, on the other hand, via the isolating valve assembly900to the gallery line95. In between the pneumatic connection are an air dryer61and a first choke62. A controllable isolating valve assembly900is formed with a solenoid valve as a 3/4-way valve. The choke62and the isolating valve assembly900form a pneumatic series arrangement in the pneumatic connection, namely in the main pneumatic line60with the compressed air connection2and the further pneumatic line96.

Furthermore, the compressed air supply installation11comprises a further pneumatic connection to the main pneumatic line60and a venting connection3to the surroundings, namely the venting line70. In the present case, the separate venting line70is connected to the compressed air supply connection52to the main pneumatic line60. A second choke72and a controllable—here a normally closed—venting valve73are disposed in the venting line in the direction of the venting connection3. A filter74is disposed downstream of the venting connection3to the surroundings. The compressed air supply installation11shown inFIG. 1provides the venting valve73as a single and directly switched valve for directly switching a compressed air volume in the venting line70. An additional control valve is not provided in the compressed air supply installation11.

The venting valve73is part of a solenoid valve assembly80formed with the isolating valve assembly900. The solenoid valve assembly80provides a first coil81for the controllable isolating valve900and a second coil82for the controllable venting valve73that is formed separately from the first coil81. In particular, the first coil81and the second coil82are each formed with a separate coil body and, in the present case, with separate control lines83,84—referred to here as third and fourth control lines. The third and fourth control lines83,84are connected to the vehicle controller ECU of a vehicle.

The isolating valve assembly900is, in the present case, a 3/4-way valve implemented as a solenoid valve and has a first port X, a second port Y and a third port Z. The reservoir92is pneumatically connected to the first port X via the reservoir branch line94. The compressed air connection2is pneumatically connected via the further pneumatic line96to the second port Y. The gallery line95is pneumatically connected to the third port Z. The isolating valve assembly900thus comprises three ports, to which—depending on the operating state of the pneumatic system101—components acting as compressed air recipients or compressed air feeds are commonly pneumatically connected, so that they can be switched together via the isolating valve assembly900in a single component. In the present case, the components comprise a reservoir92(connection via the reservoir branch line), a compressed air supply installation11(connection via the further pneumatic line96and the compressed air connection2) and the bellows91as well as the pressure sensor98(connection via the gallery line95). The isolating valve assembly900can also adopt different control states, which are associated with different operating states of the pneumatic installation901and which are explained in detail for the pneumatic system101in relation toFIG. 7,FIG. 9, and FIG.11—as representative—of diverse embodiments of the present invention.

The pneumatic system101or the pneumatic installation901in the form of an air suspension installation can also be constructed with a different isolating valve assembly700, as illustrated inFIG. 9Cby way of example. The isolating valve assembly700shown there is constructed with a solenoid valve as a 3/3-way valve and is particularly suitable for a pneumatic installation902ofFIG. 9C, in which the pressure sensor98is provided for pressure measurement via a sensor branch line99directly connected to the reservoir92—i.e., not via the gallery line95, but directly to the reservoir92. The isolating valve assembly700also comprises three ports X, Y, Z, respectively, for a reservoir branch line94to a reservoir92, a pneumatic line96to a compressed air connection2of a compressed air supply installation and to a gallery line95. In principle, the description relating to the embodiments with a 3/4-way valve ofFIG. 1,FIG. 2andFIG. 5can also apply to embodiments with a 3/3-way valve, where this is shown as Detail D. The switching state existing for a 3/4-way valve, in which all three ports X, Y, Z are blocked, can be omitted for the 3/3-way valve if, as inFIG. 9C, the pressure sensor98is connected directly to the reservoir instead of to the gallery line95.

FIG. 2shows a slightly modified embodiment of a pneumatic system201with a compressed air supply installation21and a pneumatic installation903. Reference is only made below to the differences of the pneumatic system201compared to the pneumatic system101.FIG. 2first shows the venting valve73in a normally open variant. A non-return valve71in the venting line70is disposed upstream of the venting connection3in the venting direction, which is advantageous for closing the compressed air supply installation21relative to the surroundings. The pneumatic systems101,201differ in that the otherwise identical isolating valve assembly900is not—as for the pneumatic installation901—disposed within a valve block97′, but is rather implemented separately from the solenoid valves93. The solenoid valves93of the pneumatic installation903are disposed, in the present case, in a four-fold solenoid valve block97′ and form respective air springs together with the bellows91. The air springs and the reservoir92together with the pressure sensor98form the components of the pneumatic installation903connected to the gallery line95. The isolating valve assembly900is disposed in the pneumatic system201ofFIG. 2either as part of the compressed air supply installation21in the main pneumatic line60or—as shown in the present case—in the further pneumatic line96, namely, in a series arrangement with the air dryer61, the choke62and the compressed air connection2. In the present case, the 3/4-way valve is implemented separately from the compressed air supply installation21and separately from the pneumatic installation905.

In this alternative embodiment, the pneumatic installation903does not comprise the isolating valve assembly900, but rather the isolating valve assembly900is disposed in a series arrangement in the main pneumatic line60of the compressed air supply installation21, i.e., between the choke62and the compressed air connection2. The isolating valve assembly900comprises, in turn, a second port Y, to which the compressed air connection2of the compressed air supply installation21is directly connected. The first port X is, in turn, provided for connecting a reservoir92of the pneumatic installation903. The third port Z is, in turn, provided for connecting a gallery line95of the pneumatic installation903. The operating positions of the isolating valve assembly900shown by way of example of operating states of the pneumatic system, as shown inFIG. 7,FIG. 9andFIG. 11, also apply to the pneumatic system shown inFIG. 2.

FIG. 3Ashows a pneumatic system302with a compressed air supply installation11as already described with reference toFIG. 1, and with a pneumatic installation904, which is shown, in the present case, without pressure sensor98. For the compressed air supply installation11, reference is made to the description ofFIG. 1. For the pneumatic installation904, in the present case, an isolating valve assembly800is provided. For the same design of pneumatic installation904, up to the isolating valve assembly800and a pressure sensor98, reference is made to the description of the pneumatic installation901inFIG. 1. In the present case, the isolating valve assembly800again comprises three ports X, Y, Z. The isolating valve assembly800is formed using a first control valve801, here, in the form of a 2/2-way valve—also referred to as primary valve I below—and a second control valve802, here, in the form of a 2/2-way valve—also referred to below as secondary valve II. The reservoir92is connected to the first control valve801via the first port X. The compressed air connection2of the compressed air supply installation11is connected via the second port Y and via the further pneumatic line96to the second control valve802. The gallery line95of the pneumatic installation904is connected to the third port Z formed between the first and second control valves801,802.

The isolating valve assembly800formed—as a 3/4-way valve or a 3/3-way valve—by the two control valves801,802also enables the common switching of the compressed air connection2, of the reservoir92and of the gallery line95with a single isolating valve assembly800using three ports X, Y, Z.

FIG. 3B,FIG. 3C, andFIG. 3Dshow, in relation to each other, respectively, the isolating valve assembly800, on the one hand, in View (ii) and, on the other hand, in View (i) as a dual armature solenoid valve. In the present case, a functional position of the isolating valve assembly800is shown in View (ii). In addition, a functional position of the dual armature solenoid valve respectively associated with the functional position of the isolating valve assembly800is shown in View (i), with which the solenoid valve assembly800can be implemented particularly advantageously. The switch positions (A), (B), (C) shown inFIG. 3B,FIG. 3C, andFIG. 3Dclearly show different pneumatic couplings of the air dryer61, of the reservoir92and of the bellows91depending on the operating state of the pneumatic installation904or of the pneumatic system302. The operating states are also illustrated in detail by way of example with different functional positions of an isolating valve assembly800inFIG. 8,FIG. 10andFIG. 12.

The first and second control valves801,802are referred to inFIG. 3Bas primary valve I or secondary valve II, respectively. The primary valve I comprises a first seal element Ia and a primary armature Ib, to which the first seal element Ia is attached. In View (A) the first seal element Ia sits on a valve seat Id and is held there by a valve spring Ic. The thus closed valve seat Id causes the closed position of the first control valve801(primary valve I), as symbolically shown in View (ii) of View (A) ofFIG. 3B.

Furthermore, it can be seen in View (A) ofFIG. 3Bthat a secondary armature IIb for the secondary valve II in the dual armature solenoid valve is provided with a second seal element IIa, wherein the second seal element II is lifted from valve seat IId by the valve spring lic in the functional position of the dual armature solenoid valve shown in View (A) ofFIG. 3B. This position occurs without energizing the common coil body III for primary valve I and secondary valve II. In the position thus shown with primary and secondary armatures Ib, IIb dropped, the first control valve801(primary valve I) is normally closed and the second control valve802(secondary valve II) is normally open. A pneumatic installation904can thus be used for level control installations to carry out possibly frequent venting, lowering or raising from the compressed air feed1with switching of bellows valves93without having to operate the isolating valve assembly800.

When energized, the coil body III acts inductively on the secondary armature IIb and the second seal element IIa is pressed onto the valve seat IId against the force of a valve spring IIc. When energized, the coil body III also acts inductively on the primary armature Ib and the first seal element Ia is lifted from the valve seat Id against the force of a valve spring Ic.

View (B) ofFIG. 3Cshows the dual armature solenoid valve in View (i) when energized, wherein only the primary armature Ib is now moved and the first seal element Ia is lifted from the valve seat Id. In the functional position thus shown, both the first control valve801(primary valve I) and the second control valve802(secondary valve II) are opened. For such a functional position of the isolating valve assembly800, a bellows valve93is advantageously closed.

If the current in the coil body III falls below a holding current for the secondary valve II, but the current is above a switching current of the primary valve I, the functional position of View (C) ofFIG. 3Doccurs, in which the secondary valve II is closed and the primary valve I is opened—assuming full energizing current. In other words, as can be seen from View (i) ofFIG. 3D, the primary armature Ib is in a position in which the first seal element Ia is lifted from valve seat Id. The secondary armature IIb is in a position in which the second seal element IIa is seated on the valve seat IId. This functional position has the advantage that a bellows91can be filled from the reservoir92and the air dryer61in the compressed air supply installation11is still shut off. Such a refilling action thus does not adversely affect the air dryer61.

The current limits for switching currents, holding currents or restoring currents of the primary valve I and secondary valve II can be suitably matched with respect to the spring forces of the valve springs Ic, IIc. Induction forces on the primary armature Ib and secondary armature IIb can be matched against spring forces such that the primary valve I and the secondary valve II are suitably switched when the coil body III is energized. Therefore, a common control line84for the primary valve I and the secondary valve II identifiable inFIG. 3Aand referred to as a fourth control line can be occupied by a common control signal for the first control valve801and the second control valve802. In this design, the isolating valve assembly800is implemented as a dual armature solenoid valve relatively simply and with similar compactness to the isolating valve assembly900or700.

FIG. 4shows an embodiment of a pneumatic system301modified compared toFIG. 3Awith a compressed air supply installation31and a modified pneumatic installation905. The pneumatic system301comprises, in contrast to the pneumatic system302ofFIG. 3A, a modified isolating valve assembly800′-again, with a first control valve801′ and a second control valve802′. In contrast to pneumatic system302ofFIG. 3A, the first control valve801′ and the second control valve802′ are not implemented as a dual armature solenoid valve. Rather, in the present case, a separate first and second control line84.1or84.2is provided for each of the control valves801′,802′. Moreover, the control valves801′,802′ are formed as separate 2/2-way valves. The first control valve801′ is implemented as part of a five-fold valve block97″ together with the further solenoid valves93—i.e., as part of the sequence of five 2/2-way valves in the five-fold valve block97″. However, the second control valve802′ is disposed in the main pneumatic line60on the other side of the compressed air connection2in the compressed air supply installation31. In the embodiment shown here, the second control valve802′ is thus assigned to the compressed air supply installation31and is disposed in the main pneumatic line60itself, in the present case, between the choke62and the compressed air connection2, like with the 3/4-way valve ofFIG. 2.

In other embodiments, the second control valve802′ can instead be formed in the further pneumatic line96to the compressed air connection2to the pneumatic installation905or even separately from the pneumatic installation905. Otherwise, the compressed air supply installation31is designed as is the compressed air supply installation11ofFIG. 1, so that, here, reference is made to the description of the compressed air supply installation11. For a venting process from the reservoir92of the pneumatic installation905, the pneumatic system301shown inFIG. 4thus provides three 2/2-way valves to conduct a flow—namely, the first control valve801′ as part of the isolating valve assembly800′ in the pneumatic installation905and as part of the valve block97″ and the second control valve802′ as part of the isolating valve assembly800′, whether in the main pneumatic line60or in the further pneumatic line96, and finally the venting valve73in the compressed air supply installation31. In the present case, all three 2/2-way valves are connected to the ECU via separate control lines—namely, the first control line84.1, the second control line84.2and the third control line83.

In a modified implementation, the venting valve73and the second control valve802′ of the isolating valve assembly800′ can be implemented in a relatively compact manner in the form of a dual armature solenoid valve, wherein both the venting valve73and also the second control valve802′ are in a common coil body and can be controlled via a common control line.

FIG. 5shows a further embodiment of a compressed air supply installation41as part of a pneumatic system402for supplying a pneumatic installation901. The differences with respect to the compressed air supply installations11,21,31are described herein. The compressed air supply installation41comprises a main pneumatic line60and a venting line70. An air dryer61and a first choke62are disposed in the main pneumatic line60, like with the embodiments discussed above. The controllable isolating valve900and the choke62form a series arrangement in the pneumatic connection between the pneumatic installation901and the compressed air supply installation41such that the pneumatic connection can be bidirectionally and fully closed for a compressed air flow. At the same time, all components—compressed air supply installation11, reservoir92and bellows91—can be flexibly switched via three ports X, Y, Z. The venting line70is connected to the main pneumatic line60via a compressed air supply connection52and comprises a controllable venting valve173between the compressed air supply connection52and the venting connection3. In contrast to the embodiments discussed above, the venting valve173is part of a solenoid valve assembly180for indirect switching of a compressed air volume. Here, the venting valve173is in the form of an indirectly switched relay valve part of the solenoid valve assembly180, which is controlled by a control valve175. The control valve175is, in the present case, subjected to a total pressure of a pressure flow in the main pneumatic line60via a control branch line160branching off from the main pneumatic line60. Depending on the design of the first choke62, the control valve175can also be subjected to a partial pressure of the main pneumatic line60.

In particular, a control valve175for controlling the relay valve173and subjected to only a minimal pressure, enables relatively rapid venting of the compressed air supply installation41, because a pilot pressure is relatively low. In the present case, the control valve175of the solenoid valve assembly180is in a normally open state. The venting valve173is in a preliminary state. It only then requires a minimal operating pressure dependent on the configuration to displace the venting valve173into the open state. It is advantageous with a rapidly vented solenoid valve assembly180that, because of the relatively small nominal size of the first choke62, only a low partial pressure of the compressed air volume is necessary in the main pneumatic line60to control the venting valve173via the control valve175. Nevertheless, the main pressure volume is vented via the venting line70and the choke72as well as the relay valve173to the venting connection3. An advantage of the rapidly vented solenoid valve assembly180with the compressed air supply installation41is that the entire compressed air volume does not have to be switched by a single solenoid valve, but only a low partial pressure of a compressed air volume via the control branch line160to the control valve175is sufficient. This design as a positively controlled valve assembly enables an increase of the operating pressure to a relatively high pressure level. At the same time, the switching of high compressed air volumes by the venting valve173is rendered possible. The venting valve173, acting as a relay valve, can be designed with a relatively large nominal size. Moreover, the ratio of the nominal size of the first choke62to the nominal size of the second choke72is formed so that effective regeneration of the air dryer61is still possible during venting of the compressed air supply installation41.

In the closed state, the control valve175is open via the venting branch line170to the venting connection3, wherein the further venting branch line170is combined with the venting line70before the venting connection3.

Otherwise, the function of the compressed air supply installation41with respect to the isolating valve900and the venting valve173is analogous to the operation of the previously discussed compressed air supply installations11,21,31. A pneumatic installation901is connected to the compressed air supply installation41via the compressed air connection2and the further pneumatic line96in the manner illustrated inFIG. 1. Reference is made to the description ofFIG. 1for the description of the pneumatic installation901.

FIG. 6shows a pneumatic system401with a compressed air supply installation41, as inFIG. 5, and a pneumatic installation904, as inFIG. 3A. Suitable reference is made to the corresponding illustrative parts ofFIG. 3AandFIG. 5. In particular, the current amplitudes for the switching currents can be selected analogously in relation to the isolating valve800—namely, primary valve I (first control valve801) and secondary valve II (second control valve802)—and the control and relay valve assembly of the control valve175and the venting valve173.

The functional positions of an isolating valve assembly900are illustrated inFIG. 7,FIG. 9, andFIG. 11for different operating positions of the pneumatic system402shown inFIG. 5. The functional positions of the isolating valve assembly800shown inFIG. 8,FIG. 10, andFIG. 12are shown in relation to a pneumatic system401ofFIG. 6.

FIG. 7andFIG. 8show in Views (A), (B), (C) different operating positions of a pneumatic system402,401, which is used for filling a pneumatic installation901,904. In all operating positions, a venting valve173of the compressed air supply installation41supplying the pneumatic installation901,904with compressed air is closed. Filling of the pneumatic installation901,904takes place either from the compressed air feed1via a main pneumatic line60of the compressed air supply installation41or else from the reservoir92of the pneumatic installation901,904.FIG. 7shows the operating positions for a pneumatic system402ofFIG. 5, wherein the compressed air supply installation41is only shown in View (A) for all views ofFIG. 7.FIG. 8shows the operating positions for a pneumatic system401ofFIG. 6, wherein the compressed air supply installation41is only shown in View (A) for all views ofFIG. 8.

View (A) ofFIG. 7orFIG. 8shows the isolating valve assembly900,800in a functional position that enables filling of the reservoir92with compressed air from the compressed air feed1via the main pneumatic line60, the compressed air connection2and the further pneumatic line96as well as the isolating valve assembly900or800. For this, the 3/4-way solenoid valve of the isolating valve assembly900of View (A) ofFIG. 7is in a functional position in which a connection between the first port X and the second port Y is open. In this way, the compressed air connection2to the air dryer61and the reservoir92are pneumatically connected to each other. The 3/4-way solenoid valve is energized for this purpose and is brought from the de-energized position shown inFIG. 5into the functional position shown inFIG. 7A. InFIG. 7A, filling of the gallery line95is prevented because of the functional position of the isolating valve assembly900, because the third port Z is not pneumatically open to the second port Y.

In relation toFIG. 8, View (A), energizing is carried out for the isolating valve assembly800consisting of the first control valve801and the second control valve802such that the primary valve I formed by the first control valve801changes from a normally closed position into a normally open position. In this way, a pneumatically open connection is made between the first port X and the second port Y of the isolating valve assembly800, so that the reservoir92can be filled with compressed air from the compressed air feed1, the main pneumatic line60and the compressed air connection2and the other pneumatic line96via the isolating valve assembly800. The open third port Z connected between the first and second control valves801,802principally opens the gallery line95for compressed air. Filling of the bellows91is prevented because of the normally closed solenoid valves93, which are each connected as level control valves upstream of a bellows91.

View (B) ofFIG. 7andFIG. 8shows a functional position of the isolating valve assembly900,800, in which filling of the bellows91from the compressed air feed1is possible via the main pneumatic line60, the compressed air connection2, the further pneumatic line96and the respective isolating valve assembly900,800. For this, the isolating valve assembly900, as shown inFIG. 7View (B) as a 3/4-way solenoid valve, is in a functional position in which the third port Z and the second port Y have a pneumatically open connection to each other. The functional position of the 3/4-way solenoid valve corresponds to the de-energized position of the isolating valve assembly900. Filling the bellows from the compressed air feed1can thus take place for all or individual or groups of bellows with switching through of one or a plurality of or all of the solenoid valves93. InFIG. 7View (B), a solenoid valve93is switched through as an example, so that there is a pneumatically open connection of the bellows91to the gallery line95and the bellows can be filled with compressed air from the compressed air feed1of the compressed air supply installation41.

InFIG. 8View (B), the solenoid valve assembly800is likewise held in the de-energized state for filling the bellows. In this state, the first control valve801forming the primary valve I is normally closed and the second control valve802forming the secondary valve II is normally open. In this way, there is a pneumatically open connection between the third port Z to the gallery line95and the second port Y to the compressed air connection2, while the first port X is closed. That is, the gallery line95is pneumatically connected to the compressed air feed1, while a pneumatic connection to the reservoir92is disconnected. The latter is also the case for the isolating valve assembly900of View (B) ofFIG. 7. Again, individual ones of, a plurality of or all bellows91of the pneumatic installation904can be filled with compressed air by opening individual, a plurality of or all solenoid valves93in the form of the level control valves.

View (C) ofFIG. 7andFIG. 8show an operating position of the pneumatic system402or401, in which filling the bellows91with compressed air from the reservoir92is enabled, wherein, however, a pneumatic connection between compressed air feed1of the compressed air supply installation41and the reservoir92is bidirectionally and fully isolated. In other words, cross-linking of the bellows91to the reservoir92via the gallery line95and redistribution of the compressed air from the reservoir92to the bellows91, or vice-versa, is possible without the compressed air supply installation41being adversely affected as a result. An adverse effect, in particular on the air dryer61in the compressed air supply installation41, is advantageously prevented. In installations without an isolating valve assembly, by a mere redistribution of compressed air, a compressed air consumption would occur that could only partly or wholly inadequately be used for regeneration of the air dryer61, which is avoidable. With the functional position of an isolating valve assembly900,800shown in View (C) ofFIG. 7andFIG. 8, it is possible to decouple the air dryer61from an air suspension installation and to operate the air suspension installation independently of the compressed air supply installation41.

In View (C) ofFIG. 7, the 3/4-way solenoid valve of the solenoid valve assembly900is brought into a functional position in which the first and the third ports X, Z of the solenoid valve assembly900are pneumatically connected to each other, while the second port Y is pneumatically disconnected from the compressed air connection2. In this way, compressed air can pass from the reservoir92only into the gallery line95and not into the compressed air connection2. As soon as one, a plurality of or all of the normally closed solenoid valves93shown in View (C) ofFIG. 7are opened, compressed air passes into one, a plurality of or all of the bellows91, which, e.g., can be used for level control of and/or lifting of a vehicle body.

InFIG. 8View (C), the same function can be achieved with an isolating valve assembly800, with which the first control valve801forming the primary valve I is brought from a normally closed position into an energized open position and the second control valve802forming the secondary valve II is brought from a normally open position into an energized closed position. An open pneumatic connection between the reservoir92and the gallery line95occurs by switching the primary valve I into an open position. By switching the secondary valve II into a closed position, a pneumatic connection between the compressed air feed1and the gallery line95is disconnected. In the functional position of the isolating valve assembly800, compressed air can thus pass from the reservoir92into the gallery line95. Again, by opening one, a plurality of or all of the solenoid valves93, compressed air can pass into one, a plurality of or all of the bellows91and can be used for level control of and/or lifting of a vehicle body.

FIG. 9andFIG. 10show different operating positions in Views (A), (B), (C), (D) that enable pressure measurement in the pneumatic installation901or904or cross-linking between the bellows91and the reservoir92without adversely affecting a compressed air supply installation41.

View (A) ofFIG. 9also shows a functional position of the isolating valve assembly900in which all pneumatic connections between the ports X, Y, Z are disconnected. In this way, a pressure measurement can take place by means of the pressure sensor98connected to the gallery line95and, preferably for individual bellows91; in principle, depending on whether individual, some of or all of the solenoid valves93are opened or in the normally closed position.

In View (A) ofFIG. 10, this operating position is enabled in a functional position of the solenoid valve assembly800in which the primary valve I formed by the first control valve801remains in the normally closed position and the secondary valve II formed by the second control valve802is brought into a closed position by energizing. Thereby, all three ports X, Y, Z are likewise pneumatically isolated from each other. This, again, enables a pressure measurement in the gallery line95for individual, a plurality of or all of the bellows91by means of a pressure sensor98that is connected to the gallery line95.

View (B) ofFIG. 9orFIG. 10shows an operating position of the pneumatic system402or401, in which, in the pneumatic installation901or904, a pressure in the reservoir92can be measured by means of a pressure sensor connected to the gallery line95. For this, the pneumatic installation901or904is brought into an operating position in which the reservoir92is pneumatically connected to the gallery line95, while a pneumatic connection of the gallery line95to the bellows91is disconnected. The solenoid valves93are held in the normally closed position. In View (B) ofFIG. 9, the isolating valve assembly900in the form of the 3/4-way solenoid valve is brought into an operating position in which a pneumatic connection is made between the first port X and the third port Z and a pneumatic connection to the second port Y is disconnected. A reservoir92connected via the 3/4-way solenoid valve to the gallery line95can thus also be detected with respect to a pressure measurement by a pressure sensor98in the gallery line95.

In View (B) ofFIG. 10, for the same operating position, the isolating valve assembly800is brought into a functional position in which the primary valve I formed by the first control valve801is open when energized and the secondary valve II formed by the second control valve802is closed when energized. In other words, the de-energized position of the isolating valve assembly800as shown inFIG. 8(B) is inverted. In this way, the reservoir92is pneumatically connected to the gallery line95and a pressure of the reservoir92can thus be read out by means of a pressure sensor98that is connected to the gallery line95.

View (C) ofFIG. 9andFIG. 10shows an alternative option to View (B) ofFIG. 9andFIG. 10for pressure measurement for a reservoir92, which takes place by means of a pressure sensor98, which is connected via a sensor branch line99directly to the reservoir92. For this variant of a pneumatic installation902, it is sufficient to provide an isolating valve assembly700in the form of a 3/3-way solenoid valve. In the functional position of the isolating valve assembly700shown in View (C) ofFIG. 9, this remains in the de-energized position similar to the functional position of the 3/4-way valve assembly900shown inFIG. 5. In addition, the first port X connected to the reservoir92is disconnected from any pneumatic connection. Instead, the pneumatic connection between the second and third ports Y, Z of the isolating valve assembly700is maintained. The reservoir92is thus decoupled from the remaining pneumatic installation902and also from the compressed air supply installation41and a pressure can, as described, be directly measured at the reservoir92.

As shown in View (C) ofFIG. 10, an isolating valve assembly800can also be used for the variant905of a pneumatic installation with a pressure sensor98directly connected to the reservoir92via a sensor branch line99. For this, the isolating valve assembly800remains in the de-energized position shown inFIG. 6and a pneumatic connection of the first port X, to which the reservoir92is connected, is disconnected. The pressure of the reservoir92thus decoupled from the other pneumatic installation905can thus be measured by the pressure sensor98. The other pneumatic connection between a second port and a third port Y, Z of the isolating valve assembly800is opened.

With the variant of View (C) ofFIG. 9and ofFIG. 10, a bellows91can be filled with compressed air from the compressed air feed1via the isolating valve assembly700,800in parallel with the pressure measurement in the reservoir92, as is illustrated in View (B) ofFIG. 7orFIG. 8.

FIG. 11andFIG. 12show operating positions of a pneumatic system402or401with a respective pneumatic installation901or904, according to which venting of the pneumatic installation901or904can take place. In both cases, a venting solenoid valve assembly180is opened for this, so that the pneumatic installation901or904can be vented to the venting connection3via the main pneumatic line60, the air dryer61and the venting line70—i.e., via the venting valve173in the form of a relay valve.

In View (A) ofFIG. 11andFIG. 12, venting the bellows91is provided. For this, the isolating valve assembly900is in a de-energized position, as is shown inFIG. 5, so that there is a pneumatic connection between the gallery line95and the venting connection3. For venting one or a plurality of the bellows91, it is only necessary to open one or a plurality of the level control valves, i.e., the solenoid valves93. The simultaneous opening of all solenoid valves93is avoided here if possible in order to avoid sudden pitching of a vehicle.

In the pneumatic installation904shown in View (A) ofFIG. 12, the isolating valve assembly800is likewise in the de-energized position shown inFIG. 6, namely, with a normally closed first control valve801to form a closed primary valve I and with a normally open control valve802to form an open secondary valve II. Thereby, as with the isolating valve assembly900, on the one hand, the reservoir92is pneumatically disconnected from the gallery line95, and, on the other hand, the gallery line95is pneumatically openly connected to the venting connection3.

In order to be able to vent the reservoir92in exceptional cases, such as a thermally induced pressure rise, the isolating valve assembly900,800is brought into a functional position—as shown in View (B) ofFIG. 11and FIG.12—in which the reservoir92has a pneumatically open connection to the venting connection3, namely, via the pneumatic line96, the main pneumatic line60and the venting line70. From View (B) ofFIG. 11, it is apparent that, for this, the isolating valve assembly900is in a functional position in which there is a pneumatically open connection between the first port X and the second port Y, while a pneumatic connection of the third port Z is disconnected. In this way, venting of the reservoir92can safely take place even with open level control valves, i.e., solenoid valves93, of the air springs.

With the isolating valve assembly800shown in View (B) ofFIG. 12, venting the reservoir92takes place with gallery line95open, i.e., the gallery line95has a pneumatic connection via the third port Z and the second port Y to the venting connection3. In order to prevent unintentional filling or venting of the bellows91as well, it is necessary that the level control valves, i.e., the solenoid valves93, are closed.

In summary, the present invention generally relates to embodiments of a pneumatic installation901,902,903,904,905, in particular in the form of an air suspension installation for a vehicle, provided for operation with a compressed air supply installation11,21,31,41, comprising:a collecting line in the form of a gallery line95;at least one air spring with a pressure chamber that can be pneumatically connected to the gallery line95;a reservoir92for compressed air, which can be pneumatically connected to the gallery line95; anda compressed air connection2for a pneumatic connection of the pneumatic installation901,902,903,904,905to the compressed air supply installation11,21,31,41, the pneumatic connection comprising:comprises a controllable isolating valve assembly700,800,800′,900including at least one control valve with a first, second and third port X, Y, Z, whereinthe reservoir92is pneumatically connected to the first port X,the compressed air connection2is pneumatically connected to the second port Y, andthe gallery line95is pneumatically connected to the third port Z;

wherein the second port Y can be switched into a closed state in which the pneumatic connection is bidirectionally and fully closed.