Patent Application
20130276899
The invention relates to a compressed air supply installation in accordance with the preamble of claim 1. The invention furthermore relates to a pneumatic system having a compressed air supply installation of this kind. The invention furthermore relates to a method in accordance with the preamble of claim 19 for operating a pneumatic installation, in particular an air spring installation on a vehicle.
A compressed air supply installation is used in vehicles of all kinds, in particular for supplying an air spring installation on a vehicle with compressed air. Air spring installations can also comprise leveling devices, by means of which the distance between the vehicle axle and the vehicle body can be adjusted. An air spring installation of a pneumatic system mentioned at the outset comprises a number of pneumatic bellows connected pneumatically to a common line (gallery), which can raise the vehicle body as they are filled to an increasing extent and, correspondingly, can lower the vehicle body as the filling decreases. As the distance between the vehicle axle and the vehicle body or ground clearance increases, spring travels become longer and it is possible to cope even with relatively large irregularities in the ground without the occurrence of contact with the vehicle body. Such systems are increasingly being used for preference in all-terrain vehicles and sport utility vehicles (SUV). Particularly with SUVs, it is desirable, in the case of very powerful engines, that the vehicle should, on the one hand, be provided with a relatively small ground clearance for high speeds on the road and, on the other hand, with a relatively large ground clearance for off-road use. It is furthermore desirable to implement a change in the ground clearance as quickly as possible, and this increases the demands in respect of the rapidity, flexibility and reliability of a compressed air supply installation.
In order to ensure long-term operation of the compressed air supply installation, a main pneumatic line of the compressed air supply installation has an air dryer, by means of which the compressed air can be dried. This avoids accumulation of moisture in the pneumatic system. At relatively low temperatures, moisture can lead to the formation of crystals that damage valves and can furthermore lead to unwanted faults in the compressed air supply installation and in the pneumatic installation. An air dryer has a desiccant, generally in the form of a granular fill, through which the compressed air can flow, allowing the granular fill to take up moisture contained in the compressed air by adsorption. If appropriate, an air dryer can be designed as a regenerative air dryer. This can be accomplished by arranging for the dried compressed air from the pneumatic installation, in particular an air spring installation, to flow through the granular fill—mostly in a countercurrent but also partially in a co-current pattern relative to the filling direction—during each venting cycle. Regeneration of the air dryer is made possible essentially by a pressure swing at the air dryer, with a pressure prevailing during regeneration generally being lower in comparison with adsorption in order to enable moisture to be released from the granules. For this purpose, the vent valve arrangement can be opened, with the regeneration capacity of the air dryer generally being dependent on the pressure conditions and the pressure swing amplitude in the compressed air supply installation. For a “pressure swing adsorption process” of this kind, too, it has proven desirable to make a compressed air supply installation flexible and, at the same time, reliable. In particular, the aim is, on the one hand, to allow relatively quick venting and yet to make available a pressure swing amplitude that is sufficiently high low air pressure—i.e. during regeneration—for regeneration of the air dryer.
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 a desiccant in the air dryer, and with a second compressed air supply line, through which there can be a flow without the compressed air being passed through the desiccant.
Many different approaches to the design of a first pneumatic connection between a compressed air feed mentioned at the outset and a pneumatic installation mentioned at the outset are known from the prior art. These allow for the basic functions of a compressed air supply installation when supplying air to the pneumatic installation and releasing air from the pneumatic installation. With respect to the above-mentioned requirement for relatively quick venting with an air pressure that is nevertheless sufficiently low for regeneration of the air dryer, these approaches are still in need of improvement, however.
DE 102 23 405 B4 discloses an air spring system on a motor vehicle with a compressed air supply installation having a delivery line for connecting a compressor to the air springs and a vent line, via which the delivery line can be connected to atmosphere while being capable of being shut off by means of a switching valve. A segment of the delivery line in which a restrictor is arranged in parallel with a non return valve and in parallel with a further switching valve, said segment being designed as a pneumatic parallel circuit, is provided between a dryer and level control valves in a gallery of the air spring installation. The switching valve in the vent line and the switching valve in the segment of the delivery line are connected to the same output stage of a control unit by electric control lines.
DE 101 21 582 C2 discloses an air supply unit for an air suspension installation, in which a vent valve in a vent line, an air spring valve in the gallery of the air suspension installation and an air control valve are provided. All three valves are connected to an electronic control unit. The air control valve is connected in parallel with a nonreturn valve in a segment of a delivery line between a dryer and a spring valve, said segment being designed as a pneumatic parallel circuit, with the result that, although air can be taken into the air spring installation unhindered, it can only be released again in a controlled manner via the air control valve. To release compressed air from the air suspension installation, all three of the valves mentioned above are opened.
EP 1 216 860 B1 discloses a leveling installation for a motor vehicle, having air springs and having a control unit which exercises open-loop or closed-loop control over the functions of filling and emptying in accordance with the level of the vehicle body. Among the elements connected to the control unit are a controllable directional control valve of a compressed air supply installation and a controllable directional control valve arranged ahead of a reservoir. The controllable directional control valve of the compressed air supply installation is arranged in parallel with a non return valve.
U.S. Pat. No. 6,098,967 discloses a compressed air supply installation of the type stated at the outset, in which a segment designed as a pneumatic parallel circuit and containing two branch lines connected in parallel with one another is arranged in the main pneumatic line between the air dryer and the air spring installation, wherein, in a first branch line, a nonreturn valve, through which there can be a flow for filling the air spring installation, and, in a second branch line, a nonreturn valve, through which there can be a flow for venting the air spring installation, are connected in series with a restrictor and a switching valve.
A similar compressed air supply installation is disclosed in EP 1 046 521 B1, which has a nonreturn valve that can be shutoff in the venting direction and a stepped piston of a controllable directional control valve that can be released in the venting direction, said valve and piston being arranged pneumatically in parallel.
Similarly, EP 0 978 397 B1 also provides a pneumatic parallel circuit of a nonreturn valve that shuts off in the venting direction and a pneumatically pilot-controlled directional control valve that can be released in the venting direction. A physical embodiment of this circuit can be found in EP1 233 183 B1, for example, in which a relatively complex construction of the pneumatic parallel circuit comprising at least three valves can be found. Such a construction is intended to make a venting process more effective in terms of time but proves relatively complex and expensive and requires a relatively large number of components.
The need for further improvement in the connection of an air spring installation to the compressed air supply installation is problematic in all of the compressed air supply installations mentioned owing to the fact that the abovementioned segment is generally designed as a parallel circuit in a main pneumatic line.
In
EP 1 380 453 B1 discloses a closed leveling installation for vehicles, by means of which a vehicle body is sprung relative to at least one vehicle axle and in which a compressed air reservoir is isolated from a compressed air supply installation independently of an air spring installation, by means of a 4/4-way valve.
These pneumatic systems too are capable of improvement. In particular, a compressed air installation of the kind mentioned in EP 1 165 333 B2 requires improvement—in the absence of an isolating valve between the compressed air supply installation and a pneumatic installation, this compressed air installation has the disadvantage that the dryer volume is also filled each time the pneumatic installation operates. Before the next regulating process, this volume must be completely or partially vented. This pneumatic energy (pressure multiplied by the volume) is lost during venting and must be recompressed by the compressor; this is evident from a disadvantageous loss of efficiency in the compressed air supply installation.
DE 35 42 974 A1 of the applicant discloses a leveling device provided with air filters and having a compressed air supply installation for vehicles which was mentioned at the outset, by means of which a predetermined distance between the vehicle cell and the vehicle axle can be adjusted in accordance with the vehicle loading by filling or emptying the air springs. The device has a safety valve that can be controlled by means of the pressure in the air springs and an isolating valve with respect to the pneumatic installation in the form of a first nonreturn valve. In an installation of this kind, the air dryer can be regenerated via a restrictor and a second nonreturn valve that can be opened counter to a filling direction, which is arranged in a branch line.
The compressed air supply installation in DE 35 42 974 A1 has long proven its worth but is still capable of improvement. It has admittedly been found that the installation is advantageously suitable for saving compressed air, even during regeneration of the air dryer, through isolation of the compressed air supply installation and the pneumatic installation by means of the first nonreturn valve. Nevertheless, the installation disclosed in DE 35 42 974 A1 of the applicant has proven to have limited scope, especially for advanced applications that necessitate relatively flexible and rapid handling of the compressed air within relatively short periods of time.
This is the starting point of the invention, the object of which is to indicate a compressed air supply installation and a method for operating a pneumatic installation which are an improvement over the prior art and, in particular, work reliably and yet flexibly and, if required, quickly, wherein an air dryer is to be protected from negative effects. The aim is, in particular, a compressed air supply installation which is of relatively simple construction and yet, on the one hand, allows relatively quick venting combined with dryer regeneration in a manner which is as advantageous as possible. Another particular aim is improved acoustics in the compressed air supply installation. It is likewise an object of the invention to indicate a pneumatic system of advantageous design incorporating the compressed air supply installation.
In respect of the compressed air supply installation, the object is achieved by the invention with a compressed air supply installation of the type stated at the outset in which, according to the invention, the features of the characterizing part of claim 1 are provided.
According to the invention, a compressed air supply installation for operating a pneumatic installation, in particular an air spring installation on a vehicle, is provided, which has:
The first pneumatic connection is preferably designed as a main pneumatic line, and the second pneumatic connection is preferably designed as a vent line.
The first and second pneumatic connections—i.e. the main pneumatic line and the vent line—can be separate lines, which are connected to a common compressed air feed port, for example. This concept provides a particularly advantageous basis for relatively quick venting. In an alternative development, however, it is also possible for the first and second pneumatic connections to be completely or partially combined, that is to say that, in an alternative development, it is also possible for the main pneumatic line and the vent line to be the same lines and to allow bidirectional flow both for venting and for air admission to a pneumatic installation.
The invention presents a pneumatic system of claim 17 having a compressed air supply installation according to the invention. A compressed air supply installation is advantageously operated by means of compressed air in a pneumatic system having a pneumatic installation, e.g. an air spring installation as described above.
It is advantageous if compressed air is made available to the compressed air supply installation from a compressed air feed at a pressure level within a range of from 5 to 20 bar. The compressed air for the compressed air feed can be produced, in particular, by an air compressor arranged between an air feed and a compressed air feed port. To supply the pneumatic installation, the compressed air feed is connected to a compressed air port leading to the pneumatic installation by a first pneumatic connection. The first pneumatic connection of the compressed air supply installation mentioned at the outset advantageously has a main pneumatic line, in particular in the form of a single pneumatic line. Moreover, the compressed air supply installation of the type stated at the outset has a second pneumatic connection, advantageously a vent line, having a controllable vent valve, which pneumatic connection is connected pneumatically to the main pneumatic line and to a vent port leading to the environment. The compressed air port and/or the compressed air feed is thereby connected pneumatically, in particular via a controllable vent valve, to a vent port leading to the environment. By means of the controllable vent valve, the compressed air supply installation can be vented, e.g. by discharging air, toward the vent port in order, in particular, to vent the pneumatic installation.
The invention starts from the consideration that, in principle, an advantageous design of the first pneumatic connection between the compressed air feed and a compressed air port leading to the pneumatic installation can provide a basis for improved dryer regeneration and also for flexible and, if required, quick venting of the compressed air supply installation and/or of the pneumatic installation or for the admission of air thereto. In a development, the invention starts from the consideration that a main pneumatic line for the formation of the, preferably single, pneumatic connection can be of relatively simple design for this purpose, preferably with a single pilot-operated nonreturn valve.
The invention furthermore starts from the consideration that the installation cited in DE 35 42 974 A1 provides a good basis for the pneumatic decoupling of the compressed air supply installation from a pneumatic installation by using a nonreturn valve as an isolating valve in the first pneumatic connection. However, the invention has furthermore recognized that a venting process can be carried out more flexibly and, if required, more quickly—with or without dryer regeneration—if the isolating valve is formed with a nonreturn valve, preferably a single nonreturn valve, preferably a pneumatically pilot-operated nonreturn valve. This insight on the one hand makes use of the advantages of a nonreturn valve, which is relatively simple to implement, and, with the pneumatic releasability of the nonreturn valve, furthermore provides a particularly effective concept for compressed air handling which is quick and flexible. The invention advantageously avoids a situation where an air dryer is filled with compressed air from the pneumatic installation, in particular from the gallery thereof, in any circuit configuration of a pneumatic installation, e.g. with a directional control valve arranged ahead of a bellows or a reservoir. The admission of compressed air to the air dryer, which may be disadvantageous for regeneration, is avoided by means of the nonreturn valve, which is advantageously pneumatically pilot-operated. The pneumatically pilot-operated nonreturn valve allows flow with relatively little operating resistance in the filling direction, i.e. in a direction from the air dryer to the compressed air port. In other words, the pneumatically pilot-operated nonreturn valve is in practice pneumatically open in a filling direction, i.e. in a direction from the compressed air feed to the compressed air port, in a shutoff mode. In an opposite, venting direction, the pneumatically pilot-operated nonreturn valve is pneumatically closed in a shutoff mode, i.e. cuts off the first pneumatic connection between the compressed air feed and the compressed air port, ensuring that the pneumatic installation is decoupled from the compressed air supply installation. However, the releasability of the non return valve means that said valve can be switched from a shutoff mode to a release mode when required, thus allowing compressed air to flow virtually unhindered through the first pneumatic connection, even in a direction from the compressed air port to the compressed air feed—irrespective of the pressure conditions at ports of the pilot-operated nonreturn valve in the first pneumatic connection—when the pilot-operated nonreturn valve is appropriately activated.
It is precisely this feature which proves advantageous in comparison with the previously known compressed air supply installation of the kind described in DE 35 42 974 A1—venting of a pneumatic installation can be achieved in a relatively simple manner, even via the first pneumatic connection, and therefore relatively time-consuming and complex guidance of the compressed air during venting and/or dryer regeneration via branch lines, which is possibly associated with loss of pressure, is avoided. On the contrary, the concept of the present invention furthermore offers the advantageous possibility of designing the pilot-operated nonreturn valve for a very wide variety of operating functions of the compressed air supply installation. For example, it is also possible in a development to provide the pilot-operated nonreturn valve with functional means that can act as a vent valve in the second pneumatic connection. It is also possible for the pneumatically pilot-operated nonreturn valve to be provided with suitable opening cross sections, i.e. nominal diameters, which—possibly on an adjustable basis—help with quick venting while nevertheless promoting advantageous acoustics and dryer regeneration.
In particular, the concept of the invention makes it possible, using a single pilot-operated nonreturn valve, to shut off the main pneumatic line between the compressed air feed and the compressed air port from a compressed air flow from the pneumatic installation routed via the compressed air port leading to the air dryer or to the vent port. In a particularly advantageous way, this reduces the number of components that are normally required to implement an isolating valve in the form of an isolating valve arrangement comprising a plurality of valves. The concept of the invention has recognized that it is in principle sufficient to provide a single pilot-operated nonreturn valve for shutting off the main pneumatic line.
In the present case, the term “pilot-operated nonreturn valve” should be taken to mean, in particular, a nonreturn valve which opens automatically in the direction of opening from the air dryer to the compressed air port, i.e. in practice only against a limited spring force. A nonreturn valve of this kind thus closes virtually by itself in the venting direction under the action of the spring force. The term “pilot-operated nonreturn valve” should preferably be taken to refer to the abovementioned nonreturn valve, the shutoff action of which in the venting direction can be canceled. In principle, this can be accomplished according to requirements by means of an expediently designed control line.
During a filling process of a pneumatic installation, the pilot-operated nonreturn valve opens virtually automatically, in particular by a pneumatic method. During a venting process, it shuts off the main pneumatic line but can be released mechanically, it being possible for the corresponding mechanism, e.g. that of a control piston or some other actuating element, to be actuated pneumatically. In other words, the nonreturn valve is preferably pneumatically and/or mechanically released.
As a particularly preferred option, provision is made, during the filling process, for the pilot-operated nonreturn valve to open automatically by pneumatic means when pressurized by a compressed air flow in the filling direction, i.e. from the compressed air supply installation to the pneumatic installation. In concrete terms, the control piston can have first switching position assigned to a shutoff mode, in which a shutoff valve element can be raised from the shutoff valve seat of the pilot-operated nonreturn valve automatically—i.e. pneumatically by pressurization—in a filling direction. In concrete terms, the shutoff valve element is advantageously held under a spring load on or in the direction of a shutoff valve seat in the shutoff mode, allowing said element to be raised from the shutoff valve seat against a spring force and under the action of compressed air in the filling direction, i.e. automatically.
As a particularly preferred option, a compressed air flow is routed in the opposite direction to the filling direction, i.e. in the venting direction, during venting, with the control piston being transferred pneumatically from the first switching position to a second switching position assigned to a shutoff mode by means of a control valve, using a pressure derived from the main pneumatic line, and releasing the pilot-operated nonreturn valve mechanically, in particular raising the shutoff valve element from the shutoff valve seat mechanically. In the release mode, the shutoff valve element is raised from the shutoff valve seat by the action of the control piston—i.e. mechanically—and the nonreturn valve released in this way allows flow in the venting direction.
The invention presents a method for operating a pneumatic installation by means of a compressed air supply installation as claimed in claim 19. In particular, it is advantageous if the method has the following steps:
For carrying out the method, a compressed air supply installation as claimed in one of claims 1 to 16 is provided, in particular, having:
It is advantageous if the method furthermore has the following step:
In a particularly preferred development, the concept of the invention allows the provision of a control valve and of a pneumatic pilot operation line between the control valve and a nonreturn valve designed as a pneumatic release valve. The control valve can preferably be designed at least for releasing the nonreturn valve. A control valve which is designed purely and simply for releasing the non return valve and for controlling, in particular simultaneously controlling, a vent valve has proven particularly advantageous. The control valve is preferably used to release the nonreturn valve by pressurizing the pneumatic pilot operation line with a pressure derived from the main pneumatic line via the pneumatic control line. In particular, it has proven advantageous simultaneously to activate venting of a vent valve in the vent line, i.e. to make it open.
In the context of a particularly preferred development of the method according to the invention, provision is made for the compressed air supply installation to have a control valve, a pneumatic control line between the main pneumatic line and the control valve, and a pneumatic pilot operation line between the control valve and the nonreturn valve. In particular, a vent valve is furthermore provided in the vent line. In the context of a preferred development of the method, provision is made for the control valve to be used to release the nonreturn valve by pressurizing the pneumatic pilot operation line with a pressure derived from the main pneumatic line via the pneumatic control line. In particular, the vent valve in the vent line is simultaneously controlled, in the present case, in particular, opened. This has the advantage that the nonreturn valve is simultaneously opened on both sides by activating a single control valve, allowing the compressed air flow from the pneumatic installation to be fed to the vent port by releasing said nonreturn valve.
In the context of a particularly preferred structural embodiment, the pilot-operated nonreturn valve is formed as a unit with the vent valve. This development is especially compact and particularly efficient and effective with respect to time during venting.
Such developments of the invention and other advantageous developments thereof—including also in respect of the design of the pneumatically pilot-operated nonreturn valve—can be found in the dependent claims and specify advantageous ways of implementing the concept explained above in the context of the object set and in respect of further advantages.
It has proven particularly advantageous for the pneumatically pilot-operated nonreturn valve to be arranged in the first and/or second pneumatic connection between the air dryer and the compressed air port leading to the pneumatic installation. In particular, the pneumatically pilot-operated nonreturn valve is arranged in a main pneumatic line that advantageously forms the first pneumatic connection, i.e. is advantageously arranged in the main pneumatic line itself. A relatively complex design of a branch line or parallel line to the main pneumatic line involving an increased number of components and valves is thus advantageously avoided. The main pneumatic line is advantageously the only pneumatic line of the first pneumatic connection and extends between the compressed air feed and a compressed air port leading to the pneumatic installation. The compressed air feed, the air dryer, the pneumatically pilot-operated nonreturn valve and the compressed air port leading to the pneumatic installation are advantageously arranged in the main pneumatic line in the stated sequence in the direction of air admission.
As explained below, the nonreturn valve, which is preferably pneumatically pilot-operated, can be arranged at least in part—i.e. preferably with one functional means that serves to form a vent valve in the nonreturn valve—in the second pneumatic connection. Said functional means for forming a vent valve with the nonreturn valve is preferably embodied in a single pilot-operated nonreturn valve, that is to say, in particular, is integrated into a single valve housing.
In principle, the pneumatically pilot-operated nonreturn valve can be embodied in very general terms as a shutoff valve in various forms, e.g. as a nonreturn valve, as a throttle check valve, as a shuttle valve, as a dual-pressure valve or as a fast-acting vent valve. An isolating valve with a restrictor and the nonreturn valve in a pneumatic series circuit in the first pneumatic connection, i.e. advantageously in the main pneumatic line, has proven particularly advantageous. For this purpose, it is advantageous if the pilot-operated nonreturn valve is arranged pneumatically in series with and downstream of the restrictor in the filling direction in the main pneumatic line; thus, when the pneumatic installation is being filled, the air flows first through the restrictor and then through the pilot-operated non return valve.
As an alternative or in addition, the isolating valve can also have the non return valve in the form of a throttle check valve.
In particular, both abovementioned developments provide the combination of a nonreturn valve with an—advantageously adjustable—restrictor. The—advantageously adjustable—restrictor or an advantageously provided sequence of—possibly different—restricting means, such as nominal orifice diameters or the like in the nonreturn valve, can expediently be used to provide an optimum configuration of a pressure swing amplitude for dryer regeneration. improved dryer regeneration of the air dryer is distinguished on the basis of an optimized pressure swing amplitude, wherein, as the pressure swing amplitude increases, the capacity of the air dryer for regeneration also increases. The higher the pressure loss of compressed air in the venting direction, the higher is the potential for absorption of moisture retained in the air dryer during regeneration of the air dryer. Moreover, this development makes it possible to implement venting in a particularly efficient and/or relatively rapid way.
In the context of a development that is provided to particular advantage, the compressed air supply installation furthermore has:
In this development, a control valve is provided in the compressed air supply installation for the purpose of releasing the pilot-operated nonreturn valve. The pneumatic control valve is advantageously designed as a directional control valve, in particular a 3/2-chamber directional control valve, in particular as a solenoid valve. The pneumatic control line branching off from the first pneumatic connection, in particular a main pneumatic line, can supply the control valve with pressure in such a way that—when the control valve switches—the pressure is transmitted via a control line or the like, in particular via the pneumatic pilot operation line, to a control chamber in order to release the nonreturn valve.
This construction has proven advantageous, in particular because the pneumatic control valve can be used not only to release the nonreturn valve but, in addition, also to activate a vent valve in the second pneumatic connection between the compressed air port and the vent port, as explained further below. This has the effect that, by means of a single control valve, the air dryer can be opened on both sides during venting and regeneration, namely, on the one hand, by release of the nonreturn valve and, on the other hand, by opening of the vent valve.
In a first variant, the vent valve can be formed separately from the nonreturn valve. As explained further below, it is possible in another variant for a vent valve to be embodied as a unit with the nonreturn valve. Particularly in the last-mentioned case, it is particularly advantageous for the control valve to be arranged together with the unit in a compressed air supply installation.
With reference particularly to both variants, advantageous design developments of the pilot-operated nonreturn valve are obtained as follows.
It is particularly advantageous if the nonreturn valve has, on the one hand:
In the release mode, a suitable restrictor for a compressed air flow is advantageously formed between the shutoff valve seat and the shutoff valve element.
On the other hand, it is advantageous if the pilot-operated nonreturn valve according to this development has a control chamber, which is connected pneumatically to the pneumatic pilot operation line, which is isolated pneumatically from the through flow chamber and by means of which a control piston acting on the shutoff valve element can be actuated. It is advantageous if pressurization of the control chamber by means of compressed air or a similar pressure fluid triggers actuation of the control piston pneumatically. It is advantageous if the control piston is actuable against a spring force. This has the advantage that, when the control chamber is not pressurized, it is not possible for the control piston to exert a switching action on the shutoff valve element, and/or the control piston is spaced apart from the shutoff valve element. To actuate the control piston, pressurization of the control chamber has to take place with a pressure amplitude which is sufficient to move the control piston against the spring force in such a way that it can act on the shutoff valve element.
A pilot-operated non return valve which is fundamentally known, e.g. from DE 42 34 626 C2, is improved especially as regards its attachment to the compressed air supply installation. As a development of the compressed air supply installation, a control chamber of the nonreturn valve is divided pneumatically by means of a dividing seal arranged on the control piston into a control space connected pneumatically to the pneumatic pilot operation line and into a venting space connected pneumatically to the pneumatic pilot operation line. For this purpose, the control piston advantageously has an annular bead which carries the dividing seal. The annular bead preferably has a second side facing the venting space and a first side facing the control space, wherein a surface of the second side on the venting-space side is smaller than a surface of the first side on the control-space side. In other words, the annular bead advantageously has a larger pressurizable surface area on the side thereof facing the control space than on the side thereof facing the venting space.
In a first modification of the pneumatically pilot-operated nonreturn valve, the control chamber provides a venting space in addition to the control space, said venting space being used in addition for the accelerated actuation of the control piston by virtue of its pneumatic connection to the pneumatic pilot operation line. The control space of the control chamber can be connected pneumatically to the venting space of the control chamber, with the result that, when the control piston is actuated, the movement of the annular bead with the dividing seal results in compressed air contained in the venting space being fed to the control space—on a principle similar to that of communicating tubes—and hence the actuation of the control piston being accelerated through a differential force. This takes place insofar as the control space has a lower pressure level. This, in turn, can be ensured, by means of the time sequence of the opening of the vent valve since this initially lowers a pressure level in the through flow chamber.
In a second, likewise advantageous modification of the compressed air supply installation in respect of the pilot-operated nonreturn valve, a venting space of the control chamber is, in addition or as an alternative, connected pneumatically—directly or indirectly—to the second pneumatic connection or to the environment. In particular, a connection to the second pneumatic connection can be achieved by means of a pneumatic branch line between the control valve and the vent port. In this modification, the pilot-operated nonreturn valve is provided with a separate venting function based on the venting space connected via the control valve to the vent port.
Very generally, it has proven advantageous that the compressed air supply installation has at least one controllable vent valve in the second pneumatic connection, said vent valve being separate or embodied as a unit with the nonreturn valve.
The abovementioned developments of the pilot-operated nonreturn valve are suitable in a particularly advantageous manner for incorporation into a compressed air supply installation which has a controllable vent valve that is formed separately from the pilot-operated nonreturn valve. Whether in the form of a separate vent valve or—as a particularly preferred option for improved venting—as a unit with the nonreturn valve, it has proven advantageous that the controllable vent valve, as an indirectly switched relay valve, is part of a solenoid valve arrangement for indirect switching of a compressed air volume. In this case, the solenoid valve arrangement has a control valve for pneumatic control of the relay valve which is subjected to a pressure derived from the first pneumatic connection via a pneumatic control line. A particularly preferred embodiment of a compressed air supply installation which is implemented with a separate vent valve according to this development is described in
In a preferred development, a single valve or a plurality of valves of a solenoid valve arrangement, in particular a primary valve and a secondary valve of a double-armature magnet magnet, can be provided as a vent valve. These can be arranged in parallel or in series, and can be open or closed when deenergized—in any desired combination. Series arrangement and parallel arrangement of the primary and secondary valves are suitable for a particularly flexible configuration of the switching time sequence of the primary and secondary valves. It is thereby advantageously possible to make available different nominal diameters for the vent line at different times. It is thereby possible to reduce pressure peaks during venting and thus to reduce acoustic phenomena, in particular to avoid an explosive release of air. A parallel arrangement has additionally proven particularly advantageous for a stepwise increase in the nominal diameters available for the vent line, thus allowing particularly quick venting while nevertheless avoiding an explosive release of air. Excessive acoustic phenomena or an explosive release of air are always a risk during a venting process if an excessively large compressed air volume is vented in too short a time, i.e. at too high a pressure amplitude. On the other hand, a relatively high pressure swing amplitude is desired for optimum regeneration of the air dryer. Increased efficiency as regards venting and dryer regeneration, on the one hand, and quiet operation, on the other hand, can thus have conflicting requirements. The above-described concept of the invention achieves a particularly advantageous compromise between dryer regeneration and venting efficiency, on the one hand, and acoustic phenomena, on the other hand.
The abovementioned, particularly preferred developments described here furthermore offers the advantageous possibility in principle that the control valve of the solenoid valve arrangement and the control valve of the pneumatic control line are the same control valve. For this purpose, the control valve is arranged in the pneumatic control line and is designed for pneumatic control of a vent valve and/or of a nonreturn valve.
In a particularly preferred structural embodiment, the nonreturn valve can be developed as follows in a compressed air supply installation. It is advantageous if, on the other hand, the nonreturn valve has a venting chamber which can be connected pneumatically to the second pneumatic connection. For this purpose, a vent valve seat, in particular, is provided between the venting chamber and the second pneumatic connection, and a vent valve element, which shuts off the vent valve seat in the shutoff mode and opens said seat in the release mode, is provided. It is advantageous if the vent valve element is formed on the other side of a dividing seal of a control piston, in particular is formed integrally with the control piston.
In particular, provision is made for the vent valve element to form an integral tappet with the control piston. The tappet preferably has a length which is less than a clearance between a vent valve seat of the venting chamber and a shutoff valve seat of the shutoff chamber. In this way, an acoustically particularly preferred high-pressure venting function can advantageously be implemented in a compact way, a function which would otherwise have to be implemented by means of a supplementary separate high-pressure vent valve. The development envisages that—only when a pressure in the air dryer has fallen sufficiently after the opening of the vent valve seat and the opening of the inlet of the venting chamber—the force of the control piston is sufficient likewise to open the outlet at the shutoff valve seat in the nonreturn valve by raising the shutoff valve element from the shutoff valve seat. To achieve this, the length of the tappet is preferably greater than a clearance between the shutoff valve seat of the shutoff chamber and an inlet of the venting chamber.
In the context of the abovementioned design development, it is possible in a particularly advantageous way simultaneously to open an air dryer on both sides in a release mode of the pilot-operated non return valve—namely in a process involving the actuation of the control piston together with the vent valve element; namely by opening the shutoff valve seat, on the one hand, and, on the other hand, by opening the vent valve seat. When actuated, a control piston and vent valve element advantageously embodied as a unit thus, on the one hand, open the vent valve formed as a unit with the isolating valve and, on the other hand, release the isolating valve designed as a nonreturn valve. This unit has not only proven to be particularly compact but, in addition, a separate relay valve function of a relay valve of the solenoid valve arrangement according to the variants explained above is advantageously integrated into the isolating valve.
With or without a vent valve, the pilot-operated nonreturn valve in this structural embodiment can be used to form suitable restrictor cross sections—both for a restrictor in the first pneumatic connection and for a restrictor in the second pneumatic connection. The embodiment of the control piston at the end thereof facing the shutoff valve element by means of different cross sections offset stepwise relative to one another has proven particularly advantageous. Depending on the position of the control piston, it is thus possible in the release mode to achieve an effective nominal diameter in the shutoff valve seat which is dependent on the position of the control piston, using one of the cross sections that are offset stepwise in one nominal diameter of the shutoff valve seat.
In addition or as an alternative, the shutoff chamber, the through flow chamber, the control chamber and/or the venting chamber of the pilot-operated nonreturn valve can have nominal inlet and outlet diameters which perform a restricting function for a compressed air flow.
The abovementioned developments are especially suitable for the formation of a compressed air supply installation in the form of a device having a housing arrangement that has a number of zones. In a first housing zone, a drive can be formed and/or, in a second zone, an air compressor that can be driven by the drive can be formed, and/or, in a third zone connected to the second zone by a pressure-source interface, the air dryer and the isolating valve can be formed. In such a device, it is advantageous for the pneumatically pilot-operated nonreturn valve to be accommodated in the air dryer of the third zone. Arrangement of the control valve in a drying canister recess formed by a wall of the drying canister has proven particularly advantageous. Moreover, the arrangement of the pneumatically pilot-operated nonreturn valve, especially as a unit with the vent valve, in a cap of the third zone of the housing arrangement has proven advantageous.
The invention advantageously presents a pneumatic system having the compressed air supply installation and a pneumatic installation. It is advantageous for the pneumatic installation to be in the form of an air spring installation which has a gallery and at least one branch line connected pneumatically to the gallery and having at least one bellows and, optionally, a reservoir. It is advantageous if a directional control valve is arranged ahead of the bellows and, optionally, the reservoir. Especially in the context of a solenoid valve—a suitable design of the directional control valve is as a 2/2-way valve. In terms of construction, such directional control valves or other directional control valves can be implemented to particular advantage in a valve block having a plurality of valves.
Illustrative embodiments of the invention are now described below with reference to the drawing. This is not necessarily intended to show the illustrative embodiments to scale; on the contrary, where helpful for purposes of explanation, the drawing is in schematic form and/or in slightly distorted form. For supplementary information on the teaching that is directly evident from the drawing, attention is drawn to the relevant prior art. At the same time, it should be noted that many different modifications and alterations to the form and the details of an embodiment can be made without departing from the general concept of the invention. The features of the invention which are disclosed in the description, in the drawing and in the claims may be significant for the development of the invention either individually or in any desired combination. Moreover, all combinations of at least two of the features disclosed in the description, the drawing and/or the claims fall within the scope of the invention. The general concept of the invention is not limited to the exact form or details of the preferred embodiment shown and described below, nor is it limited to subject matter that could be restricted in comparison with the subject matter claimed in the claims. Where dimensional ranges are indicated, the intention is that values which lie within the stated limits should also be disclosed as limiting values and should be capable of being used and claimed as desired. For the sake of simplicity, the same reference signs are used for identical or similar parts or parts with an identical or similar function.
Further advantages, features and details of the invention will emerge from the following description of the preferred illustrative embodiments and from the drawing, in which:
The same reference numerals are used below for identical or similar parts or parts with an identical or similar function, where appropriate.
In particular, a nonreturn valve described below as an isolating valve does not necessarily have to be arranged in the compressed air supply installation 10 in an embodiment which is not shown here. On the contrary, it is also possible for an isolating valve to be arranged in the pneumatic installation 90, also as part of the valve block 97 for example. It is likewise possible for the pneumatic installation 90 to have a voltage/pressure sensor (not shown specifically here), which can be connected to the gallery 95 in an additional branch line (not shown here), making it possible to measure a pressure in the gallery 95 of the pneumatic installation 90 by means of the voltage/pressure sensor.
The compressed air supply installation 10 is used to operate the pneumatic installation 90. For this purpose, the compressed air supply installation 10 has a compressed air feed 1 and a compressed air port 2 leading to the pneumatic installation 90. In the present case, the compressed air feed 1 is formed with an air feed 0, an air filter 0.1 arranged ahead of the air feed 0, an air compressor 51 arranged after the air feed 0 and driven by means of a motor M, and a compressed air feed port 52—according to
In the present case, a first pneumatic connection is formed by a single main pneumatic line 60 between the compressed air feed 1 and the compressed air port 2, being connected, on the one hand, to the compressed air feed port 52 and, on the other hand, to the compressed air port 2 and the further pneumatic line 96 to form the pneumatic connection. An air dryer 61 and a first restrictor 62 having a predetermined first nominal diameter are arranged in the main pneumatic line 60. Also arranged in the main pneumatic line 60 is an isolating valve with a pneumatically pilot-operated nonreturn valve 63. In the present case, the pneumatically pilot-operated nonreturn valve 63 is arranged in a pneumatic series circuit with the restrictor 62 in the main pneumatic line 60, wherein the main pneumatic line 60 is the only pneumatic line of the first pneumatic connection. The series arrangement comprising the restrictor 62 and the pneumatically pilot-operated nonreturn valve 63 is thus arranged in the main pneumatic line 60 between the air dryer 61 and the compressed air port 2 leading to the pneumatic installation 90.
Furthermore, the compressed air supply installation 10 has a second pneumatic connection, namely the vent line 70, which is connected pneumatically to the main pneumatic line 60 and to a vent port 3 and a further filter 0.3 and/or a muffler. In the present case, the vent line 70 is connected to the main pneumatic line 60 at the compressed air feed port 52. A second restrictor 72 having a second nominal diameter greater than the first nominal diameter and a controllable vent valve 73 are arranged in the vent line 70 in the direction of the vent port 3. In the present case, the vent valve 73 arranged in the second pneumatic connection formed by the vent line 70 is designed as a 3/2-way valve separate from the pneumatically pilot-operated non return valve 63.
As an indirectly switched relay valve, the controllable vent valve 73 is thus part of a solenoid valve arrangement 80 for indirectly switching a compressed air volume of the vent line 70 that can be filled from the main pneumatic line 60. In this case, the solenoid valve arrangement 80 has a control valve 74 in the form of a 3/2-way solenoid valve. The control valve 74 can be activated by means of a control signal in the form of a voltage and/or current signal transmissible via a control line 83 to the coil 82 of the control valve 74. Upon activation, the control valve 74 can be transferred from the deenergized closed position shown in
In what is, in the present case, the closed state, the control valve 74 divides the control line 110 and is connected pneumatically via a further vent line 170 to the vent port 3. In other words, in the closed position of the control valve 74 shown in
In the present case, the compressed air supply installation 10 furthermore has a pneumatic pilot operation line 130 between the control valve 74 and the nonreturn valve 63, which line is connected to the control line 110 at the branch port 77. Thus, upon application of a control pressure derived from the main pneumatic line 60 or from the further pneumatic line 96 via the pneumatic control line 110, the nonreturn valve 63 can be released by means of the control valve 74 by pressurization of the pneumatic pilot operation line 130—i.e. by transferring the control valve 74 to the opened state. It is particularly advantageous if the transfer of the control valve 74 to the opened state leads not only to the release of the pilot-operated nonreturn valve 63 but also—since the line segment of the pneumatic control line 110 which is situated between the control valve 74 and the vent valve 73 is also subjected to control pressure—to the transfer of the vent valve 73 from the closed position to an opened position. In other words, the control valve 74 of the solenoid valve arrangement 80 is used to activate the vent valve 73 provided separately from the nonreturn valve 63 and to activate the nonreturn valve 63. This leads to pneumatic opening of the air dryer 61 on both sides when the control valve 74 is transferred to the opened position. During operation, this further operating position that can be adopted by the compressed air supply installation 10 can be used to vent the pneumatic installation 90 and simultaneously to regenerate the air dryer 61. The operating position shown in
The control piston 640 has an annular bead 642 which carries the dividing seal 652 and which has a second side 642.2 facing the venting space III.2 and a first side 642.1 facing the control space III.1. In this case, a pressurizable surface of the second side 642.2 on the venting-space side is smaller than a pressurizable surface of the first side 642.1 on the control-space side. In other words: the control space has a larger pressurizable surface of an annular bead 642 on a control piston than the venting space and is furthermore in pneumatically communicating connection with the venting space via pilot operation branch line 130.1 and pilot operation branch line 130.2. When the control piston 640 with the annular bead 642 moves, pneumatic actuation is boosted by the transfer of compressed air from the venting space III.2 to the control space III.1. This advantageously leads to an accelerated release process for the nonreturn valve 63. The magnitude of the acceleration depends on the ratios of the areas of the pressurizable surfaces on the annular bead 642 and possibly on the line cross sections on the control-space side relative to the venting-space side. Another embodiment which employs this advantageous principle will be explained with reference to
In a further-modified embodiment in
As is evident from explanation of the further
On the one hand, the nonreturn valve 63 has a shutoff chamber I, which is connected pneumatically to the main pneumatic line 60, and a through flow chamber II, which can likewise be connected to the main pneumatic line 60. A shutoff valve seat 610 is provided between the shutoff chamber I and the through flow chamber II. A shutoff valve element 620 which closes off the shutoff valve seat 610 in the shutoff mode shown in the present case is held on the shutoff valve seat 610 by a valve spring 630 designed as a compression spring. Fundamentally, therefore, the nonreturn valve 63 is held in a venting direction ER leading from the compressed air port 2 to the air dryer 61 in the shutoff mode since a pressure of the pneumatic installation 90 presses on the shutoff valve element 620 and holds it on the shutoff valve seat 610 in addition to the valve spring 630.
In a filling direction BR from the air dryer 61 to the compressed air port 2, a compressed air flow D carried in the main pneumatic line 60 has only to overcome the counterpressure of the valve spring 630 in order to raise the shutoff valve element 620 from the shutoff valve seat 610. As a result, the through flow chamber II is connected pneumatically to the shutoff chamber I in the filling direction BR, thus allowing the full compressed air flow D to pass through the main pneumatic line 60 toward the pneumatic installation 90 in the filling direction BR.
The position of the nonreturn valve 63 which is shown in
For actuation of the control piston 640, the nonreturn valve 63 has a control chamber III connected pneumatically to the pneumatic pilot operation line 130, said chamber being pneumatically isolated from the through flow chamber II. Pneumatic isolation is provided by a seal 651 for the housing 650 of the nonreturn valve 63 with respect to the control piston 640. In the present case, the control chamber III of the nonreturn valve 63 is furthermore divided into a control space III.1 and a venting space III.2. The division is accomplished by means of a further, dividing seal 652 situated between the housing 650 and the control piston 640. In contrast to seal 651, which is mounted in a fixed manner in the housing 650, the dividing seal 652 is mounted in a recess in the control piston 640 and can move with the control piston 640 on the housing 650 in the region of the control chamber III. In other words, the dividing seal 652 is suitable for dividing the control chamber III pneumatically into a control space III.1 and a venting space III.2 in a variable and leaktight manner in every position of the control piston 640.
Referring to
By supplying the control chamber III.1 with a control pressure from pilot operation branch line 130.1 or the single pilot operation line 130, the control piston 640 can be subjected to a pilot operation pressure. The pilot operation control pressure is suitable for raising the seating surface 643 of the control piston 640 from the control seat 644 and for moving the piston in the direction of the shutoff valve element 620 against the spring pressure of the control spring 660. Referring to
In the present case, the vent valve 73, the nonreturn valve 63 and the restrictor 62 are embodied as a unit—namely as a nonreturn valve 64 of the kind shown in various operating positions in the other figures, namely
Moreover, a double relay piston 640′, which can be activated pneumatically by the control valve 74 and is embodied as a control piston 640 in the following figures,
The pneumatically pilot-operated nonreturn valve 64 shown in
As already explained with reference to
The functional position of the nonreturn valve 64 in the shutoff mode, said position being shown in the present case, is suitable for the pneumatic decoupling of the compressed air supply installation 20 from the pneumatic installation 90. Air transfer or pressure measurement or cross-connection of the bellows 91 and/or the reservoir 92 can take place in the pneumatic installation 90 without subjecting an air dryer 61 of the compressed air supply installation 20 to the movement of compressed air.
In contrast to
The compressed air flow
This results in an acoustically particularly preferred high-pressure venting function, which would otherwise have to be implemented by means of a separate supplementary high-pressure vent valve: only when the pressure in the dryer 61 has fallen far enough is the force of the control piston 640 sufficient likewise to open outlet A1 in the nonreturn valve 64 by a process in which the control piston 640 raises the shutoff valve element 620 from the shutoff valve seat 610. This time sequence can be achieved through selective design of the forces, areas and strokes in the nonreturn valve 64. The present nonreturn valve 64 with control piston 640 as a valve assembly with a vent valve element 680 of the vent valve 73 is already well suited for this purpose. In this case, provision is made for the vent valve element 680 to form an integral tappet with the control piston 640, the length of which is less than a distance between a vent valve seat 670 of the venting chamber IV and a shutoff valve seat 610 of the shutoff chamber I and greater than a distance between the shutoff valve seat 610 of the shutoff chamber I and an inlet A3 of the venting chamber IV.
It is advantageous if only undried air in the dryer 61 is released in the high-pressure venting position until the force of the control piston 640 is sufficient to push open the nonreturn valve 64 and the opening toward the gallery 96. Thus, the end of a reservoir filling operation is to a large extent acoustically optimized without additional outlay on circuitry since the internal pressure in the dryer controls the more or less noisy venting thereof itself.
For normal venting operations with a virtually empty air dryer 61 and pressure in the gallery 96, e.g. from the bellows 91, on the other hand, there are no restrictions. Combined with a vent valve 73 (not shown here) which opens when deenergized, this is a particularly simple modification which can also be implemented with a wide range of nominal diameters for outlets A1 and A4—e.g. between 0.8 . . . 4.0 mm. A particularly attractive aspect is that both variants—a vent valve 73 which is closed or one which is open when deenergized—are based on a largely coupled movement of the control piston 640 and the vent valve element 680, with a positive effect on the acoustics. In contrast to
As a result, on the one hand, the non return valve 64 is mechanically released and, at the same time, the vent valve 73 formed as a unit with the nonreturn valve 64 is opened. More specifically, this purpose is served, on the one hand, by the abutment surface 641 of the control piston 640 striking against the seating surface 621 of the shutoff valve element 620 and thereby raising the shutoff valve element 620 from the shutoff valve seat 610 against the pressure force of the valve spring 630. That is to say, the control piston 640 acts directly in a mechanical way on the shutoff valve element 620 and raises it from the shutoff valve seat 610 of the nonreturn valve 64. In principle, some other movement of the control piston 640 that is expedient according to the requirements is furthermore also suitable for raising the shutoff valve element 620 directly or indirectly from the shutoff valve seat 610 of the nonreturn valve 64.
For this case of a release mode, the pilot-operated nonreturn valve 64 is released mechanically; namely on the basis of the direct mechanical action or direct impact of the abutment surface 641 of the control piston 640 on the control valve element 620. Here, actuation of the control piston 640 is performed pneumatically via the control valve 74 explained.
For this purpose, provision is also made in the present case for that side 642.2 of the annular bead 642 which faces the venting space to be made to strike against a stop (not designated specifically) in the housing 650 by the control spring 660. A compressed air flow
Moreover, the vent valve seal 681 of the vent valve element 680 is raised from the vent valve seat 670 and thus opens the way for the compressed air flow
From the detail view in
Significantly improved regeneration of the air dryer 61 is also obtained in the context of the time sequence during the closing of the nonreturn valve formed inter alia by means of the shutoff valve seat 610, the shutoff valve element 620 and the valve spring 630, this effect being obtained, for example, after the filling of the bellows 91 and/or of the reservoir 92. A significant effect obtained here is a residual pressure holding function brought about by means of the control piston 640 spring-loaded by the control spring 660, since the control spring 660 acts on the second side 642.2 of the annular bead 642, that facing the venting space III.2, and thus the control piston 640 in equilibrium by virtue of the spring-loaded annular bead 642 with respect to a system or control pressure PS in the control space III.1 of the control chamber III, i.e. with respect to a retention pressure PR in the gallery 95. The system or control pressure PS is available in the control space III.1—as shown, for example, in
By means of the high-pressure venting function for venting the air dryer 61, said function having been explained by means of
Conversely, the closing of the nonreturn valve formed by means of the shutoff valve seat 610, the shutoff valve element 620 and the valve spring 630 is also subject to a time sequence resulting from the dimensions of the vent valve element 680 and of the control piston 640 in interaction with the system or control pressure PS. The closing of said nonreturn valve takes place as a result of a pressure drop in the system, that is to say also in the gallery 96. As a consequence, said nonreturn valve closes first (i.e. the shutoff valve element 620 lands on the shutoff valve seat 610) and only then does the vent valve 73 close (i.e. the vent valve element 680 lands on the vent valve seat 670). Between the landing of the shutoff valve element 620 and the landing of the vent valve element 680, there is a period of time which is characterized, on the one hand, by the fact that the system pressure PS, i.e. the pressure in the gallery 95, remains substantially at one level and, on the other hand, that the air dryer 61 can be completely emptied toward the dryer outlet, i.e. in the direction of the vent line 70. Owing to the temporarily stagnating system pressure when the nonreturn valve is closed, the system or control pressure PS remains largely unchanged in the control line 110 and the control space III.1 and is within the range of the residual pressure or retention pressure PR brought about by the control spring 660. Thus, the vent valve 73 is held open for a relatively long time, i.e. the vent valve element 680 is at a distance from the vent valve seat 670 for a certain, relatively long period of time. The nonreturn valve 64 now assumes the sealing function with respect to the gallery 96, and the inlet of the air dryer 61, i.e. the inlet of the air dryer 61 with respect to the through flow chamber II or gallery 96, is first of all closed. This has the advantage that all the available air can be used to regenerate the air dryer 61. Fundamentally, this results in improved regeneration of the air dryer 61. Improved regeneration is also fully effective even when the system or control pressure PS from the gallery 96 to the control space III.1 is low. A further contribution to this is also made by the above-explained staggering of the first and second portions 640.1, 640.2 on the control piston 640, with the result that, during the closing of the nonreturn valve formed by means of the shutoff valve seat 610, the shutoff valve element 620 and the valve spring 630, a relatively small nominal diameter is set for the compressed air flow D in venting direction ER, this being intended to make available to the air dryer 61 an advantageously low pressure level for the absorption of moisture from the air dryer 61. That is to say, the abovementioned improved regeneration as a result of the residual pressure holding function is also achieved in the case of relatively low pilot control pressures in the control line 110. This is generally the case with low bellows pressures, i.e. at pressures close to the retention pressure PR, which corresponds to a residual pressure that is counteracted by the mechanical force of the control spring 660. In the above-mentioned embodiment, there is thus no longer the risk of inadequate regeneration, even at relatively low control pressures, in contrast to the prior art.
The abovementioned complete emptying of the air dryer 61 when the nonreturn valve is already closed and the vent valve 73 is still open in the venting direction ER has the effect that the air dryer 61 is completely emptied. An empty air dryer 61 is fundamentally advantageous for enabling a relatively short and quiet startup of an air compressor 51, e.g. a compressor, of the compressed air supply installation 10, 11, 12, 20, 20′, 20″, 30. A pressure-free startup of this kind is always guaranteed in the present embodiment, irrespective of measures in the gallery 96, since the nonreturn valve 64 formed by means of the shutoff valve seat 610, the shutoff valve element 620 and the valve spring 630 is seated as a sealing element between the air dryer 61 and the gallery 96.
More particularly, the residual pressure holding function achieved in this way is explained by means of a time sequence of states of movement of the control piston 640 with the vent valve element 680, which sequence develops as a result of a falling system or control pressure PS from a state of the pilot-operated nonreturn valve 64 in
That is to say that, in the case of a control or system pressure PS which is initially significantly above a retention pressure PR, the control piston 640 of the nonreturn valve 64 adopts a position shown in
In the case of a switching state shown in
After the state shown in
A noteworthy feature of this sequence of movement is that the regeneration of the air dryer 61 which is obtained works particularly effectively precisely under system conditions of a low system or control pressure PS, which would otherwise be regarded as disadvantageous, and possibly even better than in the case of regeneration in the fully released mode of the nonreturn valve 64 (
The cap T furthermore forms a compressed air supply interface E2 for the abovementioned compressed air feed 2. The compressed air supply interface E2 is pneumatically connected pneumatically to the outlet A2 leading to the through flow chamber II, via which filling of a pneumatic installation 90 in filling direction BR also takes place (e.g. in accordance with
In
In summary, the invention relates to a compressed air supply installation 10, 11, 12, 20, for operating a pneumatic installation 90, in particular an air spring installation on a vehicle, having:
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2010 054 715.8 | Dec 2010 | DE | national |
| 10 2011 109 500.8 | Aug 2011 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2011/005915 | 11/24/2011 | WO | 00 | 6/14/2013 |
