Pneumatic actuator, pressure wave generator and method for operating a pressure wave generator

Abstract

The present invention relates to a pneumatic actuator (4b), in particular for use in a pressure wave generator (1), the pneumatic actuator comprising: a first piston surface, which acts against a gaseous working medium in a first volume (41), wherein the pressure in the first volume (41) on the first piston surface (91) causes an actuator force in a first direction; a second piston surface (92), which acts against a working medium in a second volume (42), wherein the pressure in the second volume (42) acting on the second piston surface (92) causes an actuator force in a second direction opposite to the first direction; a throttling section between the first volume (41) and the second volume (42); an inlet / outlet opening (45) of the first volume (41) for introducing the working medium into the first volume (41) or discharging it from the first volume; wherein the first piston surface (91) is larger than the second piston surface (92).

Description

Technical Field

[0001] The invention relates to a pneumatic actuator and a device and a method for generating explosions, in particular high-intensity pressure pulses, according to the independent patent claims. In particular, the invention relates to a pressure wave generator and a method for operating a pressure wave generator according to the preamble of the independent patent claim. Background Art

[0002] In a pressure wave generator, as described in WO 2007 / 028264 and in particular in WO 2010 / 025574, the auxiliary explosion and the main explosion are ignited in chambers separate from each other. The auxiliary explosion serves to release the closure of the main explosion chamber in a direct manner or via other latch / rod mechanisms, so that the subsequent main explosion does not act on the closure with full force and thus damage or destroy it. Therefore, an explosion delay occurs between the auxiliary explosion and the main explosion. This delay is achieved, for example, by a delay conduit in which the explosion is introduced from the auxiliary chamber into the main chamber, or by delayed ignition in both chambers via separate ignition devices present in the chambers.

[0003] With regard to the construction and design of the ignition and explosion delay, and with regard to exemplary embodiments and the mode of operation of the pressure wave generator, reference is made to the two aforementioned documents WO 2007 / 028264 and WO 2010 / 025574.

[0004] In particular, in the pressure wave generator of document WO 2010 / 025574, the auxiliary explosion chamber and the main explosion chamber are sealed from each other via a movable piston. The piston also closes the discharge port of the pressure wave generated in the main explosion chamber. The auxiliary explosion chamber and the main explosion chamber of the pressure wave generator are usually filled with an explosive gas mixture under overpressure just before the ignition of the explosion. Very high pressures of up to 1000 bar and temperatures of up to 4000° C. are generated due to the gas explosion in the auxiliary and main explosion chambers. Typically, the pressure is higher than 500 bar and the temperature is higher than 2000° C.

[0005] The opening should take place very quickly so that on the one hand the main explosion chamber does not open too early, otherwise the explosion energy cannot be optimally utilized, and on the other hand it does not open too late, in which way the device could be destroyed. An actuator is therefore required which allows a rapid opening of the piston but which is able to handle the prevailing conditions, operating frequencies and forces occurring with respect to the pressure wave generator. Summary of the invention

[0006] Therefore, one possible object of the present invention is to provide a pneumatic actuator which is suitable for use with a pressure wave generator and which at least partially meets these needs.

[0007] Ignition in the main explosion chamber can be achieved by spark plugs or ignition tubes from the auxiliary explosion chamber. However, for spark plugs, there is the problem that such spark plugs are subjected to great loads due to the explosion in the main explosion chamber and / or certain gas-air mixtures, such as methane-air mixtures, cannot be ignited at all under high pressure. In the case of ignition tubes, there is the problem that in some cases, especially in the case of long ignition tubes, the ignition tubes can only be filled with combustible gases (such as methane, ethane...) or only with oxidants (such as oxygen, air...) and therefore cannot lead to further explosions.

[0008] Another possible object of the present invention is to provide a pressure wave generator and a method for operating a pressure wave generator of the aforementioned type which allow an improved control of the ignition of the explosion in the main explosion chamber.

[0009] Another possible object is to provide a pressure wave generator of the aforementioned type which achieves an improved sealing between the auxiliary explosion chamber and the main explosion chamber.

[0010] At least one of these objects is achieved by a pneumatic actuator, a pressure wave generator or a method for operating a pneumatic actuator or a pressure wave generator according to the patent claims.

[0011] According to a first aspect of the present invention, there is: a pneumatic actuator, in particular a pneumatic actuator for use in a pressure wave generator according to the second aspect, comprising:

[0012] • a first piston surface acting oppositely to the gaseous working medium in the first volume, wherein the pressure in the first volume realizes an actuator force on the first piston surface in a first direction;

[0013] • a second piston surface, which acts in opposition to the working medium in the second volume, wherein the pressure in the second volume realizes an actuator force on the second piston surface in a second direction opposite to the first direction;

[0014] • a restriction between the first volume and the second volume;

[0015] • an inlet / outlet opening of the first volume for introducing a working medium into the first volume and for discharging the working medium from the first volume;

[0016] •Wherein, the first piston surface is larger than the second piston surface.

[0017] In an embodiment, the pneumatic actuator comprises an end position damping, in particular by closing the inlet / outlet opening.Thereby, the inlet / outlet opening is closed relative to the first volume.

[0018] In an embodiment, the piston closing element is arranged for closing the inlet / outlet opening.Thereby, end position damping can be achieved in a simple manner by elements of the piston itself.

[0019] In a method for operating a pneumatic actuator, the following steps are performed:

[0020] • filling the first volume with a gaseous working medium under pressure, in particular via a filling valve, such as a pressurized air valve;

[0021] • pressure compensation between the first volume and the second volume via the restriction and thereby moving the actuator in a first direction due to the surface area difference between the first piston surface and the second piston surface;

[0022] • discharging at least a portion of the working medium out of the first volume, in particular by opening an inlet / outlet opening;

[0023] • Moving the actuator in a second direction by a faster pressure drop in the first volume than in the second volume.

[0024] Thus, a back and forth movement of the actuator can be achieved with simple means, using only a filling valve and an inlet / outlet opening. This is a result of the surface area difference between the piston surfaces on the one hand and of the throttling between the two volumes on the other hand.

[0025] The inlet / outlet openings can be designed relatively large in order to achieve a rapid pressure drop in the first volume.

[0026] In an embodiment, the piston closure element is also arranged for separating the working medium filling line from the first volume.Thereby, high pressure surges in the filling line can be avoided.

[0027] In an embodiment, the two volumes are realized as part of a common working space of a cylinder, in which a single piston is arranged, on which the two piston surfaces are formed.

[0028] Therefore, the sealing of the piston relative to the (now common) cylinder is not critical. There can even be a gap between the piston and the cylinder. This has the function of a throttling between the two volumes. Pressure compensation therefore takes place via this gap. Thus, the design can be further simplified. Therefore, the throttling in this embodiment is formed by the gap between the cylinder and the piston. This is achieved without the other usual sealing of the piston.

[0029] In other embodiments, the two volumes and the piston surfaces are supported on separate pistons in separate cylinders, and the two separate pistons are mechanically coupled and their movements are also coupled here.

[0030] The end of the part being pulled forward

[0031] In an embodiment, the first piston surface and the piston closure element are designed for closing an inlet / outlet opening on the same piston. Thereby, a particularly simple and reliable design is possible.

[0032] In an embodiment, the pneumatic actuator comprises a cylinder discharge valve for rapidly discharging the working medium out of the first volume by opening the inlet / outlet opening. The cylinder discharge valve comprises a piston surface, on which a force for closing the cylinder discharge valve is generated when subjected to the working medium, and a valve surface, on which a force in the opening direction of the cylinder discharge valve is generated when subjected to the working medium, wherein the valve surface is smaller than the piston surface. Thus, by subjecting both surfaces to the same pressure, the cylinder discharge valve can be brought into a closed position and held there.

[0033] In an embodiment, the pneumatic actuator comprises a discharge pilot valve for discharging the working medium out of the valve volume, wherein the working medium acts on the piston surface. Thus, a short-term temporary pressure imbalance can be generated on the two surfaces, in which way the cylinder discharge valve is opened.

[0034] In an embodiment, a working medium filling line is provided for filling the outlet valve volume and the first volume with working medium at the same pressure. Thus, on the one hand, the same pressure can be achieved in both volumes, and on the other hand, a temporary imbalance can be achieved by the filling line between the two volumes as a throttling section.

[0035] The pressure in the working medium is, for example, between 50 bar and 100 bar.

[0036] In an embodiment, a section of the working medium filling conduit extends through the cylinder outlet valve, in particular the closing body of the valve, through which the working medium is supplied to the first volume. For example, the section is a channel in the closing body that also allows a small throughflow through the valve in the closed position of the valve.

[0037] In an embodiment, a section of the working medium-filled conduit, via which section the first volume is supplied with working medium, extends through the housing of the pressure wave generator.

[0038] In an embodiment, the linear guidance of the piston is formed by a piston and a hollow cylindrical piston connecting element, which surrounds the rear closed guide and can be linearly moved along the rear closed guide in the direction of movement, and the piston connecting element extends away from the piston in the direction of movement, and the piston connecting element surrounds a support element fixed to the rear closed guide. Here, the second volume is formed between the piston, the inner side of the piston connecting element, the support element and the rear closed guide. Usually, the rear closed guide is fixedly connected to the housing.

[0039] Thus, as an extension of the hollow cylindrical piston connecting element, the hollow cylindrical element can be driven, which is advantageous in certain applications. For example, this is the case for the pressure wave generator with a hollow cylindrical closing element described later.

[0040] A pressure wave generator comprises: a main explosion chamber; a closing element which in a closed position closes the main explosion chamber relative to an outlet and in an open position allows explosion gases to flow out of the main explosion chamber into the outlet; and an ignition device for igniting an explosion in the main explosion chamber. Here, the pressure wave generator comprises, in particular, a pneumatic actuator as described above, with which the closing element can be brought from the closed position into the open position and in particular also from the open position into the closed position. Thereby, a pressure wave generator is achieved which can repeatedly generate explosions and corresponding pressure waves.

[0041] In an embodiment, the pressure wave generator comprises a controller which is designed to activate the opening movement of the closing element when the pressure in the main explosion chamber exceeds a predetermined threshold value. Thus, the opening of the main explosion chamber can automatically adapt to changes in the explosion conditions which influence the speed of the explosion propagation. If the duration between ignition and maximum explosion pressure is known, the opening of the main explosion chamber can also be achieved after a fixed opening delay time. In this case, the pressure measurement can be dispensed with. The application is provided for conditions where the explosion propagates relatively slowly, so that the opening movement can start after ignition.

[0042] In an embodiment, the ignition device is an ignition device that can be constantly supplied with energy, in particular a glow plug. Thus, the ignition of the explosion in the main explosion chamber is achieved by means of the ignition device or the glow plug. Thus, depending on the pressure, temperature and composition of the gas mixture, a spontaneous combustion of the gas mixture is achieved.

[0043] Therefore, in an embodiment, the pressure wave generator comprises a controller which is designed to actively ignite an explosion in the main explosion chamber, or is designed to detect the time point of auto-ignition, and is also designed to activate the opening movement of the closing element after a settable ignition delay time after ignition has expired.

[0044] In an embodiment, the pressure wave generator comprises a controller designed to activate the opening movement of the closing element and, after a settable ignition delay time after the activation of the opening movement has elapsed, ignite the explosion in the main explosion chamber. This application is envisaged for situations where the explosion propagates relatively quickly, so that the opening movement will have already started before the ignition. In this case, the ignition of the explosion in the main explosion chamber can be achieved by a spark plug.

[0045] In an exemplary embodiment, the ignition time, ie the duration between ignition and reaching the maximum pressure in the main explosion chamber, is in the range of 30 ms to 150 ms.

[0046] In an exemplary embodiment, the duration between activation of the opening movement of the closure element, for example by actuation of the outlet solenoid valve, and the maximum opening of the closure element lies in the range of 20 ms to 60 ms.

[0047] A method for operating a pressure wave generator having a main explosion chamber is implemented using a pneumatic actuator, the pneumatic actuator comprising:

[0048] • a first piston surface acting oppositely to the gaseous working medium in the first volume, wherein the pressure in the first volume realizes an actuator force on the first piston surface in a first direction;

[0049] • A second piston surface, which acts in opposition to the working medium in the second volume, wherein the pressure in the second volume realizes an actuator force on the second piston surface in a second direction opposite to the first direction.

[0050] The method comprises repeatedly performing the following steps:

[0051] a) filling the first volume with a gaseous working medium under pressure, in particular via a filling valve, such as a pressurized air valve;

[0052] b) performing pressure compensation between the first volume and the second volume via the throttle and thereby, due to the difference in surface area between the first piston surface and the second piston surface, moving the actuator in a first direction and thereby moving the closing element in the closing direction and closing the main explosion chamber;

[0053] c) filling the main explosion chamber with an explosive mixture;

[0054] d) igniting an explosion in the main explosion chamber and discharging at least a portion of the working medium out of the first volume, in particular by opening an inlet / outlet opening of the first volume and thereby opening the main explosion chamber;

[0055] e) by a faster pressure drop in the first volume than in the second volume, moving the actuator in the second direction and thereby moving the closure element in the opening direction to open the main explosion chamber relative to the outlet and to discharge the explosion gas out of the main explosion chamber through the outlet.

[0056] Steps a), b) and c) can be carried out simultaneously or in a temporally overlapping manner. Step d) is usually carried out after steps a), b) and c). For step d), the opening of the main explosion chamber activated by opening the inlet / outlet opening is directly incorporated into step e).

[0057] In an embodiment, ignition of the explosion in the main explosion chamber is performed before opening the main explosion chamber, and for opening the main explosion chamber the pressure in the main explosion chamber is measured and as soon as the pressure exceeds a predetermined threshold the opening of the main explosion chamber is activated.

[0058] In an embodiment, the ignition of the explosion in the main explosion chamber is performed after opening the main explosion chamber, and the opening of the main explosion chamber is activated first, and the explosion in the main explosion chamber is ignited after a predetermined ignition delay time has elapsed.

[0059] According to a second aspect of the invention, a pressure wave generator having the features of patent claim 22 is provided.

[0060] Therefore, the pressure wave generator includes a main explosion chamber and an auxiliary explosion chamber, and

[0061] • a closing element which in the closed position closes the main explosion chamber relative to the outlet and in the open position allows the explosion gases to flow out of the main explosion chamber into the outlet,

[0062] • and an ignition duct for directing the explosion from the auxiliary explosion chamber into the main explosion chamber,

[0063] •Wherein, the ignition pipe valve is arranged in the ignition pipe.

[0064] The ignition conduit valve is therefore used to interrupt or release the conduit for the explosion from the auxiliary explosion chamber to the main explosion chamber.

[0065] Thus, the point in time at which the explosion in the main explosion chamber is activated can be controlled. In particular, in this way, the transmission of the explosion to the main explosion chamber can be delayed. In this way, the ignition duct can again be designed in a relatively short manner, and in this way, the problem of long ignition ducts being filled with only one gas - and therefore not with an explosive mixture - can again be eliminated. Even for 10 cm long ignition ducts, this problem would result in the explosion not being propagated first through the ignition duct, but only after the enclosed gas has been exhausted from the ignition duct.

[0066] In an embodiment, the ignition conduit valve is an electrically activated valve. The electrically activated valve may be activated by an electromagnet (magnetic valve). The valve may be electrically activated directly or indirectly via a pneumatic pilot valve.

[0067] Thus, within certain limits, the time of the explosion in the main explosion chamber can be freely selected. The ignition conduit valve determines the time of the explosion, and the ignition conduit transmits the explosion and provides the energy for ignition in the main explosion chamber.

[0068] In an embodiment, the ignition duct valve is mechanically actuatable by movement of the closing element. The ignition duct valve is a mechanically activated valve. "Actuable" means that movement of the closing element effects opening and / or closing of the ignition duct valve. Thus, an ignition delay in the main explosion chamber can be achieved with simple means.

[0069] Furthermore, it can be ensured that the opening of the ignition duct valve is positively coupled to the opening of the closure element, so that the main explosion can only be activated if the closure element has been opened. This is a safety-relevant aspect: without this positive dependency of the ignition in the main explosion chamber on the opening of the closure element, errors in the control could lead to the activation of the main explosion without the closure element being opened. This in turn would result in higher requirements on the pressure resistance of the main explosion chamber.

[0070] In an embodiment, the element of the ignition duct valve is formed by a part of the closure element or is fixedly connected to the closure element.Thereby, a mechanical realization of the ignition duct valve is made possible which has few additional moving parts and is therefore less prone to failures.

[0071] In an embodiment, the closure element comprises an opening which serves as or is part of the ignition duct and which is releasable by a movement of the closure element from the closed position to the open position.Therefore, a particularly simple realization of the ignition duct valve is possible.

[0072] Therefore, the opening or recess also serves as part of the ignition duct valve, in particular part of the slide valve. The opening or recess can form a passage between the main explosion chamber and the auxiliary explosion chamber through the wall of the closing element. Alternatively or additionally, a recess is formed on the surface of the wall of the closing element, which recess forms a connection between the main explosion chamber and the auxiliary explosion chamber in the case of an opening movement of the closing element.

[0073] In an embodiment, the closing element can enter the open position from the closed position by the explosion in the auxiliary explosion chamber. Therefore, the movement of the closing element can be synchronized with the explosion in the main explosion chamber by simple means, i.e., by the ignition conduit and the ignition conduit valve.

[0074] In an embodiment, the pressure wave generator comprises: an ignition device for generating a spark for triggering an explosion in the auxiliary explosion chamber, in particular a spark plug; and a second filling conduit for filling the auxiliary explosion chamber, wherein the second filling conduit is different from the ignition conduit. Thus, during filling, in particular when the ignition conduit valve is closed, the auxiliary explosion chamber can be filled without being directly connected to the main explosion chamber.

[0075] The spark-generating ignition device is intermittently supplied with (electrical) energy and in this way generates a spark, in particular for igniting a gas mixture.

[0076] During the filling of the auxiliary explosion chamber, the spark-generating ignition device is not supplied with energy, but is only supplied with energy after the filling in order to activate the auxiliary explosion.

[0077] In a method for operating a pressure wave generator having a main explosion chamber and an auxiliary explosion chamber, in particular according to the second aspect of the invention, the following steps may be performed:

[0078] • Both the main explosion chamber and the auxiliary explosion chamber are filled with explosive mixture;

[0079] • ignition of the explosion in the auxiliary explosion chamber, especially by means of an ignition device producing a spark;

[0080] • directing the explosion from said auxiliary explosion chamber through an ignition duct, wherein the directing is interrupted by an ignition duct valve;

[0081] • opening of the main explosion chamber relative to the outlet by opening the closing element;

[0082] • Opening the ignition duct valve and in this way directing the explosion into the main explosion chamber where it ignites; and

[0083] •Exhaust the explosion gases from the main explosion chamber through the outlet.

[0084] In an embodiment, the pressure wave generator comprises: an ignition device, which can be continuously supplied with energy after filling, the ignition device is in particular a glow plug, for triggering an explosion in the auxiliary explosion chamber, wherein the ignition conduit is arranged for filling the auxiliary explosion chamber from the main explosion chamber. "Can be continuously supplied with energy" is to be understood as meaning that the ignition device cannot be supplied with energy only in a pulsed manner - like a spark plug - but in a continuous manner and can be heated during a supply time of, for example, a few seconds or a few minutes or longer. In this way, it can be heated and kept at operating temperature. For example, the supply time or heating time can be at least five seconds or at least ten seconds or at least thirty seconds or at least one minute.

[0085] The ignition device can be supplied with energy after the filling of the main explosion chamber and in this way can reach high operating temperatures, usually above 800° C. or about 1000° C. or up to 1300° C., wherein it is still in contact with the explosive mixture. Only when the ignition duct is opened does the explosive gas mixture flow from the main explosion chamber through the ignition duct into the auxiliary explosion chamber and ignite when it comes into contact with the glow plug. The auxiliary explosion chamber can be designed in a relatively small manner here. In particular, it can only include a short tube section in which the glow element of the glow plug is arranged.

[0086] In another method for operating a pressure wave generator having a main explosion chamber and an auxiliary explosion chamber according to the second aspect of the invention, the following steps may be performed:

[0087] • filling said main explosion chamber with an explosive mixture;

[0088] • moving the closing element in the opening direction,

[0089] • opening the ignition duct valve, in particular by moving the closing element and in this way conducting the explosive mixture from the main explosion chamber into the auxiliary explosion chamber, wherein the auxiliary explosion chamber may comprise only the space in which the heating element of the ignition device is arranged;

[0090] • igniting the explosion in an auxiliary explosion chamber, in particular by means of an ignition device to which energy can be continuously supplied;

[0091] •Direct the explosion from the auxiliary explosion chamber into the main explosion chamber through the ignition duct;

[0092] • Further moving the closing element in the opening direction to open the main explosion chamber relative to the outlet by opening the closing element and to discharge the explosion gas out of the main explosion chamber through the outlet.

[0093] In an embodiment, the closure element can be moved from the closed position to the open position by its own actuator, in particular a pneumatic actuator. Thus, independent activation of the main explosion and the opening movement of the closure element can be achieved.

[0094] And thereby, the sealing of the auxiliary explosion chamber can be designed in a relatively simple manner, by the auxiliary explosion being used only for igniting the main explosion with high energy and not for driving the closing element.

[0095] The devices and methods described have in common that, by means of the ignition duct - whether by means of an explosion in the auxiliary explosion chamber activated by a spark plug or by a glow plug - the explosion in the main explosion chamber can be activated by such high energy that this high energy immediately leads to a rapid explosion or detonation in the main explosion chamber. Depending on the gas mixture, the ignition in the main explosion chamber by means of a spark plug will initially lead to a slow explosion.

[0096] Thus, again, a relatively weak explosive gas mixture can be used. For example, a fluid gas such as propane gas can be used. This is safer in its operation and is subject to less stringent regulations than, for example, natural gas or ethane.

[0097] The pneumatic actuator according to the first aspect of the invention may be used with a pressure wave generator having only one main explosion chamber, or with a pressure wave generator according to the second aspect having a main explosion chamber and an auxiliary explosion chamber, or in other applications.

[0098] In an embodiment, the closing element is movable in the direction of movement, and there is at least one plane which is orthogonal to the direction of movement and intersects the auxiliary explosion chamber and the main explosion chamber. Therefore, a good seal can be achieved between the main explosion chamber and the auxiliary explosion chamber. A compact structure of the device can also be achieved. Therefore, a closing element with a relatively small mass can also be achieved.

[0099] In an embodiment, the aforementioned arrangement of the main explosion chamber relative to the auxiliary explosion chamber can also be realized without an ignition conduit and without an ignition conduit valve. According to a third aspect of the present invention, a pressure wave generator having the following characteristics is thus provided:

[0100] A pressure wave generator having a main explosion chamber and an auxiliary explosion chamber,

[0101] • a closing element which in the closed position closes the main explosion chamber relative to the outlet and in the open position allows the explosion gases to flow out of the main explosion chamber to the outlet,

[0102] • wherein the closing element can be moved from the closed position to the open position by an explosion in the auxiliary explosion chamber,

[0103] • wherein the closing element is movable in a direction of movement and there is at least one plane which is orthogonal to the direction of movement and intersects the auxiliary explosion chamber and the main explosion chamber.

[0104] In an embodiment, it is considered that in the at least one plane, the auxiliary explosion chamber is separated from the main explosion chamber by a closing element. As a result, a particularly simple design and a good seal between the two explosion chambers can be achieved. In addition, an ignition duct can be arranged through the closing element, and the closing element acts as part of the slide valve.

[0105] In an embodiment, the explosion can propagate from the auxiliary explosion chamber into the main explosion chamber through a single connection through the gas spring. This means that the gas or working medium of the gas spring prevents the propagation of the explosion.

[0106] There can be one or more main explosion chambers separated from each other and one or more auxiliary explosion chambers separated from each other. A main explosion chamber can be assigned to a plurality of auxiliary explosion chambers, or vice versa, or a main explosion chamber can be assigned to exactly one auxiliary explosion chamber.

[0107] In an embodiment, the main explosion chamber and the auxiliary explosion chamber are arranged concentrically with each other.

[0108] Here, the main explosion chamber and the auxiliary explosion chamber can be designed in an annular or ring-shaped manner. In particular, the main explosion chamber can surround the auxiliary explosion chamber at least in a section extending in the movement direction of the closing element.

[0109] In an embodiment, the main explosion chamber and the auxiliary explosion chamber are arranged symmetrically with respect to the moving direction.

[0110] In an embodiment, the main explosion chamber and the auxiliary explosion chamber are arranged rotationally symmetrically with respect to the direction of movement.

[0111] Here, the main explosion chamber and the auxiliary explosion chamber as a single chamber or as a plurality of chambers may be present at least in the section considered along the circumferential section of the pressure wave generator.

[0112] Further advantageous embodiments are derived from the dependent claims. Features of the method claims can be combined with device claims where appropriate, and vice versa. BRIEF DESCRIPTION OF THE DRAWINGS

[0113] The subject matter of the present invention is explained in more detail below by means of the preferred embodiments shown in the accompanying drawings. Schematically shown:

[0114] Figure 1 is the longitudinal section through the pressure wave generator;

[0115] Figure 2 is the cross section through the pressure wave generator;

[0116] Figure 3 is a longitudinal section through another embodiment;

[0117] Figure 4 is a cross section of a longitudinal section for another embodiment; and

[0118] Figure 5 is a longitudinal section through another embodiment.

[0119] Basically, in the figures, identical components are provided with the same reference symbols. DETAILED DESCRIPTION

[0120] Figure 1 and Figure 2 A pressure wave generator 1 is shown with a main explosion chamber 2 and an auxiliary explosion chamber 3. A closing element 9 is arranged to close the main explosion chamber 2 relative to an outlet 15. The closing element 9 is driven by the explosion in the auxiliary explosion chamber 3 in order to open the main explosion chamber 2 relative to the outlet 15. A gas spring 4 is arranged for braking this opening movement of the closing element 9. The basic mode of operation of such a pressure wave generator 1 is explained in the initially cited WO 2007 / 028264 and WO 2010 / 025574.

[0121] The closing element 9 is guided on a support element 14 which allows a linear opening and closing movement of the closing element 9. The closing element 9 is shaped in a hollow cylindrical manner and surrounds the support element 14 which is fixedly connected to the housing 16. The direction of movement indicated by the double arrow is generally equal to the longitudinal direction of the pressure wave generator 1 and also equal to the outflow direction of the explosion gas outflow outlet 15. Figure 1 The closure element 9 is shown in the closed position, ie the main explosion chamber 2 is closed relative to the outlet 15 .

[0122] The outlet 15 is used for the directional discharge or extraction of the explosion gas, thereby generating a pressure wave.

[0123] The first filling conduit 12 is arranged for filling the main explosion chamber 2 and the second filling conduit 13 is arranged for filling the auxiliary explosion chamber 3. The second filling conduit 13 is guided to the auxiliary explosion chamber 3 by a support element 14. As shown, the two filling conduits can be supplied together by a fuel valve 10 or an oxidant valve 11. Alternatively, each filling conduit and explosion chamber can be supplied by a separate fuel valve or oxidant valve, thereby being supplied independently of the other filling conduits and explosion chambers.

[0124] The two explosion chambers can be filled separately from each other. For example, here, the combustion gas can first be filled at a relatively low pressure, such as 2 bar, and then the oxidant, such as air, is filled at a high pressure, such as 20 bar.

[0125] The spark plug 5 for igniting the auxiliary explosion chamber 3 is arranged in the support element 14. For this purpose, according to Figure 1 In the exemplary embodiment, the spark plug 5 is arranged centrally in the region of the axis of symmetry (generally in the direction of the longitudinal axis of the device) and can be connected to the auxiliary explosion chamber 3 via a connecting opening 6 .

[0126] In order to ignite the explosion in the main explosion chamber 2 with a delay relative to the explosion in the auxiliary explosion chamber 3, an ignition duct 8 is provided. Figure 1 Two variants of ignition ducts 8 are shown, of which only one is usually present in a realization of the pressure wave generator 1 .

[0127] The ignition duct 8 can be realized as an opening in the closure element 9, which is released when the closure element 9 performs an opening movement. This can be realized by the interaction of the closure element 9 with another component of the pressure wave generator 1. This is, for example, the support element 14, which together with the closure element 9 forms a slide valve 71 as the ignition duct valve 7: the slide valve 71 is opened by moving the closure element 9 along the support element 14.

[0128] • The ignition duct can be realized as a duct 8' (indicated by dashed lines) on which an ignition duct valve 7 is arranged. This can be a solenoid valve 72 or generally an electrically activated valve.

[0129] According to an embodiment (not shown), the ignition duct valve 7 is mechanically actuated in the event of an opening movement of the closure element 9. For this purpose, a mechanical transmission can be present. This can be adjusted so that the opening of the ignition duct valve 7 (depending on the setting) takes place at different positions of the closure element 9. Here, the opening of the ignition duct valve 7 can be coupled to the opening of the closure element 9 in a form-fitting manner so that the main explosion is activated only when the closure element 9 is already open.

[0130] By means of the ignition pipe valve 7 , the time point at which the explosion is transmitted from the auxiliary explosion chamber 3 to the main explosion chamber 2 can be controlled.

[0131] Figure 2 The main explosion chamber 2 is shown as a concentric arrangement, which surrounds the auxiliary explosion chamber 3 in the radial direction at least in the section extending in the direction of movement of the closure element 9 and is separated therefrom by the closure element 9 .

[0132] The closing element 9 surrounds the supporting element 14, wherein the auxiliary explosion chamber 3 is formed between the closing element 9 and the supporting element 14. When the closing element 9 is displaced along the movement direction, the volume of the auxiliary explosion chamber 3 changes. The volume of the gas spring 4, which is also changed by this displacement, is formed between the closing element 9 and the housing 16. The gas spring 4 also serves as a barrier to prevent the explosion from propagating from the auxiliary explosion chamber 3 to the main explosion chamber 2.

[0133] Figure 3 A pressure wave generator 1 according to another embodiment is shown. The operation of the elements: main explosion chamber 2, closing element 9, ignition duct valve 7 or slider valve 71, ignition duct 8 and outlet 15 are substantially the same as those of FIG. Figure 1 The same as the embodiment.

[0134] However, the auxiliary explosion chamber 3 is not arranged for driving the closing element 9, but only for generating the auxiliary explosion. After the slide valve 71 is released, the energy of the auxiliary explosion triggers the ignition of the explosion in the main explosion chamber 2 through the opening movement of the closing element 9.

[0135] The opening movement of the closing element 9 is achieved by an active gas spring or pneumatic actuator 4b. This comprises a cylindrical working space 43 with a piston 93 moving therein and the movement of the piston is coupled to the movement of the closing element 9, in particular by connecting them fixedly to each other, in particular in a single piece. Figure 3 and Figure 5 In the embodiment of the present invention, the coupling is realized by a piston connecting element 94. Figure 3 In the middle is the piston rod, and in Figure 5 The middle is a hollow cylinder.

[0136] The piston 93 divides the working space 43 into a first volume 41 and a second volume 42. There is no seal between the cylinder inner wall 44 of the working space 43 and the piston 93. In particular, there may also be a small gap, hereinafter referred to as a piston gap 96. This allows gas exchange between the two volumes and is particularly used as a throttle here. In other embodiments, a separate conduit may be arranged between the first volume 41 and the second volume 42 and may include a throttle that allows gas exchange in addition to or as an alternative to the piston gap 96. This throttle as a piston throttle 10 can also be realized by passing through one or more holes in the piston 93, which also allow gas exchange between the two volumes.

[0137] The gas pressure of the working medium in the first volume 41 generates a force which is directed oppositely to the opening movement of the closure element 9 , wherein the surface [area] which is effective here is the first piston surface 91 .

[0138] The gas pressure of the working medium in the second volume 42 generates a force in the direction of the opening movement of the closure element 9 , wherein the surface area effective here is the second piston surface 92 .

[0139] In this case, the second piston surface 92 is smaller than the first piston surface 91 , for example, at least 5 percent, 10 percent or 20 percent smaller.

[0140] The piston 93 comprises a piston closing element 95 which, during the opening movement, closes the cylinder inlet / outlet 45 or inlet / outlet of the first volume 41. The cylinder inlet / outlet 45 is drawn here concentrically to the working space 43, but can alternatively also be arranged laterally.

[0141] The closing of the cylinder inlet / outlet realizes the braking or end position damping of the opening movement. At the same time, the pressurized air valve 49 is also protected from pressure shocks by the pressurized air filling pipeline 48.

[0142] The cylinder inlet / outlet 45 can be opened by a cylinder discharge valve 46, and the working medium flows, for example, through the discharge or ventilation line 102. The cylinder discharge valve 46 can have a relatively large valve cross section compared to the filling line. Thus, a sudden pressure reduction in the first volume 41 can be achieved. The cylinder discharge valve 46 is kept closed by the pressure in the pressurized air filling line 48. This pressure can be reduced by opening the discharge pilot valve 47. Thus, the opening movement of the closure element is actuated by opening the discharge pilot valve.

[0143] The cylinder discharge valve 46 is, for example, a seat valve with a movable closing body. The closing body comprises a piston surface 52, against which the pressurized air from the pressurized air filling duct 48 impinges in the discharge valve volume 51. The valve surface 53, which is subject to the pressure in the cylinder inlet / outlet 45, is smaller than the piston surface 52. The forces acting on the piston surface 52 and the valve surface 53 are opposite to each other. If the discharge pilot valve 47 is closed, the gas pressure at both surfaces is the same, and the force on the piston surface 52 is greater than the force on the valve surface 53, in which way the closing body or cylinder discharge valve 46 remains in the closed position.

[0144] The pressurized air filling line 48 also supplies the first volume 41 via a section 101 of the pressurized air filling line 48. The pressurized air filling line 48 in turn is supplied via a pressurized air valve 49.

[0145] The ventilation duct 97 enables pressure compensation between the ambient air and the intermediate cylinder. The intermediate cylinder is located between the rear end of the closing element 9 and the active gas spring or pneumatic actuator 4b.

[0146] exist Figure 3 In a variant of the embodiment of the invention, the working space 43 and the piston 93 are realized in a compact manner. However, the same mode of operation can also be realized with a separate first and second volume and a separate piston with different piston surface areas. Here, a pipe with a throttle is arranged between the two volumes and the movements of the two pistons are mechanically coupled. This means that a linear movement of one of the two pistons always also causes a linear movement of the other piston.

[0147] exist Figure 3 In the embodiment of and the embodiments of the other figures, the piston path can be, for example, between 20 mm and 150 mm, in particular between 30 mm and 80 mm. The diameter of the piston can be, for example, between 20 mm and 200 mm, in particular between 40 mm and 120 mm.

[0148] Figure 3 A pneumatic actuator 4b is shown in combination with a pressure wave generator 1. However, the pneumatic actuator 4b can also be used for other applications. To this end, the piston rod 94 can be coupled to another element, or the movement of the piston rod can be coupled to the movement of another element.

[0149] Figure 4 shows details of a pressure wave generator 1 according to another embodiment, Figure 3 The operation of the components: the main explosion chamber 2, the closing element 9, the ignition pipe valve 7 or the slide valve 71, the ignition pipe 8, the outlet 15 and the pneumatic actuator 4b are basically the same as those of Figure 3 The same as the embodiment.

[0150] In this variant, the auxiliary explosion chamber 3 does not have a separate filling duct 13. It is designed in a relatively small manner. Instead of the spark plug 5, it comprises a glow plug. In the operation of the pressure wave generator 1, this is not only supplied at the ignition point in time, but can also be supplied in a constant manner, i.e., it can heat permanently or heat for a longer period of time, such as a few seconds or minutes. Therefore, it can have a high temperature and can therefore introduce enough energy into the gas mixture again to trigger a rapidly propagating explosion or deflagration in the main explosion chamber 2. Depending on the gas mixture and the pressure, this will not be possible for the spark plug, but it will first only activate combustion, which only leads to an explosion after a certain time (e.g. 30-50 ms). The ignition in the main explosion chamber 2 is achieved by supplying energy to the glow plug after the filling of the main explosion chamber 2 and bringing it to its operating temperature. This can last for several seconds, for example five or ten seconds. If the slide valve 71 then releases the ignition channel 8 by the opening movement of the closing element 9, the explosive gas mixture flows from the main explosion chamber 2 into the auxiliary explosion chamber 3 and comes into contact with the heated glow plug. This triggers an explosion in the auxiliary explosion chamber 3 and, via the ignition duct 8, also in the main explosion chamber 2. The opening movement of the closure element 9 is effected by means of the pneumatic actuator 4b as already described above.

[0151] In the operation of this variant, the following method steps may be performed:

[0152] • The pressurized air valve 49 is opened with the discharge pilot valve 47 closed. This has the following effect: the pressure in the pressurized air filling line 48 (e.g. 70 bar) closes the cylinder discharge valve 46. The first volume 41 is subjected to or impacted by pressurized air via the pressurized air filling line 48. The second volume 42 is also impacted via the piston gap 96, wherein, at the same time, the same pressure prevails in both volumes. Since the first piston surface 91 is larger than the second piston surface 92, the piston 93 and therefore the closing element 9 moves into the closed position (opposite to the direction of the opening movement).

[0153] • Close the compressed air valve 49. The closure element 9 remains in the closed position.

[0154] •Open the fuel valve 10 and the oxidant valve 11 and in this way fill the main explosion chamber 2 and, depending on the embodiment, also the auxiliary explosion chamber 3. Here, with the oxidant valve 11 closed, the fuel valve 10 can first be opened and a controlled amount of fuel can be introduced at a first pressure. Then, with the fuel valve 10 closed, the oxidant valve 11 can be opened and a certain amount of oxidant can be introduced, up to a higher second pressure. The quantitative proportion of oxidant and fuel can be adjusted by the ratio of the first pressure to the second pressure. Usually, this quantitative proportion is selected as a stoichiometric ratio, depending on the chemical reaction during combustion or explosion. For example, propane can be used as fuel and air can be used as oxidant, with a quantitative ratio or pressure ratio of 1:15 to 1:24.

[0155] • One of the following two method variations (more on this further below):

[0156] Or: the auxiliary explosion in the auxiliary explosion chamber 3 is triggered by activating the spark plug 5 , the opening movement is subsequently activated, and the explosion in the main explosion chamber 2 is triggered by opening the ignition duct valve 7 .

[0157] Or: the opening movement is activated and thereby an explosion is subsequently triggered in the main explosion chamber 2 by the combustion gases passing through the ignition duct valve 7 to the glow plug.

[0158] • In both cases, the activation of the opening movement is achieved by opening the cylinder outlet valve 46, which can be achieved in particular by opening the outlet pilot valve 47 and reducing the pressure in the pressurized air filling line 48. The pressure in the first volume 41 decreases by opening the cylinder outlet valve 46. The pressure in the second volume 42 also decreases, but more slowly than in the first volume 41 due to the throttling effect of the piston gap 96. In this way, the force on the second piston surface 82 is again greater than the force on the first piston surface 91. This enables a movement of the piston 93 and thus an opening movement of the closure element 9.

[0159] • Before the piston 93 or the closure element 9 hits the stop, the piston closure element 95 closes the cylinder inlet / outlet 45. The air remaining in the (now smaller) first volume 41 is compressed and brakes the movement of the piston 93 and the closure element 9. The pressurized air valve 49 is protected from being loaded by pressure peaks.

[0160] • The explosion gases flow out of the opening which has been released by the closing element 9.

[0161] • Closing of the cylinder outlet valve 46, in particular by closing the outlet pilot valve 47. This can be achieved by a piston surface, via which the pressurized air in the pressurized air filling line 48 presses the cylinder outlet valve 46 or its closing body into the closed position, which piston surface is larger than the surface on which the pressurized air acts in the opposite direction on the cylinder outlet valve 46 or its closing body. After closing the cylinder closing valve 46, the pressure in the first volume 41 can still be high enough (e.g. 20 bar) to also move the piston 93 backwards after compensation with the pressure in the second volume 42 and thereby bring the closure element 9 into the closed position.

[0162] • Subsequently, the method can start again by opening the pressurized air valve 49 .

[0163] The above method variant is a variant of the device with a spark plug or glow plug. The differences are:

[0164] • In the variant with spark plug, ignition in the auxiliary explosion chamber 3 is effected before the opening movement is activated, for example 50 ms in advance. At this point, an explosion with sufficient energy has already occurred in the auxiliary explosion chamber 3 to trigger the necessary rapid explosion in the main explosion chamber 2 during the opening of the ignition duct valve 7 or slide valve 71 by the opening movement.

[0165] In the variant with glow plug, if, when the ignition duct valve 7 or the slide valve 71 is opened, the gas mixture flows to the glow plug, this can already bring sufficient energy for a rapid explosion in the main explosion chamber 2 .

[0166] In both variants, due to the introduced ignition energy, which lasts only, for example, about two milliseconds, the explosion has already propagated in the main explosion chamber 2. While the opening movement has already taken place, the explosion pressure builds up in the main explosion chamber 2. The maximum energy in the gas flow is generated in the outlet 15 when the explosion pressure is maximum at the point in time when the opening of the closure element 9 between the main explosion chamber 2 and the outlet 15 is also maximum.

[0167] In other embodiments, the spark plug 5 or the glow plug 5b is arranged for igniting the gas mixture or for triggering the explosion in the main explosion chamber 2. In these embodiments, in particular, there is no auxiliary explosion chamber 3 and no ignition conduit 8. The ignition of the explosion in the main explosion chamber 2 is synchronized with the movement of the closing element in the opening direction by the controller 20. Here, depending on the speed of the explosion propagation in the main explosion chamber 2 and the speed of the pressure buildup in the main explosion chamber 2, the movement of the closing element 9 can be achieved before or after the ignition in the main explosion chamber 2.

[0168] For example, the explosion in the main explosion chamber 2 may propagate relatively slowly. In some cases, the opening may be performed only after ignition. In detail, the following exemplary steps are repeated here to operate the pressure wave generator (1) with the main explosion chamber (2):

[0169] • filling the main explosion chamber (2) with the explosive mixture;

[0170] • igniting the explosion in the main explosion chamber (2);

[0171] • measuring the pressure in the main explosion chamber ( 2 ) and activating the opening of the main explosion chamber ( 2 ) as soon as the pressure exceeds a predetermined threshold, in particular by means of a pneumatic actuator, in particular the pneumatic actuator ( 4 b ) described here;

[0172] • moving the closing element (9) in the opening direction by means of the pneumatic actuator (4b) to open the main explosion chamber (2) relative to the outlet (15) and discharge the explosion gas out of the main explosion chamber (2) through the outlet (15);

[0173] • and closing the main explosion chamber (2) by moving the closing element (9) in the closing direction by means of a pneumatic actuator (4b).

[0174] Alternatively, if the explosion propagates relatively quickly in the main explosion chamber 2, in some cases the opening can already be activated before ignition. In detail, the following exemplary steps are repeatedly performed here to operate a pressure wave generator (1) with a main explosion chamber (2):

[0175] • filling the main explosion chamber (2) with the explosive mixture;

[0176] • moving the closing element (9) in the opening direction, in particular by means of a pneumatic actuator, in particular the pneumatic actuator (4b) described here;

[0177] • after a predetermined ignition delay time has elapsed, igniting an explosion in the main explosion chamber (2);

[0178] • further moving the closing element (9) in the opening direction to open the main explosion chamber (2) relative to the outlet (15) and discharge the explosion gas out of the main explosion chamber (2) through the outlet (15);

[0179] • Closing of the main explosion chamber (2) by moving the closure element (9) in the closing direction by means of a pneumatic actuator (4b).

[0180] Whether the explosion propagates relatively slowly or relatively quickly depends inter alia on the explosive (gas) mixture used, its pressure and temperature and the ignition device used (glow plug or spark plug).

[0181] When the pneumatic actuator 4b is used, as described above, the movement of the closing element in the opening direction is achieved by the movement of the pneumatic actuator in the second direction. The movement of the closing element in the closing direction is achieved by the movement of the pneumatic actuator in the first direction.

[0182] Figure 5 An embodiment is shown which has only one main explosion chamber 2 , and therefore no auxiliary explosion chamber 3 and no ignition duct 8 . Figure 5 It also shows that Figure 3 Pneumatic actuator of a different alternative pneumatic actuator 4b. Figure 5 The complete pneumatic actuator shown in FIG. 1 or also only individual elements, such as

[0183] • Piston throttle 100 and / or

[0184] • a closing element 9 with a hollow cylinder as piston connecting element 94 instead of a piston rod and / or

[0185] • Cylinder outlet valve 46 with section 101 of pressurized air filling conduit

[0186] can be combined with a function such as Figure 3 The pressure wave generator 1 is combined with the auxiliary explosion chamber 3 shown.

[0187] The operation is basically the same as Figure 3 The embodiments of the present invention operate in the same manner, with the following differences in the implementation of the various elements:

[0188] The piston connecting element 94 connecting the piston 93 to the closing element 9 is formed by a hollow cylinder. The piston 93 includes a rear closing guide 98, which can be designed as a general cylinder, in particular as a circular cylinder, and along which the piston can move linearly in the direction of movement. The piston connecting element 94 surrounds the support element 14 fixedly connected to the housing 16. The second volume 42 is located between the rear closing guide, the piston 93 and the inner side of the hollow cylinder or the piston connecting element 94.

[0189] The throttle between the first volume 41 and the second volume 42 is realized as a piston throttle 100 by one or more holes through the piston 93. However, additionally or alternatively, the function of the piston throttle can also be assumed by the gap between the piston 93 and the rear closing guide 98.

[0190] The section 101 of the pressurized air filling line 48, through which the working medium is supplied to the first volume 41, does not extend through the housing 16, but rather through the closing body of the cylinder outlet valve 46, for example as a bore, and can also be referred to as a piston throttle of the cylinder outlet valve 46. Thus, the first volume 41 is supplied with working medium via the outlet valve volume 51.

[0191] This can be done without end position damping. Figure 5 In the embodiment of FIG. 1 , end position damping is to be achieved, this can be done as follows: Figure 3 This is achieved by a protruding closure element 95 that is moved into the cylinder inlet / outlet 45, or by the cylinder inlet / outlet 45 being guided laterally into the first volume 41 and by the piston 93 that slides on the cylinder inlet / outlet 45 during the opening movement.

Claims

1. A method for operating a pneumatic actuator (4b), the pneumatic actuator comprising: a first piston surface (91) acting in opposition to a gaseous working medium in a first volume (41), wherein a pressure in the first volume (41) generates an actuator force on the first piston surface (91) in a first direction; a second piston surface (92) acting oppositely to the working medium in the second volume (42), wherein the pressure in the second volume (42) generates an actuator force on the second piston surface (92) in a second direction opposite to the first direction; The method comprises the following steps: filling the first volume (41) with a gaseous working medium under pressure; performing pressure compensation between the first volume (41) and the second volume (42) by means of a throttling section and thereby moving the actuator in the first direction due to a surface area difference between the first piston surface (91) and the second piston surface (92); discharging at least a portion of the working medium from the first volume (41); The actuator is moved in the second direction by a faster pressure drop in the first volume (41) than in the second volume (42).

2. The method according to claim 1, wherein discharging at least a portion of the working medium out of the first volume (41) is accomplished by opening an inlet / outlet opening of the first volume (41).

3. A method for operating a pressure wave generator (1) having a main explosion chamber (2) by using a pneumatic actuator (4b), the pneumatic actuator comprising: a first piston surface (91) acting in opposition to a gaseous working medium in a first volume (41), wherein a pressure in the first volume (41) generates an actuator force on the first piston surface (91) in a first direction; a second piston surface (92) acting oppositely to the working medium in the second volume (42), wherein the pressure in the second volume (42) generates an actuator force on the second piston surface (92) in a second direction opposite to the first direction; The method comprises repeatedly performing the following steps: filling the first volume (41) with a gaseous working medium under pressure; Pressure compensation is performed between the first volume (41) and the second volume (42) through the throttle portion, and thereby, due to the surface area difference between the first piston surface (91) and the second piston surface (92), the actuator is moved in the first direction, and thereby the closing element (9) is moved in the closing direction and the main explosion chamber (2) is closed; Filling the main explosion chamber (2) with an explosive mixture; Ignite an explosion in the main explosion chamber (2) and discharge at least a portion of the working medium out of the first volume (41), thereby opening the main explosion chamber (2); By means of a faster pressure drop in the first volume (41) than in the second volume (42), the actuator is moved in the second direction and, thereby, the closing element is moved in the opening direction, so as to open the main explosion chamber (2) relative to the outlet (15) and to discharge the explosion gases out of the main explosion chamber (2) through the outlet (15).

4. The method according to claim 3, wherein: The ignition of the explosion in the main explosion chamber (2) is carried out before opening the main explosion chamber, and at this In order to open the main explosion chamber, the pressure in the main explosion chamber (2) is measured and as soon as the pressure exceeds a predetermined threshold value, the opening of the main explosion chamber (2) is activated.

5. The method according to claim 3, wherein: After opening the main explosion chamber, the ignition of the explosion in the main explosion chamber (2) is carried out, and at this First, the opening of the main explosion chamber (2) is activated, and after a predetermined ignition delay time has elapsed, the explosion in the main explosion chamber is ignited.

6. A pneumatic actuator (4b) for performing the method according to any one of claims 1 to 5, the pneumatic actuator comprising: a first piston surface (91) acting in opposition to a gaseous working medium in a first volume (41), wherein a pressure in the first volume (41) generates an actuator force on the first piston surface (91) in a first direction; a second piston surface (92) acting in opposition to the working medium in the second volume (42), wherein the pressure in the second volume (42) generates an actuator force on the second piston surface (92) in a second direction opposite to the first direction; a restriction between the first volume (41) and the second volume (42) to allow gas exchange and pressure compensation between the first volume (41) and the second volume (42); an inlet / outlet opening (45) of the first volume (41) for introducing and discharging the working medium into and out of the first volume (41); Wherein, the first piston surface (91) is larger than the second piston surface (92).

7. The pneumatic actuator (4b) according to claim 6, wherein: The throttle allows gas exchange between the first volume (41) and the second volume (42).

8. The pneumatic actuator (4b) according to claim 6 or 7, wherein the pneumatic actuator is configured to: Filling the first volume (41) with a gaseous working medium under pressure; and pressure compensation between the first volume (41) and the second volume (42) via a throttling section, and thereby moving the actuator in the first direction due to the surface area difference between the first piston surface (91) and the second piston surface (92).

9. The pneumatic actuator (4b) according to claim 6 or 7, wherein: The first piston surface (91) and the second piston surface (92) are formed on the same piston (93).

10. The pneumatic actuator (4b) according to claim 6 or 7, wherein: The first piston surface (91) and the second piston surface (92) are formed on a separate piston (93), the movements of which are mechanically coupled to each other.

11. The pneumatic actuator (4b) according to claim 6 or 7, wherein: The first piston surface (91) and the piston closing element (95) for closing the inlet / outlet opening (45) are formed on the same piston (93).

12. The pneumatic actuator (4b) according to claim 11, wherein: The piston closing element (95) is also arranged to separate a working medium filling conduit (48; 101) from the first volume (41).

13. The pneumatic actuator (4b) according to claim 6 or 7 comprises a cylinder discharge valve (46) for quickly discharging the working medium out of the first volume (41) by opening the inlet / outlet opening, wherein the cylinder discharge valve (46) comprises a piston surface (52) and a valve surface (53), on the piston surface, a force for closing the cylinder discharge valve (46) is generated when the working medium is applied, and on the valve surface, a force in the opening direction of the cylinder discharge valve (46) is generated when the working medium is applied, and wherein the valve surface (53) is smaller than the piston surface (52).

14. Pneumatic actuator (4b) according to claim 13, comprising a discharge pilot valve (47) for discharging working medium from a discharge valve volume (51) in which the working medium acts on the piston surface (52).

15. The pneumatic actuator (4b) according to claim 14, wherein: A working medium filling line (48) is arranged for filling the outlet valve volume (51) and the first volume (41) with working medium at the same pressure.

16. The pneumatic actuator (4b) according to claim 15, wherein: A section (101) of the working medium filling line (48) extends through the cylinder outlet valve (46), via which section the first volume (41) is supplied with working medium.

17. The pneumatic actuator (4b) according to claim 16, wherein: A section (101) of the working medium filling line (48) extends through the closing body of the valve.

18. The pneumatic actuator (4b) according to claim 6 or 7, wherein: A linear guide of the piston (93) is formed by a piston (93) and a hollow cylindrical piston connecting element (94), the piston surrounding a rear closed guide (98) and being linearly movable along the rear closed guide in a direction of movement, the hollow cylindrical piston connecting element extending away from the piston (93) in the direction of movement, surrounding a support element (14) fastened to the rear closed guide (98), and wherein The second volume (42) is formed between the piston (93), the inner side of the piston connecting element (94), the support element (14) and the rear closing guide (98).

19. A pressure wave generator (1) comprising a main explosion chamber (2), a closing element (9) which in a closed position closes the main explosion chamber (2) relative to the outlet and in an open position allows the explosion gases to flow out of the main explosion chamber (2) into the outlet, and an ignition device for igniting the explosion in the main explosion chamber (2), It is characterized in that The pressure wave generator (1) comprises a pneumatic actuator according to any one of claims 6 to 18, and the closing element (9) can be brought from the closing position into the open position by means of the pneumatic actuator (4b).

20. The pressure wave generator (1) according to claim 19, wherein the closing element (9) can also be brought from the open position into the closed position by means of the pneumatic actuator (4b).

21. The pressure wave generator (1) according to claim 19, wherein: The pressure wave generator (1) comprises a controller (20) designed to activate the opening movement of the closing element (9) when the pressure in the main explosion chamber (2) exceeds a predetermined threshold value.

22. The pressure wave generator (1) according to claim 21, wherein: The ignition device is an ignition device that can be constantly supplied with energy.

23. The pressure wave generator (1) according to claim 20, wherein: The pressure wave generator (1) comprises a controller (20) which is designed to activate an opening movement of the closing element (9) and to ignite an explosion in the main explosion chamber (2) after a settable ignition delay time has elapsed after the activation of the opening movement.

24. The pressure wave generator (1) according to claim 23, wherein: The ignition device is an ignition device that generates a spark.

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