WO2017109207A1

WO2017109207A1 - Free-piston linear generator and method for controlling a free-piston linear generator

Info

Publication number: WO2017109207A1
Application number: PCT/EP2016/082613
Authority: WO
Inventors: Florian Kock; Stephan Johannes SCHNEIDER; Alex HERON; Roman Virsik
Original assignee: Swengin Gmbh
Priority date: 2015-12-23
Filing date: 2016-12-23
Publication date: 2017-06-29
Also published as: DE102015122795A1

Abstract

The invention relates to a free-piston linear generator which is designed according to the opposed-piston principle, in which the inlet openings (48) are associated with a piston (14) and the outlet channels (46) are associated with the opposed piston (14') so that a purely longitudinal scavenging is produced. According to a corresponding method, the control of the movement of the pistons (14, 14') is configured in such a way that the piston (14') first releases the outlet openings (50).

Description

Free-piston linear generator and method for controlling a

Free-piston linear generator

The invention relates to a free piston linear generator for generating electrical energy and to a method for controlling a free piston linear generator.

Such a free-piston linear generator combines a so-called free-piston engine, that is to say an internal combustion engine, and a so-called electric linear generator for decoupling electrical energy from the system with one another. A free-piston engine is characterized by the fact that it couples a heat engine with internal or external combustion directly with a working machine for the provision of pneumatic, hydraulic or electrical energy. The free piston can move freely between its dead centers without kinematic forced operation. There are free piston linear generators in which the rotor is positioned as an annular or disk-shaped magnet in direct extension of the piston coaxial with the longitudinal axis and in a surrounding annular stator runs.

In addition, however, there is also another system of rotors and stators in which the rotors and stators are not coaxial with the longitudinal axis and in the immediate extension of the piston, but are arranged in groups laterally of the longitudinal axis. So if you look at such systems in the longitudinal direction, rotor-stator groups are left and right or up or down (spatial direction is not limited) side by side as packages. The invention relates to a free-piston linear generator of both systems.

In free-piston linear generators, which are constructed in the counter-piston principle, are a piston and a mechanically separated from him opposed piston opposite each other in the cylinder chamber and border with their front sides one common combustion chamber. This combustion chamber is enlarged when combustion fluid is burned in the combustion chamber. The pistons move apart and are then pushed together by a springback mechanism. In the combustion chamber, the gas and fuel supply and the combustion gas removal must be controlled. For this purpose, it is provided that open into the combustion chamber substantially diametrically opposed inlet and outlet channels. The inlet and outlet ports are open when the pistons are at bottom dead center. In the region of the bottom dead center, the outlet channels are therefore open so that the combustion gas can flow out of the combustion chamber when the pistons are subsequently moved toward one another. Such an arrangement of the inlet and outlet ports is called cross-scouring.

The invention provides a free-piston linear generator which exhibits improved mileage during operation. This is achieved by a free-piston linear generator for generating electrical

Energy is achieved, which is constructed in the counter-piston principle, comprising: a cylinder chamber having a longitudinal axis, a cylinder in the cylinder space along the longitudinal axis movable piston and a cylinder in the longitudinal axis movable, mechanically separate piston from the piston, with piston and opposed piston with their towards each other directed end faces within the cylinder chamber delimit a combustion chamber, a plurality of mechanically co-located with the piston and the piston and associated stators, in each of which electrical energy can be generated upon movement of the associated rotor, wherein at least one inlet channel opens into the combustion chamber, via the combustion fluid and / or air is introduced into the combustion chamber, at least one outlet channel emanating from the combustion chamber, escaping via the combustion gas from the combustion chamber, the at least one inlet channel or, in the case of several inlet channels, all inlet channels in the region of the bottom dead center of the piston via an or , a plurality of inlet openings open into the combustion chamber, and the at least one outlet channel or, in the case of several outlet channels, all the outlet channels in the region of the bottom dead center of the opposing piston emanate from the combustion chamber in one or more outlet openings. The free-piston linear generator according to the invention works exclusively according to the longitudinal rinsing principle. This means that there are no diametrically opposed or located in the region of a common annular section inlet and outlet ports, rather, the inlet openings are associated with the piston and arranged at the bottom dead center, whereas the outlet openings are in the region of the bottom dead center of the counter-piston. This longitudinal purge gas is more completely removed from the combustion chamber. Due to the fact that a free-piston linear generator has a variable stroke, this solution has not been considered. However, experiments have shown that the solution is very practical and advantageous.

A variant of the invention provides that the at least one inlet opening and the at least one outlet opening are closed during operation in predetermined positions by the piston or counter-piston. The piston and the counter-piston are therefore there to control the fluid supply or the fluid outlet, so that no separate valves are absolutely necessary.

It is particularly advantageous if, during the movement of the piston and the opposing piston away from one another, ie towards the bottom dead center, the at least one outlet opening or, if several are present, preferably also all the outlet openings are opened in time before the at least one or even all outlet openings , This means that the exhaust gas outlet already takes place in the stroke in the direction of bottom dead center, before the fresh gas is supplied, and not only from reaching bottom dead center.

The rinsing effect is improved by the longitudinal rinsing, in particular by the rinsing with a first opened outlet, and a short-circuit rinsing is reduced.

There are several ways to open the outlet opening in front of the inlet opening. One possibility is that the at least one outlet opening closer to the axial center of the combustion chamber, based on the top dead centers of the piston and the opposed piston, than the at least one inlet opening. The axial center is determined when the piston and the opposed piston are at top dead center, that is, when they are maximally close to each other. The axial distance between piston and piston is halved. This then results in the axial center of the combustion chamber. Provided that the piston and the opposed piston are not moved extremely rapidly to bottom dead center, the opposed piston first reaches the exhaust port, passes it, so that it is exposed and exhaust gas can flow out over it. Alternatively or additionally, piston and counter-piston can move synchronously to the axial center of the combustion chamber. This means that the movement of the piston and the counter-piston is identical; the upper and / or the lower counter-piston can reach their upper or lower dead centers at the same time or move at the same speed. Alternatively, the piston can be moved asynchronously to the counter-piston, for example following the counter-piston at least during the movement towards the bottom dead center, that is to say because of the higher speed of the counter-piston this reaches its bottom dead center and the outlet opening earlier than the piston its dead center and its inlet opening , In this variant, the (preferably all) outlet and (preferably all) inlet openings may be at the same axial distance from the axial center.

This different speed of the two pistons can be achieved by an electrical control for the stators. The term "control" stands for both control and regulation, the latter being preferred, this regulation changing the resistance that is opposed to the associated rotor when moving along its associated stator, which then controls the movement of the piston and the opposed piston The control regulates or regulates the current in the respective coils of the stators, whereby a braking of the corresponding piston is achieved by lower permitted current flow through the coil .. Alternatively or additionally, the speed or more generally the movement of the piston via variable or House made different Gas springs are controlled / regulated. For example, the amount of gas in the return chamber may be variable and / or the return piston may have different piston diameter.

Optionally, the cross-sectional areas of the or all inlet openings may be identical to the cross-sectional area or areas of the or each outlet opening.

A variant of the invention provides that the aforementioned electrical control can control the stator of the counter-piston such that it opposes the other piston, in particular lower resistance in the process along the stroke in the direction of bottom dead center as opposed to the piston of the piston.

Alternatively or additionally, it is also possible that the stator opposes different resistances due to the control of the counter-piston during the travel, ie along the stroke. For example, the resistance may increase toward bottom dead center.

Furthermore, it is also possible to adjust the resistance of the piston and the opposed piston by means of a variable return device, for example an adjustable gas spring. Such variable return devices are provided on the piston and on the counter-piston, the piston and counter-piston reset from bottom to top dead center, wherein the resistance of the piston and the counter-piston by means of their variable return part device via a control is adjustable differently to move the piston and the opposed piston asymmetrically. In this case, the pistons can simultaneously start from top dead center and different brakes can be decelerated so that the counter-piston exposes the at least one outflow opening before the piston exposes the at least one inlet opening. Again, it is possible to let all the outlet and inlet openings start axially equidistant from the axial center.

Of course, the rear part device can cooperate with the stators to realize the desired different, unsynchronous movements of the piston and the opposed piston.

In particular, inlet openings and / or outlet openings can be used be provided of different cross section. These different cross sections of the inlet openings and / or different cross sections of the outlet openings are based on the fact that the flow is split up into partial flows in a targeted manner, but the different openings are located at different distances from the not yet branched channel. This results in different flow pressures and gas quantities in the sub-channels. For example, as the distance from the not yet branched section of the inlet channel or outlet channel increases, the cross section of the respective inlet opening or outlet opening becomes increasingly smaller. As already indicated, the inlet channel can split into several subchannels towards the inlet openings. These sub-channels then lead to the inlet openings. The last part of each sub-channel, which then closes with the inlet opening, is the so-called inlet channel end. The same applies to the outlet openings. These may also have partial channels that begin at the outlet openings with outlet channel ends, ie the first piece of the sub-channel. The sub-channels then go into a common outlet channel.

The inlet channel ends and / or the outlet channel ends open at different angles in the combustion chamber or go from different angles from the combustion chamber. These angles are measured in radial section view to the longitudinal axis. Due to these different angles, the flow through the combustion chamber should be optimized.

In this context, it may be advantageous if those inlet channel ends which are maximally removed from a branching point at the inlet channel, where it splits into subchannels, are at a greater angle to the inlet channel section immediately before this branching point than the inlet channel ends which are closer to the inlet channel Branch point lie. The inlet channel ends lying close to the branching point usually extend in a straight line into the combustion chamber substantially parallel to one another, whereas the remotely extending inlet channel ends open towards the combustion chamber.

Seen in radial section, pairs of opposing inlet openings may be present, which are optionally even designed so that the inlet openings are aligned symmetrically to an axis. Constructively, the different flows to the inlet openings or from the outlet openings can be realized easily by virtue of the fact that a circumferentially closed or approximately circumferentially closed annular space extending from the inlet channel leads around the combustion chamber and the inlet openings are flow-connected to the annular space. The same can also be provided with the outlet channel.

The cross section of the annular space can be reduced with increasing distance from the inlet channel, in particular continuously. As with increasing distance from the inlet channel section in front of the annulus and less gas to inflow is present, the cross section of the annular space of the smaller amount of gas is adjusted.

The inlet channel, the inlet channel ends, the outlet channel and / or the outlet channel ends should, seen in side view, extend obliquely to the longitudinal axis in the region of the transition to the inlet openings or outlet openings, for example inclined obliquely toward the center of the combustion chamber. As a result, the incoming gas receives a component of movement which is directed in the direction of the outflow openings, with which a rapid complete inflow of the gas into the combustion chamber can be achieved. The same applies to the outflow. Again, as few deflections should be present in the sub-channels.

Further, there may be a controller coupled to and driving the stators, the controller being configured to drive the stators such that when moving the piston and the opposed piston away from each other and / or towards each other the resistance of the at least one rotor is changed when moving along its associated stator from the stator, is changed so that, starting from piston and piston from top dead center away from each other, the at least one outlet opening associated opposed piston is delayed differently compared to the at least one inlet port associated piston, so that piston and counter-piston are moved non-synchronously to their bottom dead centers and the at least one outlet opening is opened in time before the at least one inlet opening and / or so that the movements of the piston and the counter-piston starting from their bottom dead centers by different Actuation of the stators take place differently, so that the at least one outlet opening is closed in time before the at least one inlet opening.

Although it is known in the art to use the stators to synchronize the movement of the piston and the opposed piston as soon as an unsynchronized run is detected. The invention uses the stators in the opposite way, because pistons and opposed pistons are deliberately not synchronous, but run unsynchronized.

The free-piston linear generator according to the invention can have a control and sensors connected to it, with which the movement of piston and counter-piston is determined, wherein in the control a predetermined value is stored by which the counter-piston at least leads the piston. The control is programmed to differently actuate the stators when moving the piston and the opposed piston, if the opposed piston does not precede the piston by at least the predetermined value, and to oppose the piston and the opposed piston with different resistances through their associated stators and move the piston and the opposed piston less synchronously with each other to let, so that the distance of the opposing piston from the piston is larger again. The invention also relates to a method for controlling the

Piston and / or the counter-piston of a free-piston linear generator according to the invention for generating electrical energy, which is designed according to the counter-piston principle and has an electrical control for the stators. The method is characterized by the following step: driving the stators away and / or towards each other when moving the piston and the counter-piston such that the resistance, which is opposed to at least one rotor when moving along its associated stator from the stator, is changed so that Moving piston and opposed piston from top dead center starting away from each other, the at least one outlet opening associated opposed piston is differently delayed compared to the at least one inlet port associated piston and piston and opposed piston unsynchronized to their bottom dead centers are moved and the at least one Outlet opening is opened in time before the at least one inlet opening and / or the movements of the piston and the opposed piston are initiated differently from their bottom dead centers by different loading of the stators, so that the at least one outlet opening is closed in time before the at least one inlet opening.

The invention further relates to a method for controlling the piston and / or counter-piston of a free-piston linear generator for generating electrical energy, which is designed according to the counter-piston principle and has an electrical control for the stators, this method being characterized by the following steps:

Determining the movements of the piston and piston,

Determining whether the opposed piston precedes the piston, and

Driving the stators when moving the piston and the opposite piston in such a way, if the piston does not always precedes the piston at least a predetermined value that piston and piston different resistors are opposed by their associated stators to move the piston and the opposite piston less synchronous to each other.

The stators can be controlled differently so that, due to the different, the piston and the opposed piston opposing resistors, the counter-piston exposes the at least one outlet before the piston exposes the at least one inlet opening, and / or are driven so different that the at least an outlet opening is closed in time before the at least one inlet opening. The maximum distance by which the opposing piston precedes the piston is stored in the control. Stators are controlled in such a way, as soon as the maximum distance is exceeded, that the piston approaches the counter-piston to below the maximum distance.

The control can furthermore control a stator in such a way, but in particular control all stators in such a way that the stator or the stators have a different resistance during the process along the Strokes towards the bottom dead center oppose, as opposed to the piston or the stators associated with the piston during its movement in the direction of bottom dead center.

In the method according to the invention, all inlet openings and all outlet openings can likewise be equidistant from the axial center.

Further features and advantages of the invention will become apparent from the following description and from the following drawings, to which reference is made. In the drawings show:

1 shows a schematic longitudinal sectional view through an exemplary first embodiment of the free-piston linear generator according to the invention, wherein the piston and the counter-piston are shown at bottom dead center,

FIG. 2 shows the free-piston linear generator according to FIG. 1 with piston and counter-piston at top dead center.

FIG. 3 shows a sectional view in the form of a radial section through the free-piston linear generator according to FIG. 1,

FIG. 4 shows a schematic longitudinal sectional view through an exemplary second embodiment of the free-piston linear generator according to the invention, with piston and counter-piston being shown at bottom dead center,

5 shows the free-piston linear generator according to FIG. 4 with piston and counter-piston at top dead center, FIG.

FIG. 6 shows a radial section view through the combustion chamber along the line VI-VI in FIG. 1, and FIG. 7 shows a radial sectional view through the combustion chamber along the line VI-VI in FIG. 1 with an alternative gas guide.

FIG. 1 shows a free-piston linear generator which has an internal combustion engine in the form of a piston engine with variable stroke, via which electric energy is obtained by means of a linear generator. The illustrated free piston linear generator is designed in the form of an opposed piston system.

In Figure 1, the outer casing of the generator is omitted for the sake of clarity. Inside the housing, a cylinder 10 is provided in the interior of which a cylinder chamber 12 is formed. In the cylinder chamber 12, a piston 14 and an opposing piston 14 ', which are not mechanically connected, added. The pistons 14, 14 'are respectively movable back and forth along a longitudinal axis A of the cylinder chamber and the generator and define therebetween a common combustion chamber 16, which forms a part of the cylinder chamber 12.

Between the pistons 14, 14 ', preferably in the axial center between the pistons 14, an imaginary radial plane R, which is perpendicular to the longitudinal axis A, shown. The generator to be seen in FIG. 1 is constructed essentially mirror-symmetrically with respect to the radial plane R, so that a left and a right half result, the structure of which is essentially identical. In addition, there are also variants in which the left and the right half differ slightly, which may have advantages. In the following, the left half will be explained for the sake of simplicity, the corresponding explanations apply to the right half. Not shown is an injection system, which fuel in the

Can inject combustion chamber 16.

With each piston 14, 14 'is mechanically coaxially arranged to him, own return piston 18 is coupled, as well as runners 20, here in the form of plate-shaped runners. The runners 20 include a plurality of juxtaposed or even a single permanent magnet 22, the or the overall have a plate-like shape or has. The one or more permanent magnets may be arranged on a carrier plate 24. This carrier plate 24 is part of the rotor 20.

The return piston 18 is part of a rear part device 26 and is housed in the longitudinal direction in a cylindrical space in which it delimits a so-called recovery space 28. As a result, a gas spring is formed, which is provided for dividing the piston 14 back. The connection of the piston 14 with the return piston 18 and the two rotors 20 via a mechanical connection system 30th

As can be seen in Figure 1, the two runners 20 are seen in the direction of the longitudinal axis A laterally of the longitudinal axis A and form a pair of runners, which lie relative to the longitudinal axis A to each other, preferably diametrically to the longitudinal axis A.

The runners 20 do not extend axially beyond an area bounded by radial planes in which the opposite end faces of the piston 14 and its return piston 18 are located (see FIG. 1). Incidentally, these end faces limit, on the one hand, the combustion space 16 and, on the other hand, the return space 28. Thus, the runners 20 and stators are laterally completely removed from the piston 14 and return piston 18 and do not increase the axial space, although they themselves have a considerable axial length.

The connection system 30 comprises a cross-shaped coupling part 31, which is hinged to the associated piston 14, 14 ', its return piston 18 and the runners 20.

In Figure 3 is a schematic sectional view is shown, the sectional plane in the region of the cylinder 10, the radial plane R and radially outside the cylinder 10 offset thereto, namely along a radial plane which intersects the two fasteners 32 of the coupling part on the runners 20 extends.

The fasteners 32 are diametrically opposite to the longitudinal axis A and in a radial plane.

FIG. 3 further shows that stators 34, 36 are provided for the in-plane plate-shaped runners 20, the stators 34 being upper stators and the stators 36 being lower stators. Between the respective pair of stators 34, 36 results in a slight gap 38, in the side or through it, the respective plate-shaped rotor 20 protrudes. The stators 34, 36 are usually designed as induction coils, that is, windings. By a relative movement between the rotor 20 and the stators 34, 36, a voltage or a current is induced, so that a permanently excited synchronous machine is formed. Of course it is also conceivable that the rotor 20, the coil and the stators 34, 36 have / the permanent magnet (s).

In the embodiment illustrated in FIG. 3, each rotor 20 is mounted on the housing 41 independently of the attachment to the connection system 30 via at least one linear bearing 40 or a plurality of linear bearings. The one or more linear bearings 40 are parallel to the longitudinal axis A.

All stators are connected to an electrical control 42. Corresponding lines are only hinted at to improve the clarity. For supplying air and / or a mixture of combustible fluid and air, an inlet channel 44 and an outlet channel 46 are provided in the wall of the cylinder 10. This inlet channel 44 opens into the combustion chamber 16 via a plurality of inlet openings 48 when the cylinder 10 is positioned at bottom dead center (see FIG. 1) or near bottom dead center. The inlet openings 48 are distributed on an annular surface close to or immediately adjacent to the combustion chamber 16 facing the end face of the piston 14 (see Figure 1). That is, these inlet openings 48 are open to the combustion chamber 16 when the piston 14 has reached the bottom dead center.

At the opposite end of the combustion chamber 16, based on the bottom dead center, a plurality of outlet openings 50 are also distributed on an annular surface. Here, too, the outlet openings 50 adjoin the end face of the counter-piston 14 'facing the combustion chamber 16, preferably directly or are arranged in the vicinity thereof. In any event, the outlet ports 50 are opened when the opposed piston 14 'is at bottom dead center (see FIG. 1).

The free piston linear generator is operated, as will be explained in more detail below, that when moving piston 14 and opposed piston 14 'from top dead center (FIG. 2) to bottom dead center (FIG. 1), the outlet openings are first opened before the inlet openings are uncovered. As can be seen in FIGS. 1 and 2, all the inlet openings are assigned to the piston 14 and arranged at the bottom dead center, whereas all the outlet openings 50 are located opposite the piston 14 '. are assigned and are at the bottom dead center.

The possibilities of how it can be ensured that first the outlet openings 50 are opened when the pistons 14, 14 'are moved to the bottom dead center are presented below. A first option is that the outlet openings 50 are closer to the axial center of the combustion chamber 16 than the inlet openings 48. The axial center of the combustion chamber is referenced to the position of piston 14 and opposed piston 14 'in their top dead centers (FIG. in which the axial center is half the distance of the pistons 14, 14 '. The axial center coincides, for example, with the symmetry plane designated as radial plane R in FIG. If both pistons 14, 14 'learn about the same driving force and the same counterforce, for example, by the return devices 26 with their return piston 18, so both pistons 14, 14' move approximately equally fast from top dead center to bottom dead center. Thus, then the opposed piston 14 ', which otherwise covers the outlet openings 50, release them earlier, as Figure 1 shows, as the piston 14, the inlet openings 48 covers or releases.

A second option is that intake and exhaust ports begin equidistant from the axial center and, preferably, end equidistant from the axial center.

The mode of operation of the illustrated free-piston linear generator can now be described briefly below with reference to FIGS. 1 to 3.

In Figure 2, the pistons 14, 14 'are in the top dead center position, that is, they are at most close together. Fuel in the combustion chamber, which is either injected or previously introduced via the inlet openings 48, is ignited via an igniter, so that the combustion chamber increases and the pistons 14, 14 'move away from one another.

Via the respective connection system 30, the runners 20 are moved between their stators 34, 36, so that current is induced. Further, the return piston 18 to move so that the respective return chamber 28 is smaller and the gas therein is compressed. Shortly before reaching the respective bottom dead center, the outlet openings 50 from the counter-piston 14 'are first exposed so that exhaust gas can flow out. Subsequently, the inlet openings 48 are exposed by the piston 14 passing by, so that fresh gas or a gas-fuel mixture can flow into the combustion chamber 16. The incoming gas or fuel-gas mixture then pushes the combustion gases completely out of the combustion chamber 16. It is therefore a pure rinsing, without any proportion of a transverse or reverse purge.

The compressed gas in the respective return chamber 28 causes the respective return piston 18 is subjected to force and moves its piston 14, 14 'in the direction of top dead center. When moving in the direction of top dead center, the pistons 14, 14 'then close the inlet openings 48 and the outlet openings 50 again.

Of course, the return rooms 28 may also be connected to a gas storage via switchable valves in order to be able to adapt the gas volume to the movements of the return piston 18.

While in the solution just described piston and opposed piston 14 or 14 'move synchronously from and to the axial center of the combustion chamber 16, it may alternatively be advantageous if the piston 14 of the movement of the counter-piston 14' at least to bottom dead center or even permanently runs behind at least a predetermined minimum value to reach its bottom dead center and thus the inlet openings 48 later, when the counter-piston 14 'has reached the outlet openings 50 and has exposed. The last-mentioned variant can be accomplished, for example, by the electrical control 42, this is not restrictive. By means of the control unit 42, the resistance which is opposed to the runners 20 and thus to the pistons 14, 14 'of the stators 34, 36 can be controlled or regulated when moving along their stators 34, 36. It is of course possible that only the piston 14, a resistance is opposed, whereas the opposed piston 14 'may proceed without an additional caused by the control 42 resistance.

Of course, the control of the desired non-synchronous course of the counter-piston to the piston can also take place when piston opposed piston start simultaneously from its top dead center. For example, a predetermined time interval of the movements of the pistons 14, 14 'can be stored as a predetermined value, and the respective position and thus the movement of the piston 14, 14' is then permanently polled via corresponding sensors, and via the resistance of the stator 34, 36 is achieved that the respective piston runs behind the counter-piston with the desired time interval. The predetermined distance may be, for example, a minimum distance and at the same time also a maximum distance, so that the opposing piston protrudes within a range of the piston.

Furthermore, it is possible that the one or more preset limit values just explained are different over the entire stroke. Thus, it may be desirable for the piston to come relatively close to the opposed piston over part of the stroke, but in other parts of the stroke to have the greater distance from the opposed piston, which is deliberately desired.

For example, in an initial phase, the opposed piston may be moved as fast as or slightly faster than the piston, but later decelerated so that it more quickly reaches its bottom dead center and exhaust port than the piston bottom dead center and inlet port. The same can be done during the movement from bottom dead center to top dead center. In practice, the two pistons do not move exactly in synchronism from top dead center. Here, a certain tolerance threshold must be specified within which one can speak of a synchronization or, more precisely, of an accepted and desired asynchronous process. As long as the two pistons do not move so differently that they are outside the tolerance threshold, the control does not intervene. When a desired asynchronous trace is to be realized, the piston or opposed piston, usually the piston, is opposed to increased resistance from its stator as compared to the resistance opposed to the opposed piston by its stator. Thus, the piston is slower than the opposed piston. For this unsynchronous movement is constantly checked whether the distance between the two pistons is in the desired target. Is there a deviation from this, eg due to small, permanently occurring disturbances, the control intervenes again and the piston and the Opposite pistons can be braked.

This procedure can also be used for the subsequent compression phase. During the movement of the piston and the opposing piston toward one another, an increased resistance at the beginning of the movement from the bottom dead center can be counteracted to the opposing piston so that the opposing piston closes the at least one outlet opening before the piston closes the at least one inlet opening. This is also done by the controller 42.

It should be emphasized that the piston and the counter-piston can simultaneously start their movement from top dead center to the bottom dead center, however, according to an advantageous embodiment, they are permanently intended to run asynchronously, in that the counter-piston permanently leads the piston.

Below are some examples that could be explained.

If during the movement of the piston away from each other the measurement shows that the projection of the piston opposite the piston is lower than desired, the counter-piston is initially opposed to a lower resistance than would be the case in an operation without said target-actual deviation. Later, during the movement (i.e., before bottom dead center, abbreviated UT, the opposing piston), the resistance is increased again. As an alternative to these two interventions, the resistance counteracting the piston can first be increased and then lowered (before reaching the UT of the piston).

If during the movement of the piston away from each other the measurement shows that the projection of the counter-piston relative to the piston is greater than desired, the piston is initially opposed to a lower resistance than would be the case in an operation without said target-actual deviation. Later, during the movement (i.e., before the BDC of the piston), the resistance is then increased again. As an alternative to these two interventions, the resistance which counteracts the counter-piston can first be increased and then lowered (before the UT of the counter-piston is reached).

If during the movement of the piston towards each other the measurement shows that the projection of the counter-piston relative to the piston is less than desired, the counter-piston is initially opposed to a lower resistance than would be the case in an operation without said target-actual deviation. Later, during the movement (ie before top dead center, abbreviated OT, of the opposing piston), the resistance is then increased again. As an alternative to these two interventions, the resistance counteracting the piston can first be increased and then lowered (before reaching the TDC of the piston).

If during the movement of the piston towards each other the measurement shows that the projection of the counter-piston relative to the piston is greater than desired, the piston is initially opposed to a lower resistance than would be the case in an operation without said target-actual deviation. Later, during the movement (i.e., before the TDC of the piston), the resistance is then increased again. As an alternative to these two interventions, the resistance which counteracts the counter-piston can first be increased and then lowered (before the TDC of the counter-piston is reached).

A further option or additional support as to how the pistons 14, 14 'can be moved differently in time is realized by the return part devices. For example, the self-adjusting resistors can be adjusted and changed by changing the amount of gas in the return chambers 28 via valves (inlet or outlet valves). The resistance of the piston and the opposing piston is controlled differently by means of the variable return part device (here gas spring) via the control 42 in order to displace the piston and the opposed piston asymmetrically. For this purpose, a valve in the cylinder chamber of the gas spring can be controlled by the controller 42 to regulate a gas supply or gas discharge from the cylinder chamber during operation.

The non-synchronous movement is also advantageous in order to close the at least one outlet opening in time before the at least one inlet opening. The above explanations to the sequence of movements of pistons to opposed pistons are also applicable to the following embodiments and not limited to the previous embodiments. Of course, you can also create optimal combinations of all the above variants.

The embodiment according to FIGS. 4 and 5 essentially corresponds to that according to FIGS. 1 to 3, wherein the groups of rotors / stators, here runners 20 and stators 34 arranged laterally next to the longitudinal axis A, do not lie laterally next to the movable unit of piston 14, 14 ', connecting system 30 and rear part device 26 are arranged, but spatially between the cylinder 10 together with pistons 14, 14' and the respective rear part device. The stators 34 here comprise annular or disc-shaped permanent magnets 22, which are arranged next to each other and are moved within a stator 34 in the form of a toroidal coil. For reasons of clarity, the toroidal coil in FIG. 5 has been omitted.

Also in the embodiment according to FIGS. 4 and 5, the outlet openings 50 are exposed temporally in front of the inlet openings 48 when the pistons 14, 14 'are moved in the direction of the bottom dead center. This is achieved identically to the measures or combinations of measures described above with reference to FIGS. 1 to 3.

As FIGS. 1, 2, 3 and 4 show, a plurality of inlet openings 48 and a plurality of outlet openings 50 are provided. FIG. 6 illustrates in a cross section in the region of the inlet openings 48 how the channel guide can look in the interior of the cylinder 10. The inlet channel 44 splits at a branch point 52, to which it is still performed as a singular channel, in several sub-channels. First, two sub-channels are formed, which complement each other to form an annular space 54. This annular space 54 surrounds the combustion chamber 16 completely. From the annular space 54 then branch off further sub-channels radially inwardly toward the combustion chamber 16 out. These sub-channels are executed in radial section view according to Figure 6 to a plane of symmetry S symmetrical to this pairwise. The associated inlet channel ends 56, 58 and 60 form the ends of the sub-channels, which then terminate in the inlet openings 48. In addition, a central sub-channel with an inlet channel end 62 is still provided, which lies on the axis of symmetry S.

As can be seen in Figure 6, the cross-section of the annular space 54 decreases with increasing distance from the branch point 52, namely continuously. Also, the inlet openings 48 may have a different cross-section with increasing distance from the branch point 52.

However, as can be seen in FIG. 6, above all, the angle of the flow represented by arrows in the pairwise opposed inlet channel ends 56, 58 and 60 relative to the channel section upstream of the branching point 52 is greatly different. Thus, as the distance of the corresponding inlet channel end 56-60 from the branch 52 increases, the gas or fuel gas mixture flows at a greater angle to the direction of the inlet channel 44 immediately upstream of the branch 52 and also opposite the axis of symmetry S. With these different flow directions optimal flushing should be achieved.

The length of the individual inlet openings 48 in the axial direction should be the same in each case.

It can also be seen in FIGS. 1, 2, 3 and 4 that the inlet channel ends and the outlet channel ends are seen in side view and oblique to the longitudinal axis A in the region of the transition to the inlet openings 48 and outlet openings 50, obliquely inwards and obliquely to the axial one Center of the combustion chamber 16 out. As a result, a direction is to be given to the inflowing gas or fuel gas mixture and to the exiting combustion gas, as a result of which rapid purging can be achieved.

The embodiment of Figure 7 corresponds to the following difference of Figure 6. The annular space 54 does not extend circumferentially closed to the combustion chamber 16, but ends respectively at the inlet channel ends 60. Again, however, reduces the cross section of the not completely circumferentially closed annulus Also, the angles of flow in the paired opposing inlet channel ends 56, 58 and 60 relative to the channel portion in FIGS. 6 and 7 before the branching point 52 are different.

Claims

claims

1 . Free-piston linear generator for generating electrical energy, which is constructed according to the counter-piston principle, comprising: a cylinder chamber (12) having a longitudinal axis (A), a piston (14) movable in the cylinder chamber (12) along the longitudinal axis (A) and one in the cylinder space (12) along the longitudinal axis (A) movable, mechanically separate from the piston (14) opposed piston (14 '), said piston (14) and opposed piston (14') with their facing each other end faces within the cylinder chamber (12) has a combustion chamber ( 16), a plurality of the piston (14) and the counter-piston (14 ') mechanically coupled to runners (20) and associated stators (34, 36), in each of which electrical energy upon movement of the associated rotor (20) can be generated, wherein at least one inlet channel (44) opens into the combustion chamber (16), is introduced via the combustion fluid and / or air into the combustion chamber (16), at least one outlet channel (46) emanating from the combustion chamber (16) via the combustion gas from the Combustion chamber (16) escapes, the at least one inlet channel (44) or, in the case of several inlet channels, all inlet channels (44) in the region of bottom dead center of the piston (14) via one or more inlet openings (48) into the combustion chamber (16) , and the at least one outlet channel (46) or, in the case of several outlet channels, all outlet channels (46) originate in the region of the bottom dead center of the counter-piston (14 ') in one or more outlet openings (50) from the combustion chamber (16).

2. Free-piston linear generator according to claim 1, characterized in that the at least one inlet opening (48) and the at least one outlet opening (50) are closed during operation in predetermined positions by the piston (14) or counter-piston (14 ') in order to supply or supply the fluid to control the fluid outlet.

3. free piston linear generator according to claim 1 or 2, which is designed so that when moving piston (14) and opposed piston (14 ') away from each other, the at least one outlet opening (50) in time before the at least one inlet opening (48) is opened.

4. free piston linear generator according to claim 3, characterized in that the at least one outlet opening (50) closer to the axial center of the combustion chamber (16) relative to the top dead centers of the piston (14) and the opposite piston (14 ') than the at least one inlet opening (48) or that the at least one outlet opening (50) is arranged equidistant from the axial center as the at least one inlet opening.

5. free piston linear generator according to claim 3 or 4, characterized in that that the piston (14) at least during the movement to the bottom dead center towards the counter-piston (14 ') runs behind to reach its bottom dead center later than the counter-piston (14').

A free-piston linear generator as claimed in claim 5, characterized in that there is electrical regulation (42) for the stators (34, 36) adapted to provide the resistance to the associated rotor (20) when moving along its associated one Stators (34, 36) is opposite, can control or regulate, via the electrical control (42), the movement of piston (14) and opposed piston (14 ') is controlled or regulated.

7. free piston linear generator according to claim 6, characterized in that the control (42) is designed so that it allows the counter-piston (14 ') reaches its bottom dead center earlier than the piston (14) whose bottom dead center.

8. free piston linear generator according to claim 6 or 7, wherein the control (42) the counter-piston (14 ') associated, at least one stator (34, 36) such that it the counter-piston (14') another resistance in the process along the Strokes towards the bottom dead center opposite than the at least one stator (34, 36) of the piston (14) opposes the piston (14).

9. free piston linear generator according to one of the preceding claims, characterized in that a variable return device to the piston and Opposing piston is provided which resets the piston and the counter-piston from the lower to the top dead center, wherein the resistance of the piston and the counter-piston by means of at least one of the two variable return devices via a control is adjustable differently to move the piston and the opposed piston asymmetrically.

10. free piston linear generator according to any one of the preceding claims, characterized in that the inlet channel (44) a plurality of inlet openings (48) go out and / or a plurality of outlet openings (50) in the outlet channel (46) merge, in particular wherein inlet openings (48) and / or outlet openings (50) are provided with different cross sections.

1 1. The free-piston linear generator of claim 10, characterized in that the inlet channel (44) has a plurality of sub-channels toward the inlet openings (48) leading to the inlet openings (48), and each sub-channel has at least one inlet channel end terminating in an inlet opening (48) , and / or that outlet channel ends extending from the outlet openings (50) have partial channels of a common outlet channel (46), the inlet channel ends and / or the outlet channel ends opening into the combustion chamber (16) at different angles, as seen in radial section to the longitudinal axis (A) or go out from it.

A free-piston linear generator as claimed in claim 11, characterized in that the inlet channel ends farthest from the branching point (52) of the inlet duct (44) at which it divides into subchannels are at a greater angle to that duct section immediately upstream of the branching point (52) are located adjacent to the branching point (52) nearest inlet channel ends, in particular wherein the angle increases with increasing distance from the branching point (52).

13, free piston linear generator according to claim 1 1 or 12, characterized in that seen in radial section view in pairs opposing inlet openings (48) are present, in particular wherein the inlet openings (48) are aligned symmetrically to an axis.

14, free-piston linear generator according to any one of claims 10-13, characterized in that from the inlet channel (44) outgoing annular space (54) to the combustion chamber (14) and the inlet openings (48) with the annular space (54) are flow-connected, in particular wherein the cross-section of the annular space (54) decreases with increasing distance from the inlet channel (44), preferably continuously.

15. free piston linear generator according to any one of claims 10-14, characterized in that the inlet channel (44), the inlet channel ends, the outlet channel (46) and / or the outlet channel ends seen in side view and in the region of the transition to the inlet openings (48) and the outlet openings (50) extend obliquely to the longitudinal axis (A), in particular obliquely inclined to the axial center of the combustion chamber (16).

16, free piston linear generator according to one of the preceding claims, characterized in that a control (42) is provided which is coupled to the stators (34, 36) and these controls, wherein the control is formed, the stators (34, 36) such to control that when moving piston and counter-piston away from each other and / or to each other to the resistance, the at least one rotor (20) when moving along its associated stator (34, 36) is opposed by the stator (34, 36) is changed, such that, starting from the top dead center of the piston (14) and the opposing piston (14 '), the opposing piston assigned to the at least one outlet opening (50) is delayed differently than the piston assigned to the at least one inlet opening, so that the piston and the opposing piston are unsynchronized their bottom dead centers to be moved and the at least one outlet opening (50) is opened in time before the at least one inlet opening (48) and / or s or the movements of the piston and the counter-piston proceed differently from their bottom dead centers by different loading of the stators, so that the at least one outlet opening is closed in time before the at least one inlet opening.

17. free piston linear generator according to any one of the preceding claims, characterized in that a control (42) and associated sensors are provided, with which the movement of piston (14) and counter-piston (14 ') is determined, wherein in the control (42 ) a predetermined one Value by which the counter-piston (14 ') at least precedes the piston (14) and that the controller (42) is programmed to move the stators (34, 36) when moving the piston (14) and the counter-piston (14'). ), if the opposed piston does not precede the piston by at least the predetermined value, different to control and opposite piston and piston different resistances by their associated stators (34, 36) and to move the piston and the opposite piston less synchronous to each other.

18. A method for controlling the piston (14) and / or counter-piston (14 ') of a free-piston linear generator according to one of the preceding claims for generating electrical energy, which is designed according to the counter-piston principle and has an electrical control for the stators (34, 36), characterized by the following step:

Driving the stators (34, 36) away from one another and / or towards each other during movement of the piston and the counter-piston such that the resistance of the at least one rotor (20) when moving along its associated stator (34, 36) from the stator (34, 36), so that when the piston (14) and the counter-piston (14 ') move away from top dead center, the opposed piston associated with the at least one outlet port (50) is changed compared to the piston associated with the at least one inlet port delayed differently and piston and opposed piston are moved non-synchronously to their bottom dead centers and the at least one outlet opening (50) temporally before the at least one inlet opening (48) is opened and / or the movements of the piston and the counter-piston from their bottom dead centers, starting by different Actuation of the stators are initiated differently, so that the at least one outlet opening in time before zumin least one inlet opening is closed.

19. A method for controlling the piston (14) and / or counter-piston (14 ') of a free-piston linear generator according to one of claims 1 to 17 for generating electrical energy, which is designed according to the counter-piston principle and an electrical control for the stators (34, 36). has, characterized by the following steps: Determining the movements of the piston (14) and counter-piston (14 '),

Determining whether the counter-piston (14 ') precedes the piston (14), and

Driving the stators (34, 36) when moving the piston (14) and the counter-piston (14 ') in such a way, if the piston does not always precedes the piston at least a predetermined value, that the piston and the counter piston different resistances by their associated stators (34, 36 ) in order to make the piston and the counter-piston move less synchronously with each other.

20. The method according to claim 19, characterized in that the stators (34, 36) are driven so differently that, due to the different, the piston and the opposed piston opposing resistors, the counter-piston exposing the at least one outlet opening before the piston at least exposes an inlet opening and / or be controlled differently so that the at least one outlet opening is closed in time before the at least one inlet opening.

21. A method according to claim 19 or 20, characterized in that a maximum distance by which the piston precedes the piston, is stored in the control and stators (34, 36) are driven in such a way as soon as the maximum distance is exceeded, that the piston is the counter-piston approaches below the maximum distance approaches.

22. The method according to any one of claims 18 to 21, characterized in that the control at least one stator (34, 36) controls such that it opposes the counter-piston (14 ') a different resistance in the process along the stroke in the direction of bottom dead center as the or the stators (34, 36) associated with the piston (14) oppose the piston (14).