EP3798414B1 - Engine unit for a four-stroke combustion engine with fixed combustion chambers - Google Patents

Description

The invention relates to a motor unit for a four-stroke internal combustion engine for a compressible working medium, comprising a stationary central part, a transport piston and a working piston, the transport piston and the working piston each being rotatably mounted relative to the stationary central part about a common axis of rotation. The invention also relates to a method for operating such a motor unit.

The disclosure document EP 0 085 427 A1 discloses a four stroke internal combustion engine with two rotary pistons. An eccentric piston is eccentrically connected to a motor shaft and is rotatably mounted in a first piston chamber so that it can rotate about an axis of the motor shaft. A working piston, on the other hand, is centrally connected to the motor shaft and is rotatably mounted in a second piston chamber around the axis of the motor shaft. A radially outer orbit for the working piston that is arranged in the second piston chamber has a cutout for a combustion chamber. As a result of a combustion initiated by an ignition in the combustion chamber and a subsequent expansion of a mixture, a valve flap of a pivot valve is pivoted out of its valve seat at the edge of an opening in the combustion chamber opposite the second piston chamber into the second piston chamber. However, the construction is comparatively complicated and the valve cap has to move very quickly during operation. It is also directly adjacent to the combustion chamber and is consequently exposed to very high thermal loads. The combustion chamber is shaped unfavorably for as complete a combustion as possible.

WO 2006/073262 A1 describes another rotary motor. A radially outwardly extending sealing nose of a rotating rotor and a valve element divide an inner space of a cylinder into a suction space and a discharge space. The rotary engine further includes an intake port for intake of a fuel-air mixture into the intake space, a spark plug for igniting the fuel-air mixture in the intake space, and a discharge port formed in the discharge space.

Another rotary internal combustion engine is in GB 2 452 572 A1 shown. The arrangement comprises a housing with a chamber formed therein, a double cam in the center of the chamber and a rotor. The rotor is mounted in the chamber, surrounds the double cam and can be rotated around the double cam. In a cross section transverse to a direction of rotation, a shape of the double cam follows a shape of an inner wall of the chamber in order to ensure a constant distance between the double cam and the inner wall in a radial direction. As a result of the rotation of the rotor, sealing elements which are arranged in the rotor are displaced in the radial direction through the inner wall and the double cams. Depending on a rotational position, the sealing elements separate an inlet volume from a compression volume and a combustion volume from an output volume.

U.S. 5,681,157 A discloses a rotary internal combustion unit for a rotary internal combustion engine which cooperates with an upstream compressor unit. The rotary combustion unit comprises a cylinder in which a rotary piston with two radially outwardly projecting cams is rotatably mounted. Two spring-actuated, retracting and extending slide elements are retracted and extended by the cams. Depending on a rotational position of the rotary piston, each of the slide elements divides one of the two volumes in the cylinder between the two cams into a first volume for admitting the mixture, igniting the mixture and burning it and a second volume for discharging the combustion products. The compression is performed by the upstream compressor unit.

US 2011/083637 A1 shows an engine unit with a double combustion chamber and six blades.

Known rotary piston engines are often constructed in a complicated manner. For example, they often have many moving parts and complex flap or slide arrangements. In addition, such sensitive flap or slide arrangements are exposed to high pressures, high accelerations and high temperatures. This can lead to higher production costs, higher costs for suitable materials, high maintenance requirements and poor reliability. In addition, the efficiency of known rotary piston engines is often poor.

The object of the invention is to create a motor unit for a four-stroke internal combustion engine with rotary pistons which enables greater efficiency.

This object is achieved by a motor unit for a four-stroke internal combustion engine for a compressible working medium with the features of claim 1.

The motor unit comprises a stationary central part, a transport piston and a working piston, the transport piston and the working piston being firmly connected to one another and being mounted rotatably about a common axis of rotation relative to the stationary central part.

• wobei aufgrund einer Form des Transportkolbens mindestens ein erstes Arbeitsvolumen zwischen dem Transportkolben und der ersten Arbeitsfläche ausgebildet ist und
• wobei aufgrund einer Form des Arbeitskolbens zwischen dem Arbeitskolben und der zweiten Arbeitsfläche mindestens ein zweites Arbeitsvolumen ausgebildet ist.

The stationary middle part comprises a combustion chamber housing which is arranged between the transport piston and the working piston and has a first working surface for the transport piston and a second working surface for the working piston,

• wherein, due to a shape of the transport piston, at least one first working volume is formed between the transport piston and the first working surface, and
• wherein, due to a shape of the working piston, at least one second working volume is formed between the working piston and the second working surface.

In addition, the combustion chamber housing has at least one combustion chamber, the at least one combustion chamber having a first combustion chamber opening which opens on the first working surface and a second combustion chamber opening which opens on a second working surface.

The at least one combustion chamber is integrated into the burner housing of the stationary central part. A shape or geometry of the combustion chamber depends neither on a rotary position of the transport piston nor on a rotary position of the rotary piston. The geometry of the at least one combustion chamber can therefore be freely designed and optimized. This enables the motor unit to be particularly efficient.

In addition, the mechanically and thermally stressful ignition takes place exclusively in the combustion chamber and thus exclusively in the stationary combustion chamber housing. The transport piston is only minimally thermally and mechanically stressed by the ignition process as such, namely only in an area that is in contact with the first combustion chamber opening at this point in time. Even the working piston is only minimally thermally and mechanically stressed by the ignition process as such, namely only in an area that is in contact with the second inlet opening at this point in time.

In addition, the combustion chamber housing together with the at least one combustion chamber is arranged directly between the transport piston and the working piston. The combustion chamber housing thus directly separates an intake and compression side of the engine unit (a cold side of the engine unit) and one Expansion and discharge side of the motor unit (a hot side of the motor unit). As a result, the geometry and / or the materials of the motor unit on the cold side and the hot side can be selected independently of one another. This allows a further increase in the efficiency of the motor unit and a cheaper production of the same.

In a further development, lighter materials (with lower density), less temperature-resistant materials and / or lower material thicknesses are used on the cold side. That saves costs. As an alternative or in addition, this also increases the efficiency. For example, it is conceivable that material or materials with better sliding properties are used on the cold side than on the hot side due to the lower mechanical and thermal loads. In particular, the transport piston can have a lighter material, a less temperature-resistant material and / or a smaller material thickness than the working piston. Alternatively or additionally, the transport piston can have a sliding coating.

The transport piston and the working piston are each rotary piston.

The transport piston is used to suck in and compress the working medium. In particular, the first working volume is used to suck in and compress the working medium.

The working piston is used to expand and expel combustion products of the working medium. In particular, the second working volume is used to expand and expel the combustion products.

Since the combustion chamber housing is arranged between the transport piston and the working piston, the second working surface and the first working surface are formed on opposite sides of the combustion chamber housing.

For example, the first working surface can be arranged on an inner surface of the combustion chamber housing in a radial direction that is perpendicular to the axis of rotation. The second working surface is then arranged on an outer surface of the combustion chamber housing. The reverse is also possible.

With such a "radial design" of the motor unit, however, it is particularly advantageous if the second working surface is arranged on the outer surface. Due to the larger circumference of the second work surface, the hot side, in particular the hotter second work surface, can be cooled better. That increases the reliability. In addition, this arrangement makes it easier to create a large maximum expansion volume. This creates a high thermodynamic efficiency.

In particular, the combustion chamber housing can particularly preferably have an at least substantially hollow-cylindrical basic shape, the first working surface being arranged on a radially inner cylinder jacket surface and the second working surface being arranged on a radially outer cylinder jacket surface. This variant can be produced easily and inexpensively. The reverse arrangement is also possible.

In another embodiment, the first working surface can be arranged on an end surface of the combustion chamber housing in a longitudinal direction which runs parallel to the axis of rotation, for example on an upper end surface. The second working surface is then arranged on an opposite end face of the combustion chamber housing in the longitudinal direction, for example on a lower end face. Such a design is also referred to as an "axial design". In this embodiment, the transport piston and the working piston can be shaped similarly or even identically. The motor unit is in this variant easier to maintain, since both the transport piston and the working piston are located on the outside of the combustion chamber housing.

The working medium is ignited in the at least one combustion chamber. The motor unit preferably comprises an ignition device for igniting the working medium in the at least one combustion chamber. Alternatively or additionally, ignition in the combustion chamber can take place by self-ignition.

In a further development of the invention, the at least one combustion chamber has an ellipsoidal, spherical or cylindrical basic shape. Sharp-angled or obtuse-angled shapes are also possible, but have poorer combustion properties. The specific design of the combustion chamber's geometry optimizes the ignition behavior and the burn-off behavior of the working medium and thus ultimately the performance and efficiency of the motor unit.

In a preferred embodiment, the transport piston and the working piston are non-rotatably connected. This allows a particularly simple and reliable construction. In particular, the transport piston and the working piston can be rigidly connected in a rotationally fixed manner.

In a further development, the motor unit has a piston adjustment for the targeted adjustment of a relative rotation (an angular offset) between the transport piston and the working piston. For example, the piston adjustment can be set up to adjust the angular offset in an angular range of -10 ° to 10 °.

A direction of rotation of the transport piston corresponds to a direction of rotation of the working piston. In this respect, it is generally sufficient to use the term direction of rotation.

A piston surface of the transport piston (a first piston surface) is preferably in sealing contact with the first working surface in some areas and is in some areas away from the first working surface in order to form the at least one first working volume.

This ensures safe and direct guidance of the transport piston on the first working surface and, at the same time, a structurally simple and reliable design of the at least one first working volume.

In other words, the first piston surface comprises at least one sliding area of the transport piston, which is configured to slide along (sealingly) along the first working surface in the direction of rotation of the transport piston. The at least one sliding area of the transport piston serves as a sealing surface for sealing the at least one first working volume along the direction of rotation of the transport piston.

Correspondingly, the first piston surface comprises at least one working volume area in which the first piston surface is removed from the first working surface in order to form the at least one first working volume.

Particularly preferably, the first piston surface (in particular the at least one sliding area of the transport piston) closes the first combustion chamber opening when the first piston surface, depending on a rotational position of the transport piston (in particular the at least one sliding area of the transport piston), seals against an area of the first working surface with the first combustion chamber opening is applied. In particular, the first piston surface can then directly close the first combustion chamber opening.

The at least one first working volume is moved along the first working surface when the transport piston rotates. The first volume of work can be subdivided into a suction volume and a compression volume depending on the rotational position of the transport piston (and thus depending on a position of the at least one first working volume relative to the first working surface). In this way, the working medium is moved on the cold side.

Particularly preferably, a number of the sliding areas of the transport piston corresponds exactly to a number of the first working volumes. The number of sliding areas thus corresponds to a number of working volume areas of the transport piston. This number can be one or more, for example. "Several" means "at least two" in the context of this disclosure. If several working volume areas are formed, these are separated from one another in the direction of rotation of the transport piston by the sliding areas of the transport piston. In this way, several first working volumes can be formed reliably and easily, which in turn are each subdivided into a suction volume and a compression volume as a function of their respective rotational position.

According to another aspect, a piston surface of the working piston preferably lies sealingly against the second working surface in some areas (a second piston surface) and is in some areas away from the second working surface in order to form the at least one second working volume.

This ensures safe and direct guidance of the working piston on the second working surface and, at the same time, a structurally simple and reliable design of the at least one second working volume.

In other words, the second piston surface comprises at least one sliding area of the working piston which is configured to slide (sealingly) along the second working surface in the direction of rotation of the working piston. the at least one sliding area of the working piston serves as a sealing surface for sealing the at least one second working volume along the direction of rotation of the working piston.

Correspondingly, the second piston surface comprises at least one working volume area in which the second piston surface is removed from the second working surface in order to form the at least one second working volume.

Particularly preferably, the second piston surface (in particular the at least one sliding area of the working piston) closes the second combustion chamber opening when the second piston surface (in particular the at least one sliding area of the working piston), depending on a rotational position of the working piston, forms a seal on an area of the second working surface with this second combustion chamber opening is applied. In particular, the second piston surface can then directly close the second combustion chamber opening.

The at least one second working volume is moved along the second working surface when the working piston rotates. The second working volume can be subdivided into an expansion volume and an ejection volume depending on the rotational position of the working piston (and thus depending on a position of the at least one second working volume relative to the second working surface). In this way, the combustion products are routed on the hot side.

Particularly preferably, a number of the sliding areas of the working piston corresponds exactly to a number of the second working volumes. The number of sliding areas thus corresponds to a number of working volume areas of the working piston. This number can be one or more, for example. If several working volume areas are formed, these are separated from one another in the direction of rotation of the working piston by the sliding areas of the working piston. In this way, several second working volumes can be formed reliably and easily, which in turn are each subdivided into an expansion volume and an ejection volume as a function of their respective rotational position.

The first combustion chamber opening of the at least one combustion chamber, the at least one combustion chamber and the second combustion chamber opening of the at least one combustion chamber establish a fluid connection between the first working surface and the second working surface.

In a preferred embodiment it is provided that the first piston surface closes the first combustion chamber opening at a point in time of maximum compression of the working medium and / or an ignition point for the at least one combustion chamber and that at the same time the second piston surface closes the second combustion chamber opening.

As a result, the actual ignition takes place in the at least one completely closed combustion chamber. This increases security and reliability. If at least one shut-off device is designed as a flap or slide, as will be described further below, then the at least one shut-off device is not exposed to any mechanical stress from the combustion at this point in time. Furthermore, the volume of the working medium for the respective ignition process is minimal.

Alternatively, the ignition takes place preferably at a delayed ignition time, immediately at which a new expansion volume has started to open at the second combustion chamber opening. The delayed ignition point between the point in time of maximum compression of the working medium and a latest possible ignition point at which the stated expansion volume particularly preferably reaches 10% of its later, maximum volume is preferred has, most preferably 5%. The transport piston closes the first combustion chamber opening at the latest possible ignition point.

According to a further alternative, the ignition takes place preferably at a leading ignition time, immediately before the compression volume has completely collapsed at the first combustion chamber opening. The leading ignition time between the time of maximum compression of the working medium and an earliest possible ignition time at which the just mentioned compression volume is particularly preferably reduced to 10% of its earlier, maximum volume is preferred, very preferably to 5%. The working piston closes the second combustion chamber opening at the earliest possible ignition point.

In particular, the engine unit can have an ignition adjustment which automatically adjusts the ignition point between the earliest possible ignition point and the latest possible ignition point at least as a function of a speed and / or supply quantity of the working medium per unit of time. This improves efficiency, power and torque in difficult operating conditions.

An inlet opening for sucking in the working medium is preferably formed in the stationary central part for each of the at least one combustion chamber, which inlet opening is swept over by the at least one first working volume when the transport piston is rotated. So there is at least one inlet opening. If there are several combustion chambers, there is one inlet opening for each of the several combustion chambers, particularly preferably precisely one inlet opening in each case.

The at least one inlet opening serves to suck in or admit the working medium into the at least one first working volume (or more precisely its suction volume).

The at least one inlet opening is particularly preferably formed in the first working surface or in a lateral sealing surface of the stationary central part for the transport piston. The latter is a surface which adjoins the first working surface and on which the transport piston slides along in a sealing manner. The lateral sealing surface of the stationary central part for the transport piston can be formed locally perpendicular to the first working surface, viewed in a sectional plane perpendicular to the direction of rotation. It can extend in the shape of a cylinder jacket (axial design) or circular ring (radial design) around the axis of rotation along the direction of rotation.

In a particularly preferred development, a completely retractable shut-off device is arranged in the first working surface for each of the at least one combustion chamber, which, viewed along the direction of rotation of the transport piston, is positioned behind the first combustion chamber opening of this combustion chamber and in front of the next inlet opening and which depends on the rotational position of the Transport piston limits a compression volume in the at least one first working volume. In a further development, it subdivides the at least one working volume into the suction volume and the compression volume as a function of the rotational position of the transport piston.

The shut-off device divides the compression volume in the at least one first working volume as a function of the rotational position of the transport piston. A presence and a volume of this compression volume are dependent on the angle of rotation. The compression volume decreases as it sweeps over the first combustion chamber opening. This removes the working medium the compression volume is pressed through the first combustion chamber opening into the associated combustion chamber and compressed. In a further development, the compression volume is completely collapsed precisely when the associated first working volume has completely passed over the first combustion chamber opening. Complete in this special context means that a volume of the compression volume at this point in time is a maximum of 10%, even more preferably a maximum of 5% of a maximum volume of the compression volume.

Said shut-off device prevents the working medium in the at least one first working volume (or in particular in the compression volume formed therein) from being transported past the first combustion chamber opening.

Most preferably, this shut-off device is positioned immediately behind the first combustion chamber opening of this combustion chamber and / or immediately in front of the next inlet opening, viewed along the direction of rotation of the transport piston. In this specific context, direct means that a respective angular offset of the two elements about the axis of rotation is a maximum of 30 °, extremely preferably a maximum of 15 °. With this arrangement, the maximum suction volume (and thus the maximum compression volume) and consequently the compression achieved are particularly high. This ensures high performance of the motor unit.

At least one shut-off device is therefore arranged in the first work surface.

Since the shut-off device is arranged in the first working surface, the forces acting on it are safely transferred to the combustion chamber housing and thus to the stationary central part. When this shut-off device is completely sunk, no part of the shut-off device protrudes from the first work surface in the direction of the transport piston. The at least one sliding surface of the transport piston can therefore sweep over the completely sunk shut-off device completely unhindered. At this time, of course, the shut-off device cannot subdivide the at least one first working volume. When the at least one first working volume then passes over the shut-off device, the shut-off device extends into the at least one first working volume in order to subdivide it into the suction volume and the compression volume.

If exactly one combustion chamber, exactly one first combustion chamber opening and exactly one inlet opening are formed for this combustion chamber, then this inlet opening is of course also the next inlet opening (viewed in the direction of rotation of the transport piston) in the above sense. If, for example, several combustion chambers are formed, each with a combustion chamber opening and an inlet opening for each of the combustion chambers, then the next inlet opening (viewed in the direction of rotation of the transport piston) is that of the inlet openings which are used for sucking in the working medium for the (seen in the direction of rotation of the transport piston) ) next combustion chamber is used.

An outlet opening for ejecting combustion products of the working medium is preferably formed in the stationary central part for each of the at least one combustion chamber, which outlet opening is swept over by the at least one second working volume when the working piston rotates. So there is at least one outlet opening. If there are several combustion chambers, there is one outlet opening for each of the several combustion chambers, particularly preferably precisely one outlet opening in each case.

The at least one outlet opening serves to discharge or expel the combustion products from the at least one second working volume (or more precisely its expulsion volume).

The at least one outlet opening is particularly preferably formed in the second working surface or in a lateral sealing surface of the stationary central part for the working piston. The latter is a surface which adjoins the second working surface and on which the working piston slides along in a sealing manner. The lateral sealing surface of the stationary central part for the working piston can be formed locally perpendicular to the second working surface, viewed in a sectional plane perpendicular to the direction of rotation. It can extend in the shape of a cylinder jacket (axial design) or circular ring (radial design) around the axis of rotation along the direction of rotation.

In a particularly preferred development, a completely retractable shut-off device is arranged in the second working surface for each of the at least one combustion chamber, which is positioned in front of the second combustion chamber opening of this combustion chamber and behind the previous outlet opening, viewed along a direction of rotation of the working piston, and which is dependent on the rotational position of the working piston in which at least one second working volume limits an expansion volume. In a further development, depending on the rotational position of the working piston, it divides the at least one second working volume into the expansion volume and the discharge volume.

The shut-off device divides the expansion volume in the at least one second working volume as a function of the rotational position of the working piston. A presence and a volume of this expansion volume are dependent on the angle of rotation. The expansion volume increases as it sweeps over the second combustion chamber opening. This allows the products of combustion expand out of the combustion chamber through the second combustion chamber opening into the expansion volume and expand further in the expansion volume. In a further development, the expansion volume is then newly divided or newly formed, shortly before the associated at least one second working volume begins to sweep over the second combustion chamber opening. "Just before" means in this special context that a volume of the expansion volume has only reached a maximum of 10%, more preferably a maximum of 5% of its maximum volume before the associated at least one second working volume begins to sweep over the second combustion chamber opening.

Said shut-off device prevents the combustion products from flowing out of the second combustion chamber opening into a part of the at least one second working volume (it can in particular be one of the output volumes) which, viewed in the direction of rotation of the working piston, is still located in front of the second combustion chamber opening.

Most preferably, this shut-off device is positioned immediately in front of the second combustion chamber opening of this combustion chamber and immediately behind the previous outlet opening, viewed along the direction of rotation of the working piston. In this specific context, direct means that a respective angular offset of the two elements about the axis of rotation is a maximum of 30 °, extremely preferably a maximum of 15 °. With this arrangement, the maximum expansion volume and consequently the achieved expansion ratio become particularly high. This ensures high performance and high efficiency of the motor unit.

So there is at least one shut-off device in the second work surface.

Since the shut-off device is arranged in the second working surface, the forces acting on it are safely on the combustion chamber housing and thus on transfer the fixed middle part. This also specifies the direction of rotation of the working piston: While the pressure forces resulting from the expansion are transferred from this shut-off device to the stationary central part against the direction of rotation of the working piston, on the other hand, these pressure forces drive the working piston along its direction of rotation. This ensures that the expansion volume increases with further rotation. When this shut-off device is completely sunk, no part of the shut-off device protrudes from the second working surface in the direction of the working piston. The at least one sliding surface of the working piston can therefore easily pass over the completely sunk shut-off device. At this time, of course, the shut-off device cannot subdivide the at least one second working volume. When the at least one second working volume then passes over the shut-off device, the shut-off device extends into the at least one second working volume in order to subdivide it into the expansion volume and the discharge volume.

If exactly one combustion chamber, exactly one first combustion chamber opening and exactly one outlet opening are formed for this combustion chamber, then this outlet opening is of course also the previous outlet opening (viewed in the direction of rotation of the working piston) in the above sense. If, for example, several combustion chambers are formed, each with a combustion chamber opening and an outlet opening for each of the combustion chambers, then the previous outlet opening (viewed in the direction of rotation of the working piston) in the above sense is that of the outlet openings which are used to expel the combustion products from the (in the direction of rotation of the working piston) the previous combustion chamber is used.

In a particularly preferred embodiment, the at least one first shut-off device, which is arranged in the first working surface, is always sealing on the first piston surface. Anytime in this context means independent of the rotational position of the transport piston. As an alternative or in addition, the at least one second shut-off device, which is arranged in the second working surface, is in sealing contact with the second piston surface at all times.

According to a further aspect, the transport piston is particularly preferably shaped such that each of the at least one shut-off device, which is arranged in the first working surface, is subjected to a phase-wise constant acceleration when the transport piston rotates (at a constant angular velocity).

Such a configuration ensures that a contact pressure and thus frictional forces on the at least one shut-off device and its wear are minimal. Furthermore, this refinement ensures that a ratio of a maximum speed of the at least one shut-off device to the rotational speed is minimal. This enables higher speeds.

At this point it is recalled that, according to one embodiment, only exactly one shut-off device can be arranged in the first work surface. The "each" then applies to exactly one shut-off device in the first work surface.

• Ein Abstand der ersten Kolbenfläche von der ersten Arbeitsfläche wird (bei nicht drehendem Transportkolben bzw. zu einem feststehenden Zeitpunkt betrachtet) durch eine stetige, abschnittsweise definierte Funktion in Abhängigkeit von einer Winkelkoordinate um die Drehachse beschrieben, wobei ein Wert der Winkelkoordinate entgegen der Drehrichtung des Transportkolbens gesehen ansteigt.
• In dem mindestens einen Gleitbereich ist der Abstand null. Anders ausgedrückt ist die erste Kolbenfläche ist in dem mindestens einen Gleitbereich parallel zu der ersten Arbeitsfläche. In dem mindestens einen Gleitbereich ist eine Ableitung des Abstands (nach der Winkelkoordinate) null. Entsprechend ist auch eine zweite Ableitung des Abstands (nach der Winkelkoordinate) null.
• Der mindestens eine Arbeitsvolumen-Bereich weist einen Zunahmebereich auf, in welchem der Abstand zunimmt. In dem Zunahmebereich vergrößert sich der Abstand stetig differenzierbar. Dabei nimmt die Ableitung des Abstands zunächst linear von null bis zu einem Maximalwert zu und dann linear von dem Maximalwert bis nach null ab. Das heißt, die zweite Ableitung des Abstands weist in einem Anfangsteil des Zunahmebereichs einen positiven, konstanten Wert und in einem Endbereich des Zunahmebereichs einen negativen, konstanten Wert auf. Der Betrag der zweiten Ableitung des Abstands kann in dem Zunahmebereich konstant sein, sodass sich lediglich ein Vorzeichen der zweiten Ableitung ändert. Der Vorzeichenwechsel der zweiten Ableitung (von positiv zu negativ) tritt an dem Maximalwert der ersten Ableitung auf.
• Der mindestens eine Arbeitsvolumen-Bereich weist danach einen Abnahmebereich auf, in welchem der Abstand abnimmt. In dem Abnahmebereich verkleinert sich der Abstand stetig differenzierbar. Dabei nimmt die Ableitung des Abstands zunächst linear von null bis zu einem Maximalwert ab und dann linear von dem Minimalwert bis nach null zu. Das heißt, die zweite Ableitung des Abstands weist in einem Anfangsteil des Abnahmebereichs einen negativen, konstanten Wert und in einem Endbereich des Abnahmebereichs einen positiven, konstanten Wert auf. Der Betrag der zweiten Ableitung des Abstands kann in dem Abnahmebereich konstant sein, sodass sich lediglich ein Vorzeichen der zweiten Ableitung ändert. Der Vorzeichenwechsel der zweiten Ableitung (von negativ zu positiv) tritt an dem Maximalwert der ersten Ableitung auf.
• Zwischen dem Zunahmebereich und dem Abnahmebereich kann ein Konstantbereich vorgesehen sein, in welchem der Abstand konstant ist. Anders ausgedrückt ist die erste Kolbenfläche ist in dem Konstantbereich parallel und gleichmäßig beabstandet zu der ersten Arbeitsfläche. In dem Konstantbereich sind die Ableitung und die zweite Ableitung null.

The first working surface and the first piston surface are very preferably designed in accordance with the following development:

• A distance between the first piston surface and the first working surface is described (when the transport piston is not rotating or at a fixed point in time) by a continuous, sectionally defined function depending on an angular coordinate around the axis of rotation, a value of the angular coordinate opposite to the direction of rotation of the transport piston seen increases.
• The distance is zero in the at least one sliding area. In other words, the first piston surface is parallel to the first working surface in the at least one sliding area. In the at least one sliding area, a derivative of the distance (according to the angular coordinate) is zero. Correspondingly, a second derivative of the distance (according to the angular coordinate) is also zero.
• The at least one working volume area has an increase area in which the distance increases. In the increase area, the distance increases continuously differentiable. The derivation of the distance initially increases linearly from zero to a maximum value and then decreases linearly from the maximum value to zero. That is to say, the second derivative of the distance has a positive, constant value in an initial part of the increasing area and a negative, constant value in an end area of the increasing area. The magnitude of the second derivative of the distance can be constant in the increase range, so that only one sign of the second derivative changes. The change in sign of the second derivative (from positive to negative) occurs at the maximum value of the first derivative.
• The at least one working volume area then has a decrease area in which the distance decreases. In the decrease area, the distance decreases continuously differentiable. The derivation of the distance initially decreases linearly from zero to a maximum value and then increases linearly from the minimum value to zero. That is, the second derivative of the distance has a negative, constant value in an initial part of the decrease area and a positive, constant value in an end area of the decrease area. The magnitude of the second derivative of the distance can be constant in the decrease region, so that only one sign of the second derivative changes. The change in sign of the second derivative (from negative to positive) occurs at the maximum value of the first derivative.
• A constant area, in which the distance is constant, can be provided between the increase area and the decrease area. In other words, the first piston surface is parallel in the constant range and is equally spaced from the first working surface. In the constant range, the derivative and the second derivative are zero.

The distance can extend along the radial direction or along the longitudinal direction.

If the distance extends in the radial direction, the first working surface preferably has the shape of a cylinder jacket. The change in the distance as a function of the angular coordinate is thus defined solely by the shape of the first piston surface. The continuous function, defined in sections, then describes the deviation of the first piston surface from an ideal cylinder jacket shape.

If the distance extends in the longitudinal direction, the first working surface preferably has a circular ring shape. The change in the distance as a function of the angular coordinate is thus defined solely by the shape of the first piston surface. The continuous function, defined in sections, then describes the deviation of the first piston surface from an end surface of an ideal hollow cylinder.

If the transport piston has several sliding areas and several working volume areas, the function can be repeated accordingly.

When the transport piston rotates at a constant angular speed along its direction of rotation, a function corresponding to the above function describes the distance over time at the point of the at least one Locking device in the first work surface. The constant positive second derivative in the context described above then leads to a constant positive acceleration of the shut-off device along a direction of the distance, that is, perpendicular to the first working surface from the first working surface to the first piston surface. The above-mentioned refinements of the function are therefore examples of how it can be ensured that the at least one shut-off device, which is arranged in the first working surface, is subjected to a phase-wise constant acceleration when the transport piston rotates at a constant angular velocity.

Alternatively or additionally, the working piston is preferably shaped such that each of the at least one shut-off device, which is arranged in the second working surface, is subjected to a phase-wise constant acceleration when the working piston rotates at a constant angular velocity. The comments and advantages listed above apply accordingly. In particular, a distance between the second piston surface and the second working surface can be characterized in the same way by a continuous function defined in sections as a function of the angular coordinate about the axis of rotation.

If the increase area and / or the decrease area for the distance between the second working surface and the second piston surface are made steeper while the second working volume remains the same (i.e. have higher amounts of the first derivative), then a torque of the motor unit is improved as a result. It is therefore advantageous, particularly on the side of the working piston, to provide the constant area between the increase area and the decrease area.

Particularly preferably, each shut-off device comprises a slide, a flap, or a door, which in an associated matching recess in the combustion chamber housing is completely retractable. Depending on where the shut-off device is provided, the associated recess is formed in the first working surface or in the second working surface of the combustion chamber housing.

The flaps ensure safer guidance, but they take up more space than the slide. The doors also have a very small footprint.

Various designs are possible in this regard. For example, each of the at least one shut-off device in the work surface can have a slide, while each of the at least one shut-off device in the second work surface has a flap. This is particularly advantageous in radial designs when the second working surface is arranged on the radial outer surface of the combustion chamber housing. The first working surface on the radial inside of the combustion chamber housing offers less space. So the sliders are an advantage here. The second work surface offers more space due to its larger size. In addition, the mechanical and thermal loads for the at least one shut-off device in the second working area are greater. So this is where flaps are particularly suitable.

The design of the at least one shut-off device as a door is ideal for radial designs of the motor unit. When the respective door is closed, an inside of this door defines part of a wall of the associated at least one combustion chamber. As a result, the shape of the combustion chamber can be designed even more freely. For example, the inside of the door can have the shape of part of a sphere. In particular, for each of the at least one combustion chamber, a door for the first combustion chamber opening can be formed in the first working surface and a door for the second combustion chamber opening can be formed in the at least second working surface. So can at least one Combustion chamber even have a spherical wall in the area of the first combustion chamber opening and the second combustion chamber opening when these two doors are closed.

If the door is arranged in the first working surface, then it closes the first combustion chamber opening of the combustion chamber when the at least one sliding area of the transport piston passes over this first combustion chamber opening. An outside of the door can be shaped in such a way that the outside in this state continues the first work surface in the area of this first combustion chamber opening in a flush manner and conforms to its shape. In this embodiment, the first piston surface does not close the first combustion chamber opening directly, but rather indirectly via the door. However, the first piston surface (or its at least one sliding area) supports the door on the outside when the door is closed. The door can transfer the pressure forces in the associated combustion chamber directly and practically completely to the first piston surface when the door is completely closed. This ensures high stability and high reliability. In a functional sense, too, the first piston surface closes the first combustion chamber opening, since it pushes the associated door shut, that is, it closes it before ignition and keeps it closed during ignition.

If the door is arranged in the first working surface, it is preferably hinged to the combustion chamber housing on the side of the first working surface so that it can rotate along the direction of rotation of the transport piston immediately behind the associated first combustion chamber opening. The door can be pivoted about a door pivot axis, which is parallel to the axis of rotation (of the transport piston), in order to open or close the associated first combustion chamber opening. When the at least one first working volume (or the at least one working volume area of the transport piston) sweeps over the associated first combustion chamber opening, the door opens. As a result, it seals the compression volume in this first working volume. At the same time, through the open door, that compressed working medium flow from the compression volume into the combustion chamber.

A length of the door perpendicular to the door pivot axis is in this case preferably greater than the maximum distance between the first working surface and the first piston surface. Even when the door is opened to the maximum, a pressure of the working medium in the compression volume presses the door more strongly onto the first piston surface. The pressure of the working medium in the compression volume contributes to an improved sealing of the compression volume on the door.

The design of the shut-off device as a door thus has the advantage that no elastic element (such as a spring) or at least no strong elastic element has to provide this seal. In a further development, however, an opening aid (such as a spring) is still provided, which provides a force for opening the door. As a result, the door opens quickly and safely as soon as it is swept over by the at least one first working volume. Since only comparatively small forces are required for opening, the opening aid can, for example, comprise a magnetic element on an end of the door facing away from the door pivot axis and at least one magnetic element on or below the first piston surface.

If the door is arranged in the second working surface, then it closes the second combustion chamber opening of the associated combustion chamber when the at least one sliding area of the working piston sweeps over this second combustion chamber opening. An outside of the door can be shaped in such a way that in this state the outside continues the second work surface in the area of this second combustion chamber opening in a flush manner and conforms to its shape. In this embodiment, the second piston surface does not close the second combustion chamber opening directly, but rather indirectly via the door. However, the second piston surface provides support (or their at least one sliding area) the door from the outside when the door is closed. The door can transfer the pressure forces in the associated combustion chamber directly and practically completely to the second piston surface when the door is completely closed. This ensures high stability and high reliability. In a functional sense, too, the second piston surface closes the second combustion chamber opening, since it closes the associated door, that is to say it closes before ignition and keeps it closed during ignition.

If the door is arranged in the second working surface, it is preferably articulated so that it can rotate along the direction of rotation of the working piston immediately in front of the associated second combustion chamber opening on the combustion chamber housing on the side of the second working surface. The door can be pivoted about a door pivot axis, which is parallel to the axis of rotation, in order to open or close the associated second combustion chamber opening. When the at least one second working volume (or the at least one working volume area of the working piston) sweeps over the associated second combustion chamber opening, the door opens. As a result, it seals the expansion volume in this second working volume. At the same time, the highly pressurized combustion products can flow out of the combustion chamber into the expansion volume through the open door.

In this case, a length of the door perpendicular to the door pivot axis is preferably greater than the maximum distance between the second working surface and the second piston surface. Even when the door is opened to the maximum, the pressure of the products of combustion in the expansion volume presses the door more strongly on the second piston surface. The pressure thus contributes to an improved sealing of the expansion volume on the door. The design of the shut-off device as a door has the advantage that there is no elastic element (such as, for example a spring) or at least no strong elastic element has to provide this seal. In any case, the door opens automatically due to the pressure of the combustion products in the associated combustion chamber. In one development, however, an opening aid (such as a spring) is still provided, which provides a force for opening the door. As a result, the door remains safely open, even if the at least one second working volume has almost completely swept over the door and the pressure in the expansion volume approaches a minimum value. Since only comparatively small forces are required to hold open, the opening aid can for example comprise a magnetic element on an end of the door facing away from the axis of rotation and at least one magnetic element on or below the second piston surface.

In a further development of the invention, the combustion chamber housing of the stationary central part has a plurality of combustion chambers which are arranged symmetrically about the axis of rotation.

Alternatively or additionally, the combustion chambers are arranged offset from one another by the same angular distances along the direction of rotation of the working piston. For example, these angular distances between adjacent combustion chambers can be 120 ° in an embodiment with three combustion chambers, and 90 ° in an embodiment with four combustion chambers.

Such a regular arrangement simplifies production and reduces costs. It also ensures smoother running and more even engine power.

The transport piston preferably has a hollow cylindrical basic shape, with a cylinder jacket surface facing the combustion chamber housing being the first piston surface and is partially set back away from the combustion chamber housing in order to form the at least one first working volume between the transport piston and the combustion chamber housing.

For example, if the first working surface is on the radially inner cylinder jacket surface of the combustion chamber housing, then a radially outer cylinder jacket surface of the transport piston facing the combustion chamber housing is set back radially inward in some areas. This means that the radially outer cylinder jacket surface of the transport piston is - compared to an ideal hollow cylinder - recessed or indented in some areas. There is at least one such recess (indentation).

Alternatively or additionally, the working piston preferably has a hollow cylindrical basic shape, with a cylinder surface facing the combustion chamber housing forming the second piston surface and being set back in some areas away from the combustion chamber housing in order to form the at least one second working volume between the working piston and the combustion chamber housing.

In a particularly preferred embodiment, the transport piston and the working piston are concentric with one another around the axis of rotation with respect to their respective hollow cylindrical basic shapes, the combustion chamber housing being arranged in the radial direction (transverse to the axis of rotation) directly between the transport piston and the working piston. In this case, the combustion chamber housing separates an area for the transport piston (a first piston chamber) from an area for the second transport piston (a second piston chamber), viewed along the radial direction.

If, for example, the second working surface is on the radially outer cylinder jacket surface of the combustion chamber housing, then a radially inner one, the Combustion chamber housing facing cylinder jacket surface of the working piston partially set back radially outward. This means that the radially inner cylinder jacket surface of the working piston is - compared to an ideal hollow cylinder - recessed or indented in some areas. There is at least one such recess (indentation).

In another, preferred embodiment, the transport piston and the working piston are arranged offset along the longitudinal direction, the combustion chamber housing being arranged along the longitudinal direction directly between the transport piston and the working piston. In this case, the combustion chamber housing, viewed in the longitudinal direction, separates the area for the transport piston (the first piston chamber) from the area for the second transport piston (the second piston chamber) from one another.

In a particularly preferred embodiment, the transport piston has a hollow cylindrical basic shape, with an end face facing the combustion chamber housing forming the first piston surface and being partially set back along the longitudinal direction in order to form the at least one first working volume between the transport piston and the combustion chamber housing

For example, if the first working surface is an axially upper end face of the combustion chamber housing, then an axially lower cylinder jacket end face of the transport piston facing the combustion chamber housing is set back upwards in some areas in the longitudinal direction (i.e. axially). This means that the axially lower cylinder end face of the transport piston is - compared to an ideal hollow cylinder - recessed in some areas or indented upwards. There is at least one such recess (indentation).

Alternatively or additionally, it is particularly preferred that the working piston has a hollow cylindrical basic shape, with an end face facing the combustion chamber housing forming the second piston surface and being set back in some areas in order to form the at least one second working volume between the working piston (and the combustion chamber housing).

For example, if the second working surface is an axially lower end face of the combustion chamber housing, then an axially upper cylinder jacket end face of the working piston facing the combustion chamber housing is set back downwards in some areas in the longitudinal direction (i.e. axially). This means that the axially upper cylinder end face of the working piston is - compared to an ideal hollow cylinder - recessed in some areas or indented downwards. There is at least one such recess (indentation).

A further object of the invention is to provide a method with which the engine unit with rotary pistons for a four-stroke internal combustion engine can be operated with higher efficiency.

According to the invention, a method for operating a motor unit for a four-stroke internal combustion engine for a compressible working medium according to any of the previous embodiments is provided, wherein the inlet opening for sucking in the working medium is formed for the at least one combustion chamber, which when the transport piston rotates from the at least one first working volume is swept over, and wherein for the at least one combustion chamber the outlet opening is formed for ejecting combustion products of the working medium, which is swept over by the at least one second working volume when the working piston rotates.

• einen Einlassschritt, in welchem das mindestens eine erste Arbeitsvolumen die Einlassöffnung überstreicht;
• einen Verdichtungsschritt, umfassend:
  • Bewegen des mindestens einen ersten Arbeitsvolumens von der Einlassöffnung zu der ersten Brennkammeröffnung,
  • Verschließen der zweiten Brennkammeröffnung durch die zweite Kolbenfläche;
  • Abtrennen des Verdichtungsvolumens innerhalb des mindestens einen ersten Arbeitsvolumens wobei das Verdichtungsvolumen in Fluidverbindung mit der ersten Brennkammeröffnung und der mindestens einen Brennkammer steht,
  • Verkleinern des Verdichtungsvolumens,
  • Verschließen der ersten Brennkammeröffnung durch die erste Kolbenfläche, und
  • Zünden des Arbeitsmediums in der mindestens einen Brennkammer;
• einen Expansionsschritt, umfassend:
  • Bewegen des mindestens einen zweiten Arbeitsvolumens zu der zweiten Brennkammeröffnung,
  • Abtrennen des Expansionsvolumens innerhalb des mindestens einen zweiten Arbeitsvolumens, wobei das Expansionsvolumen in Fluidverbindung mit der zweiten Brennkammeröffnung und der mindestens einen Brennkammer steht,
  • Vergrößern des Expansionsvolumens; sowie
• einen Ausstoßschritt, in welchem das mindestens eine zweite Arbeitsvolumen die Auslassöffnung überstreicht.

The method comprises a continuous rotation of the transport piston and the working piston along their direction of rotation and the following further steps:

• an inlet step in which the at least one first working volume sweeps over the inlet opening;
• a compression step comprising:
  • Moving the at least one first working volume from the inlet opening to the first combustion chamber opening,
  • Closing the second combustion chamber opening by the second piston surface;
  • Separating the compression volume within the at least one first working volume, the compression volume being in fluid connection with the first combustion chamber opening and the at least one combustion chamber,
  • Reducing the compression volume,
  • The first combustion chamber opening is closed by the first piston surface, and
  • Igniting the working medium in the at least one combustion chamber;
• an expansion step comprising:
  • Moving the at least one second working volume to the second combustion chamber opening,
  • Separating the expansion volume within the at least one second working volume, the expansion volume being in fluid connection with the second combustion chamber opening and the at least one combustion chamber,
  • Increasing the expansion volume; such as
• an ejection step in which the at least one second working volume sweeps over the outlet opening.

The expansion volume is formed at the beginning of the expansion step, specifically at a front region of the at least one second working volume - viewed along the direction of rotation of the working piston. During the expansion step, the expansion volume and thus a proportion of the expansion volume in the at least one second working volume increases. Particularly preferably, the expansion volume extends over the complete at least one second working volume at the end of the expansion step.

In general, the separation or the formation of the separate suction volume is not absolutely necessary. The inlet opening then immediately comes into fluid connection with the complete at least one first suction volume as soon as the at least one first suction volume begins to sweep over the inlet opening. In such a configuration, it is advantageous if the working medium is actively pressed from the outside into the at least one first working volume in the inlet step, for example by a compressor and / or a turbocharger.

• Abtrennen des Ansaugvolumens innerhalb des mindestens einen ersten Arbeitsvolumens, wobei das Ansaugvolumen in Fluidverbindung mit der Einlassöffnung seht,
• Vergrößern des Ansaugvolumens, und
• Verschließen der Einlassöffnung mit dem Transportkolben.

Preferably the inlet step comprises:

• Separating the suction volume within the at least one first working volume, the suction volume being in fluid connection with the inlet opening,
• Increasing the suction volume, and
• Close the inlet opening with the transport piston.

In this way, the motor unit actively supports the intake of the working medium by sucking it in. The separation can be brought about, for example, by the shut-off device as described elsewhere in the disclosure.

The suction volume is formed at the beginning of the inlet step, specifically at a front region of the at least one first working volume - viewed along the direction of rotation of the transport piston. During the intake step, the intake volume and thus a proportion of the intake volume in the at least one first working volume increases. Particularly preferably, the suction volume extends over the complete at least one first working volume at the end of the inlet step.

Furthermore, the separation or formation of the separate discharge volume is generally not absolutely necessary. Then, however, a remainder of the combustion products remains in the at least one second working volume.

• Abtrennen des Ausstoßvolumens innerhalb des mindestens einen zweiten Arbeitsvolumens, wobei das Ausstoßvolumen in Fluidverbindung mit der Auslassöffnung steht,
• Verkleinern des Ausstoßvolumens, und
• Verschließen der Auslassöffnung mit dem Arbeitskolben.

In a preferred development, the ejection step comprises:

• Separating the discharge volume within the at least one second working volume, wherein the discharge volume is in fluid communication with the outlet opening,
• Reducing the ejection volume, and
• Close the outlet opening with the working piston.

This ensures that the combustion products are completely expelled from the expulsion volume by the engine unit itself. The separation can be brought about, for example, by the shut-off device as described elsewhere in the disclosure.

Particularly preferably, the ejection volume is completely collapsed at the end of the reduction in size.

The designs, modifications, advantages and processes described for the motor unit apply accordingly to the method and vice versa.

The motor unit according to the invention according to any of the described embodiments is suitable as a motor in a hybrid vehicle, in particular as a “range extender”. Since it is a rotary piston motor unit, it runs extremely smoothly, both mechanically and acoustically. It is also light and compact. The working principle allows a high speed and thus a good power density or a good power to weight ratio. The motor unit is preferably operated at a constant nominal speed, which ensures high efficiency.

The motor unit according to the invention according to any of the described embodiments is also suitable as a motor for an electricity generator, especially for a portable electricity generator, on account of the advantages described.

The invention is explained below using exemplary embodiments and with reference to the figures. In this case, all of the features described and / or illustrated form the subject matter of the invention individually or in any combination, regardless of how they are summarized in the claims or their references.

Fig. 1

einen Querschnitt einer ersten, radialen Ausführung einer erfindungsgemäßen Motoreinheit mit zwei Brennkammern in einer Ebene senkrecht zu einer gemeinsamen Drehachse zweier Rotationskolben in der Mitte;

Fig. 2

einen Längsschnitt entlang der Drehachse der radialen Ausführung mit zwei Brennkammern aus Fig. 1;

Fig. 3

eine Explosionsdarstellung der radialen Ausführung mit zwei Brennkammern aus Fig. 1, wobei oben ein rotierendes Maschinenteil abgebildet ist, in der Mitte eine Innenwand sowie die Rotationskolben, und unten ein feststehendes Maschinenteil (ein feststehendes Mittelteil), wobei die Brennkammern jeweils zwischen einem zugehörigen Paar von Schiebern angeordnet sind, zur besseren Darstellung aber separat dargestellt sind;

Fig. 4a bis 4d

charakteristische Phasen eines Maschinenzyklus in der radialen Ausführung aus Fig. 1; dabei zeigt Fig. 4a unten auf der linken Seite eine Ansaugphase (bzw. ein Ansaugvolumen) und unten auf der rechten Seite eine Verdichtungsphase (bzw. ein Verdichtungsvolumen), Fig. 4b zeigt einen Zeitpunkt kurz nach einer Zündung, Fig. 4c zeigt oben die beginnende Expansionsphase (bzw. ein Expansionsvolumen) und Fig. 4d zeigt oben auf der linken Seite das Ende der Expansionsphase und oben auf der rechten Seite das Ende einer Ausstoßphase (bzw. ein Ausstoßvolumen);

Fig. 5

eine perspektivische Ansicht einer zweiten axialen Ausführung einer erfindungsgemäßen Motoreinheit mit einem feststehenden Mittelteil in der Mitte und einem oberen, ersten Rotationskolben und einem unteren, zweiten Rotationskolben;

Fig. 6

eine Detailansicht einer Absperreinrichtung in einer Ausführung als Schieber;

Fig. 7

eine Detailansicht einer Absperreinrichtung in einer Ausführung als Klappe;

Fig. 8

die Absperreinrichtungen an einer Brennkammer der radialen Ausführungsform in einer Modifikation als schräg gestellte Schieber;

Fig. 9

einen Querschnitt senkrecht zu der Drehachse in der Modifikation der radialen Ausführung mit vier Brennkammern;

Fig. 10

unten eine Entfernung r(φ) einer zweiten Kolbenfläche von der Drehachse des Arbeitskolbens in einer Radialrichtung in Abhängigkeit von einer Winkelkoordinate φ um die Drehachse in einem Zunahmebereich eines Arbeitsvolumen-Bereichs des Arbeitskolbens bei der radialen Ausführung in Fig. 1, in der Mitte eine Ableitung v(φ) = dr(φ))/dφ und oben eine zweite Ableitung a(φ) = d²r(φ)/dφ²; und

Fig. 11

eine Detailansicht einer Absperreinrichtung in einer Ausführung als Tür bei der radialen Ausführung der Motoreinheit.

Show it:

Fig. 1

a cross section of a first, radial embodiment of a motor unit according to the invention with two combustion chambers in a plane perpendicular to a common axis of rotation of two rotary pistons in the center;

Fig. 2

a longitudinal section along the axis of rotation of the radial version with two combustion chambers Fig. 1 ;

Fig. 3

an exploded view of the radial version with two combustion chambers Fig. 1 , with a rotating machine part on top is shown, in the middle an inner wall and the rotary piston, and below a fixed machine part (a fixed central part), the combustion chambers are each arranged between an associated pair of slides, but are shown separately for better illustration;

Figures 4a to 4d

characteristic phases of a machine cycle in the radial version Fig. 1 ; thereby shows Figure 4a at the bottom on the left side a suction phase (or a suction volume) and at the bottom on the right side a compression phase (or a compression volume), Figure 4b shows a point in time shortly after ignition, Figure 4c shows the beginning expansion phase (or an expansion volume) and Figure 4d shows the end of the expansion phase at the top on the left-hand side and the end of an ejection phase (or an ejection volume) at the top on the right-hand side;

Fig. 5

a perspective view of a second axial embodiment of a motor unit according to the invention with a fixed central part in the middle and an upper, first rotary piston and a lower, second rotary piston;

Fig. 6

a detailed view of a shut-off device in an embodiment as a slide;

Fig. 7

a detailed view of a shut-off device in an embodiment as a flap;

Fig. 8

the shut-off devices on a combustion chamber of the radial embodiment in a modification as an inclined slide;

Fig. 9

a cross section perpendicular to the axis of rotation in the modification of the radial version with four combustion chambers;

Fig. 10

below a distance r (φ) of a second piston surface from the axis of rotation of the working piston in a radial direction as a function of an angular coordinate φ around the axis of rotation in an increasing range of a working volume range of the working piston in the radial version in Fig. 1 , in the middle a derivative v (φ) = dr (φ)) / dφ and at the top a second derivative a (φ) = d ² r (φ) / dφ ² ; and

Fig. 11

a detailed view of a shut-off device in an embodiment as a door in the radial design of the motor unit.

At one in the Fig. 1 A working medium flows in the radial direction from inlet openings 8 to outlet openings 9, as shown in the first, radial embodiment of a motor unit according to the invention.

At the in Fig. 5 The second, axial embodiment of a motor unit according to the invention shown, on the other hand, moves the working medium essentially along a longitudinal direction parallel to an axis of rotation 7 of the motor unit.

Where appropriate, the same reference numerals are used for the same elements in different versions and the explanations and advantages apply accordingly to the different versions.

In the Fig. 1 The motor unit shown comprises a stationary center part (also called a stationary center part 1) and two rotatably mounted rotary pistons 2 and 3 that are firmly connected to one another, namely an inner transport piston 2 and an outer working piston 3. Due to the shape of the rotary piston 2, 3, one or more working volumes 4, 31 and 30, 34 are formed between the respective rotary piston 2, 3 and a combustion chamber housing 18.

A suction (in a suction volume 30) and a compression (in a compression volume 34) of the working medium in a first working volume 30, 34 takes place in the radial version by the inner rotary piston 2 (also called transport piston 2). An expansion (in an expansion volume 4) and an ejection (from an expulsion volume 31) of the combustion products take place in a second working volume 4, 31 of the other, outer rotary piston 3 (also called working piston 3), with each of the rotary pistons 2, 3 at least one of the Working volume 30, 3 or 4, 31 forms.

The fixed central part 1 contains at least one combustion chamber 5, but several combustion chambers 5 can also be present, which are then preferably arranged symmetrically about the axis of rotation 7 in the fixed central part 1.

Motor units with several combustion chambers 5 can be operated at a lower speed and are characterized by a very smooth running. The working volumes 30, 34 or 4, 31 may cover a maximum of an angular range that is smaller than a smallest angular range between the inlet openings 6 of the combustion chambers 5.

At the in Fig. 5 In the axial design of the motor unit shown, two combustion chamber openings 6a, 6b (a first combustion chamber opening 6a and a second combustion chamber opening 6b) of the respective combustion chambers 5 are each arranged parallel to the axis of rotation 7, the transport piston 2, the stationary central part 1 with the combustion chamber housing 18 and working piston 3, viewed along a direction of the axis of rotation 7 (and thus along the longitudinal direction), lie one behind the other.

At the in Fig. 1 and Fig. 5 The radial execution of the motor unit shown, the two combustion chamber openings 6 of the (two) combustion chambers 5 are perpendicular to the axis of rotation 7 and the two rotary pistons 2, 3 are arranged concentrically to the axis of rotation 7 on both sides of the combustion chamber housing 18, with the transport piston 2 on the inside.

The inlet openings 8 and the outlet openings 9 are each opened and closed by covering sealing surfaces 10 of different widths by the rotary pistons 2, 3 during the rotary movement of the same.

More precisely, the individual inlet openings 8 are closed or not closed by the sealing surface 10 of the transport piston 2 as a function of a rotational position of the transport piston 2. When the first working volume 30, 34 is just sweeping over one of the inlet openings 8, at least part of the first working volume 30, 34, more precisely the suction volume 30, is in fluid connection with this inlet opening 8.

In a similar way, the individual outlet openings 9 are closed or not closed by the sealing surface 10 of the working piston 3 as a function of a rotational position of the working piston 3. When the second working volume 4, 31 is just sweeping over one of the outlet openings 9, at least part of the second working volume 4, 31, more precisely the discharge volume 31, is in fluid connection with this outlet opening 9.

If a sliding surface of the respective rotary piston 2, 3 (a first piston surface 22a of the transport piston 2 or a second piston surface 22b of the working piston 3) is close to an associated sliding surface (a first working surface 21a for the transport piston 2 or a second working surface 21b for the working piston 3) of the stationary combustion chamber housing 18 rests, the combustion chamber openings 6a, 6b of the combustion chambers 5 provided there in the respective working surfaces 21a, 21b are thereby closed. The shut-off devices 11 located there are then completely sunk into suitable recesses 12.

Sealing edges of the shut-off devices 11 must always lie tightly against the associated piston surface 22a, 22b and close off the suction volume 30 and the compression volume 34 or the expansion volume 4 and the discharge volume 31, which can be achieved by applying pressure from springs 13.

The springs 13 press the shut-off device 11 (more precisely, for example, the slide 33 in Fig. 6 and Fig. 8 ) against the first piston surface 22a of the transport piston 2. The springs 13 are therefore designed to press the sealing edges against the first piston surface 22a in a sealing manner.

An inclined position of the shut-off devices 11, as in Fig. 8 is shown, can also be used to generate a contact pressure adapted to the requirements of tightness. Abrasion due to friction must be avoided as far as possible. For this purpose, the sliding surfaces and sealing surfaces must be polished and can be provided with lubricants and the sealing edges of the shut-off devices 11 can be equipped with wear-resistant sealing lips 15 or sealing rollers 28 with low friction.

The shut-off devices 11 can be designed as slides 33 in both designs (both in the radial design and in the axial design) be, which each have the sealing lip 15 or the sealing rollers 28 for sealing and reducing friction. The slides 33 are guided by guide grooves 16 on both sides.

In the radial embodiment, the guide grooves 16 are embedded in an inner wall 14 and in an outer wall 26. The guide grooves 16 are thus provided at ends of the sliders 33 in the longitudinal direction.

In the axial version, the guide grooves 16 are embedded in an inner housing 32 and an outer housing 25. The guide grooves 16 are therefore provided at the ends of the slides 33 in the radial direction transverse to the axis of rotation 7.

At the level of the sealing lips 15, sealing bodies 40 are attached in the guide grooves for sealing purposes.

In the radial version, a working piston jacket 38 and a plate-shaped outer cover 39 must be separably connected, since the inner wall 14 must be firmly connected to the combustion chamber housing 18, while the rotating pistons 2, 3 and the outer cover 39 are rotatable. In the radial version, flaps 27 (see Fig. 7 ) or doors 19 (see Fig. 11 ) are used as shut-off devices 11, which also have sealing lips 15 or sealing rollers 25 installed for sealing and ensure reliable guidance, but which take up more space than the slide 33.

The first working volume 30, 34 is formed between the piston surface 22a of the transport piston 2 and the working surface 21a of the combustion chamber housing (see for example Fig. 1 , Fig. 8 , Fig. 9 ). In the in Fig. 9 The illustrated modification of the radial design with four combustion chambers 5, two first working volumes are formed.

If the first working volume 30, 34, depending on the rotational position of the transport piston 2, is just passing over one of the shut-off devices 11, then this shut-off device 11 divides this first working volume 30, 34 into a suction volume 30 and a compression volume 34 such a rotational position that the first piston surface 22a in a region of the first working surface 21a in which this shut-off device 11 is arranged is just spaced apart from the working surface 21 in order to form this first working volume 30, 34 there.

This shut-off device 11 is not completely sunk into the recess 16 at this point in time. Instead, it protrudes into said first working volume 30, 34 and thereby divides the latter into the associated suction volume 30 and the associated compression volume 34. The associated suction volume 30 is located behind this shut-off device 11, seen along a direction of rotation of the transport piston 2, and the associated compression volume 34 is Located in front of this shut-off device 11 seen along the direction of rotation (see e.g. Figure 4a below). Since the transport piston 2 and the working piston 3 are connected in a rotationally fixed manner, the direction of rotation of the transport piston 2 corresponds to a direction of rotation of the working piston 3.

During operation of the motor unit, the first working volume 30, 34 forms new suction volumes 30 again and again through the rotation of the transport piston 2 together with the shut-off devices 11. Each of the suction volumes 30 becomes one of the compression volumes 34 as the transport piston 2 continues to rotate as soon as the respective suction volume 30 does not is more in fluid communication with one of the inlet ports 8. In the further course of the rotation, the compression volumes 34 formed in this way are each collapsed again, the working medium transported therein being pressed and compressed into the combustion chamber 5 next in the direction of rotation of the transport piston. For this purpose, the first working volume 30, 34, more precisely the compression volume 34 separated therein, sweeps over the first combustion chamber opening 6a of this combustion chamber 5.

A total volume of the first working volume 30, 34 between the first piston surface 22a of the transport piston 2 and the first working surface 21a changes - apart from the shut-off device 11 extending into the working volume 30, 34 (more precisely its slide 33, flap 27 or door 19) - not.

The sequence of a work cycle of the engine unit runs in four phases, as in the known Otto engine.

In a first phase, the compressible working medium is sucked in via the inlet opening 8 into the suction volume 30, which is enlarged by the rotary movement of the transport piston 2, or is pressed in using a turbocharger (not shown). The shut-off device 11 located in front of the inlet opening 8 in the direction of rotation blocks the suction volume 30 from the adjacent compression volume 34. In the further course of the rotary movement, the inlet opening 8 is closed by the displacing transport piston 2 and the working medium is transported to the closest combustion chamber opening 6a in the working surface 21a.

In a subsequent, second phase, the working medium is pressed into the corresponding combustion chamber 5 and compressed (cf. compression volume 34) by closing one in the direction of rotation directly behind this combustion chamber opening 6a The shut-off device 11 located in this combustion chamber 5 shuts off the compression volume 34 (to the next suction volume 30 following in the direction of rotation) and the first compression volume 34 is reduced by the displacement of the first piston surface 22a, so that the working medium is pressed into the combustion chamber 5. At this point in time, the other, second combustion chamber opening 6b of the combustion chamber 5 is closed by the second piston surface 22b of the working piston 3. The ignition takes place at a point in time of maximum compression. The ignition can take place, depending on the working medium and maximum compression, by an ignition device 23 or by self-ignition, the maximum compression corresponding to a ratio of the maximum suction volume 30 to a volume of the combustion chamber 5.

In a subsequent, third phase, the working piston 3 releases the second combustion chamber opening 6b of this combustion chamber 5 in the course of the rotary movement (i.e. the second piston surface 22b of the working piston 3 no longer closes this second combustion chamber opening 6b). The burnt working medium (that is, combustion products of the working medium) that is under high pressure can expand into the increasing expansion volume 4 of the working piston 3. A shut-off device 11 located upstream of this second combustion chamber opening 6b in the direction of rotation blocks the expansion volume 4. More precisely, this shut-off device 11 blocks the expansion volume 4 from the previous ejection volume 31 seen along the direction of rotation. This shut-off device 11 thus divides the associated second working volume 4, 31, which is formed between the piston surface 22b of the working piston 3 and the second working surface 21b. This shut-off device 11 transmits a force to the stationary central part 1.

In a subsequent, final, fourth phase, the expansion volume 4 with the expanded exhaust gas is transported by the rotary movement of the working piston 3 to the (next in the direction of rotation) outlet opening 9, where one in the Direction of rotation after this outlet opening 9, the shut-off device 11 shuts off the discharge volume 31. The exhaust gas is finally completely transported out of the machine through the outlet opening. This occurs through the further rotation of the working piston 3 along its direction of rotation and the resulting reduction in the ejection volume 31. At the end of the fourth phase, the ejection volume 31 has completely collapsed.

In this sense, the expansion volume 4 can be viewed as the exhaust gas volume 31 from a point in time from which a fluid connection to the outlet opening 9 is established. Alternatively, the expansion volume 4 can be viewed as the exhaust gas volume 31 from a point in time after a volume of the expansion volume 4 has reached its maximum value.

The shape of the rotary pistons 2, 3 is determined by the requirement that the shut-off devices 11 should be subjected to an acceleration that is as low as possible, that is to say that is constant in phases. The aim of the design of the shut-off devices is to keep the contact pressure high enough in every phase of the rotation to ensure tightness. On the other hand, the contact pressure must not be too great because this creates unnecessary friction. The sums of the forces for pressing the shut-off devices 11 and the inertial forces due to their movement must be taken into account.

The motor unit is cooled by a cooling medium which is passed through the interior of the stationary central part 1 via pipes 29. The rotating rotary pistons 2, 3 can also be externally cooled e.g. by air supply and cooling fins.

In the following, the in Fig. 5 shown, axial design explained in more detail.

The four-stroke internal combustion engine in an axial design for compressible working media comprises the cylindrical stationary middle part 1 with a central axle bearing 17, the (hollow) cylindrical combustion chamber housing 18 surrounding the central axle bearing 17 and the (hollow) cylindrical outer housing 25 on both of its end faces The rotary pistons 2, 3 are attached (in the longitudinal direction parallel to the axis of rotation 7), each with a plate-shaped outer plate 20, which are firmly connected via the common axis of rotation 7.

A mechanical holder, connections for fuel, exhaust gas, cooling medium, lubricants and an ignition device 23, if present, as well as the inlet openings 8 and the outlet openings 9 are attached to the outer housing 25. An inner surface 24 of the outer housing 25 serves as a sealing surface (outer in the radial direction) for the rotary pistons 2, 3.

The combustion chamber housing 18 with the combustion chambers 5 and the shut-off devices 11 for the second working volume 4, 31 has two sliding surfaces (first working surface 21a and second working surface 21b) on the flat end faces into which the shut-off devices 11 and the combustion chamber openings 6a, 6b of the combustion chambers 5 are built in.

The rotary pistons 2, 3 each have a (front) side (the first piston surface 22a or the second piston surface 22b) partially tightly against the working surfaces 21a, 21b and form working volumes (the first working volume 30, 34, which can be subdivided into expansion volumes 4 and exhaust gas volume 31, as well as the second working volume 4, 31, can be subdivided into suction volume 30 and compression volume 34) at the points at which the respective one of the piston surfaces 22a, 22b is removed from the associated working surfaces 21a, 21b.

There must be at least one working volume 30, 34 or 4, 31 per rotary piston 2, 3. The size of the working volume 30, 34 or 4, 31 can be drawn from a greatest distance between the respective piston surface 22a, 22b and the associated working surface 21a, 21b (piston stroke), a width of the working volume 30, 34 or 4, 31 and a swept over Calculate angular range.

• dass das Arbeitsmedium über eine der Einlassöffnungen 8 in eines der Ansaugvolumen 30, welches sich durch die Drehbewegung und die spezielle Form des Transportkolbens 2 vergrößert, eingesaugt wird und im Verlauf der Drehbewegung durch die sich verlagernde erste Kolbenfläche 22a eingeschlossen und zu der nächstliegenden Brennkammeröffnung 6a transportiert wird;
• dass sich daraufhin das Verdichtungsvolumen 34 durch die dort befindliche Absperreinrichtung 11 verkleinert;
• dass anschließend gezündet wird, worauf im weiteren Verlauf der Drehbewegung das abgebrannte und unter hohem Druck stehende Arbeitsmedium durch die zweite Brennkammeröffnung 6b, welche sich auf der anderen Seite der Brennkammer 5 befindet, in das Expansionsvolumen 4 expandiert und in dem Expansionsvolumen 4 weiter expandiert, wobei sich das Expansionsvolumen 4 durch die weitere Drehbewegung des Arbeitskolbens 3 vergrößert, und mechanische Arbeit leisten kann;
• bis schließlich durch die nächste der Auslassöffnungen 9 das Abgas ausgestoßen wird.

A sequence of the four work cycles can be described in such a way that

• that the working medium is sucked in via one of the inlet openings 8 into one of the suction volumes 30, which is enlarged by the rotary movement and the special shape of the transport piston 2, and is enclosed in the course of the rotary movement by the shifting first piston surface 22a and transported to the nearest combustion chamber opening 6a will;
• that thereupon the compression volume 34 is reduced by the shut-off device 11 located there;
• that is then ignited, whereupon in the further course of the rotary movement the burnt and high pressure working medium expands through the second combustion chamber opening 6b, which is located on the other side of the combustion chamber 5, into the expansion volume 4 and continues to expand in the expansion volume 4, whereby the expansion volume 4 increases as a result of the further rotary movement of the working piston 3 and can perform mechanical work;
• until finally the exhaust gas is expelled through the next of the outlet openings 9.

The engine unit for the four-stroke internal combustion engine with the two rotary pistons 2, 3 and separate volumes, which are set up for intake (intake volume 30), for compression (compression volume 34), for expansion (expansion volume 4), for the exhaust gas (discharge volume 31), and the combustion chambers 5 does not require any valves.

The engine unit is further characterized in that the combustion chambers 5 have an egg-shaped shape, which can be adapted for the requirements of efficient and complete combustion, and are positioned centrally between the combustion chamber openings 6a, 6b. The combustion chambers 5 are each optionally smaller than an axial length of the combustion chamber housing 18 in order to achieve a higher compression.

The combustion chambers 5 are each equipped with two opposing combustion chamber openings (first combustion chamber opening 6a and second combustion chamber opening 6b), which are each located in the working surfaces 21a, 21b of the combustion chamber housing 18 and directly connect the first working surface 21a and the second working surface 21b. In this way, the combustion chambers 5 are aligned parallel to the axis of rotation 7. The combustion chambers 5 are only filled through the associated first combustion chamber opening 6a. At the time of maximum compression, the ignition time, the two combustion chamber openings 6a, 6b are closed by the tightly fitting piston surfaces 22a, 22b.

Each of the at least one combustion chamber 5 (i.e. each of the several combustion chambers 5 or precisely one combustion chamber 5, if only one combustion chamber 5 is provided) is each provided with two shut-off devices 11 (more precisely with one shut-off device 11 in the work surface 21a and one shut-off device 11 in the second working surface 21b), an inlet opening 8 and an outlet opening 9 in the combustion chamber housing 18.

If several combustion chambers 5 are provided, the combustion chambers 5 with the two associated shut-off devices 11, the associated inlet opening 8 and the associated outlet opening 9 are preferably distributed symmetrically over a circumference of the combustion chamber housing 18. The first Intake volume 30, 34 and the second intake volume 4, 31 may then cover a maximum of an angular range that is smaller than a smallest angular range between the combustion chamber openings (6a or 6b) of the combustion chambers 5. If more than one working volume 30, 34 or 4, 31 per rotary piston 2, 3 (e.g. with four combustion chambers 5 and two working volumes 30, 34 or 4, 31 per rotary piston 2, 3), the machine can be constructed completely symmetrically and not have any structural imbalance.

In the working surfaces 21a, 21b of the combustion chamber housing 18 there is a completely retractable shut-off device 11 next to each combustion chamber opening 6a, 6b, which is on the side of the intake volume 30 in the direction of rotation in front of the inlet opening 8 and behind the first combustion chamber opening 6a or on the side of the discharge volume 31 is positioned in the direction of rotation behind the outlet opening 9 and in front of the second combustion chamber opening 6b.

The in Fig. 2 and Fig. 9 shown, radial designs explained in more detail.

The motor unit of the four-stroke internal combustion engine in a radial design for compressible working media comprises the stationary middle part 1. The stationary middle part 1 comprises the plate-shaped outer wall 26 with a centrally fastened axis of rotation bearing 17 and bearing holder 36, which is fastened concentrically to the axis of rotation 7, (hollow) cylindrical Combustion chamber housing 1, and the inner wall 14.

The motor unit of the four-stroke internal combustion engine in a radial design also comprises a rotating part of the two concentrically arranged, (hollow) cylindrical rotary pistons 2, 3, which are attached to the plate-shaped end cover 39 via a transport piston holder 35 and a working piston jacket 38 together with the central axis of rotation 7 are attached, which are made in this way are that the axis of rotation 7 in the axis of rotation bearing 17 and at the same time the combustion chamber housing 18 between the rotary pistons 2, 3 can be assembled with very little play.

The mechanical holder, the connections for fuel, exhaust gas, cooling medium, lubricants and the possibly existing ignition device 23, as well as the inlet openings 8 and the outlet openings 9 are attached or arranged on the outer wall 26.

The inner surface 24 of the outer wall 26 serves as a sealing surface for the rotary pistons 2, 3, more precisely as a sealing surface for the lower end faces of the rotary pistons 2, 3.

The combustion chamber housing 18 with the combustion chambers 5 and the shut-off devices 11 for the working volumes 30, 34 or 4, 31 has two sliding surfaces (the first working surface 21a and the second working surface 21b) on the cylinder jacket-shaped sides, in which the shut-off devices 11 and the combustion chamber openings 6a, 6b of the combustion chambers 5 are installed.

The rotary pistons 2, 3 each lie with one side, more precisely with the respective piston surface 22a, 22b, partially in close contact with the associated working surface 21a, 21b. The first working volumes 4, 31 and the second working volumes 30, 34 are each at the points at which the piston surface 22a, 22b is removed from the associated working surface 21a, 21b. There must be at least one working volume 30, 34 or 4, 31 per rotary piston 2, 3.

A size of the working volume 30, 34 or 4, 31 can be determined from a greatest distance between the corresponding piston surface 22a, 22b and the associated working surface 21a, 21b (piston stroke), a height of the working volume 30, 34 or 3, 31 along the longitudinal direction and calculate a swept angular range.

• dass das Arbeitsmedium über eine der Einlassöffnungen 8 in das Ansaugvolumen 30, welches sich durch die Drehbewegung und die spezielle Form des Transportkolbens 2 vergrößert, eingesaugt wird und im Verlauf der Drehbewegung durch die sich verlagernde erste Kolbenfläche 22a eingeschlossen und zu der in Drehrichtung nächstliegenden Brennkammer 5 transportiert wird;
• dass sich daraufhin das Verdichtungsvolumen 34 durch die dort befindliche Absperreinrichtung 11 verkleinert;
• dass anschließend gezündet wird, worauf im weiteren Verlauf der Drehbewegung das abgebrannte und unter hohem Druck stehende Arbeitsmedium durch die zweite Brennkammeröffnung 6b, welche sich (in der Radialrichtung gesehen) auf der anderen Seite der Brennkammer 5 befindet, in das Expansionsvolumen 4 expandiert und in dem Expansionsvolumen 4 weiter expandiert, wobei sich das Expansionsvolumen 4 durch die weitere Drehbewegung des Arbeitskolbens 3 vergrößert, und mechanische Arbeit leisten kann;
• bis schließlich durch die nächste der Auslassöffnung 9 das Abgas ausgestoßen wird.

A sequence of the four work cycles can be described in such a way that

• that the working medium is sucked in via one of the inlet openings 8 into the suction volume 30, which is enlarged by the rotary movement and the special shape of the transport piston 2, and is enclosed in the course of the rotary movement by the shifting first piston surface 22a and to the combustion chamber 5 closest in the direction of rotation is transported;
• that thereupon the compression volume 34 is reduced by the shut-off device 11 located there;
• that is then ignited, whereupon in the further course of the rotary movement the burnt and high pressure working medium expands through the second combustion chamber opening 6b, which is (seen in the radial direction) on the other side of the combustion chamber 5, into the expansion volume 4 and in the Expansion volume 4 continues to expand, the expansion volume 4 being enlarged by the further rotary movement of the working piston 3, and being able to perform mechanical work;
• until finally the exhaust gas is expelled through the next one of the outlet opening 9.

The radial versions of the motor unit for the four-stroke internal combustion engine with the rotary pistons 2, 3 and separate volumes that are used for intake (intake volume 30), for compression (compression volume 34), for expansion (expansion volume 4) and for the exhaust gas (discharge volume 31) are set up, and the combustion chambers 5 does not require any valves.

In the axial versions, the engine unit is further characterized in that the combustion chambers 5 have an egg-shaped shape, which can be adapted to the requirements of efficient and complete combustion and are positioned centrally between the combustion chamber openings 6a, 6b. the Combustion chambers 5 are optionally smaller than a radial width of the combustion chamber housing 18 in order to achieve a higher compression.

The combustion chambers 5 are each equipped with two opposing combustion chamber openings (first combustion chamber opening 6a and second combustion chamber opening 6b), which are each located in the working surfaces 21a, 21b of the combustion chamber housing 18 and directly connect the first working surface 21a and the second working surface 21b. This brings about an alignment of the combustion chambers 5 perpendicular to the axis of rotation 7. The combustion chambers 5 are only filled through the associated first combustion chamber opening 6a. At the point in time of maximum compression, the point in time of ignition, the two combustion chamber openings 6a, 6b are closed by the piston surfaces 22a, 22b that lie close together.

Each of the at least one combustion chamber 5 (i.e. each of the several combustion chambers 5 or precisely one combustion chamber 5, if only one combustion chamber 5 is provided) is each provided with two shut-off devices 11 (more precisely with one shut-off device 11 in the work surface 21a and one shut-off device 11 in the second working surface 21b), an inlet opening 8 and an outlet opening 9 in the combustion chamber housing 18.

If several combustion chambers 5 are provided, the combustion chambers 5 with the two associated shut-off devices 11, the associated inlet opening 8 and the associated outlet opening 9 are preferably distributed symmetrically around the circumference of the combustion chamber housing 18. The first working volume 30, 34 and the second working volume 4, 31 may then cover a maximum of an angular range that is smaller than a smallest angular range between the combustion chamber openings 6a, 6b of the combustion chambers 5. If more than one working volume 30, 34 or 4, 31 per rotary flask 2, 3 (e.g. with four Combustion chambers 5 and two working volumes 30, 34 or 4, 31 per rotary piston 2, 3) are present, the machine can be constructed completely symmetrically and have no structural imbalance.

Gradients of the piston surfaces 22a, 22b determine the movement of the shut-off devices 11. The shut-off devices 11 (more precisely, for example, their slide 33, flap 27 or door 19) move with acceleration that is constant in phases. A distance r of the piston surface 22a, 22b in the radial direction from the axis of rotation 7 is - when the respective rotary piston 2, 3 is at rest - only a function of the angle of rotation φ. A second derivation of this function r (φ) according to the angle of rotation φ is constant in certain areas with the additional boundary conditions that the piston surfaces 22a, 22b at the beginning and end of the transition areas are exactly cylinder jacket-shaped, because the piston surfaces at these points are parallel to the (cylinder jacket-shaped) working surfaces 21a, 21b are aligned, and that the inlet openings 8 and the outlet openings 9 are closed or released by the lateral sealing surfaces 10 of the rotary pistons 2, 3 in the course of the rotary movement.

In the radial versions, too, there is a completely retractable shut-off device 11 in the working surfaces 21a, 21b of the combustion chamber housing 18 next to each combustion chamber opening 6a, 6b, which on the side of the intake volume 30 in the direction of rotation in front of the inlet opening 8 and behind the first combustion chamber opening 6a or the side of the discharge volume 31 is positioned in the direction of rotation behind the outlet opening 9 and in front of the second combustion chamber opening 6b.

Fig. 10 shows a distance r (φ) of the second piston surface 22b from the axis of rotation of the working piston 3 in the radial direction as a function of an angular coordinate φ about the axis of rotation in an area of increase of a working volume area of the working piston 3 in the radial version in FIG Fig. 1 . The angular coordinate φ increases against the direction of rotation.

The increase range begins at an angle coordinate φ ₁ and ends at an angle coordinate φ ₂ .

Before the angular coordinate φ ₁ - that is, before the increase area - one of the sliding areas adjoins the second piston surface 22b. In the sliding range, the distance r (φ) (at least essentially) constantly corresponds to a value r ₁ . In the sliding area, the second piston surface 22b thus has the shape of part of a cylinder jacket with the radius r ₁ .

After the angular coordinate φ ₂ - that is, after the increase area - a constant area of a working volume area adjoins the second piston surface 22b. In the constant range, the distance r (φ) corresponds (at least essentially) constantly to a value r ₂ . In the constant range, the second piston surface 22b thus has the shape of part of a cylinder jacket with the radius r ₂ .

The second working surface 21b is in the shape of a cylinder jacket and has a constant radius which at least substantially corresponds to _{the radius r 1.} The radius of the second working surface can be minimally smaller than the radius r ₁ , so that sufficient mobility of the working piston 3 is ensured.

The function r (φ) accordingly describes not only the shape of the second piston surface 22b, but also a distance between the second piston surface 22b and the second working surface 21b in the radial direction.

In the middle of Fig. 10 the derivative v (φ) = dr (φ) / dφ of the function r (φ) is shown and above in Fig. 10 the second derivative a (φ) = d ² r (φ) / dφ ^{2 of} the function r (φ) is shown.

In the sliding area to the left of φ ₁ , the derivative v (φ) and the second derivative a (φ) are constantly zero. The same applies in the constant region to the right of φ ₂ .

In an initial part of the increase range between φ ₁ and (φ ₁ + φ ₂ ) / 2, the derivative v (φ) increases linearly. At (φ ₁ + φ ₂ ) / 2 it reaches a maximum value. The second derivative a (φ) has a constant, positive value over the entire initial part. In the beginning r (φ) increases quadratically.

In an end part of the increase range between (φ ₁ + φ ₂ ) / 2 and φ ₂ , the derivative v (φ) falls linearly. The second derivative a (φ) has a constant, negative value over the entire end part.

In addition, in the embodiment shown, a magnitude of a (φ) is the same in the initial part and in the final part.

After the constant area, there follows a correspondingly shaped decrease area of the working volume area of the working piston 3. In the decrease area, the signs of the derivative v (φ) and the second derivative a (φ) are reversed. The course of r (φ) in the decrease area is - based on a center of the constant area arranged in between - as it were mirror-symmetrical to that in Fig. 10 shown below in the increase area.

If the working piston has several working volume areas, then the second piston surface 22b is total (that is, over the entire course of the Angular coordinate φ from 0 ° to 360 °) from a corresponding number of such sliding areas, increase areas, constant areas and decrease areas one after the other.

• sie wird nicht bewegt und nicht beschleunigt, solange einer der Gleitbereiche die Absperreinrichtung 11 überstreicht;
• wenn einer der Zunahmebereiche die Absperreinrichtung 11 überstreicht, wird die Absperrvorrichtung in dessen Anfangsteil mit konstanter positiver Beschleunigung in der Radialrichtung nach außen beschleunigt und dann mit konstanter negativer Beschleunigung gebremst, bis sie vollständig ausgefahren ist;
• sie wird nicht bewegt und nicht beschleunigt, solange der darauffolgende Konstantbereich die Absperreinrichtung 11 überstreicht; und
• wenn der darauffolgende Abnahmebereich die Absperreinrichtung 11 überstreicht, wird die Absperrvorrichtung in dessen Anfangsteil mit konstanter negativer Beschleunigung in der Radialrichtung nach innen beschleunigt und dann mit konstanter positiver Beschleunigung gebremst, bis sie vollständig eingefahren ist und vom nächsten Gleitbereich überstrichen wird.

If the working piston 3 moves along the direction of rotation at a constant angular speed, then the distance of the second piston surface 22b from the axis of rotation in the radial direction at a fixed angular coordinate φ _{0 can be described} by a corresponding function r (φ ₀ , t). This also applies in particular to the positions of the shut-off devices 11. The respective shut-off device 11 is accordingly moved along the radial direction as follows:

• it is not moved and not accelerated as long as one of the sliding areas passes over the shut-off device 11;
• when one of the increase areas passes over the shut-off device 11, the shut-off device is accelerated outward in its initial part with constant positive acceleration in the radial direction and then braked with constant negative acceleration until it is fully extended;
• it is not moved and not accelerated as long as the subsequent constant range sweeps over the shut-off device 11; and
• When the subsequent removal area passes over the shut-off device 11, the shut-off device is accelerated in its initial part with constant negative acceleration in the radial direction and then braked with constant positive acceleration until it is completely retracted and is swept over by the next sliding area.

The first piston surface 22a is designed in a comparable manner. The signs or courses of the in Fig. 10 However, the functions shown are reversed accordingly, since a distance r (φ) of the first piston surface 22a from the axis of rotation in the working volume areas of the transport piston is smaller than in the sliding areas.

At the in Fig. 5 In the radial embodiment shown, a height z (φ) of the piston surface 22a, 22b in the longitudinal direction - when the rotary pistons 2, 3 are at rest - is only a function of an angular coordinate φ. A second derivative d ² z (φ) / dφ ² is constant in certain areas with the additional boundary conditions that the slope dz (φ) / dφ at the beginning and at the end of the increase area and the decrease area is equal to zero, because the piston surfaces 22, 22b are aligned parallel to the circular ring-shaped, flat working surfaces 21a, 21b at these points, and that the inlet openings 8 and the outlet openings 9 are closed or released by the lateral sealing surfaces 10 of the rotary pistons 2, 3 in the course of the rotary movement.

The shapes of the piston surfaces 22a, 22b determine the movement of the shut-off devices 11. The shut-off devices 11 (more precisely, for example, the slide 33, the flap 27 or the door 19) move along the radial direction with acceleration that is constant in phases. This means that you are burdened comparatively little.

Fig. 11 FIG. 13 shows a detailed view of a modification of the radial embodiment from FIG Fig. 1 , in which doors 19 are used as shut-off devices. Similar to in Fig. 1 and Figure 4a until 4d it is a cross-sectional representation with a cutting plane perpendicular to the axis of rotation.

For the combustion chamber 5 shown, a door 19 is arranged in the first work surface 21a. When this door 19 is closed, it closes the first combustion chamber opening 6a of the combustion chamber 5. An inside of this door 19 then faces an interior of the combustion chamber 5 and forms part of a Wall of the combustion chamber 5. The inside of the door 19 has the shape of a section of an egg-shaped or spherical surface and completes, when the door 19 is closed, the egg-shaped or spherical inner wall of the combustion chamber 5, which is formed by the combustion chamber housing 18, at the first combustion chamber opening 6a flush and with a corresponding egg or spherical shape. The door 19 in the first working surface 21a is pivoted in the direction of rotation of the transport piston 2 directly behind the first combustion chamber opening 6a of the associated combustion chamber 5. In the direction of rotation of the transport piston 2, the inlet opening 8 for the closest combustion chamber 5 in the direction of rotation follows immediately behind it. The door 19 can be pivoted about a door pivot axis which runs perpendicular to the plane of the drawing and parallel to the axis of rotation. In Fig. 11 the door 19 is just open. A length of the door 19 perpendicular to its door pivot axis is longer than a maximum distance between the first working surface 21a and the first piston surface 22a. Even if the door is 19 as in Fig. 11 is maximally open, it rests against the first piston surface 22a preferably at an angle which is smaller than 80 °, particularly preferably smaller than 60 °. As a result, a pressure of the working medium in the compression volume 34 brings about a pressing force of the door 19 on the first piston surface 22a. This improves the seal between the door 19 and the first piston surface 22a. The door 19 does not have to be kept open or not only by an opening device, for example a spring. However, an opening device in the form of a spring (not shown) is provided so that the door 19 opens reliably as soon as one of the first working volumes 30, 34 reaches the first combustion chamber opening 6a. Then the door 19 divides the sweeping first working volume 30, 34 as shown in FIG Fig. 11 is shown, into the associated compression volume 34 and the associated inlet volume 30 for the next combustion chamber 5.

Analog is for the in Fig. 11 Combustion chamber 5 shown, a further door 9 is formed in the second work surface 21b. It is attached in the direction of rotation of the working piston 3 directly in front of the second combustion chamber opening 6b. In Fig. 11 is a common direction of rotation of the transport piston 2 and the working piston 3 counterclockwise. The statements relating to the door 19 in the first work surface 21a apply accordingly.

When the two doors 19 are closed, a cross-sectional area of the combustion chamber 5 therebetween has a circular shape. This enables particularly good ignition and combustion properties.

The invention is a four-stroke internal combustion engine, which is structurally simple and consists of a few parts, which does not require any valves, which almost completely avoids an imbalance due to parts moving back and forth and which is made possible by compact combustion chambers 5 with favorable Characteristics of the combustion chamber. In the above-mentioned laid-open specification EP 0 085 427 A1 with the publication date 08/10/1983 a four-stroke internal combustion engine with two rotary pistons has been described. However, the motor unit described here is of a simpler design. In particular, there is no need for a valve flap that moves very quickly and releases the ignited working medium, which is under high pressure, from the combustion chamber.

Claims (14)

1. An engine unit for a four-stroke internal combustion engine for a compressible working fluid, comprising:

   a fixed central part (1);

   a transport piston (2); and

   a working piston (3);

   the transport piston (2) and the working piston (3) being fixedly connected to one another and being mounted rotatably relative to the fixed central part (1) about a common axis of rotation (7);

   characterised in that the fixed central part (1) comprises a combustion chamber housing (18) which is located between the transport piston (2) and the working piston (3) and has a first working surface (21a) for the transport piston (2) and a second working surface (21b) for the working piston (3),

   • wherein due to a shape of the transport piston (2) at least one first working volume (30, 34) is formed between the transport piston (2) and the first working surface (21a), and

   • wherein due to a shape of the working piston (3) at least one second working volume (4, 31) is formed between the working piston (3) and the second working surface (21b); and

   in that the combustion chamber housing (18) has at least one combustion chamber (5), the at least one combustion chamber (5) having a first combustion chamber opening (6a) which opens at the first working surface (21a), and a second combustion chamber opening (6b) which opens at a second working surface (21b).
2. Engine unit according to claim 1, characterised in that the at least one combustion chamber (5) has an ellipsoidal, spherical, egg-shaped or cylindrical basic shape.
3. Engine unit according to one of the preceding claims, characterized in that a first piston surface (22a) of the transport piston (2) lies regionally in sealing contact with the first working surface (21a) and is regionally removed from the first working surface (21a) in order to form the at least one first working volume (30, 34),

   wherein the first piston surface (22a) closes the first combustion chamber opening (6a) when the first piston surface (22a) is in sealing contact with a region of the first working surface (21a) with the first combustion chamber opening (6a) in dependence on a rotational position of the transport piston (2); and

   in that a second piston surface (22b) of the working piston (3) bears in a sealing manner in regions against the second working surface (21b) and is remote in regions from the second working surface (21b) in order to form the at least one second working volume (4, 31),

   wherein the second piston surface (22b) closes the second combustion chamber opening (6b) when the second piston surface (22b) is in sealing contact with a region of the second working surface (21b) with this second combustion chamber opening (6b) in dependence on a rotational position of the working piston (3).
4. Engine unit according to claim 3, characterised in that the first piston surface (22a) closes the first combustion chamber opening (6a) at a point in time of the maximum compression of the working medium and/or an ignition time point for the at least one combustion chamber (5), and in that the second piston surface (22b) simultaneously closes the second combustion chamber opening (6b).
5. Engine unit according to one of the preceding claims, characterised in that an inlet opening (8) for drawing in the working medium is formed in the fixed central part (1) for each of the at least one combustion chamber (5), which inlet opening (8) is swept by the at least one first working volume (30, 34) during rotation of the transport piston (2), in that for each of the at least one combustion chamber (5) a completely retractable shut-off device (11) is arranged in the first working surface (21a), which shut-off device (11), viewed along a direction of rotation of the transport piston (2), is positioned behind the first combustion chamber opening (6a) of this combustion chamber (5) and in front of the next inlet opening (8) and which, depending on the rotational position of the transport piston (2), limits a compression volume (34) in the at least one first working volume (30, 31).
6. Engine unit according to one of the preceding claims, characterised in that an outlet opening (9) for expelling combustion products of the working medium is formed in the fixed central part (1) for each of the at least one combustion chamber (5), which outlet opening (9) is swept by the at least one second working volume (4, 31) during rotation of the working piston (2),
   in that for each of the at least one combustion chamber (5) a completely retractable shut-off device (11) is arranged in the second working surface (21b), which shut-off device (11), viewed along a direction of rotation of the working piston (3), is positioned upstream of the second combustion chamber opening (6b) of this combustion chamber (5) and downstream of the previous outlet opening (9) and which, depending on a rotational position of the working piston (3), limits an expansion volume (4) in the at least one second working volume (4, 31).
7. Engine unit according to claim 6 and 7, characterized in that the transport piston (2) is shaped in such a way that each of the at least one first shut-off means (11) arranged in the first working volume (21a) is subjected to a phase-wise constant acceleration upon rotation of the transport piston (2) at a constant angular velocity, and
   in that the working piston (3) is shaped in such a way that each of the at least one first shut-off device (11) arranged in the second working surface (21b) is subjected to a phase-wise constant acceleration upon rotation of the working piston (3) at a constant angular velocity.
8. Engine unit according to any one of claims 5 to 7, characterised in that each shut-off device (11) comprises a slide (33), a flap (27), or a door (19) which is fully retractable in an associated matching recess (12) in the combustion chamber housing (18).
9. Engine unit according to any one of the preceding claims, characterised in that the combustion chamber housing (18) of the fixed central part (1) has a plurality of combustion chambers (5) arranged symmetrically about the axis of rotation (7).
10. Engine unit according to one of the preceding claims, characterized in that the transport piston (2) has a hollow cylindrical basic shape, a cylinder surface facing the combustion chamber housing (18) forming the first piston surface (22a) and being set back in regions away from the combustion chamber housing (18) in order to form the at least one first working volume (30, 34) between the transport piston (2) and the combustion chamber housing (18); and/or
    in that the working piston (3) has a hollow cylindrical basic shape, a cylindrical surface facing the combustion chamber housing (18) forming the second piston surface (22b) and being set back in regions away from the combustion chamber housing (18) in order to form the at least one second working volume (4, 31) between the working piston (3) and the combustion chamber housing (18).
11. Engine unit according to claim 10, characterised in that the transport piston (2) and the working piston (3) are formed concentrically to each other about the axis of rotation (7) with respect to their respective basic hollow cylindrical shapes, the combustion chamber housing (18) containing the first piston chamber and the second piston chamber being arranged along a radial direction transverse to the axis of rotation (7) directly between the transport piston (2) and the working piston (3).
12. Engine unit according to any one of claims 1 to 9, characterised in that the transport piston (2) and the working piston (3) are arranged offset along the longitudinal direction, the combustion chamber housing (18) being arranged along the longitudinal direction directly between the transport piston (2) and the working piston (3).
13. Engine unit according to claim 12, characterised in that the transport piston (2) has a hollow cylindrical basic shape, wherein an end face facing the combustion chamber housing (18) forms the first piston surface (22a) and is recessed in regions along the longitudinal direction in order to form the at least one first working volume (30, 34) between the transport piston (2) and the combustion chamber housing (18); and/or in that the working piston (3) has a hollow-cylindrical basic shape, an end face facing the combustion chamber housing (18) forming the second piston face (22b) and being set back in regions in order to form the at least one second working volume (4, 31) between the working piston (3) and the combustion chamber housing (18).
14. Method for the operation of an engine unit for a four-stroke internal combustion engine for a compressible working medium according to one of the preceding claims, wherein for the at least one combustion chamber (5) the inlet opening (8) is formed for the intake of the working medium, which is swept by the at least one first working volume (30, 34), and wherein for the at least one combustion chamber (5) the outlet opening (9) is formed for expelling combustion products of the working medium, which is swept by the at least one second working volume (4, 31) upon rotation of the working piston (3);
    the method comprising a continuous rotation of the transport piston (2) and the working piston (3) along their direction of rotation and the following steps:

    an inlet step in which the at least one first working volume (30, 34) sweeps over the inlet opening (8) and in which the working medium flows into the at least one first working volume (30, 34);

    a compression step comprising:

    • moving the at least one first working volume (30, 34) from the inlet opening (8) to the first combustion chamber opening (6a),

    • closing the second combustion chamber opening (6b) by the second piston surface (22b);

    • separating the compression volume (34) within the at least one first working volume (30, 34), the compression volume (34) being in fluid communication with the first combustion chamber opening (6a) and the at least one combustion chamber (5),

    • reducing the compression volume (34),

    • closing the first combustion chamber opening (6a) by the first piston surface (22a), and

    • igniting the working medium in the at least one combustion chamber (5) of the fixed central part;

    an expansion step comprising:

    • moving the at least one second working volume (4, 31) towards the second combustion chamber opening (6b),

    • separating the expansion volume (31) within the at least one second working volume (4, 31), said expansion volume (4) being in fluid communication with the second combustion chamber opening (6b) and the at least one combustion chamber (5),

    • increasing the expansion volume (4); and

    an exhaust step in which the at least one second working volume (4, 31) sweeps the exhaust port (9).

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