INTERNAL GEAR FLUID MACHINE

Description

[0001] The invention relates to an internal gear fluid machine with a first gear having external teeth and mounted for rotation about a first axis of rotation, and a second gear having internal teeth that mesh with the external teeth in an engagement region and that is mounted for rotation about a second axis of rotation different from the first axis of rotation, wherein a filler piece is arranged between the first gear and the second gear, away from the engagement region, which filler piece bears on the one hand against the external teeth and on the other hand against the internal teeth in order to divide a fluid space present between the first gear and the second gear into a first fluid chamber and a second fluid chamber, and wherein housing walls of a machine housing of the internal gear fluid machine are arranged on both sides of the first gear and the second gear in the axial direction with respect to the first axis of rotation.

[0002] For example, the prior art document DE 199 30 911 C1 is known. This describes an internal gear fluid machine for reversing operation in a closed circuit; with an externally toothed pinion; with an internally toothed ring gear that meshes with the pinion; with a housing; with a filling that fills the crescent-shaped space between the pinion and the ring gear. The filling comprises two identical filling pieces; a stop pin is provided, which is mounted in the housing and against which the filling pieces rest with their end faces. Axial discs are provided on both sides of the pinion. An axial pressure field is provided between the outer side of each axial disc and the corresponding housing wall, and a control field is provided between the inner side of each axial disc and the pinion. At least one control slot is connected to each control field, which tapers towards its free end.

[0003] Furthermore, the document DE 10 2008 053 ​​318 A1 discloses a reversibly operable gear machine comprising a housing in which two gears are arranged. A first bearing chamber and a second bearing chamber are provided, wherein in a first operating direction of the gear machine, the first bearing chamber and, in an opposite second operating direction, the second bearing chamber are subjected to hydraulic fluid pressure, forming a hydrostatic bearing for a gear. Furthermore, a vehicle steering system is described, comprising a hydraulic circuit, a hydraulic cylinder, and a gear machine that operates as a pump and applies hydraulic pressure to a first working chamber in its first operating direction and to a second working chamber of the hydraulic cylinder in its second operating direction.

[0004] The document DE 10 2009 024216 A1 discloses an internal gear fluid machine with plain bearings.

[0005] The object of the invention is to propose an internal gear fluid machine which has advantages over known internal gear fluid machines, in particular enabling higher efficiency due to a particularly effective bearing of the gears in the machine housing with, at the same time, low fluid loss.

[0006] This is achieved according to the invention with an internal gear fluid machine having the features of claim 1. It is provided that the second gear is at least partially encompassed in the circumferential direction by at least one bearing recess formed in the machine housing to form a hydrostatic bearing, which bearing recess only partially overlaps the second gear in the axial direction and is fluidly connected to a fluid connection of the internal gear fluid machine via a fluid line having a flow resistance.

[0007] The internal gear fluid machine is a fluid conveying device and is used to convey a fluid, for example a liquid or a gas. For this purpose, the internal gear fluid machine has two gears, namely the first gear and the second gear. The first gear can also be referred to as a pinion and the second gear as a ring gear. The pinion has the external toothing and the ring gear has the internal toothing. Viewed in the circumferential direction, the external toothing and the internal toothing engage with each other in some areas, i.e. they mesh with each other in some areas, namely in the engagement region. The two gears are intended for fluid conveyance and are therefore designed such that they interact during a rotary movement to convey the fluid and in doing so engage or mesh with each other.

[0008] The first gear is preferably coupled to an input shaft or drive shaft of the internal gear fluid machine, preferably on the one hand rigidly and / or on the other hand detachably or permanently. In the case of detachable coupling, for example, there is a plug-in pinion that is plugged onto the drive shaft and can be removed from it without damage. The plug-in pinion preferably has internal teeth that interact with external teeth of the input shaft for drivingly coupling the plug-in pinion to the input shaft. For example, the first gear is rotatably mounted in a machine housing of the internal gear fluid machine by means of the input shaft. The first gear is preferably arranged on the input shaft so that it always has the same speed as the input shaft during operation of the internal gear fluid machine.

[0009] Both the first gear and the second gear are arranged in the machine housing and are rotatably mounted therein. The first gear is rotatably mounted about the first axis of rotation, whereas the second gear is rotatably mounted about the second axis of rotation. The first axis of rotation can also be referred to as the pinion axis of rotation and the second axis of rotation as the ring gear axis of rotation. Viewed in cross-section, i.e. in a sectional plane perpendicular to the axes of rotation, the first gear is arranged in the second gear in such a way that the external teeth of the first gear mesh with or are in engagement with the internal teeth of the second gear in the engagement region. This means that a rotational movement of the first gear is transmitted directly to the second gear and conversely a rotational movement of the second gear is transmitted directly to the first gear.

[0010] The engagement region is, for example, fixed to the housing, meaning it does not rotate with the first gear or the second gear. In the engagement region, a tooth of one of the gears engages with a tooth space of the other of the gears. The tooth space is circumferentially delimited by teeth of the respective gear. For example, a tooth of the internal gear engages with a tooth space of the external gear, or conversely, a tooth of the external gear engages with a tooth space of the internal gear. In the engagement region, the internal and external gears interact to form a seal.

[0011] The filler piece is arranged on the other side of the engagement region, i.e., preferably on the side diametrically opposite the engagement region with respect to the first axis of rotation and / or the second axis of rotation. The filler piece is located between the first gear and the second gear, or in other words, between the external toothing of the first gear and the internal toothing of the second gear. The filler piece is thus arranged in a fluid space that is bounded radially inward by the first gear and radially outward by the second gear, respectively with respect to the first axis of rotation and the second axis of rotation.

[0012] The filler piece rests on the outer toothing on one side and the inner toothing on the other. More precisely, the filler piece rests sealingly on the tooth tips of the outer toothing and sealingly on the tooth tips of the inner toothing to divide the fluid space into the first fluid chamber and the second fluid chamber. Thus, viewed in the circumferential direction, each of the two fluid chambers is bounded on the one hand by the filler piece and on the other hand by the tight meshing of the outer toothing and the inner toothing in the engagement area.

[0013] Depending on the direction of rotation of the internal gear fluid machine, one of the fluid chambers serves as the suction chamber and the other as the pressure chamber. If the internal gear fluid machine is designed as a pump or is operated as a pump, fluid is supplied to the respective suction chamber, which the internal gear fluid machine pumps towards the pressure chamber or into the pressure chamber. The suction chamber can accordingly also be referred to as the inlet chamber and the pressure chamber as the outlet chamber; what is crucial is that the fluid is always pumped from the inlet chamber towards the outlet chamber during operation of the internal gear fluid machine. When operated as a pump, the pressure in the inlet chamber is always lower than the pressure in the outlet chamber. Of course, however, the pressure in the inlet chamber can already be (significantly) greater than ambient pressure.For example, with the help of the internal gear fluid machine, pressurized fluid is pumped from the inlet chamber towards the outlet chamber.

[0014] If, however, the internal gear fluid machine is designed as a motor or is operated as a motor, fluid is supplied to the pressure chamber, which enters the suction chamber, causing the gears to rotate. In this case, the pressure chamber acts as the inlet chamber and the suction chamber as the outlet chamber; the pressure in the inlet chamber is higher than the pressure in the outlet chamber. This description does not explicitly address the operation of the internal gear fluid machine as a motor; instead, the internal gear fluid machine and its function are explained for operation as a pump. Of course, use as a motor is also possible, and the explanations are analogously applicable to such a design of the internal gear fluid machine or such a use.

[0015] It should be noted that, for the purposes of this application, the suction chamber can also be referred to as a low-pressure chamber, and the pressure chamber as a high-pressure chamber. Analogously, the suction side of the internal gear machine corresponds to a low-pressure side, and the pressure side to a high-pressure side. The terms "low pressure" and "high pressure" do not imply a restriction to a specific pressure level; rather, the pressure in the high-pressure chamber or on the high-pressure side is simply relatively higher than the pressure in the low-pressure chamber or on the low-pressure side.

[0016] The filler piece is preferably designed in several parts and thus has several segments. The segments of the filler piece are arranged next to one another in the radial direction, so that a first segment is arranged on the side of a second segment facing the first gear, and conversely, the second segment is arranged on the side of the first segment facing the second gear. The first segment bears sealingly against the first gear or its external toothing, and the second segment bears sealingly against the second gear or the internal toothing of the second gear.

[0017] The two segments are preferably displaceable relative to one another in the radial direction. Particularly preferably, a gap existing between them is subjected to fluid pressure during operation of the internal gear fluid machine in such a way that the first segment is pushed towards the first gear and the second segment towards the second gear, so that the segments bear sealingly against the respective gear or the tooth tips of the corresponding toothing. The internal gear fluid machine is thus radially compensated or gap-compensated in the radial direction. Each of the segments can be further subdivided into segments. For example, the first segment is one-piece or consists of at least two segments and / or the second segment is one-piece or consists of at least two segments. These segments of the filler piece are also preferably mounted so that they can be displaced relative to one another, i.e., they can be displaced independently of one another.This achieves particularly effective gap compensation.

[0018] The internal gear fluid machine comprises the machine housing. The two gears of the internal gear fluid machine are arranged between housing walls of the machine housing. One of the housing walls is located on a first side of the gears, and a second of the housing walls is located on a side of the gears opposite the first side in the axial direction, so that the housing walls accommodate the gears between them in the axial direction. In particular, the gap remaining between the housing walls and the gears is dimensioned so small that the housing walls ensure adequate sealing of the fluid space or chambers. For example, the gears are mounted on and / or in the machine housing.

[0019] The second gear is partially encompassed in the circumferential direction by at least one bearing recess formed in the machine housing. The bearing recess is designed such that it only partially overlaps the second gear in the axial direction and is arranged so as to completely overlap with the second gear. Thus, the bearing recess not only has a smaller extension in the axial direction than the second gear, but is also arranged such that the ends delimiting the bearing recess in the axial direction are arranged so as to overlap with the second gear. The bearing recess therefore does not protrude beyond the second gear in the axial direction.

[0020] The bearing recess is formed as a groove in the machine housing that runs in the circumferential direction. With such a configuration, the bearing recess surrounds the second gear in the circumferential direction by at least 30°, at least 60°, at least 90°, at least 120°, or at least 150°. However, the bearing recess can also be significantly smaller in the circumferential direction and surround the second gear in this direction by less than 30°, in particular by at most 15°, at most 10°, or at most 5°. In this case, the bearing recess is formed, for example, as a round bore.

[0021] The bearing recess serves to form the hydrostatic bearing or a hydrostatic bearing for the second gear. During operation of the internal gear fluid machine, the bearing recess is at least temporarily pressurized with fluid under pressure, so that the second gear is pushed radially away from the machine housing. This creates a fluid film between the second gear and the machine housing, which ensures particularly loss-free support of the second gear. In particular, the pressure present in the bearing recess counteracts the pressure present in the pressure chamber. The bearing recess is arranged and / or designed accordingly for this purpose.

[0022] Thus, while the fluid present in the pressure chamber urges the second gear in a first direction, the fluid present in the bearing recess urges the second gear in a second direction opposite to the first direction. Particularly preferably, a force exerted on the second gear by the fluid present in the bearing recess is at least as great as a force exerted on the second gear by the fluid present in the pressure chamber. For example, the former force is at least 50%, at least 60%, at least 70%, at least 80%, or at least 90% of the latter force.

[0023] In order to apply the pressurized fluid to the bearing recess, it is fluidically connected to one of the fluid connections. In fluid terms, the flow resistance exists between the fluid connection and the bearing recess, which causes a reduction in pressure. The flow resistance is preferably in the form of a cross-sectional constriction. In fluid terms, a flow cross-sectional area is preferably identical before and after the flow resistance or the cross-sectional constriction. This means that the cross-sectional constriction is only present in sections and, in particular, does not extend directly to the bearing recess. Rather, the flow cross-sectional area decreases in the area of ​​the cross-sectional constriction and then increases again, in particular also in the area of ​​the cross-sectional constriction.For example, a ratio between a length and a width or a diameter of the cross-sectional constriction is at most 25, at most 20 or at most 15. However, the ratio is preferably at most 10 or at most 5. The width or diameter is to be understood as the smallest dimension of the cross-sectional constriction over its extent.

[0024] The flow resistance reduces fluid loss from the bearing recess toward the return line. The flow resistance can be readily provided, as the fluid pressure available on the pressure side of the internal gear fluid machine is usually more than sufficient to achieve adequate bearing support. It is therefore possible to reduce the pressure without compromising the quality of the bearing. Reducing the pressure, in turn, reduces the flow, so that a smaller amount of fluid is discharged via the bearing recesses toward the return line or into the return line.

[0025] The flow resistance is preferably designed such that the amount of fluid discharged from the bearing recess into the return line per unit of time corresponds to a maximum of 50%, a maximum of 40%, a maximum of 30%, or a maximum of 25% of the total amount of fluid accumulating in the return line per unit of time. Such dimensioning of the flow resistance is in any case suitable for achieving adequate bearing support for the second gear in the machine housing. Of course, the amount of fluid per unit of time can also be higher, for example a maximum of 75%, a maximum of 70%, a maximum of 75%, a maximum of 60%, or a maximum of 55% of the stated value. However, the smaller values ​​are preferred because they can significantly limit fluid loss with sufficient bearing quality.

[0026] For example, dimensions of the flow resistance, in particular a smallest flow cross-sectional area of ​​the flow resistance, depend on a diameter of the second gear or a root diameter of the internal gearing. It can be provided that the dimensions are selected depending on an extension of the bearing recess in the circumferential direction and / or in the axial direction. Additionally or alternatively, a dependency on the bearing clearance and / or on an extension of the bearing webs in the axial direction can be provided. For example, a relationship with a displacement volume of the internal gear fluid machine is also provided.In particular, a ratio of the dimensions of the flow resistance, in particular a smallest diameter of the flow resistance over its extent, to the displacement volume of at least 15 1 / m 2< and at most 75 1 / m 2<, at least 30 1 / m 2< and at most 60 1 / m 2<, or at least 30 1 / m 2< and at most 45 1 / m 2< is provided. This results in dimensions of 0.12 mm to 0.16 mm for an internal gear fluid machine with a displacement volume of 8 cm 3<. These values ​​apply in particular to a design of the flow resistance as an orifice plate.

[0027] Particularly preferably, the bearing recess is fluidically connected to both fluid connections, in particular via a flow resistance. This ensures the provision of the hydrostatic bearing regardless of the direction of rotation of the internal gear fluid machine and regardless of operation as a pump or motor. The flow resistance is designed identically for both fluid connections. Alternatively, however, an asymmetric design can also be implemented, in which different flow resistances exist between the fluid connections and the bearing recesses.

[0028] The bearing recess only partially encompasses the second gear in the circumferential direction. Particularly preferably, there are two bearing recesses spaced apart from one another in the circumferential direction, i.e., the two bearing recesses are spaced apart from one another on both sides in the circumferential direction. In particular, the bearing recesses are arranged symmetrically in cross-section with respect to an imaginary plane which contains the axis of rotation of the second gear and / or the axis of rotation of the second gear. For example, the bearing recesses are fluidically connected to different fluid connections, preferably each via a flow resistance. In other words, a first of the bearing recesses is fluidically connected to a first fluid connection via a first flow resistance, and a second of the bearing recesses is fluidically connected to a second fluid connection of the internal gear fluid machine via a second flow resistance.

[0029] This means that each of the bearing recesses is directly connected to the corresponding fluid connection via the respective flow resistance and is only indirectly fluidically connected to the other fluid connection, in particular via the fluid space or one or more of the fluid chambers. Such a flow connection can, of course, also exist outside the internal gear fluid machine. Depending on the direction of rotation of the internal gear fluid machine, one of the bearing recesses is always fluidly connected to the pressure side and another of the bearing recesses is fluidly connected to the suction side of the internal gear fluid machine. This balances the forces within the internal gear fluid machine, resulting in particularly high efficiency.

[0030] The flow resistance is arranged in the fluid line, via which the respective bearing recesses are in fluid communication with the corresponding fluid connection. For example, it is thus provided that the bearing recesses are each connected to the corresponding fluid connection via a fluid line, with a flow resistance being arranged in each of the fluid lines. All statements regarding the bearing recess within the scope of this description are preferably optionally applicable to each of the multiple bearing recesses, if present.

[0031] It can be provided that only a single bearing recess is formed in the machine housing, which only partially or completely encompasses the second gear in the circumferential direction. This bearing recess is fluidically connected to the fluid connection of the internal gear fluid machine. Alternatively, it can also be provided that the single bearing recess is fluidically connected to several fluid connections, in particular to a fluid connection on the pressure side and a fluid connection on the suction side of the internal gear fluid machine. For example, valves, in particular check valves, are fluidically connected between the bearing recess on the one hand and the fluid connections on the other.These are preferably designed and / or adjusted in such a way that they only allow fluid flow from the respective fluid connection toward the bearing recess, thus preventing flow from the bearing recesses toward the fluid connections. This always ensures optimal fluid loading of the bearing recess, while largely preventing fluid loss or overflow of the fluid from the pressure side to the suction side via the bearing recess.

[0032] In the axial direction, the bearing recess only partially overlaps the second gear, so that conversely the second gear completely overlaps the bearing recess in the axial direction. For example, the bearing recess is delimited on both sides in the axial direction by bearing webs which are formed in circumferential overlap with the bearing recess and have at least the same extension as the bearing recess. In the case of multiple bearing recesses, each of the bearing recesses has such bearing webs. The second gear rests sealingly on the bearing webs, in particular continuously in circumferential direction in overlap with the bearing recess, or the second gear is at a smaller distance from the bearing webs than from a base of the bearing recess, which delimits the bearing recess in the direction facing away from the second gear, thus in particular in the radial direction towards the outside.This reliably prevents any unwanted fluid leakage from the bearing recess. For example, the second gear has a bearing clearance, i.e., a radial distance from the bearing lands, of no more than 0.25 mm, no more than 0.2 mm, no more than 0.15 mm, no more than 0.1 mm, no more than 0.075 mm, or no more than 0.05 mm. Distances of no more than 0.1 mm or less are preferred.

[0033] The described internal gear fluid machine enables particularly effective and loss-free mounting of the second gear in the machine housing. At the same time, excessive fluid losses, which can occur due to the use of the fluid to implement the hydrostatic bearing, are effectively avoided by the flow resistance. The flow resistance does cause a pressure loss between the fluid connection and the bearing recesses, so that the fluid pressure present in the bearing recesses is lower than the fluid pressure at the fluid connection. However, the fluid pressure remaining in the bearing recesses is sufficient for mounting the second gear. The flow resistance is preferably designed or dimensioned accordingly.

[0034] Regardless of the design of the internal gear fluid machine, it can be provided that the internal gear fluid machine is fluidly connected to a first chamber of a working cylinder on the one hand and to a second chamber of the working cylinder on the other. In other words, the first chamber of the working cylinder is fluidly connected to a first of the fluid chambers, and the second chamber of the working cylinder is fluidly connected to a second of the fluid chambers. Accordingly, the internal gear fluid machine can be used to convert either mechanical energy into a force acting on a working piston arranged in the working cylinder, or a force acting on the working piston into mechanical energy.Of course, it can be provided that the arrangement comprising the internal gear fluid machine in the working cylinder is operated temporarily to convert the mechanical energy into force and temporarily to convert the force into mechanical energy. The working cylinder is preferably designed as a hydraulic cylinder; in this case, a liquid, in particular oil, is used as the fluid. The arrangement comprising the internal gear fluid machine and the working cylinder is, for example, a component of an industrial truck, in particular a forklift truck, or of a construction machine or piece of construction equipment, in particular an excavator. In this respect, the invention also relates to such an arrangement comprising the internal gear fluid machine and the working cylinder, as well as to a method for operating such an arrangement. Reference is made to the further explanations within the scope of this description.

[0035] A further development of the invention provides that the flow resistance is in the form of a fluidic orifice, a fluidic throttle, or a fluidic nozzle. An orifice is understood to be a sudden cross-sectional constriction; at the beginning of the orifice, the flow cross-sectional area decreases abruptly and expands again just as abruptly at the end of the orifice, in particular to the same flow cross-sectional area as before the orifice. For example, the orifice has a ratio of the length of the cross-sectional constriction in the flow direction to the width or diameter of at most 2, at most 1.5, or at most 1. The same applies to the throttle as stated for the orifice, with the difference that the ratio of length to width or diameter is greater. In particular, the ratio is at least 2 or greater than 2.For example, a ratio of at least 3, at least 4 or at least 5 is used.

[0036] The nozzle is a cross-sectional constriction where the flow cross-sectional area continuously decreases until it reaches a minimum. Downstream of the minimum flow cross-sectional area, the flow cross-sectional area expands again. This can occur abruptly or continuously. In the latter case, the flow resistance comprises a diffuser in addition to the nozzle. For example, the nozzle and diffuser are symmetrical or mirror-image, i.e., they have the same longitudinal extent and the same gradient of the flow cross-sectional area over the longitudinal extent. The use of the nozzle and diffuser enables an effective reduction of pressure or flow rate without excessive losses.

[0037] A further development of the invention provides that the fluid line runs radially outwards from the bearing recess and / or is continuously straight. The fluid line opens directly into the bearing recess. On its side facing away from the bearing recess, the fluid line can also open directly into the fluid connection or, alternatively, can be fluidically connected to it only indirectly via another line. Irrespective of this, the fluid line runs radially outwards from the bearing recess, preferably exactly in the radial direction. This means that a longitudinal central axis of the fluid line is perpendicular to an imaginary plane containing the axis of rotation of the first gear and the axis of rotation of the second gear. This ensures that the fluid is introduced into the bearing recess with low loss. Additionally or alternatively, the fluid line is continuously straight.This specifically means that the longitudinal center axis of the fluid line is straight throughout. This straight line ensures minimal pressure loss across the fluid line, so this design also contributes to the efficient introduction of fluid into the bearing recess.

[0038] A further development of the invention provides that the fluid line opens radially inwards into the bearing recess by passing through a base of the bearing recesses to form an opening. The base delimits the bearing recess in the direction away from the second gear. The base is formed by the machine housing. The bearing recess is thus delimited radially outwards by the base and is open radially inwards and accordingly in the direction of the second gear. In the axial direction, the bearing recess is preferably delimited on opposite sides by walls which run at an angle to the base. The walls delimiting the bearing recess preferably run parallel to one another.However, they can alternatively also be angled relative to one another, so that, for example, the bearing recess has an axial extension that increases or decreases in the direction of the second gear or in the direction away from the base. In this case, the bearing recess is, for example, trapezoidal in cross-section. The fluid line passes through the base of the bearing recess. In doing so, it forms the outlet opening. In other words, the fluid line opens into the bearing recess via the outlet opening, with the outlet opening being formed in the base. Such a configuration also serves to efficiently introduce the fluid into the bearing recess and prevent excessive pressure losses.

[0039] A further development of the invention provides that the fluid line, on its side facing away from the bearing recess, opens into a larger connecting channel via which it is fluidically connected to the fluid connection. It has already been pointed out that the fluid line can be fluidically connected to the fluid connection either directly or only indirectly. If the fluid line is only indirectly connected to the fluid connection, the fluid line is in flow connection with the fluid connection via the connecting channel. For this purpose, the fluid line opens directly into the connecting channel, namely in particular in the radial direction. A longitudinal center axis of the fluid line is preferably angled with respect to a longitudinal center axis of the connecting channel, i.e. the two longitudinal center axes enclose an angle with each other that is greater than 0° and less than 180°.Preferably, the angle is at least 45° and at most 135°, at least 60° and at most 120°, at least 75° and at most 105° or approximately or exactly 90°.

[0040] In principle, the connecting channel can be continuously straight, i.e., it can run continuously straight between the point at which the fluid line flows into it and the fluid connection. However, the connecting channel can also have at least one bend or curve. Preferably, however, the fluid line flows into a straight region of the connecting channel. The connecting channel flows into the fluid connection on its side facing away from the fluid line, i.e., it is directly fluidically connected to it. For example, the connecting channel flows into the fluid connection in a radial direction, so that the longitudinal center axis of the connecting channel is angled relative to a longitudinal center axis of the fluid connection. In this regard, reference is made to the above explanations regarding the angle.

[0041] The connecting channel has larger dimensions than the fluid line; in particular, its flow cross-section is larger than the flow cross-section of the fluid line. This results in a particularly low pressure loss, so that the fluid line is fluidically connected to the fluid connection particularly effectively. For example, the largest flow cross-sectional area of ​​the connecting channel over its entire length is larger by a factor of at least 2, at least 3, at least 4, or at least 5 than the largest flow cross-sectional area of ​​the fluid channel over its entire length.

[0042] A further development of the invention provides that the cross-sectional constriction is formed only locally in the fluid line, so that a flow cross-section of the fluid line on both sides of the cross-sectional constriction is larger than a flow cross-section in the region of the cross-sectional constriction. The cross-sectional constriction is present in the fluid line and temporarily reduces its flow cross-sectional area. This means that the fluid line as a whole cannot be regarded as a cross-sectional constriction, even if its flow cross-sectional area is possibly smaller than the flow cross-sectional area of ​​elements that are fluidically connected to the fluid line. For example, the flow cross-sectional area of ​​the connecting channel may be larger than that of the fluid line. However, the flow resistance is not caused by the fluid line itself; rather, the cross-sectional constriction occurs in the fluid line.

[0043] On both sides of the cross-sectional constriction, the fluid line has a flow cross-sectional area that is larger than the flow cross-sectional area of ​​the cross-sectional constriction or the flow resistance. For example, the flow cross-sectional area of ​​the fluid line on both sides of the cross-sectional constriction is larger than the flow cross-sectional area of ​​the cross-sectional constriction by a factor of at least 5, at least 7.5, at least 10, at least 12.5, at least 15, or at least 20. The flow cross-sectional area of ​​the cross-sectional constriction is understood to be the smallest flow cross-sectional area of ​​the cross-sectional constriction across its entire length. The described design achieves effective flow limitation for the fluid.

[0044] A further development of the invention provides that the bearing recess, on its side fluidically facing away from the fluid line, is fluidically connected via a leakage gap to a return recess of the internal gear fluid machine, which is in direct fluid communication with a suction side of the internal gear fluid machine and / or a fluid tank. The bearing recess is fluidically connected to a return line of the internal gear fluid machine, via which return line fluid is discharged, namely in the direction of the suction side of the internal gear fluid machine and / or in the direction of the fluid tank. Leakage fluid, i.e. fluid that accrues in the internal gear fluid machine due to leaks, is collected in the return line. The fluid is discharged in the direction of the suction side and / or the fluid tank, preferably in such a way that it is again pumped by the internal gear fluid machine towards the pressure side.For example, the fluid tank is fluidly connected to the suction side of the internal gear fluid machine. The fluid tank can be part of the internal gear fluid machine or separate from it. For example, the internal gear fluid machine and the fluid tank are part of a corresponding arrangement.

[0045] The return has the return recess, which is formed in the machine housing. The return recess is, for example, a recess formed in the machine housing and open in the direction of the gears. The return recess can have at least the same dimensions in the axial direction as the at least one bearing recess or the bearing recesses, or can project beyond them in the axial direction, in particular only on one side or on both sides. The bearing recess or the bearing recesses are each designed to be spaced apart from the return recess in the circumferential direction. If there are multiple bearing recesses, the return or the return recess is preferably arranged between the bearing recesses in the circumferential direction. In particular, the bearing recesses are arranged to be equidistant from the return recess in the circumferential direction.

[0046] The return line is preferably configured such that the fluid present therein is either fed to the fluid tank and / or directly returned to the internal gear fluid machine and conveyed by it toward its pressure side. The fluid discharged from the return line into the fluid tank can also be returned to the internal gear machine. In other words, the fluid is first discharged from the return line into the fluid tank and then removed from the fluid tank by the internal gear fluid machine and conveyed toward its pressure side.

[0047] As already explained, the bearing recess is preferably spaced apart from the return recess in the circumferential direction. Alternatively, however, it can also be provided that the bearing recess is connected to the return or the return recess at exactly one point in the circumferential direction, in particular, it opens into the return recess.

[0048] The leakage gap is located between the bearing recess and the return recess, in the area of ​​which the second gear is at least partially only a small distance from the machine housing in the radial direction, for example a distance of at most 10 µm, at most 5 µm, at most 2.5 µm or at most 1 µm. In this respect, only a small amount of fluid passes from the bearing recess into the return recess via the leakage gap. In particular, this distance only exists at one point or over a certain part of the second gear in the circumferential direction. Away from this point or this part, the distance is greater. In particular, the small distance, viewed in cross-section, exists on a side of the internal gear machine on which there is a higher pressure. On a side with lower pressure, however, the distance is greater.For example, the distance away from the location or part of the second gear, in particular on the side with lower pressure, is more than 10 µm, in particular at least 25 µm, at least 50 µm, at least 75 µm, or at least 100 µm. However, the distance there is particularly preferably at most 150 µm, at most 125 µm, or at most 100 µm.

[0049] The return line or return recess, for example, is centered in the circumferential direction relative to the filler piece. This places it centrally between the pressure side and the suction side of the internal gear fluid machine, resulting in a symmetrical design. The implementation of the return recess enables effective recirculation of the leakage fluid occurring in the internal gear fluid machine.

[0050] The invention provides that the return line has return pockets on both sides of the gears in the axial direction, which are in flow communication with the return recess. The return pockets are also provided as recesses formed in the machine housing. Viewed in the axial direction, such a return pocket is present or formed on each side of the gears. The return pockets also serve to return leakage fluid accumulating in the internal gear fluid machine toward the suction side of the internal gear fluid machine and / or toward the fluid tank. This ensures efficient operation of the internal gear fluid machine.

[0051] A further development of the invention provides that a connection channel is formed in each of the two housing walls, and that the same fluid chamber is fluidly connected to the fluid connection of the internal gear fluid machine via both connection channels. A connection channel is present in each of the housing walls. This means that each of the housing walls has such a connection channel. Via the connection channels, one of the fluid chambers is fluidly connected, preferably permanently, to a fluid connection of the internal gear fluid machine. Thus, from a fluidic perspective, each of the connection channels is located between this fluid chamber and this fluid connection, so that the flow connection between the fluid chamber and the fluid connection runs via both connection channels.In this respect, the connection channels are fluidically parallel between the fluid chamber and the fluid connection, so that fluid can flow via both connection channels simultaneously from the fluid connection to the fluid chamber or vice versa.

[0052] It is therefore not intended to connect different fluid chambers to the same fluid connection or one of the fluid chambers to different fluid connections via the connection channels. Rather, the connection channels serve to establish the flow connection between exactly one of the fluid chambers and exactly one of the fluid connections. Accordingly, during operation of the internal gear fluid machine, the fluid flows either out or in through the connection channels at the same time. This makes it possible to achieve a particularly high fluid throughput of the internal gear fluid machine. Incidentally, the flow connection is to be understood as a flow connection that runs exclusively via the internal gear fluid machine, i.e. not via an external connection. In particular, the flow connection runs only via the connection channels and - optionally - via one or more axial openings in one or more optionally provided sealing disks.

[0053] In principle, the fluid chamber fluidically connected to the fluid connection via the connecting channels can be the first fluid chamber or the second fluid chamber. Accordingly, the fluid chamber can be either the suction chamber or the pressure chamber, so that during operation of the internal gear fluid machine, the connecting channels serve either to supply fluid to the suction chamber or to discharge the fluid from the pressure chamber. In either case, a particularly low flow resistance is achieved during the inflow or outflow of the fluid.

[0054] A further development of the invention provides that a sealing disk is arranged next to the first gear and the second gear in the axial direction with respect to the first axis of rotation, which sealing disk rests sealingly against the first gear and the second gear during operation of the internal gear fluid machine, wherein an axial opening is formed in the sealing disk, via which one of the fluid chambers is in flow connection with one of the fluid connections of the internal gear fluid machine. For example, viewed in the axial direction, the sealing disk is only present on one side of the first gear and the second gear. However, it is preferably provided that - again viewed in the axial direction - such a sealing disk is arranged on each side of the two gears. In the context of this description, the particularly advantageous case of multiple sealing disks is often explained.However, it goes without saying that the corresponding embodiments can also be used for a design of the internal gear fluid machine in which only a sealing disc is a component of the internal gear fluid machine.

[0055] The sealing disc is located on one side of the gears, as seen in the axial direction. During operation of the internal gear fluid machine, the sealing disc forms a sealing contact with the gears. For this purpose, it is preferably pushed in the axial direction towards the gears, for example by pressurisation, i.e. by exposure to a pressurised fluid. If there are several sealing discs, they are arranged on both sides of the gears in the axial direction. One of the sealing discs is therefore located on a first side of the gears and a second of the sealing discs is located on a second side of the gears, opposite the first side in the axial direction, so that the sealing discs hold the gears between them, as seen in the axial direction. During operation of the internal gear fluid machine, the sealing discs form a sealing contact with the gears.To this end, they are preferably forced axially toward the gears, for example, by applying pressure, i.e., by applying a pressurized fluid. The internal gear fluid machine is thus axially compensated or gap-compensated in the axial direction. This achieves a particularly high level of efficiency for the internal gear fluid machine.

[0056] The axial opening is formed in the sealing disc. If there are multiple sealing discs, each of the sealing discs has an axial opening. In other words, each of the sealing discs has such an axial opening, so that a total of several axial openings are formed in the multiple sealing discs. One of the fluid chambers is fluidically connected, preferably permanently, to a fluid connection of the internal gear fluid machine via the axial opening(s). From a fluidic perspective, the axial opening or each of the axial openings is therefore located between this fluid chamber and this fluid connection, so that the flow connection between the fluid chamber and the fluid connection runs via the axial opening or openings.

[0057] Therefore, it is not intended to connect different fluid chambers to the same fluid connection via the axial opening(s), or to connect one of the fluid chambers to different fluid connections. Rather, the axial opening(s) serve to establish the flow connection between exactly one of the fluid chambers and exactly one of the fluid connections. Accordingly, during operation of the internal gear fluid machine, the fluid either flows out or in through the axial opening or simultaneously through the axial openings. This allows a particularly high fluid throughput of the internal gear fluid machine to be achieved.

[0058] In principle, the fluid chamber fluidically connected to the fluid connection via the axial opening(s) can be the first fluid chamber or the second fluid chamber. Accordingly, the fluid chamber can be either the suction chamber or the pressure chamber, so that the axial opening(s) serve either to supply fluid to the suction chamber or to discharge the fluid from the pressure chamber during operation of the internal gear fluid machine. In either case, a particularly low flow resistance is achieved during the inflow or outflow of the fluid.

[0059] A further development of the invention provides that at least one of the connection channels is fluidically connected to the fluid chamber via the axial opening. In other words, the axial opening is fluidically connected between the connection channel and the fluid chamber. Accordingly, the fluid chamber is fluidically connected to the fluid connection via the axial opening and the corresponding connection channel. Particularly preferably, of course, both connection channels are fluidically connected to the fluid chamber via the axial openings. This means that a first of the connection channels is fluidically connected to the fluid chamber via a first of the axial openings. In addition, a second of the connection channels is fluidly connected to the same fluid chamber via a second of the axial openings.Overall, there are several flow paths between the fluid chamber and the fluid connection, with a first of the flow paths running via the first axial opening and the first connection channel and a second of the flow paths running via the second axial opening and the second connection channel.

[0060] A further development of the invention provides that the axial opening widens in the direction of the first gear and the second gear. A flow cross-sectional area of ​​the axial opening does not remain constant over its respective extent, but rather changes. In this case, the flow cross-sectional area of ​​the axial opening increases in the direction of the gears, i.e., becomes larger. For example, the widening occurs continuously, at least in sections or throughout, so that discontinuities in the flow cross-sectional area are avoided. However, the widening can also occur abruptly, so that a dimensional jump is formed in each axial opening.

[0061] Preferably, the axial opening is round, i.e., circular, in cross-section relative to its respective longitudinal extent. The widening of the axial opening enables particularly efficient inflow and outflow of the fluid. Particularly preferably, the widening occurs for both axial openings. In this respect, it is provided that the axial openings widen in the direction of the first gear and the second gear. The embodiments for widening the axial opening can be used in addition to each other.

[0062] A further development of the invention provides that the fluid connection is a first fluid connection of a plurality of fluid connections, and that the first fluid chamber is in flow order with the fluid connection present as the first fluid connection via the connection channels present as first connection channels, and that a second connection channel is formed in each of the housing walls, and that the second fluid chamber is in flow connection with a second fluid connection of the internal gear fluid machine via the second connection channels. Overall, the internal gear fluid machine therefore has a plurality of fluid connections, a plurality of first connection channels, and a plurality of second connection channels. The fluid connection already mentioned above forms the first fluid connection, and the connection channels mentioned form the first connection channels.

[0063] In addition to the first fluid connection, there is now a second fluid connection, and in addition to the first connection channels, there are second connection channels in the machine housing. The second fluid chamber is fluidly connected to the second fluid connection via the second connection channels, preferably permanently. The further explanations in this description regarding the first connection channels apply analogously to the second connection channels.

[0064] Particularly preferably, the filler piece extends circumferentially from the first connection channels to the second connection channels, thus engaging both the imaginary extension of the first connection channels and the imaginary extension of the second connection channels. Furthermore, the described taper is particularly preferably provided and formed on both the side of the filler piece facing the first connection channels and the side facing the second connection channels. The described configuration enables, in particular, direction-independent operation of the internal gear fluid machine.

[0065] Additionally or alternatively, the above statements apply to the connection channels for the axial opening(s). It can therefore be provided that the fluid connection is a first fluid connection of a plurality of fluid connections and that the first fluid chamber is in flow order with the fluid connection present as the first fluid connection via the axial opening designed as the first axial opening, and that a second axial opening is formed in the sealing disc and that the second fluid chamber is in flow connection with a second fluid connection of the internal gear fluid machine via the second axial opening. Of course, it is particularly preferred that there are again a plurality of sealing discs with a corresponding plurality of axial openings, wherein the axial openings are designed as first axial openings.In such a configuration, a second axial opening is formed in each of the sealing discs, wherein the second fluid chamber is in flow order with the second fluid connection via the second axial openings.

[0066] A further development of the invention provides that the filler piece projects in the circumferential direction up to the axial opening and / or, viewed in the circumferential direction, ends in overlap with the axial opening. The filler piece thus projects in the circumferential direction up to an imaginary extension of the axial opening. It at least engages with this imaginary extension, but it can also penetrate it completely in the circumferential direction. However, it is particularly preferred that the filler piece ends in overlap with the axial opening, viewed in the circumferential direction, i.e., in the imaginary extension of the axial opening. This achieves reliable and effective sealing of the fluid chambers from one another by means of the filler piece. It should also be noted at this point that such a configuration preferably applies to multiple axial openings.For example, it is intended that the filler piece extends in the circumferential direction up to the axial openings and / or ends in overlap with the axial openings when viewed in the circumferential direction.

[0067] A further development of the invention provides that the filler piece is tapered in the axial direction in overlap with the axial opening, in particular only on one side or both sides. It is particularly preferred that the taper of the filler piece ends in overlap with the axial openings, viewed in the circumferential direction. The taper of the filler piece causes the filler piece to move away from the axial opening or at least one of the axial openings in the axial direction, i.e., to be continuous therefrom. In other words, the distance between the filler piece and the axial opening or at least one of the axial openings increases in the circumferential direction. This facilitates the inflow and outflow of the fluid.

[0068] In addition, the taper of the filler piece can be designed such that the fluid is efficiently deflected in the circumferential direction, so that it can flow into or out of the respective fluid chamber particularly efficiently. It can be provided that the filler piece tapers only on one side, i.e. on the side facing the axial opening or one of the axial openings. However, it is particularly preferably tapered on both sides, so that the inflow or outflow through the axial opening or both axial openings can take place efficiently. The filler piece is particularly preferably designed symmetrically when viewed in longitudinal section, i.e. in the axial direction, so that the taper is identical on both sides, albeit a mirror image.

[0069] A further development of the invention provides that the taper of the filler piece, viewed in the circumferential direction, ends in overlap with the axial opening(s). The filler piece extends at least partially up to the axial opening(s) and preferably has constant dimensions in the axial direction up to the taper, viewed in the circumferential direction. For example, the filler piece has an extension in the axial direction up to the imaginary extension of the axial opening(s) that corresponds to the distance between the sealing discs, so that it rests against the sealing discs away from the axial opening(s), in particular continuously in the circumferential direction.Only then, i.e., in overlap with the axial opening(s), does the filler piece taper, so that its axial extension decreases in the circumferential direction, namely up to a free end of the filler piece. In other words, the taper only begins in overlap with the axial opening(s) and preferably extends to the free end of the filler piece. This ensures a reliable sealing effect of the filler piece.

[0070] A further development of the invention provides that one of the connection channels is fluidically connected to the fluid connection directly, and another of the connection channels is fluidically connected to the fluid connection via the connecting channel that axially extends over the first gear and the second gear. For example, the connection channels have the same flow cross-sectional area. Preferably, at least one of the connection channels opens into the axial opening, if present. Particularly preferably, both connection channels open into the optionally provided, multiple axial openings.

[0071] For example, it can be provided that the flow cross-sectional area of ​​the connecting channel on its side facing the gears and / or the respective axial opening is smaller than the flow cross-sectional area of ​​the axial opening on its side facing the gears and / or the respective connecting channel. From the direction of the connecting channel toward the gears and / or the axial opening, there is thus a widening of the flow cross-section and a corresponding increase in the flow cross-sectional area.

[0072] It can be provided that the connecting channels have the same axial length with respect to their respective longitudinal center axes. One of the connecting channels is fluidically connected directly to the fluid connection, for example, it opens directly into the fluid connection. The other of the connecting channels is fluidically connected to the fluid connection only indirectly via the connecting channel. The connecting channel completely overlaps the two gears in the axial direction.

[0073] Additionally, it can be provided that the connecting channel overlaps at least one of the sealing discs or both sealing discs, if present. For example, it is provided that the connecting channel opens into the connection channel on a side of a first sealing disc facing away from the gears, and into the fluid connection on a side of another sealing disc facing away from the gears. For example, one connection channel opens into the fluid connection in the axial direction, and the other connection channel opens into the radial direction.

[0074] The fluid connection has a flow cross-sectional area that is larger than the flow cross-sectional area of ​​the connecting channels. For example, the flow cross-sectional area of ​​the fluid connection is larger than the flow cross-sectional area of ​​the connecting channels by a factor of at least 2.5, at least 3, at least 4, or at least 5. Additionally or alternatively, the flow cross-sectional area of ​​the connecting channel is larger than the flow cross-sectional area of ​​the connecting channels, for example, by a factor of at least 1.25, at least 1.5, at least 1.75, or at least 2.0. This ensures particularly effective operation of the internal gear fluid machine.

[0075] A further development of the invention provides that the axial opening is encompassed by a seal, which is in sealing contact with the sealing disc on one side and the machine housing on the other. Outside of the area encompassed by the seal, a pressure field is formed that is fluidly connected to a pressure side of the internal gear fluid machine, so that the sealing disc is at least temporarily forced toward the gears. The seal ensures a fluid-tight connection between the axial opening or the respective axial opening and the respective connection channel.

[0076] Away from the seal, i.e., outside the area enclosed by the seal into which the axial aperture and the connection channel open, lies the pressure field, which is at least temporarily exposed to pressurized fluid. For this purpose, the pressure field is fluidically connected to the pressure side of the internal gear fluid machine. The pressurized fluid pushes the sealing disc toward the gears, so that the fluid chambers are reliably sealed axially by the axial disc. This is particularly preferred for multiple sealing discs, if present.It can therefore be provided that the axial openings are each encompassed by a seal which, on the one hand, is in sealing contact with the respective sealing disc and, on the other hand, with the machine housing, wherein outside of an area encompassed by the seal, a pressure field is formed which is fluidically connected to a pressure side of the internal gear fluid machine, so that the sealing disc is at least temporarily urged in the direction of the gears.

[0077] A further development of the invention provides that the filler piece is designed symmetrically in the circumferential direction, so that the internal gear fluid machine is reversible. This means that the filler piece is divided into several segments in the circumferential direction. Particularly preferably, the filler piece has a total of four segments, since it is divided into individual segments both in the radial direction and in the circumferential direction. This realizes the radial compensation of the internal gear fluid machine regardless of its direction of rotation. Such an internal gear fluid machine can also be referred to as a four-quadrant internal gear fluid machine or a reversible internal gear fluid machine.

[0078] A further development of the invention provides that the bearing recess is a first bearing recess of a plurality of bearing recesses and the flow resistance is a first flow resistance of a plurality of flow resistances and a second of the bearing recesses is formed in the machine housing at a distance in the circumferential direction from the first bearing recess, which at least partially overlaps the second gear in the axial direction, wherein the first bearing recess is fluidically connected to the first fluid connection via the first flow resistance and the second bearing recess is fluidically connected to the second fluid connection via a second of the flow resistances.

[0079] As already explained, in addition to the bearing recess, there may be a further bearing recess. The bearing recess is referred to as the first bearing recess and the further bearing recess as the second bearing recess. The two bearing recesses, i.e. the first bearing recess and the second bearing recess, are arranged in the machine housing at a distance from one another in the circumferential direction. The statements regarding the bearing recess and the first bearing recess are preferably fully applicable to the second bearing recess. Reference is therefore made to the corresponding statements. Both bearing recesses are each fluidically connected to one of several fluid connections, namely the first bearing recess to the first fluid connection and the second bearing recess to the second fluid connection different from the first fluid connection.For example, the first fluid connection is located on a pressure side and the second fluid connection on a suction side of the internal gear fluid machine or vice versa.

[0080] In terms of fluid dynamics, one of several flow resistances exists between the respective bearing recess and the respective fluid connection. The first flow resistance corresponds to the flow resistance already explained, while the second flow resistance is additional to this. Regarding the second flow resistance, the explanations regarding the first flow resistance apply, so reference is made to them. Preferably, the two bearing recesses are arranged symmetrically to each other and to the filler piece of the internal gear fluid machine. Accordingly, the internal gear fluid machine can be operated efficiently in different directions of rotation.

[0081] A further development of the invention provides for the flow resistances to be arranged symmetrically to one another. This means that the flow resistances are located symmetrically within the machine housing and are symmetrically aligned. For example, the flow resistances are arranged symmetrically with respect to an imaginary plane that includes both the first and second rotational axes. This results in a simple and compact design of the internal gear fluid machine, which is also characterized by low flow losses and high efficiency.

[0082] The invention is explained below with reference to the exemplary embodiments shown in the drawings, without limiting the invention. In the drawings: Figure 1 shows a schematic cross-sectional view of an internal gear fluid machine, Figure 2 shows a schematic longitudinal section of the internal gear fluid machine, Figure 3 shows a further schematic longitudinal section of the internal gear fluid machine, Figure 4 shows a first detailed view of a filler piece of the internal gear fluid machine, and Figure 5 shows a further schematic detailed view of the filler piece.

[0083] The Figure 1shows a schematic cross-sectional view of an internal gear fluid machine 1, which has a machine housing 2, in which a first gear 3 and a second gear 4 are rotatably mounted. The first gear 3 can also be referred to as a pinion and the second gear 4 as a ring gear. The first gear 3 is rotatably mounted in the machine housing 2 about a first axis of rotation 5 and the second gear 4 about a second axis of rotation 6. It can be seen that the first axis of rotation 5 and the second axis of rotation 6 are arranged parallel and spaced from one another, so that the first gear 3 and the second gear 4 have different axes of rotation. The first gear 3 has an external toothing 7 and the second gear 4 has an internal toothing 8, which mesh with one another in an engagement region 9, i.e. are in engagement with one another.

[0084] The first gear 3 and the second gear 4 jointly define a fluid chamber 10. The first gear 3 defines the fluid chamber 10 radially inward, and the second gear 4 defines the fluid chamber 10 radially outward. The fluid chamber 10 is circumferentially divided into a first fluid chamber 12 and a second fluid chamber 13 by the meshing of the gears 3 and 4 on the one hand and a filler piece 11 on the other. Depending on the direction of rotation of the internal gear fluid machine 1, one of the fluid chambers 12 and 13 serves as a suction chamber and another of the fluid chambers 12 and 13 serves as a pressure chamber.

[0085] In the exemplary embodiment illustrated here, the filler piece 11 is designed symmetrically to enable reversing operation of the internal gear fluid machine 1. The internal gear fluid machine 1 can therefore be operated in both directions of rotation. Additionally or alternatively, the filler piece 11 is designed in several parts and has several segments 14 and 15, or 16 and 17. The segments 14 and 15, or 16 and 17, are divided radially. Accordingly, the first segment 14 or 16 rests against the first gear 3, and the second segment 15 or 17 rests against the second gear 4.

[0086] Between segments 14 and 15, or 16 and 17, there is a gap 18 or 19, which can be pressurized with fluid. This fluid pressure forces segments 14 and 15, or 16 and 17, toward the respective gears 3 and 4, respectively. This provides radial compensation for the internal gear fluid machine 1.

[0087] Furthermore, it can be seen that the second gear 4 is encompassed in the circumferential direction at least in regions, in particular only in regions, by one or more bearing recesses 20. The bearing recesses 20 are fluidically connected to fluid connections 21 and 22 of the internal gear fluid machine 1 (not shown here), preferably each via a flow resistor 23. The flow connections between the respective bearing recess 20 and the fluid connections 21 and 22 can be established via a respective connecting channel 24 or 25. The bearing recesses 20 are designed such that they are at least temporarily supplied with pressurized fluid, for example from the fluid connections 21 and 22, so that they form a hydrostatic bearing for the second gear 4.

[0088] It can be provided that one of the bearing recesses 20 is fluidly connected only to that one of the fluid connections 21 and 22 that is assigned to a pressure side of the internal gear machine 1. This is particularly the case if the internal gear machine 1 is not designed to be reversible or is only operated in one preferred direction of rotation. However, if the internal gear machine 1 is intended for reversing operation and is operated with temporarily alternating directions of rotation, the bearing recesses 20 are preferably fluidly connected to both fluid connections 21 and 22, namely one of the bearing recesses 20 to the fluid connection 21 and another of the bearing recesses 20 to the fluid connection 22.Thus, one of the bearing recesses 20 is always subjected to the pressure present on the pressure side of the internal gear fluid machine 1, whereas the other of the bearing recesses 20 is subjected to any pressure, for example to the pressure present on the suction side, which is lower.

[0089] The Figure 2 shows a longitudinal section of the internal gear fluid machine 1. It can be seen that the gears 3 and 4 are mounted in the axial direction in the machine housing 3 by means of—purely optional—sealing disks 26. The sealing disks 26 are arranged on opposite sides of the gears 3 and 4 and bear against them in a sealing manner during operation of the internal gear fluid machine 1. First axial openings 27 and second axial openings 28 are formed in the sealing disks 26. The axial openings 27 and 28 extend completely through the respective sealing disk 26 in the axial direction.

[0090] It can be seen that the axial openings 27 and 28 each widen in the direction of the gears 2 and 4. For example, the axial openings 27 and 28, viewed in section on their side facing the gears 3 and 4, are aligned in the radial direction inside with a root circle of the external toothing 7 and / or in the radial direction outside with a root circle of the internal toothing 8, although only the former is shown here. At least, viewed in section, the axial openings 27 and 28 are located between the root circle of the external toothing 7 and the root circle of the internal toothing 8, thus not projecting beyond them in the radial direction. This ensures high efficiency of the internal gear fluid machine 1.

[0091] The axial openings 27 are arranged on both sides of the first fluid chamber 12, and the second axial openings 28 are arranged on both sides of the second fluid chamber 13. The first fluid chamber 12 is fluidically connected to the first fluid connection 21 via the first axial openings 27. Similarly, the second fluid chamber 13 is fluidically connected to the second fluid connection 22 via the second axial openings 28. For this purpose, connection channels 29 and 30 are formed in the machine housing 2. The first axial openings 27 are connected to the respective fluid connection 21 and 22 via the connection channels 29, and the second axial openings 28 are connected to the respective fluid connection 21 and 22 via the second connection channels 30. The sealing disks 26 and the axial openings 27 formed therein can be omitted. In this case, there is a direct flow connection between the connecting channels 29 and 30 and the fluid chambers 12 and 13.Of course, only one of the sealing discs 26 can be realized.

[0092] In the exemplary embodiment illustrated here, one of the connecting channels 29 opens directly into the corresponding fluid connection 21 or 22, whereas the other of the connecting channels 29 and 30 is connected to the corresponding fluid connection 22 via the respective connecting channel 24 or 25. The connecting channels 24 and 25 completely overlap the gears 3 and 4 and the sealing discs 26 in the axial direction.

[0093] As shown here, it can be provided that the first connection channels 29 open in the axial direction and the connecting channels 24 and 25 open in the radial direction into the respective fluid connection 21 and 22, respectively. The axial openings 27 and 28 are each encompassed by a seal 31 and 32, respectively, which ensures a fluid-tight connection of the respective axial opening 27 and 28 to the respective connection channel 29 and 30, respectively.

[0094] It can be seen that the axial discs 26 have common dimensions in the axial direction that at least correspond to the dimensions of the gears 3 and 4 in the same direction. These large dimensions in the axial direction ensure particularly reliable mounting of the gears 3 and 4 in the machine housing 2. In particular, tilting of the axial discs 26 and the associated uneven sealing of the fluid chambers 12 and 13 are reliably prevented.

[0095] The Figure 3 shows another longitudinal section of the internal gear fluid machine 1. It is clear that the filler piece 11 extends in the circumferential direction up to the axial openings 28 and ends in the region of the axial openings 28. The same applies, of course, analogously to the first axial openings 27. The filler piece 11 has a taper 34, through which it tapers in the axial direction, on both sides in the embodiment shown here. The taper 34 is formed at the end of the filler piece 11 in the circumferential direction.

[0096] The taper 34 ends—also viewed in the circumferential direction—in overlap with the axial opening 28, so that the filler piece 11, in overlap with the axial opening 28, has dimensions in the axial direction that correspond to the distance between the two sealing discs 26. Only when it overlaps with the axial opening 28 does the filler piece 11 begin to taper toward its free end. The taper 34 ensures optimized flow guidance, allowing the fluid to flow unhindered into or out of the respective fluid chamber 12 or 13.

[0097] A pressure field is preferably formed away from the seal 32, which can be subjected to pressurized fluid to apply a force directed toward the gears 3 and 4 to the sealing disks 26. For example, fluid is supplied to the pressure field from one of the fluid connections 21 and 22 or both fluid connections 21 and 22. A corresponding fluid connection can be implemented for this purpose. The described configuration ensures that the fluid chambers 12 and 13 are reliably sealed in the axial direction by the sealing disks 26.

[0098] The Figure 4shows a first detailed representation of the filler piece 11. This is designed symmetrically in the circumferential direction, i.e., it has at least one axis of symmetry 35, with respect to which it is designed mirror-symmetrically. A taper 34 is formed on each end of the filler piece in the circumferential direction. The filler piece 11 has an extension of at least 180° in the circumferential direction, preferably more than 180°, in particular at least 190°, at least 200°, at least 210°, or at least 220°. In the exemplary embodiment shown here, the extension in the circumferential direction is at least 225°. The described design of the filler piece 11 enables reversible operation of the internal gear fluid machine 1, i.e., operation in any direction of rotation. The internal gear fluid machine 1 can also be operated optionally as a pump and / or as a motor, without the need for conversion.In addition, it ensures reliable sealing of the fluid chambers 12 and 13 from each other in the circumferential direction.

[0099] The Figure 5 shows a further schematic representation of the filler piece 11, wherein the end-side, bilateral taper 34 can be seen again. This enables a particularly effective flow of fluid into and out of the fluid chambers 12 and 13. Preferably, the filler piece has constant dimensions in the axial direction apart from the taper 34 or tapers 34.

[0100] In the Figure 1 and 4A return line 36 can also be seen, via which fluid, in particular leakage fluid, can be discharged from the internal gear fluid machine 1 and / or fed back to the internal gear fluid machine 1 or the respective suction chamber. For example, the return line 36 is connected directly to the suction side or the suction chamber. However, it can also be provided that the return line 36 is fluidically connected to a fluid tank. This fluid tank can be a component of the internal gear fluid machine 1, but can also be located separate from it. For example, it is fluidically connected to the suction side of the internal gear fluid machine 1. Viewed in the circumferential direction, the return line 36 is arranged approximately centrally with respect to the filler piece 11, preferably exactly centrally. Particularly preferably, the return line 36 is arranged symmetrically with respect to an imaginary plane which accommodates both the first axis of rotation 5 and the second axis of rotation 6.

[0101] The return 36 has a return recess 37 which passes through an inner circumferential surface of the machine housing 2 facing the second gear 3, so that the return recess 37 is open in the direction of the gears 3 and 4. In addition, the return 36 has return pockets 38 which are preferably in flow connection with the return recess 37. While the return recess 37 overlaps with the gears 3 and 4 in the axial direction, the return pockets 38 are located on both sides of the gears 3 and 4 in the axial direction, in particular they are formed on the sides of the sealing disks 26 in the machine housing 2 facing away from the gears 3 and 4.

[0102] The fluid can be discharged via the return line 36, i.e., via the return recess 37 and the return pockets 38, and preferably fed back into the respective suction chamber. For example, the bearing recess 20 opens into the return recess 37. It can be provided that the bearing webs that delimit the bearing recess 20 in the axial direction also delimit the return recess 37 in the axial direction. However, the bearing recesses 20 are preferably arranged at a distance from the return recess 37 in the circumferential direction. The bearing recesses are preferably designed symmetrically with respect to the return recess 37, in particular, they are at the same distance from it.

[0103] In order to limit the amount of leakage fluid, in particular when the pressure on both the suction side and the pressure side significantly exceeds the ambient pressure, flow resistors 23 are provided. These are preferably designed identically and, for example, have a smallest diameter over their respective extent, which, based on a displacement volume of the internal gear fluid machine 1, is at least 15 l / m 2 and at most 75 l / m 2 . This allows for effective mounting of the second gear 4 in the machine housing 2 and, at the same time, a significant reduction in the amount of leakage fluid. One of the flow resistors 23 is fluidically arranged between one of the bearing recesses 20 and the pressure side, and another of the flow resistors is fluidically arranged between another of the bearing recesses 20 and the suction side of the internal gear fluid machine.A fluidic connection between the bearing recesses 20 is preferably only present via unavoidable leaks and / or via the internal gear fluid machine 1 itself, i.e. via the fluid space 10 or at least one or both of the fluid chambers 12 and 13.

[0104] The described design of the internal gear fluid machine 1 enables particularly efficient fluid flow and high fluid throughput. Furthermore, due to the symmetrical design of the filler piece 11, it can be operated reversibly and / or pressurized on both its pressure and suction sides. Since the filler piece 11 is designed in several parts, a four-segment internal gear fluid machine is realized, which ensures effective sealing of the fluid chambers 12 and 13 from one another in the circumferential direction by means of the filler piece 11 in any direction of rotation.

Claims

1. Internal gear fluid machine (1), having - a first gearwheel (3) comprising an outer toothing (7) and mounted for rotation about a first axis of rotation (5) and a second gearwheel (4) comprising an inner toothing (8) meshing with the outer toothing (7) in an engagement region (9) and mounted for rotation about a second axis of rotation (6) different from the first axis of rotation (5), wherein - housing walls of a machine housing (2) of the internal gear fluid machine (1) are arranged on both sides of the first gearwheel (3) and the second gearwheel (4) in the axial direction with respect to the first axis of rotation (5), wherein - the second gearwheel (4) is embraced in the circumferential direction, at least partially, by at least one bearing recess (20) configured as a groove in the machine housing (2) in order to form a hydrostatic bearing, which bearing recess only partially overlaps the second gearwheel (4) in the axial direction and is completely in superposition with the second gearwheel (4), and is fluidically connected to a fluid connection (21, 22) of the internal gearwheel fluid machine (1) via a fluid conduit comprising a flow resistance (23), characterised in that - a filler piece (11) is arranged between the first gearwheel (3) and the second gearwheel (4) away from the engagement region (9), which filler piece (11) bears on the outer toothing (7) on the one hand and on the inner toothing (8) on the other hand in order to divide a fluid space (10) present between the first gearwheel (3) and the second gearwheel (4) into a first fluid chamber (12) and a second fluid chamber (13), and in that - the bearing recess (20) is fluidically connected on its side facing away from the fluid conduit via a leakage gap to a return recess (37) of a return (36) of the internal gear fluid machine (1), which is in flow connection with a suction side of the internal gear fluid machine (1) directly and / or with a fluid tank, wherein the return (36) comprises return pockets (38) in the axial direction on both sides of the gearwheels (3, 4), which are in flow connection with the return recess (37) and are provided for returning leakage fluid occurring in the internal gear fluid machine (1) in the direction of the suction side of the internal gear fluid machine (1) and / or the fluid tank.

2. Internal gear fluid machine according to claim 1, characterised in that the fluid conduit extends radially outwards from the bearing recess (20) and / or is straight throughout.

3. Internal gear fluid machine according to one of the preceding claims, characterised in that the fluid conduit opens radially inwards into the bearing recess (20) by engaging through a base of the bearing recess (20) to form a mouth opening.

4. Internal gear fluid machine according to one of the preceding claims, characterised in that the fluid conduit on its side facing away from the bearing recess (20) opens into a connecting channel (24, 25) of larger dimensions, via which it is connected to the fluid connection (21, 22) in terms of flow.

5. Internal gear fluid machine according to one of the preceding claims, characterised in that the flow resistance (23) is present as a cross-sectional constriction configured only locally in the fluid conduit, so that a flow cross-section of the fluid conduit on both sides of the cross-sectional constriction is greater than a flow cross-section in the region of the cross-sectional constriction.

6. Internal gear fluid machine according to one of the preceding claims, characterised in that a connecting channel (29) is configured in each of the two housing walls and the same one of the fluid chambers (12, 13) is in flow connection with the fluid connection (21, 22) of the internal gear fluid machine (1) via both connecting channels (29).

7. Internal gear fluid machine according to one of the preceding claims, characterised in that the fluid connection (21, 22) is a first fluid connection (21) of a plurality of fluid connections (21, 22) and the first fluid chamber (12) is in flow order with the fluid connection (21) present as a first fluid connection (21) via the connecting channels (29) present as first connecting channels (29), and in that a second connecting channel (30) is configured in each of the housing walls and the second fluid chamber (13) is in flow connection with a second fluid connection (22) of the internal gear fluid machine (1) via the second connecting channels (30).

8. Internal gear fluid machine according to one of the preceding claims, characterised in that one of the connecting channels (29, 30) is connected directly and another of the connecting channels (29, 30) is connected to the fluid connection (21, 22) in terms of flow via the connecting channel (24, 25) overlapping the first gearwheel (3) and the second gearwheel (4) in the axial direction.

9. Internal gear fluid machine according to one of the preceding claims, characterised in that the bearing recess (20) is a first bearing recess (20) of a plurality of bearing recesses (20) and the flow resistance (23) is a first flow resistance (23) of a plurality of flow resistances (23) and a second of the bearing recesses (20) is configured in the machine housing (2) at a distance from the first bearing recess (20) in the circumferential direction, which at least partially overlaps the second gearwheel (4) in the axial direction, wherein the first bearing recess (20) is fluidically connected to the first fluid connection (21) via the first flow resistance (23) and the second bearing recess (20) is fluidically connected to the second fluid connection (22) via a second of the flow resistances (23).