Internal gear fluid machine

Abstract

The invention relates to an internal gear fluid machine (1) comprising a first gear (3) which has an outer toothing (7) and which is rotatably mounted about a first rotational axis (5) and comprising a second gear (4) which has an inner toothing (8) that meshes with the outer toothing (7) in some regions in an engagement region (9) and which is rotatably mounted about a second rotational axis (6) that differs from the first rotational axis (5). The second gear (4) is surrounded by at least one bearing recess (29) formed in the machine housing (2) at least in some regions in the circumferential direction in order to form a hydrostatic bearing (27), said bearing recess passing through a bearing surface (28) which rests against the second gear (4) in a sliding manner. The bearing recess (29) has different dimensions in the axial direction over the extension thereof in the circumferential direction and / or the bearing surface (28) has different dimensions in the axial direction over the extension thereof in the circumferential direction.

Description

[0001] DESCRIPTION

[0002] Internal gear fluid machine

[0003] The invention relates to an internal gear fluid machine, with a first gear having external teeth and mounted so as to be rotatable 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 are mounted so as to be rotatable about a second axis of rotation different from the first axis of rotation, wherein the second gear is at least partially encompassed in the circumferential direction by at least one bearing recess formed in the machine housing in order to form a hydrostatic bearing, said bearing recess passing through a bearing surface that bears slidingly against the second gear.

[0004] For example, the prior art document DE 10 2004 021 216 A1 is known. This document describes a high-pressure internal gear machine, in particular an internal gear pump, comprising a housing, an externally toothed pinion rotatably mounted in the housing, and an internally toothed ring gear that rotates with the pinion and is circumferentially mounted in the housing and meshes with the pinion. In this case, a housing section opposite a circumferential surface of the ring gear contains several pressure pockets that are open toward the ring gear and delimited by sealing webs for hydrostatic mounting of the one-piece and / or integrally formed ring gear.

[0005] It is an object of the invention to propose an internal gear fluid machine which has advantages over known internal gear fluid machines, in particular implementing a particularly effective hydrostatic bearing of the second gear in the machine housing.

[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 bearing recess has / has different dimensions in the axial direction over its extension in the circumferential direction and / or the bearing surface has / has different dimensions in the axial direction over its extension in the circumferential direction.

[0007] Advantageous embodiments with expedient further developments of the invention are specified in the dependent claims. It is pointed out that the exemplary embodiments explained in the description are not restrictive; rather, any variations of the features disclosed in the description, the claims, and the figures can be implemented. The internal gear fluid machine represents 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 a first gear and a second gear. The first gear can also be referred to as a pinion, and the second gear as a ring gear. The first gear has a first set of teeth, and the ring gear has a second set of teeth. The first set of teeth is an external set of teeth, and the second set of teeth is an internal set of teeth.The first gear and the second gear engage with each other in a circumferential direction, i.e., they mesh with each other in a certain area, namely in an engagement zone. The two gears are intended for fluid conveyance and are therefore designed such that they interact during a rotational movement to convey the fluid, thereby engaging or meshing 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 detached 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 the 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 preferably arranged in the machine housing and 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 first toothing or external toothing of the first gear meshes or engages with the second toothing or internal toothing 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.The engagement region is, for example, fixed to the housing and therefore does not rotate with the first gear or the second gear. In the engagement region, a tooth of one of the gears engages in 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 first gear engages in a tooth space of the second gear, or conversely, a tooth of the second gear engages in a tooth space of the first gear. In the engagement region, the first gear and the second gear interact to form a seal.

[0010] 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, a filler piece is arranged, for example - purely optionally. 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 chamber which is bounded in the radially inward direction by the first gear and in the radially outward direction by the second gear, in each case with respect to the first axis of rotation and the second axis of rotation. The filler piece rests on the one hand against the external toothing and on the other hand against the internal toothing.More precisely, the filler piece seals against the tooth tips of the external gearing and against the tooth tips of the internal gearing, dividing the fluid space into a first fluid chamber and a 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 external gearing and the internal gearing in the engagement area.

[0011] Preferably, the filler piece - if provided - is designed in several parts and thus has a plurality of 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. The two segments are preferably displaceable relative to one another in the radial direction.

[0012] Particularly preferably, a gap existing between the segments is subjected to fluid pressure during operation of the internal gear fluid machine in such a way that the first segment is forced 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 gearing. 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 therefore 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., can be displaced independently of one another. This achieves particularly effective gap compensation.Of course, a one-piece filler piece can also be used. In this case, the internal gear fluid machine is uncompensated in the radial direction.

[0013] As an alternative to the filler piece, on the other side of the engagement region, i.e. again preferably on the side diametrically opposite the engagement region with respect to the first axis of rotation and / or the second axis of rotation, at least one tooth tip of the internal toothing and one tooth tip of the external toothing lie against one another in a sealing manner, in particular with a tip circle surface of the respective tooth delimited by the respective tip circle of the corresponding toothing. In other words, a tip circle surface of the tooth tip of the internal toothing is delimited by the tip circle of the internal toothing and a tip circle surface of the tooth tip of the external toothing is delimited by a tip circle of the external toothing. The tip circle surface of the internal toothing and the tip circle surface of the external toothing now lie against one another in a sealing manner. This in turn divides the fluid space into the first fluid chamber and the second fluid chamber.Each of the two fluid chambers is circumferentially delimited, on the one hand, by the tight contact of the tip surfaces and, on the other hand, by the tight meshing of the external and internal gears in the engagement area. This type of internal gear fluid machine can also be referred to as a ring gear fluid machine.

[0014] The two gears of the internal gear fluid machine are arranged between housing walls of the aforementioned machine housing of the internal gear fluid machine. 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 second side of the gears, axially opposite the first side, so that the housing walls accommodate the gears between them in the axial direction. For example, a 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.

[0015] However, it is particularly preferred for a sealing disk to be arranged in the axial direction relative to the first axis of rotation next to the first gear and the second gear, i.e. in particular between one of the housing walls and the gears, which sealing disk rests sealingly against the first gear and the second gear during operation 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 in which multiple sealing disks are present will be 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 single sealing disc is part of the internal gear fluid machine.

[0016] The sealing disc is preferably forced in the axial direction towards the gears, for example by pressurisation, i.e. by exposure to a pressurised fluid, so that it bears sealingly against the gears. 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 in the axial direction. The sealing discs are preferably forced towards one another in the axial direction and thus each in the direction of the gears, for example by pressurisation, i.e. by exposure to the pressurised fluid, so that the sealing discs bear sealingly against the gears on opposite sides.The internal gear fluid machine is therefore axially compensated or gap-compensated in the axial direction. This results in particularly high efficiency of the internal gear fluid machine.

[0017] 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. The pressure in the inlet chamber is always lower than the pressure in the outlet chamber when the pump is operating. Of course, however, the pressure in the inlet chamber can already be (significantly) greater than ambient pressure.For example, the internal gear fluid machine is used to pump pressurized fluid from the inlet chamber towards the outlet chamber.

[0018] 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, its structure, 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.

[0019] It should be noted that, for the purposes of this description, the suction chamber can also be referred to as the low-pressure chamber, and the pressure chamber as the high-pressure chamber. Analogously, the suction side of the internal gear fluid 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.

[0020] The second gear is partially encompassed in the circumferential direction by at least one bearing recess which is formed in the machine housing. The bearing recess is designed such that it at least partially, in particular only partially, overlaps the second gear in the axial direction and is arranged in complete overlap with the second gear. The bearing recess therefore not only has a smaller extension in the axial direction than the second gear, but is also arranged such that bearing webs which delimit the bearing recess in the axial direction and which also form the bearing surface are arranged in overlap with the second gear when viewed in the axial direction. The bearing recess therefore does not protrude beyond the second gear in the axial direction, but is completely closed inwards in the radial direction by the second gear sliding against the bearing surface or the bearing webs.In other words, the second gear completely engages the bearing recess and continuously interacts with an edge delimiting the bearing recess in order to close the bearing recess radially inward. The edge is formed in particular in the bearing surface and / or by the bearing webs. The sliding contact of the second gear against the machine housing or the bearing surface occurs in particular via a fluid film made up of the fluid present in the bearing recess. It is therefore not necessary for the second gear to bear directly against the machine housing, although this can of course be the case at least temporarily, particularly when the internal gear fluid machine is stationary.

[0021] For example, the bearing recess is in the form of a groove or channel formed in the machine housing and running in the circumferential direction. 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 subjected to pressurized fluid, 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 bearing 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] While the fluid in the pressure chamber urges the second gear in a first direction, the fluid 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 in the bearing recess is at least as great as a force exerted on the second gear by the fluid 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. In order to supply the bearing recess with the pressurized fluid, it is preferably fluidically connected to one of the fluid connections. For example, the pressure chamber is fluidically connected to a fluid connection of the internal gear fluid machine via the bearing recess.In this case, for example, a fluid channel passes through the bottom of the bearing recess, providing the fluid connection between the pressure chamber and the fluid connection. Preferably, the flow cross-sectional area of ​​the fluid channel is smaller than the flow cross-sectional area of ​​the bearing recess to ensure sufficient pressure buildup in the bearing recess to form the hydrostatic bearing.

[0023] It can be provided that the bearing recess completely encompasses the second gear in the circumferential direction. However, it preferably only partially encompasses the second gear in the circumferential direction, for example, it extends over at least 30°, at least 60°, at least 90°, at least 120°, at least 150°, or at least 180°. Particularly preferably, the bearing recess extends in the circumferential direction over a maximum of 240°, a maximum of 210°, or a maximum of 180°. For example, the bearing recess extends over at least 90° and a maximum of 180°, at least 120° and a maximum of 180°, at least 150° and a maximum of 180°, or approximately or exactly 180°.

[0024] 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 preferably 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, for example, designed and / or adjusted in such a way that they only allow the fluid to flow from the respective fluid connection towards the bearing recess, i.e., they prevent flow from the bearing recess towards the fluid connections. This always ensures optimal fluid supply to the bearing recess, but largely prevents fluid loss or overflow of the fluid from the pressure side to the suction side via the bearing recess. However, it can also be provided that there are several bearing recesses spaced apart from one another in the circumferential direction, i.e., the 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 that includes the axis of rotation of the first gear and / or the axis of rotation of the second gear.For example, the bearing recesses are fluidically connected to different fluid connections, in particular a first of the bearing recesses is connected to a first fluid connection and a second of the bearing recesses is connected to a second fluid connection of the internal gear fluid machine. This means that each of the bearing recesses is directly connected to the corresponding fluid connection 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 always fluidly connected to the suction side of the internal gear fluid machine.This achieves a balance of forces within the internal gear fluid machine, regardless of its direction of rotation, resulting in particularly high efficiency.

[0025] 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. In this case, the bearing recess is delimited on both sides in the axial direction by the 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 the circumferential direction in overlap with the bearing recess, or the second gear is at a smaller distance from the bearing surface or 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 millimeters or less are preferred.

[0026] This achieves the sliding fit or the sealing fit.

[0027] In order to further improve the support of the second gear by means of the hydrostatic bearing, the bearing recess is designed with different dimensions in the axial direction over its extension in the circumferential direction. This means that the bearing recess has different dimensions in the axial direction at a first position in the circumferential direction than at a second position in the circumferential direction. For example, the axial dimensions of the bearing recess change continuously or stepwise over its extension in the circumferential direction. Preferably, the axial dimensions of the bearing recess decrease in the direction of rotation of the second gear, so that during operation of the internal gear fluid machine, the second gear first sweeps over a region of the bearing recess in which it has larger dimensions in the axial direction, and then a region with smaller axial dimensions.A reverse configuration can also be provided. This allows the fluid force acting on the second gear in the radial direction to be adjusted to achieve a low-friction bearing. Furthermore, it can be provided that the axial dimensions of the bearing recess initially increase and then decrease in the direction of rotation of the second gear, or vice versa. This allows the internal gear to be prepared for reversing operation.

[0028] In addition or alternatively to the different dimensions of the bearing recess, the bearing surface has different axial dimensions over its extension in the circumferential direction. The bearing surface is understood to be an area of ​​the internal gear fluid machine, in particular its machine housing, against which the second gear rests in a sliding manner and through which the bearing recess passes, forming an opening. The bearing surface therefore has first axial dimensions at a first circumferential position and second axial dimensions different from the first axial dimensions at a second circumferential position different from the first circumferential position. In this case, it can be provided, for example, that the axial dimensions of the bearing surface initially increase and then decrease again, in particular continuously or in steps.Preferably, the bearing surface is designed symmetrically with respect to a center plane, so that at any given circumferential position, it has the same axial extent in both directions starting from the center plane. While it is of course possible for the different axial dimensions to be used either for the bearing recess or for the bearing surface, it is particularly preferred for both the bearing recess and the bearing surface to be designed with different dimensions in the axial direction. This allows the fluid pressure exerted on the second gear by the fluid present in the bearing recess to be adjusted particularly precisely, thus realizing an effective hydrostatic bearing for the second gear.

[0029] The described internal gear fluid machine enables a particularly effective and low-loss bearing arrangement for the second gear in the machine housing. Thanks to the different axial dimensions of either the bearing recess, the bearing surface, or both the bearing recess and the bearing surface, the bearing force acting on the second gear can be aligned with particular precision. This reduces friction losses in the internal gear fluid machine, ensuring high efficiency.

[0030] A further development of the invention provides that the bearing recess is delimited by inner walls on opposite sides in the axial direction, wherein in order to achieve the different dimensions of the bearing recess, the inner walls have different distances from one another in the axial direction over the extent of the bearing recess in the circumferential direction. The inner walls are preferably present on the side of the bearing webs facing the bearing recess. In other words, the inner walls are arranged on the sides of the bearing webs facing one another. They are preferably formed by the machine housing. The inner walls delimit the bearing recess in the axial direction and, for this purpose, extend in the radial direction, in particular starting from a base of the bearing recess to an edge that encompasses the opening of the bearing recess into the fluid space, preferably continuously.

[0031] The different dimensions of the bearing recess are achieved by the different distances between the inner walls in the same direction. The inner walls can in principle have any shape or any shape, as long as they have different axial distances from one another at different circumferential positions. With the described design of the internal gear fluid machine, the explained advantages can be achieved in a structurally simple manner. A further development of the invention provides that, in order to achieve the different distances, at least one of the inner walls is angled and / or curved with respect to an imaginary inner wall reference plane perpendicular to the second axis of rotation and / or has an inner wall step.The different distances between the inner walls are thus achieved by the oblique or curved arrangement of the at least one inner wall relative to the inner wall reference plane, or the at least one inner wall has a step over which its distance from the other of the inner walls changes abruptly. The inner wall reference plane is to be understood as an imaginary plane that is perpendicular to the second axis of rotation and runs through the at least one inner wall. The inner wall encloses an angle with the inner wall reference plane that is greater than 0° and less than 180°, in particular no more than 90°. For example, the angle is at least 10°, at least 20°, or at least 30°. Additionally or alternatively, the angle is less than 90° or no more than 45°.It can of course be provided that the inner wall is angled in some areas relative to the inner wall reference plane and additionally has at least one inner wall step. In the area of ​​the inner wall step, the inner wall is perpendicular or at least almost perpendicular to the inner wall reference plane, thus forming an angle of approximately or exactly 90° with it. Alternatively or additionally, the inner wall is curved, i.e., it runs in an arc shape. For example, the inner wall is curved with a radius of curvature that is constant over its entire extent. However, the radius of curvature can also change over its extent, in particular continuously. With the described design of the internal gear fluid machine, the hydrostatic bearing can be optimized particularly easily.

[0032] A further development of the invention provides that a base of the bearing recess is arranged offset parallel to the bearing surface. The base of the bearing recess is to be understood as a floor of the bearing recess which delimits the bearing recess in the direction facing away from the second gear, i.e. in the radial outward direction. This recess base should run parallel to the bearing surface, i.e. have a constant distance from it in the radial direction over the extent of the bearing recess in the circumferential direction. For example, the bearing surface runs along a lateral surface of a circular cylinder with a first diameter, whereas the recess base runs along a lateral surface of a circular cylinder with a second diameter different from the first diameter.This ensures a uniform pressure distribution in the bearing recess and consequently a uniform distribution of the force caused by the fluid present in the bearing recess onto the second gear.

[0033] A further development of the invention provides that the bearing surface is delimited by outer walls on its side facing away from the bearing recess in the axial direction, wherein at least one of the outer walls, in particular in the circumferential direction in overlap with the bearing recess or in the circumferential direction away from the bearing recess, is angled and / or curved with respect to an imaginary outer wall reference plane perpendicular to the second axis of rotation or has an outer wall step. The outer walls form a closure of the bearing surface in the axial direction and for this purpose accommodate the bearing surface between them. Preferably, the second gear rests against the machine housing in the region of the bearing surface, whereas away from the bearing surface it is spaced from the machine housing or at least spaced further than in the region of the bearing surface.In other words, the bearing surface is consistently at a smaller distance in the radial direction from the second gear than the machine housing outside the bearing surface.

[0034] The bearing surface is defined by the outer walls. The bearing surface located between the outer walls slides against the second gear, while the machine housing, on the sides facing away from the bearing surface in the axial direction, does not rest against the second gear or is at least at a greater distance from it. At least one of the outer walls, preferably both outer walls, are at least partially not arranged parallel to the outer wall reference plane. The outer wall reference plane is understood to be an imaginary plane that is perpendicular to the second axis of rotation and runs through the respective outer wall. The angle between the outer wall and the outer wall reference plane is greater than 0° and less than 180°, preferably it is more than 0° and at most 90°. For example, the angle is at least 10°, at least 20°, or at least 30°, and is preferably less than 75°, less than 60°, or less than 45°.However, the outer wall can also be perpendicular to the outer wall reference plane in some areas; this creates the outer wall step.

[0035] Due to the angled and / or curved profile of at least one outer wall or the presence of the outer wall step, the outer walls have different axial distances from one another over the circumferential extension of the bearing surface. For example, it is provided that the distance between the outer walls, viewed in the direction of rotation of the second gear, initially increases and then decreases again. Preferably, the distance initially increases, then remains constant, in particular at least over the circumferential extension of the bearing recess, before subsequently decreasing again. As a result, the bearing force exerted by the hydrostatic bearing can be adjusted in a particularly precisely dosed manner. If the outer wall has the curved profile at least in some areas, it has an arcuate extension. For example, the outer wall is curved with a radius of curvature that is constant over its entire extension.However, the radius of curvature can also change over the extension, especially continuously.

[0036] A further development of the invention provides that the at least one outer wall, viewed in the circumferential direction, runs in a first region at a first distance parallel to the outer wall reference plane and in a second region has a second distance from the outer wall reference plane that is different from the first distance. The at least one outer wall therefore has a plurality of sections, wherein in at least one of the sections it is arranged parallel to the outer wall reference plane and has the first distance from it. In at least one second region, the outer wall is arranged at a second distance from the outer wall reference plane that is different from the first distance. For example, in the second section the outer wall runs at an angle relative to the outer wall reference plane or has the outer wall step.It can be provided that the second region, viewed in the circumferential direction, is located between the first region and a third region of the outer wall, wherein the regions directly adjoin one another. In the third region, the outer wall again runs parallel to the outer wall reference plane and thus parallel to the outer wall in the first region. However, in the third region, it is at a distance from the outer wall reference plane that is different from the first distance. The advantages achievable with such a design of the internal gear fluid machine have already been mentioned.

[0037] A further development of the invention provides for the inner walls and / or the outer walls to be symmetrical. This means that the inner walls are arranged symmetrically to one another with respect to a center plane perpendicular to the second axis of rotation. The same applies additionally or alternatively to the outer walls. The symmetrical design of the inner walls and / or outer walls largely prevents forces exerted in the axial direction by the hydrostatic bearing.A further development of the invention provides that in a first region corresponding to the engagement region, the external toothing and the internal toothing engage with one another in the circumferential direction, and in a second region, tooth tips of the external toothing and the internal toothing bear against one another in a sealing manner 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, or that a filler piece is arranged between the first gear and the second gear, away from the first region, which filler piece bears on the one hand against the external toothing and on the other hand against the internal toothing in order to divide the fluid space present between the first gear and the second gear into the first fluid chamber and the second fluid chamber. This embodiment of the internal gear fluid machine and its respective advantages have already been mentioned, so reference is made to the corresponding explanations.

[0038] A further development of the invention provides that the bearing recess is fluidly connected to one of the fluid chambers. The bearing recess is pressurized with fluid during operation of the internal gear fluid machine. This can be accomplished particularly simply by fluidly connecting the bearing recess to one of the fluid chambers, in particular to the fluid chamber acting as a pressure chamber. This has also been discussed in detail above.

[0039] A further development of the invention provides that the flow connection is provided via a fluid channel configured in the machine housing and / or via flow channels formed in the second gear. In principle, the flow connection between the bearing recess and the fluid chamber can be established in any desired way. Preferably, it is provided via the flow channel and / or the flow channels of the second gear. The flow connection is provided, for example, via the fluid channel if the fluid chamber is fluidically connected to the respective fluid connection of the internal gear fluid machine in the axial direction. For this purpose, the fluid channel opens in the axial direction next to the gears into the fluid space or one of the fluid chambers. It can also be provided that the flow connection additionally runs via the sealing disk or one of the sealing disks.In this case, a corresponding passage opening is formed in the sealing disc, via which the fluid channel is at least temporarily fluidically connected to the fluid space or the fluid chamber. Alternatively, the flow connection is provided at least partially via the flow channels formed in the second gear. The flow channels open into the cavity through the internal toothing on the inside, viewed radially with respect to the axis of rotation, and penetrate an outer circumferential surface of the second gear on the outside, in the radial direction. Via these flow channels, the first fluid chamber is fluidly connected to a first fluid connection of the internal gear fluid machine, and the second fluid chamber is fluidly connected to a second fluid connection of the internal gear fluid machine, and is at least temporarily fluidly connected to it.The fluid can thus enter one of the fluid chambers via some of the flow channels and exit the other fluid chamber via another of the flow channels. The flow channels are preferably evenly distributed in the circumferential direction. The number of flow channels can, in principle, be chosen arbitrarily. For example, a single-row arrangement of the flow channels would result in an odd number. The described design of the internal gear fluid machine ensures a reliable supply of fluid to the bearing recess.

[0040] A further development of the invention provides that a first fluid connection of the internal gear fluid machine is fluidly connected to the first fluid chamber via a first fluid channel formed in the machine housing, and a second fluid connection of the internal gear fluid machine is fluidly connected to the second fluid chamber via a second fluid channel formed in the machine housing, wherein a longitudinal center axis of the first fluid channel and / or a longitudinal center axis of the second fluid channel runs at a distance from the first axis of rotation and / or the second axis of rotation and / or a region present between the first axis of rotation and the second axis of rotation. Both the first fluid channel and the second fluid channel preferably run continuously straight, i.e. each have a continuously straight longitudinal center axis.The first fluid channel preferably runs from the first fluid connection to the fluid space and the second fluid channel also runs from the second fluid connection to the fluid space.

[0041] At least one of the fluid channels, preferably both fluid channels, are (each) arranged off-center with respect to at least one of the axes of rotation, such that the longitudinal center axis of the respective fluid channel is arranged away from the first axis of rotation, away from the second axis of rotation and / or away from the region between the two axes of rotation. In other words, the longitudinal center axis of the respective fluid channel does not run through one of the axes of rotation or between them. Preferably, the longitudinal center axes of both fluid channels run on the same side of the axes of rotation, in particular on a side of the first axis of rotation facing away from the second axis of rotation. Preferably, a distance between at least one of the longitudinal center axes, preferably both longitudinal center axes, and the first axis of rotation is greater than a distance between the first axis of rotation and the second axis of rotation. For example, the distance is twice as great or more than twice as great.Particularly preferably, at least one of the longitudinal center axes runs through the engagement region in which the teeth of the two gears mesh. This preferably applies to both longitudinal center axes. This enables a particularly low-loss inflow and outflow of the fluid from the fluid space or the fluid chambers.

[0042] A further development of the invention provides that the longitudinal center axis of the first fluid channel and the longitudinal center axis of the second fluid channel run parallel at a distance from one another or coincide. It can be provided that the longitudinal center axes of the two fluid channels are spaced apart from one another, i.e., they neither intersect nor coincide. However, the longitudinal center axes particularly preferably coincide, with the longitudinal center axis of the first fluid channel simultaneously forming the longitudinal center axis of the second fluid channel, and vice versa. This ensures particularly low-loss inflow and outflow of the fluid.

[0043] A further development of the invention provides that the longitudinal center axis of the first fluid channel and / or the longitudinal center axis of the second fluid channel intersect a tooth of the internal toothing and / or a tooth of the external toothing, in particular in an imaginary plane that is perpendicular to the respective longitudinal center axis and accommodates the first axis of rotation and / or the second axis of rotation. It has already been explained above that at least one of the longitudinal center axes can run through the engagement region. In doing so, it intersects the tooth of at least one of the toothings, i.e. runs between a tip circle and a root circle of the respective toothing. This achieves the advantages already explained. Particularly preferably, the tooth intersects the respective longitudinal center axis in the imaginary plane that is perpendicular to the respective longitudinal center axis and accommodates one of the axes of rotation. This is the case in at least one position of the gears.With such an embodiment, a particularly efficient internal gear fluid machine is created.

[0044] A further development of the invention provides that the two fluid channels have different flow cross-sectional areas. The fluid channels have the flow cross-sectional areas at least in some regions; in particular, the respective flow cross-sectional area describes the smallest flow cross-section over the extent of the respective fluid channel. However, it can also be provided that the fluid channels have their respective flow cross-sectional areas continuously, i.e. over their entire extent along their respective longitudinal center axis. The flow cross-sectional areas of the two fluid channels are different from one another. For example, a fluid channel with a larger flow cross-sectional area is provided on a suction side than on a pressure side of the internal gear fluid machine. As a result, the respective fluid channel is adapted to the respective existing pressure level and high efficiency is achieved.

[0045] A further development of the invention provides that, to form the hydrostatic bearing, the second gear is encompassed at least partially in the circumferential direction by at least one further bearing recess formed in the machine housing, which is arranged axially next to the bearing recess and slides through the bearing surface resting against the second gear, wherein the further bearing recess has different dimensions in the axial direction over its extent in the circumferential direction. This means that several bearing recesses are present next to one another in the axial direction, namely the bearing recess and the further bearing recess. These together form the hydrostatic bearing. The bearing recesses penetrate the bearing surface, forming separate mouth openings, in particular mouth openings delimited by continuous and uninterrupted edges.

[0046] The additional bearing recess preferably overlaps the bearing recess in the circumferential direction; in particular, the bearing recess and the additional bearing recess extend the same distance in the circumferential direction. If there are multiple bearing recesses in the circumferential direction, a further bearing recess is preferably arranged next to each of these bearing recesses. The additional bearing recess is preferably designed in accordance with the bearing recess; in particular, it is further developed according to the explanations in this description. The bearing recesses are pressurized with the fluid together or separately. Such a multi-row, in particular two-row, arrangement of the bearing recesses achieves a particularly effective bearing arrangement.

[0047] The features and feature combinations described in the description, in particular the features and feature combinations described in the following description of the figures and / or shown in the figures, can be used not only in the respective combination specified, but also in other combinations or on their own, without departing from the scope of the invention. Thus, embodiments are also considered to be encompassed by the invention that are not explicitly shown or explained in the description and / or the figures, but which follow from or can be derived from the explained embodiments.

[0048] The invention will be explained in more detail below with reference to the exemplary embodiments shown in the drawings, without limiting the invention. In the drawings:

[0049] Figure 1 is a schematic sectional view of an internal gear fluid machine,

[0050] Figure 2 shows another sectional view of the internal gear fluid machine,

[0051] Figure 3 is a schematic rolling representation of a bearing surface present on a machine housing of the internal gear fluid machine with a bearing recess produced therein in a first embodiment,

[0052] Figure 4 is a schematic rolling representation of the bearing surface with the bearing recess in a second embodiment, as well as

[0053] Figure 5 is a schematic rolling representation of the bearing surface with the bearing recess in a third embodiment.

[0054] Figure 1 shows 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.

[0055] The first gear 3 and the second gear 4 together delimit a fluid chamber 10. The first gear 3 delimits the fluid chamber 10 in the radially inward direction and the second gear 4 in the radially outward direction. 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 is present as a suction chamber and another of the fluid chambers 12 and 13 is present as a pressure chamber. The filler piece 11 is designed in several parts and has a plurality of segments 14 and 15. Between the segments 14 and 15 there is a gap which can be pressurized with fluid. Due to this fluid loading, the segments 14 and 15 are pushed in the direction of the respective gear 3 and 4.Thus, there is a radial compensation of the internal gear fluid machine 1.

[0056] The second gear 4 has a central cavity 17 in which the first gear 3 is arranged. The fluid chamber 10 is formed by the cavity 17. The cavity 17 is delimited outwards in the radial direction with respect to the second axis of rotation 6 by the internal toothing 8. The internal toothing 8 has a plurality of teeth 18 and tooth spaces 19, with one of the tooth spaces 19 being located between each two of the teeth 18 and one of the teeth 18 being located between each two of the tooth spaces 19, as seen in the circumferential direction. A flow channel 20 opens into at least some of the tooth spaces 19, in the exemplary embodiment shown here into each of the tooth spaces 19, with only a few of the flow channels 20 being identified as examples.

[0057] The fluid chambers 12 and 13 are at least temporarily fluidly connected to a first fluid channel 21 and a second fluid channel 22 via the flow channels 20. The first fluid chamber 12 is fluidly connected to a first fluid connection 23 via the first fluid channel 21, and the second fluid chamber 13 is fluidly connected to a second fluid connection 24. The first fluid channel 21 has a first longitudinal central axis 25, and the second fluid channel 22 has a second longitudinal central axis 26. In the internal gear fluid machine 1 described, the fluid channels 21 and 22 are not arranged centrally with respect to the axes of rotation 5 and 6, but rather offset from them. The longitudinal central axes 25 and 26 are parallel to one another or—as shown here—are even identical. They are arranged at a distance from both axes of rotation 5 and 6 and do not run between them.Rather, the longitudinal center axes 25 and 26 intersect the gear teeth 7 and 8 in the engagement region 9, thus extending between a root circle and a tip circle of the respective gear teeth. The fluid channels 21 and 22 have different flow cross-sectional areas; in particular, the flow cross-sectional area of ​​the first fluid channel 21 is larger than the flow cross-sectional area of ​​the second fluid channel 22.

[0058] The second gear 4 is rotatably mounted in the machine housing 2 by means of a hydrostatic bearing 27. To form the hydrostatic bearing 27, the second gear 4 slides against a bearing surface 28, which in the illustrated embodiment is formed on the machine housing 2 or by the machine housing 2. A bearing recess 29 extends through the bearing surface 28, forming an opening 30 facing the second gear 4. An extension of the bearing surface 28 in the circumferential direction is indicated by an arrow 31. An extension of the bearing recess 29 in the same direction, however, is indicated by the arrow 32. It can be seen that the second fluid channel 22 opens into the bearing recess 29, namely through a base 33 of the bearing recess 29. This means that the second fluid channel 22 is fluidically connected to the second fluid chamber 13 via the bearing recess 29.

[0059] Figure 2 shows a further schematic sectional view of the internal gear fluid machine 1. It can be clearly seen here again that the second fluid channel 22 opens into the hydrostatic bearing 27 or its bearing recess 29.

[0060] Figure 3 shows a rolling view of the hydrostatic bearing 27, or rather, the bearing surface 28 and the bearing recess 29 of the hydrostatic bearing 27. A rolling view means that the bearing surface 28, which was originally curved and manufactured on the machine housing 2, is now shown flat. This represents a geometric development of the curved bearing surface 28 with the bearing recess 29 formed therein into a plane. The circumferential extensions of the bearing surface 28 and the bearing recess 29 are again indicated by arrows 31 and 32.

[0061] The bearing recess 29 is delimited in the axial direction with respect to the second axis of rotation 6 on opposite sides by inner walls 34 and 35. It is clear that a distance between the inner walls 34 and 35 changes over the extent of the bearing recess 29 in the circumferential direction. Thus, viewed in the circumferential direction, the bearing recess has larger dimensions in the axial direction on one side, indicated by arrow 36, and smaller dimensions on an opposite side, indicated by arrow 37. As a result, an axial extent of the bearing recess 29 changes over its extent in the circumferential direction. In particular, the axial dimensions of the bearing recess 29 decrease in the direction of rotation of the gear 4, so that the gear 4 first sweeps over the bearing recess 29 on its wider side before reaching the narrower areas.The different distances between the inner walls 34 and 35 are achieved in the exemplary embodiment shown here by each of the inner walls 34 and 35 having a plurality of inner wall steps 38, through which the width of the bearing recess 29, i.e., its extension in the axial direction, changes abruptly, in particular decreases. In the region of the inner wall steps 38, the inner walls 34 and 35 are perpendicular to an imaginary inner wall reference plane, which is perpendicular to the second axis of rotation 6 and runs through the respective inner wall 34 and 35.

[0062] In the illustrated embodiment, the bearing recess 29 is composed of three regions 39, 40, and 41, in which the bearing recess 29 has different dimensions in the axial direction, i.e., different widths. In the first region 39, the bearing recess 29 has a first width, in the second region 40 a second width, and in the third region 41 a third width. The first width is greater than the second width, which in turn is greater than the third width. For example, a difference between the first width and the second width is identical to a difference between the second width and the third width, so that the inner wall steps 38 have the same dimensions in the axial direction.

[0063] The bearing recess 29 is delimited in the axial direction by bearing webs 42 and 43, which form the inner walls 34 and 35. The bearing webs 42 and 43 are connected to one another at the ends of the bearing recess 29 via connecting webs 44 and 45. The connecting webs 44 and 45 delimit the bearing recess 29 in the circumferential direction. The bearing webs 42 and 43 and the connecting webs 44 and 45 together form the bearing surface 28. In other words, the bearing surface 28 is located on the surfaces of the bearing webs 42 and 43 and the connecting webs 44 and 45 facing the second gear 6.

[0064] The bearing surface 28 is delimited on the outside in the axial direction by outer walls 46 and 47. These extend in the circumferential direction over the entire extent of the bearing surface 28 or of the hydrostatic bearing 27. It can be seen that the bearing surface 28 also has different axial dimensions over its extent in the circumferential direction. For example, it has smaller dimensions, indicated by arrow 48, on the one hand, and larger dimensions, indicated by arrow 49, on the other. In the exemplary embodiment shown, the bearing surface 28 is composed of regions 50, 51, and 52. In the first region 50, it has first dimensions, in the second region 51, second dimensions, and in the third region, third dimensions in the axial direction.

[0065] For example, the second dimensions are larger than the first dimensions and the third dimensions are smaller than the second dimensions. Preferably, the third dimensions correspond to the first dimensions. The second region 51 extends in the circumferential direction over an extent indicated by the arrow 53. It can be seen that the bearing recess 29 is arranged centrally in the second region 51, viewed in the circumferential direction, i.e., is equidistant in the circumferential direction from the first region 50 and the third region 52. It can also be seen that the regions 50 and 52 have an extension in the axial direction that is greater than a greatest extension of the bearing recess 29 in the same direction over their extension in the circumferential direction. The regions 50 and 52 therefore have a width that is greater than the greater width of the bearing recess 29 indicated by the arrow 36.To achieve the different widths of the storage area 28, the outer walls 46 and 47 have outer wall steps 54.

[0066] Figure 4 shows a schematic rolling representation of the bearing surface 28 and the bearing recess 29 in a second embodiment. This is fundamentally similar to the first embodiment, so reference is made to the corresponding embodiments and only the differences will be discussed. These consist in the fact that instead of the inner wall steps 38 and the outer wall steps 54, there are now inner wall inclined surfaces 55 and outer wall inclined surfaces 56, by means of which the axial dimensions of the bearing recess 29 and the bearing surface 28 are changed. Since there is no longer any abrupt change in dimensions, intermediate regions 57 and 58 exist between the regions 39, 40 and 41, and intermediate regions 59 and 60 exist between the regions 50, 51 and 52.In the intermediate regions 57 and 58, the axial dimensions of the bearing recess 29 and in the intermediate regions 59 and 60, the axial dimensions of the bearing surface 28 change continuously, in particular with a constant gradient over an angle in the circumferential direction. In the intermediate regions 57 and 58, the inner walls 34 and 35 are angled relative to the inner wall reference plane, while in the intermediate regions 59 and 60, the outer walls 56 and 57 are angled relative to the outer wall reference plane. In the regions 39, 40 and 41 as well as in the regions 50, 51 and 52, however, the axial dimensions of the bearing recess 29 and the bearing surface 28 are constant. Figure 5 shows a schematic rolling representation of the bearing surface 28 and the bearing recess 29 in a third embodiment. Express reference is made to the above statements, in particular regarding the first embodiment, and only the differences are discussed below.The outer walls 46 and 47, which axially delimit the bearing surface 28, are configured identically to the first embodiment.

[0067] The only difference is that the axial dimensions of the bearing recess 29 change continuously and steadily in the circumferential direction, for example, as shown here, with a constant gradient over an angle in the circumferential direction. The inner walls 34 and 35 are thus angled relative to the respective inner wall reference plane over the entire extent of the bearing recess 29 in the circumferential direction.

[0068] With the described design of the internal gear fluid machine 1, a particularly effective hydrostatic bearing of the second gear 4 in the machine housing 2 can be achieved. Furthermore, the special arrangement of the fluid channels 21 and 22 improves the inflow and outflow of fluid from the fluid chambers 12 and 13.

[0069] LIST OF REFERENCE SYMBOLS

[0070] 1 internal gear fluid machine

[0071] 2 machine housings

[0072] 3 1. Gear

[0073] 4 2nd gear

[0074] 5 1. Axis of rotation

[0075] 6 2nd axis of rotation

[0076] 7 External gearing

[0077] 8 Internal gearing

[0078] 9 Intervention area

[0079] 10 Fluid chamber

[0080] 11 Filler piece

[0081] 12 1. Fluid chamber

[0082] 13 2. Fluid chamber

[0083] 14 segments

[0084] 15 segments

[0085] 16 gap

[0086] 17 Cavity

[0087] 18 teeth

[0088] 19 Interdental space

[0089] 20 flow channel

[0090] 21 1. Fluid channel

[0091] 22 2nd fluid channel

[0092] 23 1. Fluid connection

[0093] 24 2. Fluid connection

[0094] 25 1. Longitudinal center axis

[0095] 26 2. Longitudinal center axis

[0096] 27 hydrostatic bearing

[0097] 28 storage areas

[0098] 29 Storage recess

[0099] 30 muzzle opening

[0100] 31 Arrow

[0101] 32 Arrow 33 Reason

[0102] 34 Interior wall

[0103] 35 interior wall

[0104] 36 Arrow

[0105] 37 Arrow

[0106] 38 interior wall step

[0107] 39 Area

[0108] 40 area

[0109] 41 Area

[0110] 42 bearing bridge

[0111] 43 Bearing bridge

[0112] 44 Connecting bridge

[0113] 45 connecting bridge

[0114] 46 exterior wall

[0115] 47 Exterior wall

[0116] 48 Arrow

[0117] 49 Arrow

[0118] 50 area

[0119] 51 Area

[0120] 52 Area

[0121] 53 Arrow

[0122] 54 exterior wall step

[0123] 55 Interior wall slope

[0124] 56 Exterior wall sloping surface

[0125] 57 Intermediate area

[0126] 58 Intermediate area

[0127] 59 Intermediate area

[0128] 60 intermediate area

Claims

CLAIMS 1. Internal gear fluid machine (1), with a first gear (3) having external teeth (7) and mounted for rotation about a first axis of rotation (5), and a second gear (4) having internal teeth (8) that mesh with the external teeth (7) in an engagement region (9) in some areas and that are mounted for rotation about a second axis of rotation (6) different from the first axis of rotation (5), wherein the second gear (4) is at least partially encompassed in the circumferential direction by at least one bearing recess (29) formed in the machine housing (2) to form a hydrostatic bearing (27), which bearing recess extends through a bearing surface (28) that bears slidingly against the second gear (4), characterized in that the bearing recess (29) has / has different dimensions in the axial direction over its extent in the circumferential direction and / or the bearing surface (28) has / has different dimensions in the axial direction over its extent in the circumferential direction.

2. Internal gear fluid machine according to claim 1, characterized in that the bearing recess (29) is limited on opposite sides in the axial direction by inner walls (34, 35), wherein in order to achieve the different dimensions of the bearing recess (29), the inner walls (34, 35) have different distances from one another in the axial direction over the extent of the bearing recess (29) in the circumferential direction.

3. Internal gear fluid machine according to one of the preceding claims, characterized in that, in order to achieve the different distances, at least one of the inner walls (34, 35) is angled and / or curved with respect to an imaginary inner wall reference plane perpendicular to the second axis of rotation (6) and / or has an inner wall step (38).

4. Internal gear fluid machine according to one of the preceding claims, characterized in that a base (33) of the bearing recess (29) is arranged offset parallel to the bearing surface (28).

5. Internal gear fluid machine according to one of the preceding claims, characterized in that the bearing surface (28) is delimited on its side facing away from the bearing recess (29) in the axial direction by outer walls (46, 47), wherein at least one of the outer walls (46, 47) is delimited relative to a perpendicular to the second axis of rotation (6) imaginary outer wall reference plane is angled and / or curved or has an outer wall step (54).

6. Internal gear fluid machine according to one of the preceding claims, characterized in that the at least one outer wall (46, 47), viewed in the circumferential direction, runs in a first region with a first distance parallel to the outer wall reference plane and in a second region has a second distance from the outer wall reference plane which is different from the first distance.

7. Internal gear fluid machine according to one of the preceding claims, characterized in that the inner walls (34, 35) and / or the outer walls (46, 47) run symmetrically.

8. Internal gear fluid machine according to one of the preceding claims, characterized in that in a first region corresponding to the engagement region, viewed in the circumferential direction, the external toothing (7) and the internal toothing (8) engage with one another, and in a second region, tooth tips of the external toothing (7) and the internal toothing (8) bear against one another in a sealing manner in order to divide a fluid space (10) present between the first gear (3) and the second gear (4) into a first fluid chamber (12) and a second fluid chamber (13), or in that a filler piece (11) is arranged between the first gear (3) and the second gear (4) away from the first region, which filler piece bears on the one hand against the external toothing (7) and on the other hand against the internal toothing (8) in order to divide the fluid space (10) present between the first gear (3) and the second gear (4) into the first fluid chamber (12) and the second fluid chamber (13).

9. Internal gear fluid machine according to one of the preceding claims, characterized in that the bearing recess (29) is in flow connection with one of the fluid chambers (12, 13).

10. Internal gear fluid machine according to one of the preceding claims, characterized in that the flow connection is provided via a fluid channel (21, 22) formed in the machine housing (2) and / or via flow channels (20) formed in the second gear (4).

11. Internal gear fluid machine according to one of the preceding claims, characterized in that a first fluid connection (23) of the internal gear fluid machine (1) is fluidically connected to the first fluid chamber (12) via a first fluid channel (21) formed in the machine housing (2), and a second fluid connection (24) of the internal gear fluid machine (1) is fluidically connected to the second fluid chamber (13) via a second fluid channel (22) formed in the machine housing (2), wherein a longitudinal center axis (25) of the first fluid channel (21) and / or a longitudinal center axis (26) of the second fluid channel (22) runs at a distance from the first axis of rotation (5) and / or the second axis of rotation (6) and / or a region present between the first axis of rotation (5) and the second axis of rotation (6).

12. Internal gear fluid machine according to one of the preceding claims, characterized in that the longitudinal center axis (25) of the first fluid channel (21) and the longitudinal center axis (26) of the second fluid channel (22) run parallel at a distance or coincide.

13. Internal gear fluid machine according to one of the preceding claims, characterized in that the longitudinal center axis (25) of the first fluid channel (21) and / or the longitudinal center axis (26) of the second fluid channel (22) intersect a tooth of the internal toothing (8) and / or a tooth of the external toothing (7).

14. Internal gear fluid machine according to one of the preceding claims, characterized in that the two fluid channels have different flow cross-sectional areas.

15. Internal gear fluid machine according to one of the preceding claims, characterized in that the second gear (4) for forming the hydrostatic bearing (27) is encompassed in the circumferential direction at least in regions by at least one further bearing recess formed in the machine housing (2), which is arranged in the axial direction next to the bearing recess (29) and passes through the bearing surface (28) which bears slidingly against the second gear (4), wherein the further bearing recess has different dimensions in the axial direction over its extent in the circumferential direction.

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