Gear for an internal gear fluid machine, method for producing such a gear, and internal gear fluid machine

Abstract

The invention relates to a gear (4) for an internal gear fluid machine (1), comprising a hollow chamber (17), through which a main part of the gear (4) passes in the axial direction with respect to a rotational axis (6) of the gear (4) and which is outwardly delimited by an inner toothing (8) in the radial direction. Flow channels (20) open into tooth intermediate spaces (19) of the inner toothing (8), said flow channels passing through the outer circumferential surface of the main part on the flow channel side facing away from the tooth intermediate spaces (19) and having central longitudinal axes (22) which are offset with respect to the rotational axis (6) relative to central axes (21) of the tooth intermediate spaces (19) in the circumferential direction. According to the invention, the flow channels (20) only partly pass through the gear (4) from the exterior to the interior in the radial direction in some regions. The invention additionally relates to a method for producing a gear (4) for an internal gear fluid machine (1) and to a corresponding internal gear fluid machine (1).

Description

[0001] DESCRIPTION

[0002] Gear for an internal gear fluid machine, method for producing such a gear and internal gear fluid machine

[0003] The invention relates to a gear for an internal gear fluid machine, comprising a cavity extending through a base body of the gear in the axial direction relative to a rotational axis of the gear, which cavity is bounded outwardly in the radial direction by internal toothing. Flow channels open into the interspaces of the internal toothing. On their side facing away from the interspaces, the flow channels extend through an outer circumferential surface of the base body and have longitudinal center axes offset in the circumferential direction relative to the rotational axis relative to the center axes of the interspaces. The invention further relates to a method for producing a gear for an internal gear fluid machine and to an internal gear fluid machine.

[0004] For example, the prior art document DE 38 05 186 A1 is known. This document describes an internal gear machine, in particular an internal gear pump, with an internally toothed ring gear, an externally toothed pinion meshing with the ring gear, and a filler piece arranged between the ring gear and the pinion. The ring gear has openings that connect the outer circumference of the ring gear with its inner surface in the area of ​​the tooth gaps. These openings are each offset so far into the non-load-bearing tooth flank bordering the tooth gap on one side that they simultaneously create a connection between the tooth root and the tooth tip.

[0005] It is an object of the invention to propose a gear for an internal gear fluid machine which has advantages over known gears, in particular reducing or even completely avoiding pressure peaks within the internal gear fluid machine.

[0006] This is achieved according to the invention with a gear for an internal gear fluid machine having the features of claim 1. It is provided that the flow channels only partially penetrate the base body in the radial direction from the outside to the inside.

[0007] Advantageous embodiments with useful further developments of the invention are specified in the dependent claims. It should be noted that the exemplary embodiments explained in the description are not limiting; rather, any variations of the features disclosed in the description, the claims, and the figures are feasible.

[0008] The gear is preferably a component of the internal gear fluid machine, but can of course also be present separately from it. 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 corresponding to the gear described here. 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 second 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 set of teeth and the second set of teeth engage with one another in regions viewed in the circumferential direction, i.e. they mesh with one another in regions, namely in an engagement region.The two gears are intended for fluid conveyance and are therefore designed in such a way that they interact during a rotary movement to convey the fluid and engage or mesh with each other.

[0009] 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. Preferably, the plug-in pinion 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. Preferably, the first gear is 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.

[0010] 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 a first axis of rotation, whereas the second gear is rotatably mounted about a second axis of rotation corresponding to the 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 vice versa, a rotational movement of the second gear is transmitted directly to the first gear.

[0011] 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.

[0012] 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.

[0013] 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.

[0014] 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.

[0015] 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 close contact of the tip surfaces and, on the other hand, by the close meshing of the external gearing and the internal gearing in the engagement area. Such a design of the internal gear fluid machine can also be referred to as a gear ring fluid machine. 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 therefore located on a first side of the gears, and a second of the housing walls is located on a second 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.For example, the gap remaining between the housing walls and the gears is dimensioned so small that the housing walls provide sufficient sealing of the fluid space or chambers. For example, the gears are mounted on and / or in the machine housing.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] The gear, corresponding to the second gear of the internal gear fluid machine, has the cavity that completely penetrates the gear or the base body of the gear in the axial direction. The cavity is bounded radially outward by the internal toothing. If the gear forms a component of the internal gear fluid machine, the first gear of the internal gear fluid machine is arranged in the cavity. A portion of the cavity forms the aforementioned fluid space, which is jointly bounded by the first gear and the second gear of the internal gear fluid machine. This fluid space is further divided into the first fluid chamber and the second fluid chamber.

[0022] The gearwheel has a plurality of flow channels which, viewed in the radial direction relative to the axis of rotation, open into the cavity through the internal toothing and extend radially outward through the outer circumferential surface of the base body or gearwheel. Via these flow channels, the first fluid chamber is fluidically connected to a first fluid connection of the internal gear fluid machine, and the second fluid chamber is fluidically connected to a second fluid connection of the internal gear fluid machine, and is at least temporarily fluidically 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 part 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, if the flow channels are arranged in a single row, there is an odd number.

[0023] During operation of the internal gear fluid machine, the fluid must flow radially outward or inward through the inter-tooth spaces to reach the flow channels or to enter the respective fluid chamber from the flow channels. The inter-tooth spaces represent flow resistances, which cause a pressure loss and thus a power loss. For this reason, the flow channels should be designed such that their longitudinal center axes are offset in the circumferential direction with respect to the center axes of the inter-tooth spaces. The longitudinal center axes of the flow channels are axes that run in the longitudinal direction of the flow channels and are located centrally within them.The central axes of the tooth spaces are axes that, viewed in a cross-section through the gear, run centrally through the tooth spaces and are located centrally between the teeth that circumferentially delimit the tooth spaces. Preferably, the central axes run symmetrically between the tooth flanks of the teeth of the internal gearing that delimit the tooth spaces. Preferably, each of the central axes runs through the axis of rotation of the gear, in particular, it is perpendicular to the axis of rotation.

[0024] The off-center arrangement of the flow channels in cross-section, i.e., offset in the circumferential direction with respect to their center axis, significantly reduces the aforementioned flow resistance and thus the power loss of the internal gear fluid machine. The off-center arrangement means that, viewed in cross-section, each of the flow channels is arranged asymmetrically with respect to the intertooth space into which it opens. The respective longitudinal center axis of each of the flow channels is therefore offset from the center axis of the intertooth space into which the flow channel opens. This means, in particular, that the longitudinal center axis is angled with respect to the center axis, i.e., forms an angle with it that is greater than 0° and less than 180°.

[0025] In order to ensure simple production of the gear and at the same time to reduce flow resistance and achieve high operational strength in the manner already mentioned, the flow channels are not continuous in some areas in the direction of their longitudinal center axes in the radial inward direction, but only partially penetrate the base body in the radial direction from outside to inside. The base body is understood to be the part of the gear that delimits the cavity in the radial outward direction. The base body is delimited in the radial inward direction by the internal toothing formed on it and in the radial outward direction by the outer peripheral surface. The flow channels that only partially penetrate the base body are preferably delimited - viewed from the outside in the radial direction - by channel bottoms that are present in the teeth of the internal toothing.

[0026] This means that a wall defining each of the flow channels up to its opening into the corresponding intertooth space has a projection formed by the tooth defining the intertooth space, which projection projects into the flow channel in the form of the channel base. To form the flow channels, these are created, for example, by drilling in a radial direction from the outside to the inside on the base body, with the drill only partially penetrating the base body. In particular, the created flow channels end in the teeth of the internal gearing in some areas when viewed radially from the outside, and therefore do not extend as far as the tip circle of the internal gearing. In other words, the flow channels are created at a distance from the gearing in some areas when viewed in their respective cross-sections, and therefore only open into it in some areas.

[0027] Each flow channel opens into one of the intertooth spaces via its respective opening and ends in the tooth defining the respective intertooth space, particularly at the respective channel base. This ensures simple production of the flow channels without mechanically weakening the tooth and / or penetrating the tooth tip or a tooth tip surface of the respective tooth, which would cause a leak and reduce the efficiency of the internal gear fluid machine.

[0028] As mentioned, the flow channels are in the form of bores, for example, whose longitudinal center axes intersect the axis of rotation of the gear, in particular are perpendicular to it. During production of the gear, the flow channels are created by drilling, with the drilling taking place in a radial direction from the outside to the inside in such a way that each of the flow channels is partially present as a blind bore and is fundamentally delimited by its respective channel. The measure described makes it possible to design the flow channels with a significantly larger flow cross-sectional area. For example, the flow channels are fundamentally designed up to the respective channel in such a way that they penetrate the respective tooth away from the channel base in the circumferential direction by at least 30%, at least 40% or at least 50%.

[0029] A further development of the invention provides that, in a central plane perpendicular to the rotational axis, the flow channels are each blocked on a first side and open unblocked into the inter-tooth spaces on a second side opposite the first side in the circumferential direction. The central plane is preferably understood to be an imaginary plane perpendicular to the rotational axis of the gear and extending centrally through the flow channels, particularly when viewed in the axial direction. In the central plane, the flow channels thus have their greatest extent in the circumferential direction.

[0030] Each of the flow channels is defined by a wall formed by the base body of the gear. The wall of each flow channel ends – viewed in cross-section and in the circumferential direction – on the first side at the base of the respective channel, whereas on the second side it opens into the inter-tooth space and thus ends directly adjacent to it. On the second side, the wall of the respective flow channel thus forms the edge of an opening through which the respective flow channel opens into the corresponding inter-tooth space. On the first side, however, the wall is spaced from the inter-tooth space in the circumferential direction. With the described design, the advantages already mentioned are achieved in a simple manner.

[0031] A further development of the invention provides that the longitudinal center axes intersect the axis of rotation, in particular, are perpendicular to it. This means that the flow channels are not angled in the circumferential direction, but are aligned with the axis of rotation. This enables simple manufacturing and low-loss filling of the internal gear fluid machine. Furthermore, the longitudinal center axes of the flow channels preferably lie entirely in an imaginary plane, at least the longitudinal center axes of the flow channels arranged in the same row.

[0032] A further development of the invention provides that the flow channels, viewed in the circumferential direction, penetrate the teeth of the internal toothing to at least 30%, at least 40% or at least 50%. This applies in particular in the center plane. At at least one point in the axial direction with respect to the longitudinal center axis of the respective flow channel, this therefore penetrates the tooth to at least one of the stated proportions. The flow channels therefore have comparatively large dimensions in the circumferential direction, in particular angular dimensions; in particular, the dimensions in the circumferential direction amount to at least 70%, at least 80% or at least 90% of the dimensions of the teeth of the internal toothing on the root circle or base circle of the internal toothing. With this type of gear design, a particularly high level of efficiency is achieved.

[0033] A further development of the invention provides that the flow channels engage in the circumferential direction with the first of the teeth, which delimit the inter-tooth spaces on a first side, and pass through the first tooth flanks of the first teeth. Each of the inter-tooth spaces is delimited in the circumferential direction by two teeth of the internal toothing, namely on a first side by a first tooth and on a second side by a second tooth. The first tooth has a first tooth flank facing the respective inter-tooth space, and the second tooth has a second tooth flank facing the respective inter-tooth space, so that ultimately the first tooth flank and the second tooth flank delimit the inter-tooth space in the circumferential direction. The flow channels are arranged and designed such that they engage in the respective first tooth and pass through the first tooth flank.In particular, they penetrate the first tooth flank between the base circle and / or the root circle on the one hand and the tip circle of the internal gearing on the other, preferably at least starting from the base circle or the root circle. They preferably penetrate the respective first tooth flank in the radial direction to at least 40%, at least 60%, or at least 80%, for example, at least up to a pitch circle of the internal gearing. This ensures good filling of the internal gear fluid machine.

[0034] A further development of the invention provides that the tooth spaces are delimited in the circumferential direction on a second side opposite the first side by second of the teeth, wherein the flow channels are spaced apart from second tooth flanks of the second teeth in the circumferential direction or border on them. Each of the second teeth accommodates exactly one of the tooth spaces in the circumferential direction between them with one of the first teeth and delimits it in this direction. The flow channels are arranged and designed such that they do not penetrate the second tooth flanks. For this purpose, they are preferably arranged at a distance from them. However, they are at least adjacent to them. This ensures the tight interaction of the teeth of the internal toothing and the teeth of the external toothing.

[0035] A further development of the invention provides that the flow channels engage with the second teeth in the circumferential direction and penetrate the second tooth flanks of the second teeth to a lesser extent than the first tooth flanks. The flow channels are therefore arranged and designed such that they engage with both the first teeth and the second teeth, namely such that they penetrate both the first tooth flanks and the second tooth flanks. To nevertheless ensure the tight interaction of internal and external teeth, they penetrate the second tooth flanks to a lesser extent than the first tooth flanks, particularly when viewed in cross-section. This means in particular that the flow channels penetrate the first tooth flanks further outwards in the radial direction than the second tooth flanks.

[0036] Particularly preferably, the flow channels extend through the second tooth flanks in a radial outward direction, starting from the base circle, but not as far as a useful root circle of the internal gearing. Openings formed by the flow channels in the second tooth flanks extend only partially as far as the useful root circle and, as viewed in the radial direction, end at a distance from the useful root circle. For example, the flow channels extend through the second tooth flanks in a radial direction, starting from the base circle as far as the useful root circle, to a maximum of 90%, a maximum of 80%, or a maximum of 70%. This continues to ensure tight interaction, but at the same time improves the filling of the internal gear fluid machine.

[0037] A further development of the invention provides that a channel base which partially delimits each of the flow channels in the axial direction with respect to its longitudinal center axis and is formed in one of the teeth of the internal gearing is at a distance from a tip circle of the internal gearing which corresponds to a maximum of 25%, a maximum of 20%, a maximum of 15% or a maximum of 10% of a tooth height of the internal gearing. The distance between the respective channel base and the tip circle is in the radial direction. The tooth height is to be understood as the difference between the root circle diameter and the tip circle diameter of the internal gearing, if necessary as an absolute value. It is clear that the flow channels largely penetrate the teeth of the internal gearing in the direction of their longitudinal center axes. As a result, they penetrate the tooth flanks of the teeth of the internal gearing and thus form a comparatively large mouth opening through which the aforementioned advantages are achieved.

[0038] A further development of the invention provides that the internal gearing is an involute gearing, wherein a distance between a tip circle and a base circle of the involute gearing is greater by a factor of at least 4, at least 6, or at least 8 than a distance between the base circle and a root circle of the involute gearing. This ultimately means that the tooth flanks of the teeth of the internal gearing extend far in the direction of the root circle, and a tooth root present as part of the intertooth space has a comparatively small volume. This achieves a high level of efficiency of the internal gear fluid machine.

[0039] A further development of the invention provides that the flow channels have smaller dimensions in the axial direction than the base body, in particular, they have at most the same dimensions in the axial direction as in the circumferential direction and / or have a round flow cross-section. The flow channels only partially penetrate the base body in the axial direction relative to the axis of rotation; in particular, they are each designed with a closed edge in the base body, i.e., they have a continuous edge at at least one point. Preferably, an opening formed by the outer circumferential surface passing through the respective flow channel is closed at the edge.

[0040] For example, it is provided that the flow channels have the same dimensions in the axial direction and in the circumferential direction and are, for example, round. Of course, the flow channels can also be oval, in particular elliptical or stadium-shaped, whereby they have larger dimensions in the axial direction than in the circumferential direction. For example, the dimensions in the axial direction are larger than the dimensions in the circumferential direction by a factor of at least 2, at least 4 or at least 6. The stadium-shaped design of the flow channels is to be understood as meaning that their cross-section is delimited by two parallel straight lines which are connected to one another on opposite sides via two partial circles, in particular via two semicircles. The described design of the gear enables a large flow cross-sectional area of ​​the flow channels and thus a high efficiency of the internal gear fluid machine.

[0041] A further development of the invention provides that the flow channels are designed as bores. This ultimately means that they are created by drilling using a drill. The drilling of the flow channels in the base body takes place in a radial direction relative to the axis of rotation from the outside to the inside. Drilling is completed when a head of the drill, on the one hand, projects into the intertooth space, but on the other hand is located in the tooth delimiting the intertooth space and is still at a distance from the tip circle of the internal gearing, so that the drill only partially penetrates the tooth in the radial direction. This enables a cost-effective design of the flow channels in the base body.

[0042] A further development of the invention provides that each channel base, viewed in section, has an extension in the circumferential direction which corresponds to at least 20%, at least 30%, or at least 40% of the basic dimensions of the flow channels. The basic dimensions are to be understood in particular as dimensions of the flow channels away from the interdental spaces, for example their dimensions on the side facing away from the interdental spaces. For example, the flow channels are delimited by an imaginary cylinder, in particular a circular cylinder. If this cylinder is imaginarily extended to the respective channel base, the cylinder penetrates the imaginary cylinder, viewed in cross-section, by at least one of the stated proportions. Preferably, the proportion is at most 50%, at most 45%, or at most 40%. This achieves the large flow cross-sectional area mentioned above.

[0043] A further development of the invention provides that the flow channels are arranged in several parallel, spaced-apart rows on the base body. The flow channels or their longitudinal center axes are therefore not located in a single imaginary plane, but in several planes arranged parallel and spaced from one another. Preferably, the same number of flow channels are produced in the base body in each row or in each corresponding plane. More preferably, the flow channels in the several rows are located at the same positions in the circumferential direction with respect to the axis of rotation. The flow channels of the various rows are arranged at a distance from one another in the axial direction, i.e., they do not directly border one another or do not merge into one another.The presence of the flow channels in the several rows enables the production of a large flow cross-section while at the same time making it easier to produce the flow channels, for example as bores.

[0044] The invention further relates to a method for producing a gear for an internal gear fluid machine, in particular a gear according to the embodiments within the scope of this description, wherein the gear has a cavity which passes through a base body of the gear in the axial direction with respect to a rotational axis of the gear, said cavity being delimited outwardly in the radial direction by an internal toothing, wherein flow channels open into the tooth spaces of the internal toothing, which flow channels pass through an outer circumferential surface of the base body on their side facing away from the tooth spaces and have longitudinal center axes offset in the circumferential direction with respect to the rotational axis relative to the center axes of the tooth spaces. The flow channels are designed in such a way that they only partially pass through the base body in the radial direction from the outside to the inside.

[0045] The advantages of such a procedure or such a gear design have already been pointed out. Both the gear and the method for its manufacture can be further developed according to the explanations in this description, so reference is made to these in this regard.

[0046] The invention further 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 are mounted for rotation about a second axis of rotation different from the first axis of rotation, in particular designed as a gear according to the explanations in the context of this description, wherein the second gear has a cavity that passes through a base body of the second gear in the axial direction with respect to a rotation axis of the second gear, which cavity is delimited outwards in the radial direction by internal teeth, wherein flow channels open into the spaces between the teeth of the internal teeth,which, on their side facing away from the interdental spaces, penetrate an outer circumferential surface of the base body and have longitudinal center axes offset from the center axes of the interdental spaces in the circumferential direction relative to the axis of rotation. It is intended that the flow channels only partially penetrate the base body in the radial direction from the outside to the inside.

[0047] With regard to the advantages and possible advantageous embodiments, reference is again made to the explanations in this description.

[0048] 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.

[0049] 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:

[0050] Figure 1 is a schematic sectional view of an internal gear fluid machine,

[0051] Figure 2 is a schematic sectional view through a gear of the internal gear fluid machine in a first embodiment, and

[0052] Figure 3 shows a schematic sectional view through the gear in a second embodiment. 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 external teeth 7 and the second gear 4 has internal teeth 8, which mesh with one another in an engagement region 9, i.e., are in engagement with one another.

[0053] 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 16 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.

[0054] 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 outwardly 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 by way of example. It can be seen that the flow channels 20 are arranged offset in the circumferential direction relative to the tooth spaces 19, i.e., as seen in section, they are asymmetrical with respect to them.Each of the interdental spaces 19 has a central axis 21 and each of the flow channels 20 has a longitudinal central axis 22, wherein the central axes 21 and the longitudinal central axes 22 are indicated only by way of example for one of the interdental spaces 19 and one of the flow channels 20. However, it can be clearly seen that the central axis 21 of each interdental space 19 and the longitudinal central axis 22 of the flow channel 20 opening into it are offset from one another in the circumferential direction. Preferably, both the central axis 21 and the longitudinal central axis 22 each run through the second axis of rotation 6. Additionally, it can be seen that the flow channels 20 have a changing flow cross-section in the radial direction from the outside to the inside; in particular, the flow channels 20 are each closed in the radial direction to the inside by a channel base 23 which is arranged in one of the teeth 18 of the internal toothing 8.

[0055] Figure 2 shows a schematic cross-sectional view of the second gear 4 in a first embodiment. For the internal toothing 8 with its teeth 18 and tooth spaces 19, a tip diameter is indicated by arrow 24, a base circle diameter by arrow 25, and a root circle diameter by arrow 26. An arrow 27 indicates the tooth width of the teeth 18 in the circumferential direction. The tooth width extends along the base circle from a first tooth flank of the tooth 18 to an opposite second tooth flank of the same tooth 18. It is clearly visible that the flow channel 20 penetrates a significant portion of the respective tooth 18 in the circumferential direction, namely at least 30%, at least 40%, or—as shown here—at least 50%. Accordingly, the flow channel 20 extends as far as the respective center axis 21 of the corresponding tooth 18.The flow channel 20 also largely penetrates the respective tooth 18 in the radial direction. Thus, the channel base 23 is spaced from the tip circle of the internal toothing 8 by a maximum of 25% or less of the tooth height of the tooth 8, wherein the tooth height corresponds to a difference between the root diameter 26 and the tip diameter 24, or alternatively, a difference between the base diameter 25 and the tip diameter 24.

[0056] It can be seen that each of the inter-tooth spaces 19 is delimited in the circumferential direction by adjacent teeth 18. On a first side in the circumferential direction, the inter-tooth spaces 19 are delimited by first teeth 18 and on a second side opposite the first side by second teeth 18. The first teeth 18 have first tooth flanks 28, and the second teeth 18 have second tooth flanks 29, so that each of the inter-tooth spaces 19 is located in the circumferential direction between one of the first tooth flanks 28 and one of the second tooth flanks 29. In the first embodiment of the second gear wheel 4, the flow channels 20 are intended to engage with the first teeth 18 and to pass through the first tooth flanks 28, in particular a large part of the first tooth flanks 28. However, engagement with the second tooth flanks 29 is not provided; at most, the flow channels 20 are directly adjacent to the second tooth flanks 29, as shown here.

[0057] Figure 3 shows a schematic cross-sectional view of the second gear 4 in a second embodiment. The second embodiment is similar to the first embodiment, so reference is made to the above explanations, and only the differences between the two embodiments will be discussed below. These differences lie in the fact that the flow channels 20 again engage with the first teeth 18 and penetrate the first tooth flanks 28, in particular to the same extent as for the first embodiment. In addition, however, engagement with the second teeth 18 and penetration of the second tooth flanks 29 through the flow channels 20 are provided. The second tooth flanks 29 are penetrated by the flow channels 20 to a lesser extent than the first tooth flanks 28.

[0058] Preferably, openings 30 formed by the passage of the second tooth flanks 29 through the flow channels 20 end outside a root useful circle of the internal toothing 8 in the radial direction with respect to the second axis of rotation 6. The root useful circle is a measure of the maximum engagement of teeth of the external toothing 7 in the tooth spaces 19 of the internal toothing 8. In particular, tooth flanks of the teeth of the external toothing 7 bear against the second tooth flanks 29 of the teeth 18 of the internal toothing 8 at most up to the root useful circle. By means of such a configuration of the second gear 4, the flow channels 20 can be made wider than in the first embodiment without impairing the sealing interaction of the gears 3 and 4.

[0059] The described configuration of the second gear 4 and the internal gear fluid machine 1 as a whole enables fluid to flow in and out of the internal gear fluid machine 1 at a high throughput, particularly with low pressure loss. Accordingly, a high efficiency of the internal gear fluid machine 1 is achieved.

[0060] 1 internal gear fluid machine

[0061] 2 machine housings

[0062] 3 1. Gear

[0063] 4 2nd gear

[0064] 5 1. Axis of rotation

[0065] 6 2nd axis of rotation

[0066] 7 External gearing

[0067] 8 Internal gearing

[0068] 9 Intervention area

[0069] 10 Fluid chamber

[0070] 11 Filler piece

[0071] 12 1. Fluid chamber

[0072] 13 2. Fluid chamber

[0073] 14 segments

[0074] 15 segments

[0075] 16 gap

[0076] 17 Cavity

[0077] 18 teeth

[0078] 19 Interdental space

[0079] 20 flow channel

[0080] 21 Central axis

[0081] 22 Longitudinal center ach se

[0082] 23 channel green

[0083] 24 tip diameter

[0084] 25 base circle diameter

[0085] 26 root diameter

[0086] 27 Arrow

[0087] 28 1st tooth flank

[0088] 29 2nd tooth flank

[0089] 30 Breakthrough

Claims

CLAIMS 1. Gear (4) for an internal gear fluid machine (1), with a cavity (17) which passes through a base body of the gear (4) in the axial direction with respect to an axis of rotation (6) of the gear (4), which cavity is delimited outwards in the radial direction by an internal toothing (8), wherein flow channels (20) open into tooth spaces (19) of the internal toothing (8), which flow channels pass through an outer circumferential surface of the base body on their side facing away from the tooth spaces (19) and have longitudinal central axes (22) which are offset in the circumferential direction with respect to the axis of rotation (6) with respect to central axes (21) of the tooth spaces (19), characterized in that the flow channels (20) only partially pass through the base body in the radial direction from the outside to the inside in some regions.

2. Gear according to claim 1, characterized in that, viewed in a central plane perpendicular to the axis of rotation (6), the flow channels (20) are each blocked on a first side and open unblocked into the inter-tooth spaces (19) on a second side opposite the first side in the circumferential direction.

3. Gear according to one of the preceding claims, characterized in that the longitudinal central axes (22) intersect the axis of rotation (6).

4. Gear according to one of the preceding claims, characterized in that the flow channels (20) penetrate teeth (18) of the internal toothing (8) to at least 30%, at least 40% or at least 50%, viewed in the circumferential direction.

5. Gear according to one of the preceding claims, characterized in that the flow channels (20) engage in the circumferential direction in the first of the teeth (18) delimiting the tooth spaces (19) in the circumferential direction on a first side and pass through first tooth flanks of the first teeth (18).

6. Gear according to one of the preceding claims, characterized in that the tooth spaces (19) are delimited in the circumferential direction on a second side opposite the first side by second of the teeth (18), wherein the flow channels (20) are spaced from second tooth flanks of the second teeth (18) in the circumferential direction or adjoin them.

7. Gear according to one of the preceding claims, characterized in that the flow channels (20) engage in the second teeth (18) in the circumferential direction and penetrate the second tooth flanks of the second teeth (18) to a lesser extent than the first tooth flanks.

8. Gear according to one of the preceding claims, characterized in that a channel base (23) which partially delimits each of the flow channels in the axial direction with respect to its longitudinal center axis and is formed in one of the teeth (18) of the internal toothing (8) has a distance from a tip circle of the internal toothing (8) which corresponds to at most 25%, at most 20%, at most 15% or at most 10% of a tooth height of the internal toothing (8).

9. Gear according to one of the preceding claims, characterized in that the internal toothing (8) is an involute toothing, wherein a distance between a tip circle and a base circle of the involute toothing is greater by a factor of at least 4, at least 6 or at least 8 than a distance between the base circle and a root circle of the involute toothing.

10. Gear according to one of the preceding claims, characterized in that the flow channels (20) have smaller dimensions in the axial direction than the base body.

11. Gear according to one of the preceding claims, characterized in that the flow channels (20) are designed as bores.

12. Gear according to one of the preceding claims, characterized in that each channel base (23) has, in section, an extension in the circumferential direction which corresponds to at least 20%, at least 30% or at least 40% of the basic dimensions of the flow channels (20).

13. Gear according to one of the preceding claims, characterized in that the flow channels (20) are arranged in several parallel spaced rows on the base body.

14. Method for producing a gear (4) for an internal gear fluid machine (1), in particular a gear (4) according to one or more of the preceding claims, wherein the gear (4) has a base body of the gear (4) in the axial direction with respect to a Rotational axis (6) of the gear (4) passing through a hollow space (17) which is delimited in the radial direction outwards by an internal toothing (8), wherein flow channels (20) open into the tooth spaces (19) of the internal toothing (8), which flow channels (20) on their side face the tooth spaces (19) facing away from an outer circumferential surface of the base body and have longitudinal central axes (22) offset in the circumferential direction relative to the axis of rotation (6) relative to central axes (21) of the interdental spaces (19), characterized in that the flow channels (20) are designed in such a way that they only partially penetrate the base body in the radial direction from the outside to the inside.

15. Internal gear fluid machine (1), comprising 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) and mounted for rotation about a second axis of rotation (6) different from the first axis of rotation (5), in particular configured as a gear (4) according to one or more of claims 1 to 10, wherein the second gear (4) has a cavity (17) that passes through a base body of the second gear (4) in the axial direction relative to a rotation axis (6) of the second gear (4), which cavity is delimited outwardly in the radial direction by internal teeth (8), wherein flow channels (20) open into tooth spaces (19) of the internal teeth (8),which, on their side facing away from the interdental spaces (19), pass through an outer circumferential surface of the base body and have longitudinal central axes (22) offset in the circumferential direction relative to the axis of rotation (6) relative to central axes (21) of the interdental spaces (19), characterized in that the flow channels (20) only partially pass through the base body in the radial direction from the outside to the inside.

Images