Electromechanical energy converter with temperature-controlled housing

Abstract

An electromechanical energy converter with a temperature-controlled housing for use in a motor vehicle, has at least a stator, a rotor and a housing, the rotor is mounted in the housing so that it can rotate around a rotor longitudinal axis relative to the stator, at least one fluid channel (2) is arranged in a region of the housing (housing segment (1)), the fluid channel (2) extends, at least substantially, in the direction of the rotor longitudinal axis (7) and is designed to be flowed through by a temperature control medium, a cross-sectional area of ​​the fluid channel (2) arranged orthogonally to the longitudinal extent has a first extent I1 in the circumferential direction and a second extent I2 radially to the rotor longitudinal axis (7), the housing segment (1) is limited radially outwards by an outer housing surface (3a, b) and the fluid channel (2) is limited radially outwards by an outer channel surface (4), the first extension I1 is at least 1.2 I2 and, the outer channel surface (4) has a flat profile, and the outer casing surface (3b) has a flat profile and the outer channel surface (4) and the outer housing surface (3b) are parallel to each other and wherein a lateral channel surface (6b) has, at least in sections, a variable radius of curvature, characterized in that the radius of curvature is greatest at the transition points (8) between the inner / outer channel surface (4, 5a, b) and the lateral channel surface (6b) and that starting from these points (8) the radius of curvature (6b) becomes smaller in the further course of the lateral channel surface until it reaches a smallest radius of curvature and that the lateral channel surface (6b), at least with respect to the outer or inner channel surface, is designed according to the method of tension triangles and that the housing has several housing segments (1) and that the housing segments (1) are connected to one another by connecting areas and that the housing segments (1) and the connecting areas result in a housing which surrounds the stator, at least in sections.

Description

[0001] The invention relates to an electromechanical energy converter with a temperature-controlled housing. Such an electromechanical energy converter is known from DE102006006839 A1. Housings of electromechanical energy converters, in particular of electric motors and generators in motor vehicle drive trains, are subject to greater stress than before due to increasing power density. Therefore, it is often necessary for the housings of such devices to have fluid channels for temperature control of the devices. This can be to preheat the electromechanical energy converter during start-up at very low temperatures or to dissipate waste heat during regular operation. An electromechanical energy converter typically has at least one rotor, which is rotatably mounted in a housing relative to a stator.

[0002] The stators are often pressed into the housing or even inserted with a temperature difference (housing warm, stator cold) to achieve a particularly secure connection between stator and housing. The high joint pressures generated by these connections in the parting line between stator and housing cause significant mechanical stresses in the housing, particularly tensile and bending stresses. These stresses are further exacerbated by the inclusion of fluid channels in stressed sections of the housing. As a result, multiaxial stress states arise and, in some cases, the component strength is exceeded, at least locally, so that such highly stressed housings can fail after sometimes a short period of operation.

[0003] Electromechanical energy converters with a housing interspersed with coolant channels are known from the prior art. DE102006006839 A1 shows an electric motor housing with at least one fluid channel.

[0004] WO 97 / 44882 A1 discloses a liquid cooling system for an electrical machine comprising a housing having cooling channels formed by tubes. These cooling channels have an outer channel surface that, at least in sections, has a planar profile. Furthermore, the cross-sectional area of ​​these cooling channels in the circumferential direction of the housing has a large width compared to the height of the cooling channels.

[0005] US 5 084 642 A deals with a channel structure for a coolant in an engine, in particular in an electric motor.

[0006] The final report of the BMBF-funded joint project: Development of efficient, easy-to-apply design principles for technical components based on nature (funding code 01 RI 0638) from October 2010, deals with design principles for components.

[0007] It is an object of the invention to provide an electromechanical energy converter with improved operational reliability. This object is achieved by a subject matter according to claim 1; preferred developments of this electromechanical energy converter are the subject matter of the dependent claims.

[0008] For the purposes of the invention, an electromechanical energy converter is a device for converting electrical energy into mechanical energy, in particular for converting electrical current into rotary motion or vice versa. An electromechanical energy converter is preferably an electric motor / generator. Furthermore, the invention can be used regardless of the design of the electric motor / generator, in particular regardless of whether it is a synchronous or asynchronous motor or the like. The electromechanical energy converter preferably has at least one rotatable rotor, a stator, and a temperature-controlled housing.

[0009] For the purposes of the invention, a temperature-controlled housing is understood to be a device of the electromechanical energy converter, which is configured, on the one hand, to support at least one further component, in particular the rotor, and, on the other hand, to supply or discharge a heat flow. A temperature-controlled housing preferably completely or partially surrounds the rotor and stator of the energy converter. Furthermore, the housing, or a housing wall, is preferably capable of being permeated by a temperature-control medium.

[0010] For the purposes of the invention, a rotor longitudinal axis is understood to be an imaginary axis around which a rotor of the electromechanical energy converter is rotatably mounted in the temperature-controlled housing. Preferably, the rotor longitudinal axis runs as a line of symmetry through a motor-generator output shaft, by means of which the motor-generator outputs or receives power.

[0011] For the purposes of the invention, a fluid channel is understood to be a recess in the temperature-controlled housing through which a temperature-controlling medium flows. A temperature-controlling medium is understood to be, in particular, a gaseous or liquid fluid. The fluid channel is preferably designed as a recess in this temperature-controlling housing.

[0012] For the purposes of the invention, a cross-sectional area of ​​the fluid channel is understood to mean the area which at least partially describes the cross-section of the fluid channel, orthogonal to its extension in the direction of the rotor longitudinal axis.

[0013] For the purposes of the invention, the extension I1 of this cross-sectional area in the circumferential direction is to be understood as an extension of the fluid channel in the direction around the rotor's longitudinal axis. I1 corresponds in particular to the width of the fluid channel. This extension I1 is preferably specified in Cartesian coordinates; more preferably, the extension I1 is specified in cylindrical coordinates (radian measure, circumferential length of a circular arc). More preferably, the extension I1 is to be understood as the extension of the fluid channel between the transition points to the lateral channel surface. For the purposes of the invention, the extension I2 is to be understood as the extension of this cross-sectional area in the radial direction, orthogonal to the rotor's longitudinal axis. In particular, the extension I2 is to be understood as the height of the fluid channel.

[0014] For the purposes of the invention, an outer housing surface is understood to mean the radially outwardly bounding surface of the temperature-controlled housing, particularly in the region of the fluid channel. Preferably, the outer housing surface extends in the circumferential direction exactly as far as, or further than, the fluid channel in the same direction.

[0015] For the purposes of the invention, an outer channel surface is understood to be the surface of the fluid channel that radially separates it from the temperature-controlled housing. Figuratively, the outer channel surface is thus located within the temperature-controlled housing.

[0016] For the purposes of the invention, the planar course of lateral surfaces is to be understood as meaning that these preferably have two straight lines that are not parallel to one another as generators.

[0017] The flat profile of the outer housing surface results in a polygonal housing for the electromechanical energy converter if this housing has multiple housing segments with fluid channels. For the purposes of the invention, a polygonal housing is understood to mean a housing that has multiple flat outer housing surfaces. The flat outer housing surfaces preferably abut one another directly; more preferably, these surfaces are indirectly connected to one another via a connecting region. Furthermore, a connecting region preferably has a rounded portion, which preferably merges tangentially into the flat outer channel surfaces.

[0018] For the purposes of the invention, a housing segment is understood to be the region of the temperature-controlled housing in which the fluid channel is arranged. Preferably, the circumferential extension of the housing segment corresponds to the extension of the fluid channel in this direction or extends beyond it in this direction.

[0019] Calculations have shown that for a fluid channel with an extension I1 that is at least 1.2 times or greater than the extension I2, and with a flat outer channel surface, the stress on the housing is particularly low. In particular, the combination of geometric properties described above makes it possible to create an improved electromechanical energy converter.

[0020] The outer channel surface and the outer housing surface are arranged parallel to each other, at least in sections. Preferably, the outer channel surface and the outer channel surface are completely parallel to each other. It has been shown that two parallel, flat surfaces (outer housing surface, outer channel surface) result in particularly low stresses in the area of ​​the fluid channels in this housing, and in particular, this allows for the creation of an improved electromechanical energy converter.

[0021] The outer housing surface has a flat profile. Preferably, the outer housing surface is parallel to the outer channel surface; more preferably, these surfaces are arranged at an oblique angle to each other. It has been shown that a flat outer housing surface in combination with a flat outer channel surface leads to particularly low stresses on the housing in this area, thus enabling the realization of an improved electromechanical energy converter.

[0022] In a preferred embodiment, the first extension I1 is selected from a specific range with respect to the second extension I2. The extension I1 is >1.2 I2, preferably >2 I2, more preferably >4 I2, and particularly preferably >6 I2. Furthermore, the extension I1 is <25 I2, preferably <20 I2, and particularly preferably <12 I2. In particular, selecting the extensions I1 and I2 with respect to one another from the proposed range results in a particularly slim fluid channel. Calculations have shown that this slim fluid channel, in particular, has a positive effect on the stress on the housing in this area, thus enabling increased operational reliability for the electromechanical energy converter.

[0023] In a preferred embodiment, the fluid channel is delimited radially inward by an inner channel surface. This inner channel surface preferably has a planar profile at least in sections. Further preferably, this inner channel surface runs at least in sections, preferably completely, parallel to the outer channel surface, preferably at an oblique angle. Further preferably, this inner channel surface and this outer channel surface are designed identically, particularly preferably both as planes. Calculations have shown that, in particular, the design of the inner channel surface with respect to the outer channel surface in the proposed manner has a beneficial effect on the stress on the housing in this area.The proposed design of the inner channel surface in relation to the outer channel surface enables a higher operational reliability for the electromechanical energy converter to be achieved.

[0024] In a preferred embodiment, the inner channel surface has a curved profile, at least in sections. Further preferably, the inner surface is formed concentrically to the rotor's longitudinal axis. The curvature of the inner channel surface increases its surface area compared to a flat design of this channel surface, thus increasing the amount of heat that can be transferred. In particular, a greater amount of heat that can be transferred results in greater operational reliability of the electromechanical energy converter.

[0025] In a preferred embodiment, the outer and inner channel surface each merge into a lateral channel surface at a transition point. This transition point is preferably characterized by the tangential transition of the outer or inner channel surface into the lateral channel surface. Further preferably, the outer or inner channel surface has a discontinuous profile at the transition point, in particular a kink or jump. Further preferably, the profile is continuous at this transition point. The lateral channel surface preferably has a continuously curved profile. Further preferably, the lateral channel surface has a monotonic curvature. It has been shown that a curved lateral channel surface has a positive effect on the stress on the temperature-controlled housing, and thus increased operational reliability can be achieved for the electromechanical energy converter.

[0026] In a preferred embodiment, the lateral channel surface has, at least in sections, a variable radius of curvature, in particular in a plane orthogonal to the rotor longitudinal axis. The radius of curvature is preferably greatest at the transition points (inner / outer channel surface to lateral channel surface). Preferably, starting from these transition points, the radius of curvature becomes smaller as the lateral channel surface progresses. The lateral channel surface preferably has the smallest radius of curvature in a region remote from the transition points. Further preferably, the lateral channel surface has the shape of an ellipse in this region. The shape of the lateral channel surface can preferably be described using a spline.In particular, by adapting the radius of curvature over the course of the lateral channel surfaces, it is possible to further reduce the stress on the temperature-controlled housing in the area of ​​the fluid channel and thus increase the operational reliability of the electromechanical energy converter.

[0027] In a preferred embodiment, at least the profile of one of the lateral channel surfaces is designed according to the tension triangle method. In particular, the profile of this in a plane orthogonal to the rotor longitudinal axis. In this case, the tension triangle method, in particular, leads to a variable radius of curvature of this lateral channel surface over the profile of the lateral channel surface. The tension triangle method is also known from the prior art, in particular as the method according to Prof. Mattheck. Further preferably, several of the lateral channel surfaces are designed with a variable radius of curvature; preferably, all lateral channel surfaces are designed according to this method.Calculations have shown that, in particular, the described type of design of the lateral channel shell surfaces can reduce the stresses on the temperature-controlled housing in this area, thus making it possible to achieve an improved electromechanical energy converter with increased operational reliability.

[0028] A housing according to the invention for an electromechanical energy converter comprises a plurality of housing segments, wherein these housing segments are preferably connected to one another in one piece. Furthermore, the housing segments are preferably connected to one another by means of connecting regions, which preferably do not have fluid channels, preferably in one piece. Each housing segment preferably has at least one fluid channel; preferably, several fluid channels can be arranged in one housing segment, preferably adjacent to one another in the circumferential direction or one above the other in the radial direction, in each case relative to the rotor's longitudinal axis.

[0029] The figures shown below show preferred developments of the device according to the invention in a partially schematic representation.

[0030] It shows: Fig. 1 a housing segment as known from the prior art, in a sectional view, Fig. 2 different variants of a housing segment in a sectional view, Fig. 3 a sectional view of a housing in which the section is orthogonal to the rotor longitudinal axis, Fig. 4 a partial section of a housing for an electromechanical energy converter.

[0031] Fig. 1 shows a cross-sectional area of ​​a housing segment, as is known from the prior art. A fluid channel 2 is arranged in the housing segment 1. The fluid channel 2 extends along the rotor longitudinal axis 7 and has an extension I1 and I2. The fluid channel is delimited radially outwards by the outer channel surface 4. The temperature-controlled housing is delimited radially outwards by the curved outer housing surface 3a, which has a radius of curvature 9. The outer channel surface 4 and the inner channel surface 5a merge into the lateral channel surface 6c at the transition points 8. The lateral channel surface 6c has an essentially straight profile. The transition points 8 are arranged at the tangential transition of the inner / outer channel surface into the lateral channel surface 6a.A temperature-controlled housing of an electromechanical energy converter usually consists of several of the housing segments 1 shown, so that a radially closed circumferential housing is usually produced.

[0032] In Fig. 2, different variants of a housing segment 1 are shown, marked with the letters a to d, whereby the Fig. 2b is in accordance with the invention. Preferably, an entire housing of an electromechanical energy converter is formed from several of these housing segments and preferably further intermediate regions between them. Several of these housing segments are formed integrally with one another. The following primarily focuses on the differences from the known prior art, which is described in Fig. 1 is shown.

[0033] The fluid channel in Fig. 2a) has an extension I1 and an extension I2. In contrast to the known prior art, the outer housing surface 3b is not curved, but has a straight profile. A housing made up of several housing segments 1 with a flat outer housing surface 3b has a polygonal basic shape on the outside. Furthermore, the outer channel surface 4 also has a straight profile and is designed as a plane parallel to the outer housing surface 3b. In the Fig. 2a), the lateral channel surfaces 6a have a constant radius of curvature, which is therefore not according to the invention.

[0034] Fig. 2b) shows a variant in which the lateral channel surfaces 6b have a variable radius of curvature. This variable radius of curvature of the lateral channel surfaces 6b is created by the construction method of the tension triangles according to Prof. Mattheck, which is known from the state of the art for various applications. Fig. In the variant shown in Figure 2b), the outer channel surface 4b is designed as a plane parallel to the outer housing surface 3b.

[0035] In Fig. 2c) shows a variant of a fluid channel 2 in a housing segment 1, wherein the fluid channel 2 has an inner channel surface 5b without curvature. The lateral channel surfaces 6a have a constant radius of curvature and are therefore not in accordance with the invention. The outer channel surface 4 is designed as a plane parallel to the outer housing surface 3b.

[0036] In Fig. 2d) shows a variant of a fluid channel 2 in a housing segment 1, not according to the invention. The fluid channel 2 has an inner channel surface 5a with a curvature. The lateral channel surfaces 6b are formed according to the tensile triangle method according to Prof. Mattheck. The outer housing surface has a radius of curvature 9 around the rotor's longitudinal axis 7.

[0037] In Fig. Figure 3 shows a cross-section of a housing for an electromechanical energy converter. The housing has several fluid channels 2 and housing segments 1. The fluid channels 2 extend in the direction of the rotor's longitudinal axis 7. The outer housing surfaces 3a are flat in sections, and the outer channel surfaces 4 are also flat in at least some sections and parallel to the outer housing surfaces 3a. The lateral channel surfaces 6b have a variable radius of curvature and are designed according to the tensile triangle method. The housing, with the housing segments 1, surrounds the rotor (not shown) and the stator (not shown) of the electromechanical energy converter.

[0038] In Fig.Figure 4 shows two directly adjacent and integrally formed housing segments 1 in a cross-section orthogonal to the rotor's longitudinal axis 7. Fluid channels 2 are arranged in the housing segments 1. The fluid channels 2 have flat outer channel surfaces 4 and flat outer housing surfaces 3b, thus creating a polygonal housing, only a portion of which is shown here. The lateral channel surfaces 6b are rounded using the tensile triangle method. List of reference symbols 1 housing, housing segment 2 fluid channels 3a Curved outer casing surface 3b Plane outer casing surface 4 Outer channel surface 5a Curved inner channel surface 5b Plane inner channel surface 6a Lateral channel surface with constant radius of curvature 6b Lateral channel surface according to the tension triangle method 6c Lateral channel surface with at least partially flat course 7 Rotor longitudinal axis 8 Transition point 9 Radius of curvature of outer casing surface

Claims

[1] An electromechanical energy converter with a temperature-controlled housing for use in a motor vehicle has at least a stator, a rotor and a housing, the rotor is mounted in the housing so that it can rotate around a rotor longitudinal axis relative to the stator, at least one fluid channel (2) is arranged in a region of the housing (housing segment (1)), the fluid channel (2) extends, at least substantially, in the direction of the rotor longitudinal axis (7) and is designed to be flowed through by a temperature control medium, a cross-sectional area of ​​the fluid channel (2) arranged orthogonally to the longitudinal extent has a first extent I1 in the circumferential direction and a second extent I2 radially to the rotor longitudinal axis (7), the housing segment (1) is limited radially outwards by an outer housing surface (3a, b) and the fluid channel (2) is limited radially outwards by an outer channel surface (4), the first extension I1 is at least 1.2 I2 and, the outer channel surface (4) has a flat profile, and the outer casing surface (3b) has a flat profile and the outer channel surface (4) and the outer housing surface (3b) are parallel to each other and wherein a lateral channel surface (6b) has, at least in sections, a variable radius of curvature, characterized by , that the radius of curvature is greatest at the transition points (8) between the inner / outer channel surface (4, 5a, b) and the lateral channel surface (6b) and that starting from these points (8) the radius of curvature (6b) becomes smaller in the further course of the lateral channel surface until it reaches a smallest radius of curvature and that the lateral channel surface (6b), at least with respect to the outer or inner channel surface, is designed according to the method of tension triangles and that the housing has several housing segments (1) and that the housing segments (1) are connected to one another by connecting areas and that the housing segments (1) and the connecting areas result in a housing which surrounds the stator, at least in sections. [2] Electromechanical energy converter according to claim 1, characterized by that the first extension I1 with respect to the second extension I2 is selected from a range for which I1 > 2 I2 and further I1 < 25 2. [3] Electromechanical energy converter according to one of the preceding claims, characterized by , that the fluid channel (2) is limited radially inwards by an inner channel surface (5b) and, that it has a flat course at least in sections and that it runs at least in sections parallel to the outer channel surface (4). [4] Electromechanical energy converter according to one of claims 1 to 3, characterized by , that the fluid channel is limited radially inwards by an inner channel surface (5a) and, that it has a curved course at least in sections. [5] Electromechanical energy converter according to one of the preceding claims, characterized by that the outer and inner channel surface (4, 5a, b) each merge tangentially into a lateral channel surface (6a, b, c) at transition points (8).

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