Method of manufacturing gap tube for electric machine

Abstract

The invention relates to a method for producing a spacer tube (1) for an electric machine, in particular for an electric machine of a motor vehicle, which spacer tube (1) can be arranged or is arranged in a base body opening of a stator base body of the electric machine, said spacer tube (1) separating a stator chamber and a rotor chamber of the electric machine in the state of being mounted in the base body opening, according to the invention, at least one structural layer (2), in particular a laid article or a woven fabric, is provided which has a plurality of structural elements (3), the structural elements (3) of which are connected to at least one connecting element (4), in particular a sewing thread, the at least one structural layer (2) being arranged on a core and impregnated and hardened with a matrix material (5), the at least two structural elements (3) of the at least one structural layer (2) are connected to a connecting element (4) designed as a multifilament.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a gap tube for an electric motor, particularly an electric motor for a motor vehicle. The gap tube may be arranged or disposed in a base opening of the stator base of the motor, wherein the gap tube, when installed in the base opening, separates the stator cavity and the rotor cavity of the motor. The method includes at least one structural layer, particularly a fabric or woven material, having a plurality of structural elements connected to at least one connecting element, particularly a sewing thread. The at least one structural layer is disposed on a core and impregnated and hardened with a matrix material. Background Technology

[0002] Methods for manufacturing gap tubes for electric motors (e.g., motors for motor vehicles) are substantially known from existing technology. Such gap tubes are arranged within an opening in the stator matrix of the motor, thereby spatially separating the rotor cavity (in which the rotor is rotatably supported) from the stator cavity (in which the stator matrix is ​​arranged). Specifically, this separation prevents different fluids (e.g., oil) in the stator and rotor cavities from mixing, and particularly prevents liquid from one cavity from seeping into the other.

[0003] A known method for manufacturing such gap tubes is the so-called "RTM" (Resin Transfer Molding) process, in which one or more structural layers (e.g., a covering made of fabric or fabric) are impregnated in a mold having a matrix material (particularly resin), which is then cured at a controlled temperature. The described structural layers are laid on a core that ultimately defines the inner radius or inner surface of the gap tube. To enable the structural layers to be processed in the process, these layers are interconnected by connecting elements (particularly sewing thread).

[0004] Such sewing threads can be made of thermoplastic materials. This causes the matrix material to behave differently in the areas of the sewing thread than it does in the areas of the structural elements within the structural layer. In particular, the bond between the matrix material and the sewing thread may weaken or be lost entirely, for example, due to insufficient adhesion, shrinkage, or different thermal expansion, potentially leading to cracks, channels, or channel segments along the sewing thread. Since the sewing thread extends through the structural layer at different locations, in the worst case, the individual channels formed due to the separation between the matrix material and the sewing thread may interconnect, making it impossible to reliably prevent conductive connections between the external and internal spaces of the gap tube.

[0005] However, since the structural layers need to be processed, it is impossible to omit the aforementioned connecting elements, or more precisely, the sewing threads, because the various structural elements of the structural layers are interconnected by the sewing threads, and only in this way can they be processed as “layers”, especially by applying the structural layers to the core in the form of rolling or winding processes. Summary of the Invention

[0006] The object of the present invention is to provide an improved method for manufacturing a gap tube for an electric motor, in which the weakening of the gap tube due to connecting elements is prevented.

[0007] This objective is achieved by a method having the features described in claim 1. The preferred design is the subject of the dependent claims.

[0008] As described, the present invention relates to a method for manufacturing a gap tube for an electric motor, particularly an electric motor for a motor vehicle. The gap tube itself is formed of at least one or more structural layers, which are applied, for example, to a core and impregnated with a matrix material. The matrix material can then be hardened to form the gap tube. Thereafter, the gap tube can be demolded from the described core and inserted into a base opening in the stator matrix of the motor, i.e., disposed there, to form an assembly for the motor.

[0009] In the assembled state where the gap tube is arranged in the base opening, the gap tube separates the stator cavity and the rotor cavity of the motor. In order to process the structural layer according to the described process, and in particular to lay the individual structural elements of the structural layer form on the core, these structural elements need to be connected to each other, that is, connected by the described connecting elements or multiple connecting elements (especially sewing threads).

[0010] The present invention is based on the understanding that at least two structural elements of at least one structural layer are connected to a connecting element constructed as multifilament. In particular, by using multifilament instead of monofilament to form the connecting element, the disadvantages of the sewing thread used above as described with reference to the prior art are overcome. "Multifilament" is specifically understood as a connecting element or sewing thread composed of multiple single-thread or single-fiber elements, that is, the total cross-section of the multifilament is composed of the cross-sections of the single-fiber elements or the individual cross-sections of the individual fiber elements.

[0011] Therefore, multifilaments can be understood as bundles composed of single fiber elements or individual fiber elements. This offers numerous advantages over the previously described problem of channel formation, which will be described in detail below. In particular, it significantly reduces the tendency to form channels, and even if channels are formed, the size and length of each channel can be significantly reduced, thus preventing the formation of large channels extending parallel to the connecting elements within the matrix material. These channels might interconnect and, in the worst case, establish conductive connections between the external and internal spaces of the gap tube. Instead, channels or cracks are not formed, or at most, smaller channels or cracks that are not interconnected are formed.

[0012] Regarding the selection of materials for multifilaments, there is, in principle, considerable freedom; therefore, any fiber element or material suitable for connecting structural elements in the structural layers can generally be used. For example, the single fiber element of a multifilament can be made of or have thermoplastic properties. Additionally or alternatively, the single fiber element of a multifilament can be made of, or have, glass fiber, aramid fiber, bio-fiber, or other fibers.

[0013] In an improved version of the method, it can be proposed that the total cross-section of at least one connecting element is formed by the individual cross-sections of the single-fiber elements forming the connecting element. As previously described, the connecting element constructed as a multifilament has multiple single-fiber elements, each having a cross-section, more precisely, a fiber cross-section. Therefore, the total cross-section of the connecting element is composed of the individual cross-sections, more precisely, fiber cross-sections of the single-fiber elements, which are arranged in a “bundle” and thus form the connecting element. In other words, instead of individual relatively thick connecting elements, the “bundle” can be formed by relatively thinner single-fiber elements, which provide a comparable overall diameter to the monofilament but each has a significantly smaller diameter.

[0014] For example, the total cross-section of the connecting elements as multifilaments can be comparable to the diameter of a commonly used monofilament, where the individual cross-sections of the single-fiber elements are significantly smaller, and only their sum is comparable to the total cross-section. As described, since the size of the single-fiber elements is already significantly smaller than that of a commonly used monofilament, the effect between the matrix material and the connecting elements is significantly reduced. This also results in the formation of channels, but the corresponding channel sizes are significantly smaller, particularly in terms of smaller diameter and shorter length, thus significantly reducing or even completely eliminating the weakening of the structural layers.

[0015] Furthermore, the aforementioned method can be proposed to form receiving spaces for matrix material between the single fiber elements of at least one connecting element. As described, the structural layer, together with the connecting elements that hold the structural elements of the structural layer together, is applied to the core and subsequently impregnated with the matrix material. By forming receiving spaces for matrix material "inside" the connecting element, i.e., between the single fiber elements, the matrix material can also penetrate into the connecting element, rather than simply wrapping the connecting element externally.

[0016] This significantly improves the connection between the matrix material and the connecting elements. Viewing the connecting elements as bundles of single-fiber elements, the matrix material can thus surround each single-fiber element, and also penetrate into the intermediate spaces between the single-fiber elements, also known as "reception spaces." Therefore, each individual single-fiber element can be surrounded by the matrix material, thus significantly enhancing the connection with the matrix material. This results in a significantly larger cross-section surrounded by the matrix material in the multifilament, and a significantly better distribution of the matrix material relative to the connecting elements. Even if channel formation occurs, it extends over a significantly smaller area and, if possible, a significantly shorter length compared to monofilaments.

[0017] As previously stated, at least one connecting element is composed of or comprises such a multifilament, i.e., multiple single-fiber elements. In an improved embodiment of the method, it may be proposed that at least one connecting element defines a longitudinal direction, wherein at least one single-fiber element, and in particular all single-fiber elements, are arranged at least partially along an orientation deviating from this longitudinal direction. Therefore, in this design, it is proposed that the connecting element as a whole, i.e., the multifilament, defines the longitudinal direction, i.e., along its longitudinal axis or longitudinal central axis.

[0018] The single-fiber elements forming the connecting element are also generally oriented along the longitudinal axis, but their orientation changes due to their arrangement relative to other single-fiber elements. For example, the single-fiber elements do not extend straight and parallel to the longitudinal axis, but rather extend in an orientation that changes along the longitudinal direction. However, in principle, the single-fiber elements can also be oriented parallel to each other along the entire length of the connecting element, and thus, in the current design, they are proposed to have a defined interlacing pattern or entangled structure. For example, the single-fiber elements can be twisted, interlaced, or "twisted" to form the connecting element, thereby changing their position relative to the entire longitudinal axis of the connecting element along its length.

[0019] Therefore, compared to the cross-section at the second position along the length of the connecting element, the position of the single-fiber element changes in the cross-section at the first position along the length of the connecting element. For example, the position of the single-fiber element relative to the center point of the cross-section of the connecting element can be examined, where these positions can vary orderly or randomly, thus forming twisted, coiled, or interwoven portions, deviating from the purely parallel orientation of the single-fiber elements. This also allows for the prevention or blocking of the formation of channels or cracks, even if cracks or channels appear. If mutually twisted or interwoven single-fiber elements meet, cracks or channels can be blocked at that location, thus preventing the formation of continuous channels. Furthermore, in this region, the disordered or interwoven arrangement of the single-fiber elements significantly increases the flow resistance of the liquid, especially compared to a purely parallel arrangement of single-fiber elements or a larger, continuous channel.

[0020] Furthermore, the described method may also propose that at least one connecting element is connected to at least two structural elements by a defined connection type, wherein the connection type can prevent cracks in the matrix material along at least one single-fiber element. Within the scope of this application, the term "connection type" refers to, as is commonly done in the prior art, the arrangement of connecting elements within a structural layer for connecting the individual connecting elements to each other. By selecting the defined connection type, it can be ensured that the single-fiber elements are arranged such that cracks or channels formed along the single-fiber elements can be interrupted as quickly as possible by single-fiber elements with orientations different from those of the aforementioned single-fiber elements.

[0021] As previously stated, the defined type of connection used to establish a connection between a connecting element and at least two structural elements influences the tendency for crack or channel formation. Within the scope of this application, "crack" or "channel" is essentially understood as a weakening of the connection between the connecting element and the matrix material, such as separation of the matrix material from the connecting element. Therefore, these terms are interchangeable, and the description can be used accordingly.

[0022] Specifically, this method may propose that at least one connecting element is connected to at least two structural elements via a chain connection or a braided connection. In a chain connection embodiment, one or more connecting elements each form a chain, the links of which are laid around the structural element (i.e., the reinforcing fibers in the structural layer). This forms continuous connecting elements surrounding the structural element. In other words, a braid or a link can pass through successive braids or links. The braids and / or links can be interconnected. In the case of a braided connection, a zigzag arrangement of the connecting elements can be particularly achieved. In both cases, the connection type can reduce the tendency for crack formation or achieve a crack-blocking effect.

[0023] As described above with reference to the preceding embodiments, the single-fiber element can, in principle, be arbitrarily oriented or arranged within at least one connecting element, and its orientation and arrangement can also be varied along the length of the connecting element. In another embodiment of the method, the single-fiber element of at least one connecting element is twisted in the circumferential direction. In other words, the connecting element itself can be twisted or torsioned about its longitudinal axis, wherein the single-fiber element forming the connecting element is thus arranged in a twisted manner in the circumferential direction. For example, the single-fiber element can be formed into a helix about the longitudinal axis. Due to the twisted or torsioned arrangement of the single-fiber element, an undercut for the matrix material (e.g., resin) is formed on the surface of the connecting element, thereby improving the connection between the matrix material and the connecting element.

[0024] In addition to this method, the present invention also relates to a gap tube for an electric motor, which is manufactured, in particular, by the aforementioned method. The gap tube can be arranged or placed in a base opening of the stator base of the electric motor, wherein the gap tube, when installed in the base opening, separates the stator cavity and the rotor cavity of the electric motor. The gap tube has at least one structural layer, particularly a fabric or lining, having a plurality of structural elements connected to at least one connecting element, particularly a sewing thread. The at least one structural layer is impregnated and hardened with a matrix material, and at least two structural elements of the at least one structural layer are connected to a connecting element configured as multifilament.

[0025] Furthermore, the present invention also relates to an electric motor including the aforementioned clearance tube. Furthermore, the present invention also relates to a motor vehicle including such an electric motor and / or the aforementioned clearance tube. Attached Figure Description

[0026] The present invention will now be explained with reference to the accompanying drawings and embodiments. The drawings are schematic diagrams and:

[0027] Figure 1 This is a schematic diagram of the structural layers of the gap tube.

[0028] Figure 2 This is a schematic cross-sectional view of the first axial position of the connecting element;

[0029] Figure 3 This is a schematic cross-sectional view of the connecting element at the second axial position; and

[0030] Figure 4 A schematic diagram of a part of a connecting element. Detailed Implementation

[0031] Figure 1 A schematic portion of the gap tube 1, particularly the structural layer 2, is shown, which has an exemplary plurality of structural elements 3. The structural layer 2 may, for example, be a layer composed of specific fibrous elements, wherein the structural elements 3 can be understood as individual fibers, such as glass fibers or aramid fibers. To ensure reliable handling of the structural layer 2 during the manufacture of the gap tube 1, the structural elements 3 are interconnected by connecting elements 4. Figure 1 The views shown should be understood as illustrative only, as the number and arrangement of structural elements 3 can be arbitrarily changed. In particular, multiple structural elements 3 can also be interconnected by connecting elements 4, for example, in pairs or groups, instead of as shown. Figure 1 The knots are braided separately as shown.

[0032] Figure 1A so-called chain connection is shown purely by example, in which connecting elements 4 form a chain composed of individual "links" or "knots" arranged around one or more structural elements 3 and fixed in place within the structural layer 2. This allows the structural layer 2 to be processed in the process, for example, laid onto a core (not shown in detail) and subsequently impregnated with a matrix material. The individual structural elements 3 are held in place by the connecting elements 4, which can also be called "sewing thread," i.e., the structural layer 2 is held together, thus allowing the structural layer 2 to be treated as a covering layer, especially without disintegration. In addition to the chain connection shown, any other type of connection, such as a braided connection, can be implemented.

[0033] At least one of the connecting elements 4 is provided or designed as multifilament. In particular, all connecting elements 4 are designed as multifilament. Figure 2 and Figure 3 The diagram shows one state of the gap tube 1 in which the structural layer 2, having structural elements 3 and connecting elements 4, is impregnated with a matrix material 5. Figure 2 and Figure 3 The state shown can represent, for example, a hardened state.

[0034] Figure 2 and Figure 3 For example, a detailed view is shown along the connecting element 4 in structural layer 2, that is, in Figure 2 and Figure 3 In the drawing, the longitudinal axis of the connecting element 4 points inward into the drawing plane or outward from the drawing plane. It can be seen that the connecting element 4 is designed as a multifilament, that is, the connecting element 4 has multiple single fiber elements 6.

[0035] For example only, Figure 2 and Figure 3 The four single-fiber elements in single-fiber element 6 are labeled with numbers, which can be seen, for example, in the first axial position shown. Figure 2 The cross-section shown and, for example, the second axial position shown Figure 3 In the cross-section shown, the single-fiber element 6 changes its position. Therefore, along the longitudinal direction of the connecting element 4, the single-fiber element 6 does not merely extend parallel, but rather the single-fiber element can change its radial position, for example, relative to the center point or central axis of the connecting element 4, or more precisely, the longitudinal axis.

[0036] Specifically, the monofiber elements 6 are interwoven, entangled, or twisted. In this case, the arrangement of the monofiber elements 6 can provide a defined interweaving or an arbitrarily arranged entangled structure. Advantageously, on the one hand, since the diameter of the monofiber element 6 is significantly smaller than that of a single monofilament, the weakening of the connection between the matrix material 5 and the connecting element 4 is significantly less, and even if cracks or channels are formed, they are limited to the corresponding monofiber element 6, thereby achieving a crack-blocking effect, which is particularly enhanced by interweaving or entanglement with other individual monofiber elements 6.

[0037] By providing the connecting element 4 as a multifilament, the following advantage is also obtained: receiving spaces 7 are formed between the monofilament elements 6, into which the matrix material 5 penetrates during impregnation. Compared to multifilaments with a significantly larger diameter (e.g., comparable to the diameter of the entire cross-section of the connecting element 4), a significantly enlarged connection is achieved between the matrix material 5 and the connecting element 4. In other words, each monofilament element 6 is individually surrounded by the matrix material 5, thus significantly increasing the contact area between the matrix material 5 and the connecting element 4 compared to monofilaments that only contact the matrix material 5 at their outer periphery.

[0038] Figure 4 A schematic diagram of connecting element 4 is shown. Figure 4 The connecting element 4 shown is only exemplarily twisted about its longitudinal direction, such that, for example, in Figure 2 and Figure 3 The monofiber element 6 shown is twisted in the circumferential direction about the longitudinal direction or longitudinal axis of the connecting element 4. The monofiber element 6 forms, for example, a spiral around the longitudinal axis of the connecting element 4. This forms an undercut portion 8 or a gathering portion, for example, in the form of a braid, into which the matrix material 5 can penetrate, and thus significantly improves the connection between the matrix material 5 and the connecting element 4 compared to the generally cylindrical design of a monofilament. In other words, a form-fit connection is formed between the matrix material 5 and the connecting element 4 through the undercut portion 8, which further improves the closure and positioning of the connecting element 4 within the structural layer 2.

[0039] The gap tube 1 shown can be manufactured as a component of an assembly for an electric motor (particularly an electric motor for motor vehicles). As previously described, at least one structural layer 2 can be applied to the core and impregnated with a matrix material 5. The matrix material 5 can then be hardened to form the gap tube 1. Afterward, the gap tube 1 can be demolded from the core and introduced into a matrix opening in the stator matrix. In its assembled state in the matrix opening, the gap tube 1 separates the stator cavity from the rotor cavity in the motor in a manner known per se, preventing liquids (e.g., coolant) from seeping from the rotor cavity into the stator cavity, and vice versa.

[0040] Therefore, the foregoing description of the method for manufacturing the clearance tube 1 can be fully applied to the clearance tube 1, the electric motor, and the motor vehicle. In principle, the advantages, details, and features shown in the figures can be arbitrarily combined, interchanged, and transferred to each other. List of reference numerals in the attached diagram: 1. Gap tube 2 Structural Layer 3 Structural Components 4 Connecting elements 5. Matrix Materials 6 Single-fiber elements 7. Acceptance Space 8. Undercut.

Claims

1. A method for manufacturing a gap tube (1) for an electric motor, particularly an electric motor for a motor vehicle, said gap tube (1) being arable or disposed in a base opening of the stator base of the electric motor, wherein, The gap tube (1) separates the stator cavity and rotor cavity of the motor when installed in the opening of the base, wherein at least one structural layer (2), particularly a covering or fabric, is provided, the at least one structural layer having a plurality of structural elements (3), the structural elements (3) of the structural layer being connected to at least one connecting element (4), particularly a sewing thread, wherein the at least one structural layer (2) is arranged on the core and impregnated and hardened with a matrix material (5), characterized in that at least two structural elements (3) of the at least one structural layer (2) are connected to a connecting element (4) constructed of multifilament.

2. The method according to claim 1, characterized in that, The total cross-section of the at least one connecting element (4) is formed by the individual cross-sections of the single fiber element (6) forming the connecting element (4).

3. The method according to claim 1 or 2, characterized in that, A receiving space (7) for the matrix material (5) is formed between the single fiber elements (6) of the at least one connecting element (4).

4. The method according to any one of the preceding claims, characterized in that, The at least one connecting element (4) defines a longitudinal direction, wherein at least one single fiber element (6), in particular all single fiber elements (6), are arranged at least partially along an orientation deviating from the longitudinal direction.

5. The method according to any one of the preceding claims, characterized in that, The at least one connecting element (4) is connected to at least two structural elements (3) by a defined connection type, wherein the connection type is capable of preventing cracks in the matrix material (5) along at least one single fiber element (6).

6. The method according to any one of the preceding claims, characterized in that, The at least one connecting element (4) is connected to the at least two structural elements (3) by a chain connection or a braided connection.

7. The method according to any one of the preceding claims, characterized in that, The single fiber element (6) of the at least one connecting element (4) is twisted in the circumferential direction.

8. A gap tube (1) for an electric motor, said gap tube being manufactured, in particular, by the method according to any one of the preceding claims, said gap tube (1) being arranged or disposed in a base opening of the stator base of the electric motor, wherein, The gap tube (1) separates the stator cavity and rotor cavity of the motor when installed in the opening of the base, wherein the gap tube (1) has at least one structural layer (2), particularly a fabric or woven material, the at least one structural layer having a plurality of structural elements (3), the structural elements (3) of the structural layer being connected to at least one connecting element (4), particularly a sewing thread, wherein the at least one structural layer (2) is impregnated and hardened with a matrix material (5), characterized in that at least two structural elements (3) of the at least one structural layer (2) are connected to a connecting element (4) constructed of multifilament.

9. An electric motor, said electric motor comprising the gap tube (1) according to the preceding claim.

10. A motor vehicle, the motor vehicle comprising the motor according to the preceding claim and / or the gap tube (1) according to claim 8.

Images