Laminated core and method for sealing at least one liquid channel in laminated core

Abstract

A laminated core (3) and a method for sealing at least one liquid channel (2) in the laminated core (3) are presented. In order to achieve high repeatability, it is proposed that a first liquid fluid (6) having silane is introduced into at least one liquid channel (2), the first liquid fluid (6) is held in the liquid channel (2) at a first pressure (p1) for a first holding time and subsequently discharged from the liquid channel (2), in particular by blowing out, and thereafter a second liquid fluid (8) containing at least one amino group is introduced into the at least one liquid channel (2).

Description

Technical Field

[0001] The present invention relates to a laminated iron core and a method for sealing at least one liquid channel in the laminated iron core having metal plates bonded to each other by at least one adhesive layer, particularly a hot melt adhesive varnish layer, especially in a full-surface manner, wherein the liquid channel passes through at least a plurality of the metal plates. Background Technology

[0002] Laminated iron cores (made of electrical steel strip or sheet) with interbonded metal plates are typically cooled by liquid in high-power applications to minimize heat generation caused by power loss. For this purpose, cooling liquid flows through the liquid channels in the laminated iron core, usually under relatively high pressure. For this reason, the bonded surfaces of the individual metal plates must be constructed relatively firmly to withstand hydraulic loads in order to achieve pressure resistance and leak-proofness. Laminated iron cores that do not meet these requirements are unusable and are disadvantageously considered scrap. Summary of the Invention

[0003] The objective of this invention is to provide a method for sealing the liquid channels of a laminated iron core with mutually bonded metal plates. Furthermore, the method should be quick and easy to operate.

[0004] The present invention achieves the proposed objective through the features of claim 1.

[0005] If a first liquid fluid containing silane is introduced into at least one liquid channel, held at a first pressure for a first residence time, and then discharged from the liquid channel, measures and preparations can be made to seal the liquid channel. The pressurized silane, due to its relatively low surface tension, can penetrate even the smallest gaps (e.g., crevices or gaps) between metal plates, thereby preparing it for sealing and / or sealing it. This can also reliably fill and thus repair unintended adhesion defects, such as unbonded areas, or even areas between two adhesive layers. Preferably, the first liquid fluid is discharged from at least one liquid channel by blowing, which can be achieved quickly in the process. Furthermore, blowing also protects the silane that has penetrated between the metal plates for sealing, preventing unintended backflow, for example, due to surface tension. Therefore, the silane that has penetrated into gaps, for example, due to adhesion defects, can remain more reliably at the location where sealing is required.

[0006] The sealing of the liquid channel can be further improved by introducing a second liquid fluid containing at least one amino group into at least one liquid channel in a separate step. Due to the interaction between the amino group and the silane (e.g., chemical reaction and / or pH change), a high-viscosity substance can be obtained at the defect site, which reliably induces sealing and is also relatively fast in the process.

[0007] Therefore, it can reliably prevent coolant from seeping into the area between the metal plates.

[0008] Furthermore, if necessary, the adhesion of highly viscous substances to the adhesive can be improved through further chemical reactions between the adhesive and the amino group. This is especially true when the adhesive is a hot-melt adhesive varnish (particularly a baking varnish). For example, this could be a bisphenol-based epoxy resin system with a curing agent (e.g., a dicyandiamide group).

[0009] According to the present invention, the liquid channels of laminated iron cores can be sealed repeatedly and quickly, and this can be done in a relatively simple manner.

[0010] When, for example, the first liquid fluid is a low molecular weight (especially partially hydrolyzed) silane or (especially such) silane mixed with triethylene glycol, even the smallest open space between metal plates, starting from the liquid channel, can be successfully sealed. For example, such silane can be GLYEO (3-glycidoxypropyltriethoxysilane) or AMEO (3-aminopropyltriethoxysilane).

[0011] Preferably, the second liquid fluid containing at least one amino group is urea, which can cause a relatively rapid reaction with the first liquid fluid. For example, urea can cause accelerated thickening of silanes in the first liquid fluid, which can significantly reduce the cycle time of the method.

[0012] The foregoing is more effective when the first liquid fluid is introduced into at least one liquid channel in such a way that it completely fills the liquid channel. This also does not incur additional costs, primarily because the first liquid fluid discharged during this process, after deducting the amount that seeps into the gaps between the metal plates, can be transported for reuse. The method according to the invention is therefore also relatively cost-effective.

[0013] The method can be further improved by maintaining the introduced first liquid fluid at a first pressure in the range of 1 to 10 bar. For example, the first liquid fluid can penetrate the open space to be sealed in sufficient quantity. This is further improved when the first liquid fluid is maintained at a first pressure in the range of 2 to 6 bar.

[0014] If the first liquid fluid is held at the first pressure for a first residence time in the range of 0.5 to 5 seconds, it can reliably ensure penetration into the defect location within a relatively short cycle time.

[0015] For example, in the aforementioned situation, a first dwell time within the range of 1 to 3 seconds is sufficient.

[0016] For example, by maintaining the introduced second liquid fluid in at least one liquid channel for a second residence time ranging from 0.5 seconds to 10 seconds, the viscosity grade, depending on the interaction (e.g., reaction) between the amino and silane, can be advantageously adjusted. For example, a second residence time in the range of 2 seconds to 5 seconds is sufficient for this.

[0017] Preferably, the second liquid fluid is introduced into at least one liquid channel in such a way that it completely fills the liquid channel, thereby achieving a reliable seal.

[0018] For example, the second liquid fluid is discharged from the liquid channel by means of blowing to ensure a high rhythmic frequency (Taktrate) in the method.

[0019] The repeatability of the method can be further improved, for example, by performing a pressure test on the leakage of the liquid channel after the second liquid fluid is discharged.

[0020] If the first liquid fluid and / or the second liquid fluid are introduced into at least one liquid channel of the heated laminated iron core, this can further facilitate the filling of even the smallest open spaces between the metal plates. The compressive strength of the laminated iron core can thus be further increased, for example.

[0021] The aforementioned can be further improved if the heated laminated iron core has a temperature higher than the glass transition temperature (Tg) of the hot melt adhesive and lower than the drying temperature (Verbackungstemperatur) of the hot melt adhesive.

[0022] The present invention also aims to create a laminated iron core that is configured to have better resistance to liquid leakage.

[0023] The present invention achieves the proposed objective through the features of claim 13.

[0024] Because the laminated core has silane-filled gaps between the metal plates, the liquid channels are sealed in a particularly leak-proof manner according to the invention. Furthermore, this laminated core is suitable for liquid cooling at relatively high hydraulic pressures.

[0025] The above improvements can be further enhanced if the voids are filled with high-molecular-weight silanes or high-molecular-weight silane compounds. If necessary, the laminated core can also contain urea between the metal plates.

[0026] The laminated iron core according to the present invention is particularly suitable for electric motors. Attached Figure Description

[0027] The subject matter of the invention is described in detail by way of exemplary embodiments in the accompanying drawings. Figure 1 An apparatus for performing the method according to the invention is shown. Figure 2 It shows Figure 1 Detailed sectional views, and Figure 3 This illustrates another method step in performing the method according to the invention. Figure 1 Detailed sectional view. Detailed Implementation

[0028] according to Figure 1 Device 1 is shown, which is used to seal the liquid channel 2 in the laminated iron core 3. The laminated iron core 3 consists of metal plates 4 bonded together in a full-surface manner in this embodiment. More precisely, for this purpose, an adhesive layer 5, i.e., a hot-melt adhesive layer, is provided between the metal plates 4 on their respective surfaces in a full-surface manner. The metal plates 4, made of electrical steel strip or electrical steel sheet, are connected to each other by the adhesive layer in a material-fit manner. These metal plates 4 are often also referred to as laminations.

[0029] The hot melt adhesive coating layer is a baked enamel layer (Backlackschicht). Here, the adhesive of the adhesive layer 5 can be partially cured or fully cured, which is also known as "C-state" or "dried".

[0030] Preferred hot melt adhesives that are thermosetting and thus thermoactivate can, for example, have an epoxy resin base. Preferably, the hot melt adhesive is a bisphenol-based epoxy resin system with a curing agent (e.g., having a dicyandiamide group). Specifically, the aforementioned hot melt adhesive can be a bisphenol-A-epoxychloropropane resin system with dicyandiamide as a curing agent. The glass transition temperature (Tg) of exemplary hot melt adhesives, measured according to ISO 11357-2, is in the range of 65°C to 85°C. Their drying temperature is in the range of 180°C or higher.

[0031] In addition, Figures 1 to 3At least one liquid channel 2 can be observed that completely penetrates the laminated iron core 3 and thus all the metal plates 4. In this embodiment, the liquid channel 2 extending in the laminated iron core 3 is elongated in the longitudinal direction of the laminated iron core, i.e., the axial direction. For example, a notch in the metal plates 4 of the laminated iron core 3 defines the liquid channel 2. The liquid channel 2 is used for liquid cooling of the laminated iron core, which is advantageous, for example, in high-power applications.

[0032] The bonded laminated iron core 3 underwent a sealing test. For this purpose, the laminated iron core 3 was installed in... Figure 1 In the apparatus shown, the liquid channel 2 is, for example, filled with compressed gas. If a pressure drop is detected, the liquid channel 2 is sealed by means of the device 1.

[0033] According to the invention, for this purpose, in the first step, a first liquid fluid 6, namely silane, is introduced into the liquid channel 2, more precisely, in such a way that the liquid channel 2 is completely filled, such as... Figure 1 and Figure 2 This can be observed. Preferably, GLYEO (3-glycidoxypropyltriethoxysilane) is used as the silane. This silane has low surface tension and can therefore penetrate from the liquid channel 2 and fill at least one (e.g., extremely fine) void 7 between the metal plates 4, such as... Figure 2 As can be more clearly observed in the text.

[0034] Silane that may flow from the void 7 and thus from the laminated iron core 3 can be removed, for example, by a separation method. According to Figure 2 and Figure 3 The gap 7 shown is located within the adhesive layer 5 itself. However, it could also be located between the adhesive layer 5 and the connected metal plate 4, which is not shown in detail.

[0035] The first liquid fluid 6 is held in the liquid channel 2 at a first pressure p1 for a first residence time t1, such that at least one gap 7 located between the metal plates 4 starting from the liquid channel 2 is at least partially filled by the first liquid fluid 6, as shown in the figure. The first liquid fluid 6 is then drained from the liquid channel 2 and, if necessary, can be reused to seal subsequent laminations of the iron core 3, which is not shown in detail here. This draining process is achieved by blowing from the liquid channel 2, which rapidly empties the liquid channel 2 in a process manner, but still keeps the outflow from the filled gap 7 very low or minimizes it. Therefore, after the first liquid fluid 6 is drained from the liquid channel 2, the residual portion of the first liquid fluid 6 remains more reliably in the corresponding gap 7. The first liquid fluid 6 can then react in the gap 7, for example, with the adhesive layer 5, to seal the gap 7.

[0036] Subsequently, or more precisely immediately thereafter, a second liquid fluid 8 containing at least one amino group, namely urea, is introduced into this liquid channel 2, such as... Figure 3 As shown in the diagram, the second fluid 8 interacts with the first liquid fluid 6, for example, by undergoing a chemical reaction and forming a high-viscosity substance 9, at least in the connection region between the liquid channel 2 and the void 7. It is also conceivable that the second fluid 8 alters the pH of the first liquid fluid 6, thereby further accelerating the condensation of its silanes. This creates a blockage in the region, which stably and quickly seals the liquid channel 2.

[0037] Thus, the first liquid fluid 6 can continue to react, for example, solidify, in a manner independent of the pressure applied in the liquid channel 2. This improves the seal and thereby further improves the stability of the laminated core 3 under relatively high hydraulic pressure. Furthermore, this results in a liquid channel 2 that prevents leakage of cooling liquid.

[0038] The second liquid fluid 8 is also introduced into the liquid channel 2 in a filling manner and subsequently discharged from the liquid channel 2 by blowing. It should be understood that the discharged second liquid fluid 8 is a residual portion of the introduced second liquid fluid 8, which interacts with the first liquid fluid (e.g., through chemical reactions and / or by changing the pH value).

[0039] For laminated iron cores 3 (C state) bonded by an epoxy resin-based varnish (i.e., Rembrandtin's EB549), which have a 10 µm thick cross-linked adhesive layer 5 between each metal plate 4 with a thickness of less than 0.25 mm, the following process conditions have proven advantageous: First liquid fluid: Silane GLYEO (3-glycidoxypropyltriethoxysilane) First pressure p1: 2 bar First pause time: 2 seconds Second liquid fluid: urea Second pressure p2: No additional pressure applied Second dwell time: 3 seconds.

[0040] The first liquid fluid 6 and the second liquid fluid 8 are introduced into the liquid channel 2 in such a way that they completely fill the liquid channel, and are discharged from the liquid channel 2 by means of blowing.

[0041] This completely eliminates the 5 ml / min leakage at the start of the measurement, as demonstrated by a pressure test conducted with ATF oil at a test pressure of 1.5 bar after sealing.

[0042] By performing this method on a heated laminated iron core 3, the pressure resistance can be further improved to over 20 bar. The laminated iron core 3 is heated to 90 degrees Celsius, and then steps involving a first liquid fluid 6 and a second liquid fluid 8 are performed.

[0043] The glass transition temperature (Tg) of the exemplary hot melt adhesive is in the range of 65°C to 85°C, as measured according to ISO 11357-2. Its drying temperature is in the range of 180°C or higher.

[0044] according to Figure 1 The device 1 shown is placed on the end side of the laminated iron core 3 by two plates 10a and 10b, which are tensioned together by multiple tensioning elements, namely bolted connections 11. The plates 10a and 10b carry connectors 12 for introducing the first liquid fluid 6 and the second liquid fluid 8 into the corresponding liquid channels 2 of the laminated iron core 3.

[0045] Preferably, the void 7, which exists within the adhesive layer 5 itself and / or between the adhesive layer 5 and the connected metal plate 4, is sealed by the present invention. Therefore, the laminated core 3 contains silane or silane compounds between the metal plates 4, and urea if necessary, more precisely, the aforementioned substances are present in the void 7 within the adhesive layer 5 itself and / or in the void 7 between the adhesive layer 5 and the connected metal plate 4. This can be a high molecular weight silane or high molecular weight silane compound, such as a condensed silane.

[0046] Generally, "particularly" can be translated as "more particularly" in English. Features preceded by "particularly" are considered optional features that can be omitted and do not impose limitations, such as on claims. The same applies to "preferably," which is translated as "preferably" in English.

Claims

1. A method for sealing at least one liquid channel (2) in a laminated iron core (3), the laminated iron core having metal plates (4) bonded together by at least one adhesive layer (5), particularly, the adhesive layer being a hot-melt adhesive paint layer, particularly, the metal plates being bonded together by at least one adhesive layer in a full-surface manner, wherein, The liquid channel (2) penetrates at least one of the metal plates in the metal plate (4), in the method: A first liquid fluid (6) containing silane is introduced into the at least one liquid channel (2). The first liquid fluid (6) is held in the liquid channel (2) at a first pressure (p1) for a first residence time, after which the first liquid fluid is discharged from the liquid channel (2), specifically by blowing the first liquid fluid out of the liquid channel, and subsequently... A second liquid fluid (8) containing at least one amino group is introduced into the at least one liquid channel (2).

2. The method according to claim 1, characterized in that, The first liquid fluid (6) is a low molecular weight silane or a mixture of silane and triethylene glycol. In particular, the first liquid fluid is a mixture of low molecular weight silane and triethylene glycol. In particular, the low molecular weight silane is a partially hydrolyzed silane.

3. The method according to claim 1 or 2, characterized in that, The second liquid fluid (8) containing at least one amino group is urea.

4. The method according to any one of claims 1 to 3, characterized in that, The first liquid fluid (6) is introduced into the at least one liquid channel (2) in such a way that it completely fills the at least one fluid channel (2).

5. The method according to any one of claims 1 to 4, characterized in that, The first liquid fluid (6) introduced is held at a first pressure (p1) in the range of 1 bar to 10 bar, and in particular, the first liquid fluid introduced is held at a first pressure in the range of 2 bar to 6 bar.

6. The method according to any one of claims 1 to 5, characterized in that, The first liquid fluid (6) introduced is kept in the liquid channel (2) at a first pressure (p1) in the range of 1 bar to 10 bar for a first residence time. In particular, the first liquid fluid introduced is kept in the liquid channel at a first pressure in the range of 2 bar to 6 bar for a first residence time.

7. The method according to any one of claims 1 to 6, characterized in that, The first liquid fluid (6) introduced is held at a first pressure (p1) for a first residence time ranging from 0.5 seconds to 5 seconds. In particular, the first liquid fluid introduced is held at a first pressure (p1) for a first residence time ranging from 1 second to 3 seconds.

8. The method according to any one of claims 1 to 7, characterized in that, The introduced second liquid fluid (8) is kept in the at least one liquid channel (2) for a second residence time ranging from 0.5 seconds to 10 seconds, and in particular, the introduced second liquid fluid is kept in the at least one liquid channel (2) for a second residence time ranging from 2 seconds to 5 seconds.

9. The method according to any one of claims 1 to 8, characterized in that, The second liquid fluid (8) is introduced into the at least one liquid channel in such a way that it completely fills the at least one fluid channel (2) and / or the second liquid fluid (8) is discharged from the at least one liquid channel (2), in particular, the second liquid fluid is discharged from the at least one liquid channel by blowing.

10. The method according to any one of claims 1 to 9, characterized in that, After the second liquid fluid (8) is discharged, a pressure test is performed on the leakage of the liquid channel (2).

11. The method according to any one of claims 1 to 10, characterized in that, The first liquid fluid (6) and / or the second liquid fluid (8) are introduced into at least one liquid channel (2) of the heated laminated iron core (3).

12. The method according to claim 11, characterized in that, The temperature of the heated laminated iron core (3) is greater than the glass transition temperature (Tg) of the hot melt adhesive and less than the drying temperature of the hot melt adhesive.

13. A laminated iron core, particularly, said laminated iron core being sealed by the method according to any one of claims 1 to 12, said laminated iron core having metal plates (4) bonded together by an adhesive layer (5) and at least one liquid channel (2) penetrating at least one of the metal plates (4) of said laminated iron core (3), particularly, said metal plates being bonded together by a hot-melt adhesive paint layer, wherein, The laminated iron core (3) has gaps (7) filled with silane between the metal plates (4).

14. The laminated iron core according to claim 13, characterized in that, The voids (7) are filled with high molecular weight silanes or high molecular weight silane compounds.

15. An electric motor having a laminated iron core according to claim 13 or 14.

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