METHOD FOR PRODUCING A COOLING DEVICE

Abstract

The invention relates to a method for producing a cooling device (10), which has at least one hollow body (30) made of a first material having good thermal conduction and a base body made of a second material having good thermal conduction, and a pre-product for the production of a cooling device (10) and a cooling device (10) for an electrical assembly and an electrical assembly having a cooling device of this kind. The hollow body (30) is coated on the outside with a third material and is filled on the inside with the third material, which has a lower melting temperature than the first material and the second material, wherein the filling (5) completely fills the hollow body and is then cooled, wherein the filled hollow body (30) is placed in a die-casting mould, wherein the second material is introduced into the die-casting mould as die casting with a first temperature and flows around the hollow body (30) at least partially, wherein the die casting melts off the third material of the surface coating (36) and melts on the first material of the hollow body (30) so that at least in regions an integral connection is formed between the die casting of the second material, which forms the base body (20), and the first material of the hollow body (30), wherein the die casting of the second material becomes rigid and solid, wherein during the solidification phase, the die casting of the second material heats the filling (5) made of the third material in the interior of the hollow body (30) until the melting temperature is reached, and wherein the melted third material is removed from the hollow body (30) under pressure.

Claims

1. A method (1) for producing a cooling apparatus (10) comprising at least one hollow body (30) made of a first material having good thermal conductivity and a base body (20) made of a second material having good thermal conductivity, the method comprising coating the outside of the hollow body (30) is coated with a third material to provide a surface coating (36) of the third material, filling the inside of the hollow body with the third material to provide a filled hollow body (30) with a filling (5) of the third material, which has a lower melting temperature than the first and second materials, subsequently cooling the filling (5), subsequently putting the filled hollow body (30) into a die casting mold, subsequently introducing the second material as a die casting at a first temperature into the die casting mold, wherein the second material flows around the hollow body (30) at least in part, and wherein the die casting melts away the third material of the surface coating (36) and melts onto the first material of the hollow body (30), so that a material bond between the die casting of the second material, forming the base body (20), and the first material of the hollow body (30) is obtained at least in regions, wherein the die casting of the second material sets and becomes solid during a setting phase, wherein during the setting phase the die casting of the second material heats the filling (5) made of the third material inside the hollow body (30) until the filling (5) reaches the melting temperature and becomes molten third material, and removing the molten third material from the hollow body (30) under pressure.

2. The method (1) as claimed in claim 1, characterized in that the first material of the hollow body (30) and/or the second material of the base body (20) is aluminum or an aluminum alloy and the third material of the surface coating (36) of the hollow body (30) is zinc or a zinc alloy or tin or a tin alloy.

3. The method (1) as claimed in claim 1, characterized in that the hollow body (30) is treated using a zincate method before coating and filling.

4. The method (1) as claimed in claim 1, characterized in that the hollow body (30) is coated and filled with the third material in a coating bath (9).

5. The method (1) as claimed in claim 1, characterized in that the filled and cooled hollow body (30) is bent and cut into a desired shape.

6. The method (1) as claimed in claim 1, characterized in that during the setting phase the temperature of the filling (5) is ascertained at ends of the hollow body (30).

7. The method (1) as claimed in claim 6, characterized in that pressure to remove the filling (5) is applied to the hollow body (30) when the temperature of the filling (5) reaches and/or exceeds a prescribed threshold value.

8. A precursor (3) for producing a cooling apparatus (10), having a tubular hollow body (30) made of a first material having good thermal conductivity, characterized in that the hollow body (30) in an unbent state has a surface coating (36) on an outside (34) of the hollow body and a filling (5) made of a third material which has good thermal conductivity and which has a lower melting point than the first material, wherein the filling (5) fills the hollow body (30) completely.

9. The precursor (3) as claimed in claim 8, characterized in that the coated and filled tubular hollow body (30) is configured to be bent and cut to length into a desired shape.

10. A cooling apparatus (10) for an electrical assembly, having at least one hollow body (30) made of a first material having good thermal conductivity that is embedded in a base body (20) made of a second material having good thermal conductivity, characterized in that a material bond is formed, at least in regions, between the first material of the at least one hollow body (30) and the second material of the base body (20) on an outside (34) of the at least one hollow body (30), wherein the hollow body (30) has, on an inside (32), a surface coating (36) made of a third material having good thermal conductivity, which has a lower melting temperature than the first material of the hollow body (30) and the second material of the base body (20).

11. The cooling apparatus (10) as claimed in claim 10, characterized in that the first material is aluminum or an aluminum alloy.

12. The cooling apparatus (10) as claimed in claim 10, characterized in that the second material is aluminum or an aluminum alloy.

13. The cooling apparatus (10) as claimed in claim 10, characterized in that the third material is zinc or a zinc alloy or tin or a tin alloy.

14. An electrical assembly having at least one electrical power subassembly and a cooling apparatus (10) that cools the at least one electrical power subassembly, characterized in that the cooling apparatus (10) is embodied as claimed in claim 10.

15. The electrical assembly as claimed in claim 14, characterized in that the cooling apparatus (10) is integrated in a housing of the electrical assembly and/or forms a baseplate of the electrical assembly.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] FIG. 1 shows a longitudinal sectional depiction of an exemplary embodiment of a cooling apparatus according to the invention for an electrical assembly.

[0020] FIG. 2 shows a cross sectional depiction of the exemplary embodiment of a cooling apparatus according to the invention for an electrical assembly from FIG. 1.

[0021] FIG. 3 shows a schematic flow chart for an exemplary embodiment of a method according to the invention for producing a cooling apparatus.

[0022] FIG. 4 shows a schematic depiction of a coating bath with an exemplary embodiment of a precursor according to the invention for producing a cooling apparatus.

[0023] FIG. 5 shows a graph of characteristic curves that depicts a first characteristic curve having the temperature characteristic of a die casting and a second characteristic curve having the temperature characteristic of a filling of a hollow body during the production of a cooling apparatus according to the invention for an electrical assembly.

DETAILED DESCRIPTION

[0024] As can be seen from FIGS. 1 and 2, the depicted exemplary embodiment of a cooling apparatus 10 for an electrical assembly has at least one hollow body 30 made of a first material having good thermal conductivity, which is embedded in a base body 20 made of a second material having good thermal conductivity. In this case, a material bond is formed, at least in regions, between the first material of the at least one hollow body 30 and the second material of the base body 20 on the outside 34 of the at least one hollow body 30. Also, the hollow body 30 has a surface coating 36 on its inside 32, made of a third material having good thermal conductivity, which has a lower melting temperature than the first material of the hollow body 30 having good thermal conductivity and the second material of the base body 20 having good thermal conductivity.

[0025] In the depicted exemplary embodiment of the cooling apparatus 10, the first material of the hollow body 30 is a wrought aluminum alloy and the second material of the base body 20 is an aluminum die casting. The third material of the surface coating 36 of the hollow body 30 is zinc in the depicted exemplary embodiment. It goes without saying that other material combinations are also conceivable, for example the hollow body 30 can also be manufactured from copper or a copper alloy or another suitable metal having good thermal conductivity or a metal alloy, for example. The surface coating 36 of the hollow body 30 can also be a zinc alloy or tin or a tin alloy, for example. In the depicted exemplary embodiment, the hollow body 30 is in the form of a meanderously bent pipe having a round cross section. It goes without saying that the hollow body 30 can also have other shapes and cross sections and be embodied as a pipe bent in a U-shape having a square cross section, for example.

[0026] Preferably, exemplary embodiments of the cooling apparatus 10 according to the invention for cooling at least one electrical power subassembly are used in an electrical assembly, not depicted in more detail, embodied as a control unit, for example. As such, the cooling apparatus 10 can be used as a baseplate of the electrical assembly and/or as part of a housing of the control unit, for example. This baseplate or the housing part can then have the power subassemblies to be cooled arranged on it. In this case, the cooling apparatus 10 can be used as a gas cooler, in the case of which a gas is routed through the hollow body 30 to remove heat, or as a liquid cooler, in the case of which a liquid is routed through the hollow body 30 to remove heat.

[0027] As can be seen from FIGS. 3 and 4, the depicted exemplary embodiment of a method 1 according to the invention for producing a cooling apparatus 10 comprising at least one hollow body 30 made of a first material having good thermal conductivity and a base body 20 made of a second material having good thermal conductivity comprises the following steps:

[0028] In a step S100, the outside of the hollow body 30 is coated with a third material and the inside of said hollow body is filled with the third material, which has a lower melting temperature than the first material of the hollow body 30 and the second material of the base body 20. The filling 5 fills the hollow body 30. Subsequently, the filled hollow body is cooled in step S110 and the filled hollow body 30 is put into a die casting mold in step S120. In a step S130, the second material is put into the die casting mold as a die casting at a first temperature and flows around the hollow body 30 at least in part. In this case, the die casting melts away the third material of the surface coating 36 and onto the first material of the hollow body 30, so that a material bond between the die casting of the second material, forming the base body 20, and the first material of the hollow body 30 is obtained at least in regions. In step S140, the die casting of the second material sets and becomes solid, wherein the die casting of the second material heats the filling 5 made of the third material inside the hollow body 30 during the setting phase in step S140 until it reaches the melting temperature. In step S150, the molten third material is removed from the hollow body 30 under pressure.

[0029] In the depicted exemplary embodiment of the method 1 according to the invention, the first material used for the hollow body 30 and the second material used for the base body 20 is aluminum or an aluminum alloy. The third material used for the surface coating 36 and filling 5 of the hollow body 30 is zinc or a zinc alloy. It goes without saying that other material combinations are also conceivable, for example the hollow body 30 can also be manufactured from copper or a copper alloy or another suitable metal having good thermal conductivity or a metal alloy. The surface coating 36 of the hollow body 30 can also be tin or a tin alloy, for example.

[0030] As can also be seen from FIG. 3, the hollow body 30 can be treated using a zincate method in an optional step S50, depicted in dashes, before the coating and filling, in order to remove an oxide layer on the surface of the hollow body 30.

[0031] As can also be seen from FIG. 4, the hollow bodies 30 as a precursor 3 in unbent form having a length of approximately 6 m are coated and completely filled with the third material in a coating bath 9 in step S100 after the zincate method in step S50. As can be seen from FIG. 4, the hollow body 30 is dipped into the coating bath 9 at an angle and maintains this position during coating and filling, so that the hollow body 30 can be filled with the third material, in this case zinc, completely and air 7 can escape from the hollow body 30. When lifting the hollow body 30 out of the coating bath 9, the end of the hollow body 30 situated at the bottom is closed to produce a seal. In this state, the hollow body 30 is cooled, so that the third material in the still liquid state cannot flow out.

[0032] As can also be seen from FIG. 3, the filled and cooled hollow body 30 or the precursor 3 can be bent and cut into a desired shape in an optional step S115, depicted in dashes. The filling 5 increases the robustness of the hollow body 30 during the bending process or the mechanical working already.

[0033] In order to detect an optimum time window for removing the filling 5 from the hollow body 30, the temperature of the filling 5 can be ascertained at the ends of the hollow body 30 during the setting phase in step S140. In step S150, the pressure for removing the filling 5 can then be applied to the hollow body 30 when the temperature of the filling 5 reaches and/or exceeds a prescribed threshold value. The prescribed temperature threshold value can be chosen in this case such that the third material of the filling 5 has exceeded its melting point and is liquid. In order to detect this time window in optimum fashion and independently of the product, there can be provision made for temperature sensors at the ends of the hollow body 30. The pressure for blowing out the hollow body 30 can then be controlled by the measured values of the temperature sensors. If the hollow body 30 has a zinc filling, the pressure could be activated at a temperature of over 450 C. for the filling 5, for example. The pressure could be deactivated again when the temperature falls below 420 C. If the hollow body 30 has a tin filling 5, the pressure could be activated at a temperature of above 250 C. for the filling 5, for example. The pressure could be deactivated again when the temperature falls below 235 C. During this process, the pressure loss can be measured and hence the continuity of the hollow body 30 can also be monitored or checked. As such, it can become necessary to provide for temperature sensors at the position of the ends of the hollow body 30, for example. The third material of the filling 5 that is removed from the hollow body 30 can be collected and reused (recycling).

[0034] As can be seen from FIG. 5, the aluminum used in the depicted exemplary embodiment, which is introduced as a die casting into the die casting mold in step S130 and the temperature characteristic of which shows a first characteristic curve K1, has a solid first state Z1 up to the time t1. During a first time window tF(Al) between the time t1 and a second time t2, the aluminum die casting introduced has a liquid or viscous state Z2 and a temperature in the range from 400 to 580 C. From the time t2 onward, the aluminum die casting sets and has the solid first state Z1 again. As the first characteristic curve K1 shows, the aluminum die casting cools slowly.

[0035] As can also be seen from FIG. 5, the filling 5 of the hollow body 30, the temperature characteristic of which shows a second characteristic curve K2, still has the solid first state Z1 during casting, i.e. the hollow body 30 remains robust. After the first time window tF(Al), which is very short (approximately 1 second), the die casting sets and becomes solid. In parallel, the filling 5 in the hollow body 30 is heated by the hot die casting, and the melting temperature of the filling 5 is reached or exceeded. When tin is used, the filling 5 reaches its melting temperature at a third time t3 and changes to the liquid or viscous state Z2 for the duration of a second time window tF(Zn). When zinc is used, the filling 5 reaches its melting temperature at a fourth time t4 and changes to the liquid or viscous state Z2 for the duration of a third time window tF(Sn). From a fifth time t5 onward, the filling 5 sets again and has the solid first state Z1 again. Therefore, the molten filling 5 can be removed from the hollow body 30 at high pressure during the second time window tF(Zn) when tin is used. When zinc is used, the molten filling 5 can be removed from the hollow body 30 at high pressure during the third time window tF(Sn), the third time window tF(Sn) being substantially shorter than the second time window tF(Zn), the end of which and the transition to the solid first state no longer being visible on account of the scaling of the graph.