Cooler for cooling a power electronics device

Abstract

The present invention relates to a housing (2) for carrying a power electronic device (101) and a cooling rib assembly (7) in a cooling passage (6) of the housing (2) comprising a number of ribs (9), the cooling rib assembly (7) allowing a fluid to flow therethrough along a longitudinal axis (30), the cooling rib assembly (7) including at least one strong cooling area (20) having a first flow resistance to the fluid and at least one weak cooling area (21) having a second flow resistance to the fluid, the first flow resistance being higher than the second flow resistance.

Description

Technical Field

[0001] The present invention relates to a cooler for cooling a power electronics device. Further, the present invention shows an assembly including both the cooler and the power electronics device.

Background Art

[0002] Power semiconductors in power electronics devices conduct high currents. The resulting conduction losses, together with switching losses, cause a high loss heat output, which has to be dissipated through a relatively small surface. In this regard, minimizing the thermal resistance between the semiconductor and the coolant is of central importance since the maximum allowable semiconductor temperature is related to malfunction. For efficient cooling, the power electronics devices considered here are attached to a cooler through which a fluid flows. Usually, there is a cooling rib assembly in this cooler through which the fluid flows.

Summary of the Invention

Means for Solving the Problems

[0003] The cooler according to the present invention is formed, inter alia, for cooling power electronics equipment. This power electronics equipment usually has one or more power semiconductors arranged in a substrate. The cooler includes a housing formed for mounting the power electronics equipment. The housing is preferably formed in a plate shape, for example, by two plates that define a cooling channel therebetween, and this cooling channel can be traversed by a cooling fluid. The cooling channel is a hollow space. Inside this hollow space, there is a cooling rib assembly provided with a large number of ribs. The cooling channel and the cooling rib assembly are formed for passing a cooling fluid. In particular, it is cooled by a fluid in a liquid-aggregated state. The cooling rib assembly is formed so as to be able to traverse the fluid along the longitudinal axis. A short axis is defined perpendicular to the longitudinal axis and thus also perpendicular to the flow direction. An altitude axis is defined perpendicular to the short axis and perpendicular to the longitudinal axis. The cooling rib assembly extends much longer in the direction of the longitudinal axis and the short axis, in particular, than in the direction of the altitude axis. The power electronics equipment is positioned above or below the cooling rib assembly along the altitude axis. A plurality of heat sources of the power electronics equipment, in particular a plurality of power semiconductors, can be positioned along the longitudinal axis and partly also along the short axis. In the cooling channel of the housing or in the cooling rib assembly, a pressure drop occurs along the flow direction due to the resistance of the cooling rib assembly of the flowing fluid. Generally, the higher the heat transfer rate by the cooling rib assembly, the greater the pressure drop. In the cooling system, the maximum allowable pressure drop is limited based on the fluid pump. Therefore, it is also necessary to limit the pressure drop across the entire cooler, whereby, depending on the circumstances, the maximum possible heat transfer rate cannot be utilized. The cooler according to the present invention has the advantage that it can reduce the pressure drop in the cooler. This is achieved by the cooling rib assembly including at least one strong cooling region having a first flow resistance to the fluid and at least one weak cooling region having a second flow resistance to the fluid. The cooling rib assembly in the strong cooling region and the weak cooling region is formed such that the first flow resistance is higher than the second flow resistance.It is particularly preferred that the first flow resistance is at least 10% higher than the second flow resistance. At least one weakly cooled region having the second flow resistance can be deliberately positioned within the cooler at locations where little or no cooling is required. In particular, the strongly cooled regions are positioned as close as possible to the power semiconductors, while the weakly cooled regions are rather positioned at the edges of the cooling rib assembly and / or between two power semiconductors. Thereby, it is achieved that a correspondingly high flow resistance is applied only to the flowing fluid within the deliberately selected strongly cooled regions where cooling is required, and this high flow resistance also results in a correspondingly high heat transfer rate. In regions where less or no cooling is required, i.e., within the weakly cooled regions, the flow resistance is reduced as much as possible, so that, considering the entire cooling rib assembly, the lowest possible flow resistance or a flow resistance adapted to the thermal requirements occurs.

[0004] The cited form claims show preferred variants of the present invention. As described above, it is preferred that the housing is formed from two plates, which define a cooling channel therebetween. Both plates are joined to each other, in particular via a hard solder layer, and form a cooling channel for accommodating the cooling rib assembly. Preferably, a fluid inlet and an outlet communicate within this cooling channel.

[0005] The cooling rib assembly preferably has at least two, more preferably at least three, and particularly preferably at least four of the aforementioned weakly cooled regions. These weakly cooled regions can be formed identically or differently. The weakly cooled regions are distributed and spaced along the longitudinal axis, and thus there is preferably one strongly cooled region between the weakly cooled regions. In addition to these weakly cooled regions arranged successively along the longitudinal axis, one or more weakly cooled regions can also be arranged side by side along the short axis.

[0006] The weak cooling region occupies the first area of the cooling rib assembly as a whole, and the strong cooling region occupies the second area as a whole. It is preferable that these areas are each defined within a plane defined by the longitudinal axis and the short axis. It is preferable that the first area occupies at least 10%, especially at least 20% of the total area of the cooling rib assembly, and at the same time the second area occupies at least 10%, especially at least 20% of the total area of the cooling rib assembly.

[0007] Within at least one strong cooling region, it is preferable that the ribs of the cooling rib assembly stand more densely than the ribs in at least one adjacent weak cooling region when measured across the longitudinal axis. That is, the distance between two ribs measured parallel to the short axis is smaller in the strong cooling region than in the weak cooling region, thereby creating a greater flow resistance in the strong cooling region than in the weak cooling region. In addition or alternatively, it is possible that no ribs are formed within at least one weak cooling region.

[0008] Furthermore, it is preferable that the cooling rib assembly is produced by deforming a sheet metal into a turbulator sheet metal. This turbulator sheet metal especially has a number of rib rows. A single rib row extends along the short axis perpendicular to the longitudinal axis. A single rib row has a number of ribs. Especially, the rib row has a waveform. Due to this waveform, two adjacent ribs are connected to each other via the mountain or valley section of the waveform. Especially, the waveform or the mountain or valley section of the rib row extends substantially within the plane defined by the longitudinal axis and the short axis.

[0009] Within the turbulator sheet metal, it is preferable that at least one of the weak cooling regions is formed by a cut-out cavity. This cavity is especially punched out or cut out in another way. Especially, the turbulator sheet metal is first produced without a cavity, and the cavity is cut out at the desired location after the production of the turbulator sheet metal. This creates a rib-free region in the cavity, which produces as low a flow resistance as possible within the weak cooling region.

[0010] At least one weak cooling region can be used to induce a flow, for example, to induce a flow having a direction component parallel to the short axis, and / or to concentrate the fluid flow in a region to be cooled more strongly. To achieve such flow induction, among other things, the above-described voids in the turbulator sheet metal are formed to taper. In particular, the voids taper in the flow direction, whereby the fluid can be deliberately induced and directed.

[0011] The individual ribs of the cooling rib assembly are preferably installed at a first angle of attack with respect to the longitudinal axis, at least within the strong cooling region. In particular, the ribs are installed at an angle so as to increase the flow resistance compared to the non-inclined state, and as a result, also increase the heat transfer rate.

[0012] Preferably, within the strong cooling region, the ribs are installed at an angle of attack with respect to the longitudinal axis, and within at least one adjacent weak cooling region, the ribs are installed with less inclination or not inclined at all, that is, standing parallel to the longitudinal axis.

[0013] It is preferable that a single strong cooling region has a plurality of rib rows arranged one after another. As described in the scope of the turbulator sheet metal, the rib rows extend along the short axis and are in direct contact with each other along the longitudinal axis. It is preferable that the ribs in adjacent rib rows are installed at different inclination directions with respect to the longitudinal axis. Thus, for example, the ribs in one row are installed at 10° with respect to the longitudinal axis, and the ribs in the next row are installed at -10°. This alternating inclination of the ribs deliberately increases the flow resistance, whereby the highest possible heat transfer rate within the strong cooling region is achieved.

[0014] Preferably, the rib has a first length in at least one strong cooling region, and the rib in at least one adjacent weak cooling region has a second length. In this regard, the length of a single rib is measured parallel to the longitudinal axis. Preferably, the second length is greater than the first length. Thereby, the rib in the weak cooling region is formed longer than the rib in the strong cooling region and is preferably formed without an angle of attack. This is particularly noteworthy in combination with the alternating inclination directions of the above-mentioned single rib rows, because the relatively long rib in the weak cooling region creates a relatively long section with an unchanged angle of attack, thereby providing a reduced flow resistance.

[0015] The different configurations described herein for deliberately varying the flow resistance in the weak cooling region and the strong cooling region may be combined with each other within one cooling rib assembly. That is, for example, one weak cooling region within the cooling rib assembly is formed by a cut-out void, and another weak cooling region within the same cooling rib assembly may be achieved by varying the rib length or the angle of attack.

[0016] The present invention further includes an assembly. This assembly also has both the above-mentioned cooler and a power electronics device of attribution equipped with at least one power semiconductor. In this regard, as described above, the power electronics device is arranged on the cooler. When the power semiconductor is conceptually projected onto the plane of the cooling rib assembly along the altitude axis, the positioning of the weak cooling region and the strong cooling region with respect to the power semiconductor can be considered. In particular, a strong cooling region is formed exclusively directly below the power semiconductor, and the weak cooling region is between the power semiconductors.

[0017] Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0019] Hereinafter, an assembly 100 including a cooler 1 will be described in detail with reference to FIGS. 1 to 5. The assembly 100 includes power electronics equipment 101 placed on the cooler 1 based on a schematic cross-sectional view in FIG. 1. The power electronics equipment 101 includes one or more power semiconductors 102 regarded as the main heat source here.

[0020] Furthermore, FIG. 1 shows that the cooler 1 is formed in a plate shape by two cooling plates 3 and 4 (which constitute the housing 2) that are coupled to each other and arranged in parallel, and there is a cooling channel 6 between the cooling plates 3 and 4. Both cooling plates 3 and 4 are coupled to each other via a solder layer 5.

[0021] There is a cooling rib assembly 7 in the cooling channel 6 that can also be coupled to the housing 2 via a solder layer 5. FIG. 2 shows a plan view of the cooler 1. Since the upper cooling plate 3 is erased for easy viewing, the lower cooling plate 4 can be viewed together with the cooling rib assembly 7 housed therein.

[0022] Based on FIGS. 1 to 5, a longitudinal axis 30, a short axis 31, and an altitude axis 32 are defined beside the cooler 1. The three axes 30, 31, and 32 are perpendicular to each other. The housing 2 is formed to pass a cooling fluid along the flow direction 34. The flow direction 34 extending parallel to the longitudinal axis 30 is the main flow direction of the fluid from the housing-side inlet to the housing-side outlet. Within the cooling rib assembly 7, the fluid can also flow in a direction component parallel to the short axis 31.

[0023] In the illustrated exemplary embodiment, the cooling rib assembly 7 is formed by a deformed sheet metal and can also be called a turbulator sheet metal. The cooling rib assembly 7 is composed of a number of rib rows 8. Each rib row 8 extends along the short axis 31. A number of rib rows 8 are arranged directly adjacent to each other in succession along the longitudinal axis 30. FIG. 4 shows these rib rows 8 in detail in FIG. 3. In this regard, a single rib row 8 is wavy, and two adjacent ribs 9 are connected to each other by a mountain or valley section 10 of the wave. A gap 11 occurs between two adjacent ribs 9 parallel to the short axis 31. A single rib 9 extends over a first length 12 parallel to the longitudinal axis 30.

[0024] The detailed view in FIG. 5 shows that the rib 9 can be inclined obliquely at an angle of attack 14 with respect to the longitudinal axis 30. FIG. 2 purely schematically reveals the positioning and configuration of the weak cooling regions 21. These weak cooling regions 21 of the cooling rib assembly 7 are surrounded by the strong cooling regions 20 of the cooling rib assembly 7. Along the longitudinal axis 3, that is, along the flow direction 34, a plurality of weak cooling regions 31 of various shapes and sizes are incorporated into the cooling rib assembly 7. Within the weak cooling regions 31, a lower flow resistance is imposed on the flowing-through fluid than in the strong cooling regions 20. From this, it can be seen that a higher heat transfer rate is possible in the strong cooling regions 20. Accordingly, preferably, there is a strong cooling region 20 under the power semiconductor 102, while the weak cooling regions 21 are arranged between the power semiconductors 102.

[0025] FIG. 2 schematically reveals two triangular weak cooling regions 21 formed to taper along the flow direction 35 to correspondingly guide or direct the fluid. As already described in the general part, in order to form the weak cooling region 21, voids can be cut out within the cooling rib assembly 7. In addition to or instead of that, within the weak cooling region 21, the length of the rib 9 can also be formed longer than in the strong cooling region 20. FIG. 3 exemplarily shows two weak cooling regions 21 extending across the width of the cooling rib assembly 7 (along the short axis 31). Within both of these weak cooling regions 21 based on FIG. 3, the rib 9 is formed with a second length 13 that is longer than the first length 12 of the rib 9 within the three strong cooling regions 20.

[0026] The angle of attack 14 has already been described based on FIGS. 4 and 5. In order to generate a lower flow resistance within the weak cooling region 21 than within the surrounding strong cooling regions 20, it is preferable that this angle of attack 14 can be smaller or can be 0 within the weak cooling region 21.

Claims

1. A cooler (1) for cooling a power electronics device (101), ・ A housing (2) for mounting the power electronics device (101); ・ A cooling rib assembly (7) having a plurality of ribs (9) in a cooling channel (6) of the housing (2), ・ The cooling rib assembly (7) being capable of allowing a fluid to flow therethrough along a longitudinal axis (30), ・ The cooling rib assembly (7) including at least one strong cooling region (20) having a first flow resistance to the fluid and at least one weak cooling region (21) having a second flow resistance to the fluid, the first flow resistance being higher than the second flow resistance, ・ The weak cooling region (21) being formed to taper for flow induction. Cooler (1).

2. The cooling rib assembly (7) having at least two, preferably at least three, particularly preferably at least four weak cooling regions (21), the weak cooling regions (21) being dispersed and spaced along the longitudinal axis, the cooler according to claim 1.

3. In at least one strong cooling region (20), the ribs (9) of the cooling rib assembly (7) being denser than the ribs (9) in at least one adjacent weak cooling region (21) when measured across the longitudinal axis (30), the cooler according to claim 1.

4. The cooler according to claim 1, wherein no ribs (9) are formed in at least one weak cooling region (21).

5. The cooling rib assembly (7) being produced by forming sheet metal into turbulator sheet metal, and at least one weak cooling region (21) being a cut-out, particularly punched-out, void in the turbulator sheet metal, the cooler according to claim 1.

6. In at least one strong cooling region (20), the rib (9) is adjusted at an attachment angle with respect to the longitudinal axis, and in at least one adjacent weak cooling region (21), the rib (9) is adjusted to be smaller, preferably parallel to the longitudinal axis (30), the cooler according to claim 1.

7. At least one strong cooling region (20) includes a plurality of rib rows (8) each extending across the longitudinal axis (30), and the rib rows (8) are directly adjacent to each other along the longitudinal axis (30), and the ribs (9) within each one rib row (8) are adjusted in the same set direction in a direction opposite to the longitudinal axis (30), and the ribs (9) are adjusted oppositely with respect to two adjacent rib rows (8), the cooler according to claim 1.

8. In at least one strong cooling region (20), the rib (9) has a first length (12) measured parallel to the longitudinal axis (30), and in at least one adjacent weak cooling region (21), the rib (9) has a second length (13) measured parallel to the longitudinal axis (30), and the second length (13) is greater than the first length (12), the cooler according to claim 1.

9. An assembly (100) including the cooler (1) according to claim 1 and a power electronics device (101) having a plurality of power semiconductors (102) disposed on the housing (2).

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