Fastening device for connecting thermally stressed components

Abstract

The invention relates to a fastening device (10) for connecting heat-stressed components to each other, in particular a heat-generating body (44) with a heat sink (42), comprising a fixing pin (12) and a fixing element (16), wherein the fixing pin (12) is connected to a fixing head (14), the fixing pin (12) extends through the fixing element (16), the fixing head (14) is in contact with the fixing element (16), and the fixing element (16) is engaged with the body (44) or the heat sink (42) and fixed in the fastening direction (26) of the fixing pin (12). According to the invention, the fixing element (16) is designed to be transversely engaged with the body (44) or the heat sink (42), wherein the fixing element (16) has a fixing groove (24) on its side facing the body (44) or the heat sink (42) extending in a longitudinal direction intersecting the fastening direction, wherein at least one groove surface (24a, 24b) is in contact with the body (44) or the heat sink (42) at least in a partial area in the assembled state.

Description

Technical Field

[0001] The invention relates to a fastening device for connecting thermally stressed components. In addition, the invention also relates to the use of the fastening device and a method for connecting two thermally stressed components. Background Art

[0002] A universal fastening device for connecting thermally stressed components to each other, in particular for connecting a heat generating body to a heat sink, comprises a fixing pin and a fixing element. The fixing pin is connected to a fixing head. The fixing pin passes through the fixing element. The fixing head rests on the fixing element. The fixing element engages with the body or the heat sink and fixes it along the fastening direction of the fixing pin. In the installed position, the fixing head connected to the fixing pin holds the fixing element in the position, and the fixing element in turn fixes the body or the heat sink in place. If a power module that generates heat energy is to be fixed, the fixing pin is fixed in a hole in a component (e.g., a heat sink).

[0003] DE 103 06 227 A1 discloses a power module as a thermal stress subject, which comprises at least one circuit board and a heat-generating component. In addition, a heat sink is disclosed, which is designed as a hollow body and through which a cooling medium flows to dissipate heat. The heat-generating component is arranged on a cooling surface outside the heat sink and is connected to the cooling surface in a heat-conducting manner. The heat sink is symmetrical in design and has a plurality of cooling surfaces arranged at a certain angle around the longitudinal axis of the heat sink. A fastening screw with a screw head is provided on the central longitudinal axis of the heat sink, which connects the heat sink to the circuit board via a star-shaped clamping spring. The clamping spring presses the heat-generating component onto the cooling surface of the heat sink and is used to dissipate heat. This design is very complicated because it requires a fixing element in the form of a star-shaped clamping spring to be provided for each heat sink.

[0004] DE 196 30 173 C2 discloses a power module with semiconductor elements and a circuit board on which a number of chip-shaped power semiconductor elements and contact pads are provided. A housing with pressure contacts is provided on the board in order to switch the board. The pressure piece is fixed to the housing using a centrally arranged fastening screw and the printed circuit board is firmly connected to the pressure piece. The pressure piece is made of an electrically insulating material. In order to insulate the fastening element from the housing of the circuit board, a sleeve is provided in the housing, which surrounds the fastening screw. The problem with this design is that the interconnected parts made of different materials (circuit board, housing and pressure piece) expand differently when exposed to the temperatures generated during operation and cannot therefore move relative to each other. This leads to stresses and premature material failure. Summary of the invention

[0005] The object of the present invention is to provide a fastening device which makes it possible in a simple manner to prevent stresses due to thermal expansion of thermally stressed bodies and other bodies while avoiding the above-mentioned disadvantages.

[0006] This object is achieved by combining the features in the preceding part with the features in the characteristic part, by providing a fastening device to connect the heat generating body to the heat sink. It includes a fastening pin and a fixing element, wherein the fastening pin is connected to a fixing head, the fastening pin passes through the fixing element, the fixing head contacts the fixing element, and the fixing element bites into the body or the heat sink and fixes it along the fastening direction of the fastening pin, wherein the fixing element is designed to bite into the body or the heat sink laterally, and the fixing element has a fixing groove extending longitudinally perpendicular to the fastening direction on its side facing the body or the heat sink, wherein in the assembled state, at least one of the first groove surface and the second groove surface contacts a partial area of ​​the body or the heat sink.

[0007] According to the present invention, the fixing element is designed to engage with the body or the heat sink transversely, and the fixing element is provided with a fixing groove on the side facing the body or the heat sink, and the groove extends in a longitudinal direction perpendicular to the fastening direction, and at least in the installed state, at least a partial area of ​​the groove surface is in contact with the body or the heat sink. This is a simple method to enable relative movement when the heat sink or the body undergoes thermal expansion (if installed correctly).

[0008] According to an advantageous improvement of the present invention, the fixing groove is formed into a V-shape by two groove surfaces, one of which is aligned parallel to the longitudinal axis of the fastening pin, and the other groove surface is inclined relative to the longitudinal axis of the fastening pin, and the groove surfaces are particularly arranged to be acute or obtuse angles relative to each other. Such a V-shaped fixing groove allows different edge areas of the heat sink to be fixed in place in a simple manner without restricting movement along the fixing groove. Depending on the design of the edge area of ​​the body or heat sink, or the expected thermal stresses, acute or obtuse angles are useful. This will result in at least one groove surface of the fixing groove being in linear or planar contact with the body or heat sink to be fixed in place.

[0009] Preferably, the fixing element has a rectangular bottom area. It is therefore easy to manufacture, but can also be easily aligned with the body so as to be fixed in place during assembly. In particular, the fixing element has a longitudinal length in the fixing slot that is greater than a transverse length perpendicular to the longitudinal direction of the fixing slot.

[0010] According to another embodiment of the present invention, the fixing element is symmetrically formed and has two fixing grooves, so that the fixing element can lean against different adjacent bodies or heat sinks at the same time, which expands its application range and increases the flexibility of the fastening device.

[0011] In order to particularly protect the fixing element from rotation relative to the body or the heat sink, the fixing element has an elongated protrusion extending perpendicularly to the fixing pin from its center to the side of the fixing pin, which in turn has another groove on the side facing away from the fixing head. In particular, this groove engages with the strip. This results in a form fit in the direction of rotation, but does not affect the movement relative to the fixing groove due to thermal expansion. This therefore prevents twisting of the fixing element, while still allowing thermal expansion in the longitudinal direction of the groove and the fixing groove arranged parallel to it.

[0012] Preferably, the further groove is also V-shaped. This is a simple way to obtain both linear and planar contact, depending on the design of the contact surface of the body or the heat sink located opposite the groove.

[0013] To prevent the fastening device from being too high, the fixing head is inserted into a recess in the fixing element and abuts there.

[0014] In particular, the fixing head and the groove of the fixing element are of cylindrical design, with one end face of the fixing head resting on the end face of the groove, thereby allowing a relative compensating movement around the cylindrical axis. During assembly, this is very important for aligning the fixing element relative to the body or heat sink to be fixed in place. In addition, in certain body and heat sink designs, this is also conducive to compensating stresses.

[0015] However, as an alternative, the side of the fixing head facing the recess may also be at least partially spherical, and the recess may be partially spherical to match the fixing head, so that the spherical surfaces facing each other can move compensatingly with each other in the manner of a ball joint. This ensures that the interconnected body and heat sink will not generate stress due to torque under any thermal expansion.

[0016] The pin may have a thread disposed at an end remote from the fixing head, the thread being adapted to engage with a thread in a hole of the heat sink or the body. In this way, the fastening device and the body and the heat sink may be screwed together by the fastening device.

[0017] Optionally, the pin has at least one stop means at its end remote from the fixing head, the stop means having an undercut adapted to engage in a hole in the heat sink or the body. The pin is slotted at the end remote from the fixing head. Using a locking connection, the body and the heat sink can be connected to each other by means of a fastening device. This simplifies installation.

[0018] Preferably, the body consists of a power semiconductor. Power semiconductors generate a lot of heat and must therefore be cooled by a heat sink. The fastening device according to the invention is particularly suitable for this, since the heat sink will expand.

[0019] The heat sink may be an air heat sink and / or a liquid heat sink.

[0020] According to one embodiment of the present invention, the fixing head of the fastening device is made of a thermally insulating and / or electrically insulating material or a conductive material.

[0021] According to another aspect, the invention is characterized in that at least two fastening devices of the above type are used to connect the radiator and the body, wherein the two fastening devices are mounted on the body or the radiator corresponding to each other and form a floating support with the body or the radiator. This is a simple method to achieve relative movement between the body and the radiator along the fixing grooves of the fixing elements of the fastening devices.

[0022] During installation, the fastening grooves of the fastening devices should in particular be aligned parallel to one another.

[0023] According to another aspect, the invention is generally characterized by a method for connecting two thermally stressed components to each other, in particular a heat sink and a body, by means of a floating support which allows movement of the one component relative to the other along at least one axis, in particular using a fastening device of the type described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Further advantages, features and possible applications of the invention emerge from the following description, in which reference is made to the exemplary embodiments shown in the drawings.

[0025] Throughout the specification and drawings, these terms and associated reference numerals are used as indicated in the following list of reference numerals. In the drawings:

[0026] Figure 1a is a side view of a fastening device according to a first embodiment of the present invention;

[0027] Figure 1b It is taken from above at a certain angle Figure 1a A perspective view of a fastening device;

[0028] Figure 1c yes Figure 1b Exploded diagram of

[0029] Figure 2a is a side view of a fastening device according to a second embodiment of the present invention;

[0030] Figure 2b It is taken from above at a certain angle Figure 2a A perspective view of a fastening device;

[0031] Figure 2c yes Figure 2b Exploded diagram of

[0032] Figure 3ais a side view of a fastening device according to a third embodiment of the present invention;

[0033] Figure 3b It is taken from above at an angle Figure 3a A perspective view of a fastening device;

[0034] Figure 4a is a side view of a fastening device according to a fourth embodiment of the present invention;

[0035] Figure 4b It is taken from above at an angle Figure 4a A perspective view of a fastening device;

[0036] Figure 5 is a cross-sectional view of a first application example of the third embodiment of the present invention in its installed state;

[0037] Figure 6 is a cross-sectional view of the second application example of the third embodiment of the present invention in its installed state; and

[0038] Figure 7 is a cross-sectional view of the third application example of the first embodiment of the present invention in its installed state.

[0039] 10 Fastening device

[0040] 10a Upward side

[0041] 10b Long side - right

[0042] 10c Long side - left

[0043] 12 Fastening pin

[0044] 12a Hexagon socket, internal drive

[0045] 14 Fixed head

[0046] 16 Fixing elements

[0047] 18 Through Holes

[0048] 20 grooves

[0049] 22 Fixed arm

[0050] 22a Fixed arm - left

[0051] 22b Fixed arm - right

[0052] 24 Fixing slot

[0053] 24a is parallel to the groove surface of the through hole 18

[0054] 24b Groove surface inclined relative to through hole 18

[0055] 24c Fixed slot - left

[0056] 24d Fixing slot-right

[0057] 26 Fastening direction

[0058] 28 belly plate

[0059] 30 Another groove

[0060] 30a Belly

[0061] 32 Thread

[0062] 34 Free end

[0063] 36 slots

[0064] 38 Stop device

[0065] 40 holes

[0066] 42 Radiator

[0067] 44 Power Semiconductors DETAILED DESCRIPTION

[0068] like Figure 1a , 1b 1c, a first embodiment of a fastening device 10 is shown. The fastening device 10 comprises a fastening pin 12 integrally connected to a fixing head 14. In this embodiment, the fastening pin 12 and the fixing head 14 are integral. The fixing head 14 is cylindrical and has a hexagonal socket 12a into which the fastening pin 12 is screwed during assembly. The hexagonal socket 12a constitutes an internal driver of the fastening pin 12.

[0069] Furthermore, the fastening device 10 comprises a fixing element 16 having a through hole 18 and a cylindrical groove 20 arranged concentrically on its upward side 10a. The basic shape of the fixing element 16 is rectangular when viewed from above. The longitudinal length of the fixing element 16 is greater than the transverse length. On the first long side 10b, a fixing arm 22 protrudes along the entire long side 10b and extends at an angle relative to the upward side 10a. A V-shaped fixing groove 24 parallel to the long side 10a is provided below the fixing arm 22, wherein the groove surface 24a closest to the through hole 18 is parallel to the through hole 18 and the other groove surface 24b and extends at a certain angle thereto.

[0070] Especially in Figure 1a As can be seen in FIG. 2 , the groove surfaces 24 a and 24 b of the fixing groove 24 form an acute angle therebetween.

[0071] The groove surface 24a extends downward, and a portion of the bottom surface of the fixing element 16 is inclined relative to the groove surface 24a.

[0072] The fastening pin 12 with the fixing head 14 is inserted into the through hole 18 in the fastening direction designated by reference numeral 26 until the end face of the fixing head 14 abuts against the upward surface of the groove 20. In this state, the upper surface of the fixing head 14 is flush with the upward side 10a.

[0073] When the fastening pin 12 with the fixing head 14 is inserted into the through hole 18 and the groove 20 of the fixing element 16, the fastening pin 12 will also be fixed in the heat sink or other component, as will be described in more detail below.

[0074] Figure 2a , 2b 2a and 2b show a second embodiment of the present invention. Figure 1a , Figure 1b and Figure 1c Similar to the fastening device 10 of the embodiment, this embodiment also has a fastening pin 12 with a fixing head 14. Only the design of its fixing element 16 is different, on the long sides 10b and 10c, a fixing arm 22a, 22b protrudes laterally along the entire long sides 10b and 10c, respectively, and each fixing arm 22a and 22b is provided with a fixing groove 24c, 24d extending downwardly parallel to the groove surface 24a of the through hole 18. This produces a web extending transversely with respect to the fastening pin 12 and having a central groove 30. The fixing element 16 has two fixing grooves 24c and 24d of symmetrical design and a further central groove 30. The groove 30, the web 30a and the fixing grooves 24c and 24d are parallel to each other and perpendicular to the longitudinal axis of the fastening device 10 and the fastening direction 26.

[0075] Figure 3a and 3b 3 is a view of a third embodiment of the invention which corresponds substantially to the second embodiment, wherein the fastening pin 12 has a thread 32 adapted to engage with a thread (not shown here) in a heat sink (also not shown). Thus, the fastening pin 12 is designed to be screwed into the associated thread.

[0076] Figure 4a and 4b A fourth embodiment of the invention is shown, which corresponds essentially to the second embodiment, in which the fastening pin 12 has a groove 36 extending from its free end 34 into the fixing element 16. Furthermore, the fastening pin 12 and the fixing element 16 are integrally formed and made in one piece. A stop 38 is provided on the free end 34, which forms a shoulder 38a and tapers towards the free end 34. The fastening pin 12 and the stop 38 are essentially cylindrical or conical. An undercut is formed in the hole (not shown) of the heat sink (also not shown). In the mounted state, the stop 38 engages with this undercut, with the shoulder 38a resting against the undercut. The stop 38 serves to fix the fastening device 10 in the hole.

[0077] Figures 5 to 7are illustrations of different embodiments of the application of the fastening device 10 according to the invention.

[0078] Figure 5 and 6 3 are views of fastening devices 10 according to the first and third embodiments, which have a fastening pin with a thread 32 and each fastening device 10 is screwed into a threaded hole 40 of a heat sink 42 .

[0079] exist Figure 5 In the embodiment, the heat sink 42 is cubic. At its top, a power semiconductor 44 that generates heat energy is connected to the heat sink by a fastening device 10, so that the fixing arms 22 with the fixing grooves 24 of the fastening device will each lean against the edge of the power semiconductor 44. On the outside of the heat sink, a fastening device 10 according to the first embodiment of the present invention is provided, which bites only one edge of the power semiconductor 44 to fix it in place, while the fastening device 10 according to the third embodiment of the present invention is provided in the central area, and its fixing arms 22a, 22b and fixing grooves 24c, 24d bite on the edges of two different power semiconductors 44 to fix them in place. The fixing arms 22a, 22b and their fixing grooves 24c, 24d each lean against the edge of the power semiconductor 44 in a linear or planar manner. All the fixing grooves 24 of the fastening device 10 are aligned parallel to each other.

[0080] Figure 6 is a cross-sectional view of a trapezoidal heat sink. In this case, the power semiconductor 44 is also arranged on the top side of the heat sink 42. On the outside of the heat sink 42, the fastening device 10 according to the first embodiment is screwed into the heat sink 42 and fixes the power semiconductor 44 in place at the edge. In the central area, the fastening device 10 according to the third embodiment is screwed into the corresponding holes at the edge of the heat sink 42, thereby engaging and fixing each adjacent two power semiconductors 44. As can be clearly seen from this view, the V-shaped fixing groove 24 provides a simple way to fix the power semiconductor 44 set at a relative angle in the appropriate position without having to adjust the fixing element 16 for this purpose.

[0081] Figure 7 The view of 4 shows how the fastening device 10 is arranged in the heat sink 42 relative to the edge of the power semiconductor. The fastening pins 12 are screwed into the designated holes 40 of the heat sink 42. These devices are fastening devices 10 according to a first embodiment.

[0082] The use of the fixing groove 24 and the connection of the fastening device 10 on the opposite side enables the power semiconductor 44 to expand parallel to the fixing groove 24. In this way, pressure is avoided. For example, two fastening devices 10 are arranged on each long side of the power semiconductor 44. Depending on whether the fastening device 10 fixes one or two adjacent power semiconductors 44 in place, an embodiment of the fastening device 10 with one fixing arm 22 or an embodiment with two fixing arms 22a, 22b will be used. Therefore, the power semiconductor 44 is fixed in place by the floating support, which means that it can move in one direction. This direction is the main expansion direction of the power semiconductor 44.

[0083] The distance between two power semiconductors 44 and between the hole of the fastening pin 12 and the edge of the power semiconductor 44 can be adjusted by the length of the lateral projection of the fixing arm 22 .

[0084] Preferably, a set of fixing elements 16 is provided, which have fixing arms 22 protruding with different lengths. Depending on the requirements, fixing elements 16 with longer protruding fixing arms 22 or shorter protruding fixing arms 22 will be used. The fastening pin 12 with the fixing head 14 can remain the same for different fixing elements 16. However, it is also possible to provide fastening pins 12 of different lengths and diameters for assembly.

[0085] Depending on the specific application, the fastening device 10 can be designed to be electrically conductive, electrically insulating, thermally conductive or thermally insulating. On the other hand, the fastening element 16 and the fastening pin 12 with the fastening head 14 can also have different material properties.

[0086] Thus, in a simple manner, the fastening device 10 according to the invention allows expansion of the power semiconductor 44 and thus relative movement between the power semiconductor 44 and the heat sink 42. The secure anchoring of the fastening pin 12 prevents elastic deformation along the fastening axis. This is a simple way to prevent operating pressure.

Claims

1. A fastening device (10) for connecting thermally stressed components to each other and for connecting a heat generating body (44) to a heat sink (42), comprising a fastening pin (12) and a fixing element (16), wherein: A fastening pin (12) is connected to a fixing head (14), the fastening pin (12) passes through the fixing element (16), the fixing head (14) contacts the fixing element (16), and the fixing element (16) bites into the body (44) or the heat sink (42) and fixes it along the fastening direction (26) of the fastening pin (12), characterized in that the fixing element (16) is designed to be transversely engaged with the body (44) or the heat sink (42), and the fixing element (16) has a fixing groove (24) extending longitudinally perpendicular to the fastening direction on its side facing the body (44) or the heat sink (42), wherein, in the assembled state, at least one of the first groove surface (24a) and the second groove surface (24b) contacts a partial area of ​​the body (44) or the heat sink (42).

2. The fastening device according to claim 1, characterized in that: The fixing groove (24) is formed into a V shape by two groove surfaces (24a, 24b), wherein one of the first groove surface (24a) and the second groove surface (24b) is aligned parallel to the longitudinal axis of the fastening pin (12), and the other of the first groove surface (24a) and the second groove surface (24b) is inclined relative to the longitudinal axis, wherein the groove surfaces (24a, 24b) extend at an acute angle or an obtuse angle to each other.

3. The fastening device according to claim 1 or 2, characterized in that: The bottom area of ​​the fixing element (16) is rectangular.

4. The fastening device according to any one of claims 1 or 2, characterized in that: The length of the fixing element (16) in the longitudinal direction of the fixing groove (24) is greater than the transverse length relative to the longitudinal direction of the fixing groove (24).

5. The fastening device according to any one of claims 1 or 2, characterized in that: The two fixing grooves (24) are symmetrically designed, so that the fixing element (16) can simultaneously bear different adjacent bodies (44) or heat sinks (42).

6. The fastening device according to claim 5, characterized in that: On one side of the fastening pin (12), the fixing element (16) has an elongated protrusion (web 30a) extending perpendicularly to the fastening pin (12), and the protrusion has another groove (30) on the side away from the fixing head (14).

7. The fastening device according to claim 6, characterized in that: The other groove (30) is V-shaped.

8. The fastening device according to any one of claims 1 or 2, characterized in that: The fixing head (14) is inserted into and abuts against the groove (20) of the fixing element (16).

9. The fastening device according to claim 8, characterized in that The fixed head (14) is cylindrical, the groove (20) is cylindrical, and the end surface of the fixed head (14) is located on the end surface of the groove (20), so that relative compensating movement can be performed around the cylindrical axis.

10. The fastening device according to claim 1, characterized in that The fixing head (14) is at least partially spherical on the side facing the groove (20), and the groove (20) has a partially spherical shape adapted to the fixing head (14), so that the spherical surfaces facing each other allow relative compensating movement in the manner of a ball joint.

11. The fastening device according to claim 10, characterized in that The fastening pin (12) has a thread (32) at its end (34) away from the fixing head (14), and the thread (32) is suitable for engaging the thread (32) in a hole (40) on the heat sink (42) or the body (44).

12. The fastening device according to claim 11, characterized in that The end (34) of the fastening pin (12) remote from the fixing head (14) has at least one stop device (38) adapted to engage with an undercut in a hole (40) in a heat sink (42) or in a body (44), and the fastening pin is slotted in the region of the end (34) remote from the fixing head (14).

13. The fastening device according to claim 12, characterized in that The body (44) is formed by a power semiconductor.

14. The fastening device according to claim 13, characterized in that The radiator (42) is an air radiator and / or a liquid radiator.

15. The fastening device according to claim 14, characterized in that The fixing head (14) is made of thermal insulation material and / or electrical insulation material or conductive material.

16. Use of at least two fastening devices according to any one of claims 1 or 2 to connect a heat sink (42) and a body (44) to each other, characterized in that: The two fastening devices (10) are mounted on the edge of the body (44) or the radiator (42) opposite to each other, thereby forming a floating support with the body (44) or the radiator (42).

17. The use according to claim 16, characterized in that In the installed state, the fixing grooves (24) of the fastening device (10) are aligned parallel to each other.

18. A method for interconnecting two thermally stressed components, the two thermally stressed components being a heat sink (42) and a body (44), by means of a floating support, the floating support allowing one component to move relative to the other along at least one axis, using a fastening device (10) as claimed in any one of claims 1 or 2.

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