Power unit for an electric steering system
Patent Information
- Authority / Receiving Office
- DE · DE
- Patent Type
- Patents
- Current Assignee / Owner
- ROBERT BOSCH GMBH
- Filing Date
- 2016-07-14
- Publication Date
- 2026-07-23
AI Technical Summary
Existing power units for electric steering systems face challenges in achieving a low overall height while effectively dissipating heat generated by control electronics, as shrink fits require a minimum distance that increases the unit's height.
The heat sink is connected to the motor housing via caulking, welding, or screwing, eliminating the need for a minimum distance, allowing for a lower overall height and enhanced thermal conductivity.
This connection method reduces the power unit's height and improves thermal conductivity, enabling more efficient heat dissipation and increased component placement without increasing the unit's dimensions.
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Abstract
Description
State of the art
[0001] The invention relates to a power unit for an electric steering system comprising a motor housing for accommodating a motor, a heat sink, and control electronics for the motor arranged on the heat sink. The heat sink and the motor housing are connected to each other in such a way that heat exchange from the control electronics via the heat sink to the motor housing is possible.
[0002] Such a power unit is disclosed, for example, in German patent application DE 10 2009 000 169 A1. In this document, the heat sink is connected to the motor housing by means of a shrink fit. During assembly of the power unit, the motor housing is heated, the heat sink is then inserted into the motor housing, and the motor housing is subsequently cooled again to achieve a shrink fit.
[0003] The connection between the heat sink and the motor housing allows the heat generated by the control electronics through power loss to be dissipated via the motor housing.
[0004] The invention also relates to a method for assembling a power unit. Disclosure of the invention
[0005] The invention relates to a power unit for an electric steering system comprising a motor housing for accommodating a motor, a heat sink, and control electronics for the motor arranged on the heat sink. The heat sink and the motor housing are connected to each other in such a way that heat exchange from the control electronics via the heat sink to the motor housing is possible.
[0006] The core of the invention consists in the fact that the heat sink is at least partially connected to the motor housing by means of crimping, welding or screwing.
[0007] The advantage here is that by connecting the heat sink to the motor housing using riveting, welding, or bolting, a lower overall height of the power unit can be achieved compared to a shrink fit. This is because a shrink fit requires a certain minimum distance between the heat sink and the motor within the motor housing, particularly the motor's end shield, due to the mostly inductive heating during assembly of the power unit. In contrast, riveting, welding, or bolting eliminates this minimum distance, thus allowing the overall height of the power unit to be kept low.
[0008] An advantageous embodiment of the invention provides that the cooling element projects at least partially beyond the motor housing in its main extension plane at an end face of the motor housing in which an opening of the motor housing is located.
[0009] A key advantage here is that the surface area of the heat sink is larger than the cross-sectional area of the motor housing at its front face. This allows for a greater number of electrical components for the motor's control electronics to be mounted on the heat sink. Furthermore, components can be positioned on both sides of the heat sink in the area that extends beyond the motor housing. This allows, for example, components that are very large and would otherwise increase the overall height of the power unit to be mounted on the underside of the heat sink, thus to the side of and outside the motor housing, without increasing the overall height of the power unit. Additionally, connectors for the control electronics can be positioned on the side of the motor housing.
[0010] According to an advantageous embodiment of the invention, it is provided that an end face of the motor housing, in which an opening of the motor housing is located, is stepped.
[0011] The advantage here is that the heat sink can be partially attached to an inner wall of the motor housing and partially to the front face of the motor housing. This results in a good mechanical connection and, consequently, good thermal conductivity between the heat sink and the motor housing.
[0012] According to a further advantageous embodiment of the invention, the riveting is formed by means of at least one bent or riveted tab formed on an end face of the motor housing, which forms an opening of the cup-shaped motor housing, and at least one associated recess in the cooling body.
[0013] The advantage here is that this provides a good way to thermally connect the heat sink to the motor housing, thus ensuring heat exchange between the heat sink and the motor housing. Furthermore, bending or riveting the tab either does not increase the overall height of the power unit at all or only minimally.
[0014] In an advantageous embodiment of the invention, it is provided that the heat sink is at least partially riveted to the motor housing by having a groove on an end face of the heat sink and a spring on an inner wall of the motor housing, which are riveted together.
[0015] The advantage here is that a close-fitting connection is achieved between the heat sink and the motor housing, which has a low thermal resistance.
[0016] In a further advantageous embodiment of the invention, it is provided that the motor housing has at least a partial gap on an end face of the motor housing in an area in which the motor housing has the spring on the inner wall of the motor housing.
[0017] The advantage here is that the gap makes it easier to caulk the motor housing to the heat sink. A caulking tool can be inserted into the gap from above through recesses in the heat sink, and with sufficient force, the motor housing can be caulked to the heat sink, especially the spring to the groove.
[0018] In a further advantageous embodiment of the invention, it is provided that a screw engages through an opening in the cooling sink into a thread formed in the motor housing and thus forms the connection between the cooling sink and the motor housing.
[0019] The advantage here is that this offers a straightforward way to thermally connect the heat sink to the motor housing.
[0020] According to an advantageous embodiment of the invention, it is provided that laser beam welding is used for welding.
[0021] The advantage here is that this allows for a precise connection between the heat sink and the motor housing, and even complex seam geometries can be implemented.
[0022] According to a further advantageous embodiment of the invention, the heat sink has at least one recess, wherein an edge of the recess at least partially abuts an end face of the motor housing in which an opening of the motor housing is located, and the motor housing is welded to the heat sink at least partially along the abutting edge.
[0023] The advantage here is that this creates a particularly stable connection between the motor housing and the heat sink.
[0024] According to a further advantageous embodiment of the invention, it is provided that the heat sink with the control electronics arranged thereon is at least partially enclosed by an additional housing, in particular a plastic housing.
[0025] The advantage here is that the additional housing protects the motor's control electronics from environmental influences, thus increasing the service life of the power unit.
[0026] According to a further advantageous embodiment of the invention, it is provided that the motor housing or the cooling element is formed from an aluminum wrought alloy by means of deep drawing.
[0027] A key advantage here is that the wrought aluminum alloy possesses high thermal conductivity, thus improving heat exchange between the control electronics, heat sink, and motor housing. Furthermore, deep drawing offers a technically simple method for manufacturing the heat sink or the motor housing. Unlike die casting, this process eliminates the need for dies that require regular replacement. Consequently, the power unit can be manufactured more cost-effectively.
[0028] The invention further relates to a method for assembling a power unit comprising a cup-shaped motor housing for accommodating a motor, a heat sink, and control electronics for the motor arranged on the heat sink. The connection between the heat sink and the motor housing is achieved by riveting, welding, or bolting.
[0029] The advantage here is that by connecting the heat sink to the motor housing using riveting, welding, or bolting, a lower overall height of the power unit can be achieved compared to a shrink fit. This is because a shrink fit requires a certain minimum distance between the heat sink and the motor within the motor housing, particularly the motor's end shield, due to the mostly inductive heating during assembly of the power unit. In contrast, riveting, welding, or bolting eliminates this minimum distance, thus allowing the overall height of the power unit to be kept low.
[0030] In an advantageous embodiment of the method according to the invention, it is provided that after the connection has been made, a first housing shell is pushed onto the motor housing and fixed to an outer wall of the motor housing, in particular by bonding, and then a second housing shell is placed on top and connected to the first housing shell, in particular by means of laser beam welding.
[0031] The advantage here is that the additional housing formed from the first housing shell and the second housing shell protects the motor's control electronics from environmental influences, thus increasing the service life of the power unit.
[0032] According to an advantageous embodiment of the inventive method, it is provided that the motor housing or the cooling element is manufactured by deep drawing a wrought aluminum alloy.
[0033] A key advantage here is that the wrought aluminum alloy possesses high thermal conductivity, thus improving heat exchange between the control electronics, heat sink, and motor housing. Furthermore, deep drawing offers a technically simple method for manufacturing the heat sink or the motor housing. Unlike die casting, this process eliminates the need for dies that require regular replacement. Consequently, the power unit can be manufactured more cost-effectively. Drawings
[0034] Fig. Figure 1a shows a first embodiment of a power unit according to the invention for an electric steering system in cross-section.
[0035] Fig. Figure 1b shows the first embodiment of a power unit according to the invention for an electric steering system in a top view.
[0036] Fig. Figure 2 shows a second embodiment of a connection according to the invention between a heat sink and a motor housing in cross-section.
[0037] Fig. Figure 3 shows a third embodiment of a connection according to the invention between a heat sink and a motor housing in cross-section.
[0038] Fig. Figure 4 shows a fourth embodiment of a connection according to the invention between a heat sink and a motor housing in cross-section.
[0039] Fig. Figure 5 shows a fifth embodiment of a connection according to the invention between a heat sink and a motor housing in a perspective view. Description of exemplary implementations
[0040] Fig. Figure 1 shows a first embodiment of a power unit according to the invention. 10 for an electric steering system in cross-section. The power unit 10 includes a cup-shaped motor housing 20for a motor (not shown), usually an electric motor. This cup-shaped motor housing 20 has a bottom 21 on, which is usually penetrated by a motor shaft (not shown) of the engine. The bottom 21 has in the Fig. 1 a circular base, whereby the motor housing 20 It is cylindrical in shape. However, it can also have a square base or another shape of base. 21 conceivable. The engine housing 20 points to one of the ground 21 an opening on the opposite side 25 on. Furthermore, the power unit includes 10 a heat sink 30 , which has a main extension plane, and one on the heat sink 30 arranged control electronics 40 , which is used to control the motor. The control electronics 40 for example, it is used as a printed circuit board41 with electrical components arranged on it 42 trained. These electrical components 42 These could be, for example, switches or diodes of the inverter required to control the motor, or capacitors or parts of the logic unit for regulating the control. The circuit board 41 for example, by means of a thermally conductive adhesive on the heat sink 30 appropriate.
[0041] Furthermore, the heat sink 30 such a connection with the engine housing 20 associated with a heat exchange between the heat sink 30 and engine housing 20 is possible and thus especially those controlled by the electronics 40 heat generated via the heat sink 30 to the engine housing 20 can be released. The heat sink 30 is arranged in such a way that the opening 25 of the engine housing 20is essentially sealed, thus the heat sink 30 as a kind of cover for the engine casing 20 serves this purpose. Furthermore, the heat sink is located there. 30 at least partially on one end face 23 of the engine housing 20 , in which the opening 25 of the engine housing 20 is located on top of and also protrudes, at least partially, in its main plane of extension beyond the engine housing 20 out. At another point on the engine casing 20 The heat sink is located 30 with one front face 33 on an interior wall 24 of the engine housing 20 Furthermore, the heat sink 30 Exclusions 37 on, which provides access to the front 23 of the engine housing 20 enable the various possibilities of connecting a heat sink 30 and the engine housing 20 are in the Fig. 2 to Fig. 5 shown in detail. The heat sink 30 is also equipped with the control electronics arranged on it 40 at least partially from an additional housing 60 surrounded. This additional housing 60 for example, it is made of plastic and is formed from a first housing half 61 and a second housing half 62 The first half of the casing 61 is over the engine casing 20 pushed or onto the engine housing 20 pressed onto and attached to an outer wall 26 of the engine housing 20 with this. The fixing is achieved by gluing along a sealing contour. 64 This creates a seal between the two halves of the housing. 61 and the engine housing 60 The second half of the casing 62 is attached and with the first half of the housing 61joined, for example by means of laser beam welding or also by means of gluing.
[0042] In an alternative embodiment, not shown in the illustration, the electrical components can 42 at least partially directly, that is, without a circuit board 41 , on the heat sink 30 be arranged.
[0043] Fig. 1b shows the first embodiment of a power unit according to the invention. 10 for an electric steering system in a top view. Here, the power unit is shown. 10 without the control electronics 40 and the additional housing 60 The diagram shows a straight line from A to B. Additionally, a dashed line is shown from A to B, along which the cross-section is measured. Fig. 1 is carried out. The heat sink 30 It lies on the front side. 23 of the engine housing 20 on, with exceptions 37 in the heat sink 30are designed to provide access to the frontal surface 23 the engine casing 20 to have. Furthermore, the heat sink protrudes. 30 in its main extension plane at least partially on the front 23 of the engine housing 20 over the engine housing 20 out.
[0044] Fig. Figure 2 shows a second embodiment of a connection according to the invention between a heat sink and a motor housing in cross-section. On one end face 23 of the engine housing 20 are tabs 27 as extensions of the engine housing 20 trained. These tabs 27 reach through associated exceptions 37 of the heat sink 30 and are after passing through the openings 37 bent in such a way that the heat sink 30 on the front 23 of the engine housing 20 is fixed and a heat exchange between the heat sink 30and the engine housing 20 This can be done. The exceptions 37 can either be complete openings in the heat sink 30 or simply cutouts on one end face 33 of the heat sink 30 be.
[0045] In an alternative embodiment, not shown in the illustration, the tabs can 27 Instead of being bent, it can also be riveted to allow a connection between the heat sink and the motor housing.
[0046] In another alternative embodiment, not shown in the illustration, the heat sink 30 also be designed in such a graduated manner that an additional front face 33 of the heat sink 30 on an interior wall 24 or the heat sink 30 on an exterior wall 26 of the engine housing 20 , in an area where the heat sink 30 over the engine housing 20protrudes, lies adjacent.
[0047] Fig. Figure 3 shows a third embodiment of a connection according to the invention between a heat sink and a motor housing in cross-section. A section of the motor housing is shown. 20 , which is on an inner wall 24 of the engine housing 20 a feather 28 exhibits. The spring 28 reaches into one on a front side 33 of the heat sink 30 trained nut 38 one and is crimped to this. Additionally, the front face has 23 of the engine housing 20 a gap 29 in an area where the engine housing 20 on the inner wall 24 the spring 28 Furthermore, the heat sink exhibits 30 partially in the area of the forehead 23 of the engine housing 20 an exception 37 features which allow access to the front 23and accordingly the gap 29 made possible. The gap 29 allows the heat sink 30 easier into the engine housing 20 , and then the spring 28 into the groove 38 , can be introduced, since the gap 29 It has a slightly springy feel. Additionally, a caulking tool can be inserted into the gap. 29 caulking the heat sink 30 with the engine housing 20 can be achieved.
[0048] In an alternative embodiment not shown in the illustration, the heat sink 30 a spring and the engine housing 20 a groove, which is accordingly a reverse formation of the tongue-and-groove connection, as in Fig. 3 shown.
[0049] In another alternative embodiment, not shown in the illustration, the front face 23 of the engine housing 20 even without the gap 29must be designed in such a way that the caulking tool, for example, can be designed to... 23 split the motor housing itself or otherwise crimp the tongue-and-groove connection.
[0050] Fig. Figure 4 shows a fourth embodiment of a connection according to the invention between a heat sink and a motor housing in cross-section. The heat sink 30 lies on the forehead 23 of the engine housing 20 Furthermore, the heat sink 30 Breakthroughs 53 and the engine housing 20 in the front 23 inserted threads 52 which are aligned with each other, each with one screw 50 through the breakthroughs 53 into the threads 52 grips and thus the heat sink 30 with the engine housing 20 connects.
[0051] In an alternative embodiment, not shown in the illustration, the breakthrough can also 53 in the heat sink 30 and the thread 52 in the engine housing 20 be arranged in such a way that at least one of the screws 50 through or alongside the engine housing 20 The thread runs through this area. 52 then, for example, in the ground 21 of the engine housing 20 or also in the bearing shield of the motor (not shown) or also in a radial projection of the motor housing (not shown). 20 trained.
[0052] Fig. Figure 5 shows a fifth embodiment of a connection according to the invention between a heat sink and a motor housing in a perspective view. A section of the motor housing is shown. 20 on its front 23 a heat sink 30 is arranged. On the front side 33of the heat sink 30 are exceptions 37 introduced, which are designed in such a way that each has a border 36 the exceptions 37 on the front 23 of the engine housing 20 is attached. Furthermore, the heat sink 30 at least partially along the front face 23 of the engine housing 20 resting edge 36 the exceptions 37 with the engine housing 20 welded. It would also be sufficient to weld only a section of the edge. 36 to weld on.
[0053] In an alternative embodiment, not shown in the illustration, the recess can 37 also designed as a breakthrough and therefore not on the front surface 33 of the heat sink 30 be trained as long as there is a border 36 the exclusion 37 on the engine housing 20 is pending.
[0054] In an alternative embodiment not shown in the illustration, the heat sink 30 no exceptions 37 on. The heat sink 30 is then at least partially in contact with the engine housing along an edge that rests against the engine housing 20 welded together.
[0055] In an embodiment of the inventive method for assembling the power unit (not shown) 10 For a steering system, a connection is made between a heat sink 30 , on which a control electronics 40 is arranged for a motor of the steering system, and a motor housing 20 by means of crimping, welding, or screwing.
[0056] Optionally, after the connection between the heat sink has been made, 30 and engine housing 20 a first housing shell 61 on the engine housing 20pushed or pressed and against the outer wall 24 of the engine housing 20 fixed, especially glued, and then a second housing shell 62 attached and with the first housing shell 61 connected, in particular by laser beam welding or bonding. Before the connection between the heat sinks has been made. 30 and engine housing 20 For example, the heat sink 30 or the engine housing 20 They are manufactured by deep drawing, bending and stamping of a wrought aluminum alloy. QUOTES INCLUDED IN THE DESCRIPTION
[0057] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature
[0058] DE 102009000169 A1
[0002]
Claims
[1] Unit of power ( 10 ) for an electric steering system – a motor housing ( 20 ) to house an engine, – a heat sink ( 30 ), and – one on the heat sink ( 30 ) arranged control electronics ( 40 ) for the engine, where the heat sink ( 30 ) and the engine housing ( 40 ) are connected to each other in such a way that heat exchange from the control electronics ( 40 ) via the heat sink ( 30 ) on the engine housing ( 20 ) is possible, characterized by that the heat sink ( 30 ) at least partially with the engine housing ( 20 ) is connected by means of crimping and / or welding and / or screwing. [2] Device according to claim 1, characterized by that the heat sink ( 30 ) in its main extension plane at least partially on one end face ( 23) of the engine housing ( 20 ), in which there is an opening ( 25 ) of the engine housing ( 20 ) is located above the engine housing ( 20 ) protrudes. [3] Device according to claim 1 or 2, characterized by that a front face ( 23 ) of the engine housing ( 20 ), in which there is an opening ( 25 ) of the engine housing ( 20 ) is located, is designed in a graduated manner. [4] Device according to any one of claims 1 to 3, characterized by that caulking by means of at least one on one end face ( 23 ) of the engine housing ( 20 ), in which there is an opening ( 25 ) of the engine housing ( 20 ) is located, formed and bent or riveted tab ( 27 ) and at least one associated exception ( 37 ) in the heat sink ( 30 ) is formed. [5] Device according to any one of claims 1 to 4, characterized by that the heat sink ( 30) at least partially with the engine housing ( 20 ) is caulked by the heat sink ( 30 ) on one end ( 33 ) of the heat sink ( 30 ) a groove ( 38 ) and the engine housing ( 20 ) on an inner wall ( 24 ) of the engine housing ( 20 ) a spring ( 28 ) exhibiting features that are interlocked. [6] Device according to claim 5, characterized by that the engine housing ( 20 ) at least partially a gap ( 29 ) on one end ( 23 ) of the engine housing ( 20 ) in an area where the motor housing ( 20 ) on the inner wall ( 24 ) of the engine housing ( 20 ) the spring ( 28 ) exhibits. [7] Device according to any one of claims 1 to 6, characterized by that the screwing together by means of at least one screw ( 50 ), which is caused by a breakthrough ( 53 ) in the heat sink ( 30) into a thread ( 52 ) in the engine housing ( 20 ) attacks, is formed. [8] Device according to any one of claims 1 to 7, characterized by that the welding is designed as laser beam welding. [9] Device according to any one of claims 1 to 8, characterized by that the heat sink ( 30 ) at least one exception ( 36 ) has a border ( 37 ) the exclusion ( 36 ) at least partially on one end face ( 23 ) of the engine housing ( 25 ), in which there is an opening ( 25 ) of the engine housing ( 20 ) is located, is adjacent and the motor housing ( 20 ) with the heat sink ( 30 ) at least partially along the adjacent edge ( 36 ) is welded together. [10] Device according to any one of claims 1 to 9, characterized by that the heat sink ( 30 ) with the control electronics arranged on it ( 40) at least partially from an additional housing ( 60 ), in particular enclosed in a plastic housing. [11] Device according to any one of claims 1 to 10, characterized by that the engine housing ( 20 ) and / or the heat sink ( 30 ) is formed from an aluminum wrought alloy by deep drawing. [12] Method for assembling a power unit ( 10 ) having a motor housing ( 20 ) to house a motor, a heat sink ( 30 ), and one on the heat sink ( 30 ) arranged control electronics ( 40 ) for the engine, characterized by that a connection between heat sink ( 30 ) and the engine housing ( 20 ) by means of crimping and / or welding and / or screwing. [13] Method according to claim 12, characterized by that after the connection has been made, a first housing shell ( 61 ) on the engine housing ( 20) pushed and against an outer wall ( 26 ) of the engine housing ( 20 ) is fixed, in particular glued, and then a second housing shell ( 62 ) placed and with the first housing shell ( 61 ), in particular by means of laser beam welding. [14] Method according to claim 12 or 13, characterized by that the engine housing ( 20 ) and / or the heat sink ( 30 ) are produced by deep drawing a wrought aluminum alloy.