ELECTRIC MOTOR OF A MOTOR VEHICLE

Abstract

An electric motor of a motor vehicle, in particular a steering motor, includes a housing having a motor compartment and an electronics compartment. The motor compartment and the electronics compartment are separated by a housing wall that has a plurality of openings. A stator is situated in the motor compartment and an electronics system is situated in the electronics compartment. The stator and the electronics system electrically contact one another through phase connections which project through the openings. A separating element is situated between the stator and the electronics system. The separating element at least partially covers the openings and the housing wall.

Claims

1. An electric motor or a steering motor of a motor vehicle, the electric motor comprising: a housing having a motor compartment, an electronics compartment and a housing wall separating said motor compartment and said electronics compartment from each other, said housing wall having a plurality of openings formed therein; a stator disposed in said motor compartment and an electronics system disposed in said electronics compartment; phase connections protruding through said openings and placing said stator and said electronics system in electrical contact with each other; and a separating element disposed between said stator and said electronics system, said separating element at least partially covering said openings and said housing wall.

2. The electric motor according to claim 1, wherein said separating element is disposed between said housing wall and said stator.

3. The electric motor according to claim 1, wherein said separating element is film-shaped.

4. The electric motor according to claim 3, which further comprises a number of said phase connections and a number of main slots formed in said separating element corresponding to said number of phase connections, each of said phase connections protruding through a respective one of said main slots.

5. The electric motor according to claim 4, which further comprises further slots, at least a respective one of said further slots opening into each of said main slots, and said further slots extending nonparallel to said main slots.

6. The electric motor according to claim 1, wherein said separating element has a bonding layer adhering to said housing wall.

7. The electric motor according to claim 1, wherein said separating element has at least one electrically insulating layer.

8. The electric motor according to claim 1, wherein said separating element has a layer having at least one of an electrically or magnetically shielding effect.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0037] FIG. 1 is a diagrammatic, perspective view of an electric steering system of a motor vehicle, including an electric motor;

[0038] FIG. 2 is an exploded, perspective view of sections of the electric motor, which includes a separating element;

[0039] FIGS. 3 and 4 are longitudinal-sectional views of the electric motor;

[0040] FIG. 5 is a fragmentary, longitudinal-sectional view of the separating element;

[0041] FIG. 6 is a fragmentary, plan view of one alternative embodiment of the separating element; and

[0042] FIGS. 7, 8 and 9 are fragmentary, plan views of further alternatives of the separating element.

DETAILED DESCRIPTION OF THE INVENTION

[0043] Referring now in detail to the figures of the drawings, in which mutually corresponding parts are provided with the same reference characters, and first, particularly, to FIG. 1 thereof, there is seen a diagrammatically simplified view of an adjustment drive 2 of a motor vehicle 4 in the form of an electric steering system (power steering system). The motor vehicle 4 has a steering wheel 6 which is coupled to a toothed rack 10 by a steering track rod 8 and a pinion 12. The toothed rack 10 is coupled to two front wheels 14, each of which is to be pivoted about a substantially perpendicularly extending axis 16 when the steering wheel 6 is turned for steering. The steering track rod 8 is split into two parts which are connected to each other by a rod 18. A first sensor 20 is assigned to the part of the steering track rod 8 located between the rod 18 and the steering wheel 6 and a second sensor 22 is assigned to the part of the steering track rod 8 located between the pinion 12 and the rod 18, the first sensor 20 and the second sensor 22 being connected to a control unit 24 by signaling.

[0044] Moreover, an electric motor 26 is assigned to the part of the steering track rod 8 located between the pinion 12 and the rod 18. The electric motor 26 is controlled by the control unit 24 and is configured as a brushless DC motor (BLDC). An angular offset between the two parts of the steering track rod 8 is detected by the two sensors 20, 22 and therefore a desired steering angle of the front wheels 14 is ascertained. If the angular offset is present, the electric motor 26 is energized in such a way that the rotation of the steering track rod 8 is assisted.

[0045] FIG. 2 shows an exploded representation of the electric motor 26 in sections, wherein the individual integral parts are pulled apart from one another along a longitudinal axis 28. In FIG. 3, the electric motor 26 is shown in a longitudinal section along the longitudinal axis 28 in a partially pulled-apart state and, in FIG. 4, in a longitudinal section along the longitudinal axis 28 in a joined state. The electric motor 26 has a housing 30 which has been made of aluminum in a cold extrusion process. The housing 30 is substantially hollow cylindrical and has a round base surface, the axis of the cylinder coinciding with the longitudinal axis 28. The housing has a housing wall 32 which is disposed perpendicularly to the longitudinal axis 28 and is integral with and disposed inside of the hollow cylinder. The housing wall 32 is disposed between the two ends of the hollow cylinder, forming a motor compartment 34 and an electronics compartment 36, which are separated from each other by the housing wall 32.

[0046] The housing wall 32 has three openings 38 which have a circular cross-section and which connect the motor compartment 34 and the electronics compartment 36 to each other. The openings 38 are offset from the longitudinal axis 28 and a cut-out 40 is introduced into the housing wall 32 in the center with respect to the longitudinal axis 28 and is delimited by a collar 42. The collar 42 is a hollow cylindrical section which is disposed concentrically to the longitudinal axis 28 and which delimits the cut-out 40 at its radially outer end.

[0047] The electric motor 26 also has a stator 44 which includes multiple electrical coils 46 which are connected by an interconnection ring 48 to form a total of three phases. The electrical phases are connected by the interconnection ring 48 to form a delta connection. The electrical coils 46 are each on a laminated core and are joined to form a circular structure 50 and are stabilized with respect to one another. The axis of each of the electrical coils 46 is disposed on a radial straight line with respect to the longitudinal axis 28.

[0048] The interconnection ring 48 forms one of the end faces of the stator 44 and three phase connections 52 are in electrical contact with and fastened to the interconnection ring 48. The phase connections 52 extend parallel to the longitudinal axis 28 and are offset with respect to one another by 120° with respect to the longitudinal axis 28. Each of the phase connections 52 has a copper sheet strip 54, each of which is stabilized by a mounting 56 made of a plastic. The mounting 56 is integrally formed on a part of the interconnection ring 48 which is also made of a plastic, and is integral therewith. Each of the copper sheet strips 54 is in electrical contact with an assigned electrical conductor of the interconnection ring 48, which is used to electrically contact the electrical coils 46. In the assembled state, each phase connection 52, namely the particular copper sheet strip 54, protrudes at the end through one assigned opening 38 into the electronics compartment 36.

[0049] A rotor 58 is surrounded by the stator 44 and has a laminated core and multiple permanent magnets fastened thereto. The rotor 58 is fastened to a motor shaft 60, which is disposed along the longitudinal axis 28. The motor shaft 60, the rotor 58 and the stator 44 are disposed concentrically to the longitudinal axis 28. The motor shaft 28 is mounted by a B-side bearing 62 and an A-side bearing 64 so as to be rotatable about the longitudinal axis 28. The B-side bearing 62 is guided on the housing wall 32 and is therefore a floating bearing. To this end, the B-side bearing 62 is inserted into the collar 42. The motor shaft 60 protrudes through the housing wall 32 into the electronics compartment 36. The A-side bearing 64 is fastened to an A-side bearing shield 66, through the use of which the motor compartment 34 is closed on the side opposite the housing wall 32. To this end, the A-side bearing shield 66 is placed onto the edge of the housing 30 and fastened there.

[0050] An electronics system 70 is disposed in the electronics compartment 36, the electronics system 70 not being shown in greater detail in FIG. 4. The electronics system 70 has a printed circuit board 72, on which multiple semiconductor switches 74 are disposed, of which two are shown. The semiconductor switches 74 are connected to one another to form a B6 circuit and the semiconductor switches 74 are activated by using further electrical/electronic components which are also fastened to the printed circuit board 72. In the assembled state, the phase connections 52 are in electrical contact with the electronics system 70, so that the electrical coils 46 can be energized by using the electronics system 70. The electronics system 70 is therefore used to energize the electrical coils 46. In other words, the stator 44 and the electronics system 70 are in electrical contact with each another.

[0051] A separating element 76, which is disposed perpendicularly to the longitudinal axis 28, is disposed between the electronics system 70 and the stator 44. The separating element 76 is disposed in the motor compartment 34 and, therefore, is disposed between the housing wall 32 and the stator 44. The separating element 76 is made of a film and thus is film-shaped and is adhesively bonded to the housing wall 32. To this end, the separating element 76, as shown in FIG. 5 in a sectional representation along the longitudinal axis 28, has a bonding layer 78 which adheres to the housing wall 32. Two layers 80 are mounted on the bonding layer 78 and are stacked one on top of the other. One of the layers 80 has an electrically shielding effect. To this end, this layer 80 is made of an electrically conductive material and is electrically contacted to ground. The further layer 80 has a magnetically shielding effect and is made of a plastic, into which diamagnetic particles are introduced. In a variant which is not shown in greater detail, the two layers 80 are not present.

[0052] However, the separating element 76 always has an electrically insulating layer 82 which is made of a polyester film. Therefore, if the two layers 80 are not present, only the insulating layer 82, i.e., the polyester film, and the bonding layer 78 are present.

[0053] The thickness of the separating layer 76 is less than 0.1 mm and the separating element 76 is flexible. The separating element 76 has an annular cross-section, wherein the outer diameter of the separating element 76 is slightly smaller than the inner diameter of the motor compartment 34, i.e., of the housing 32, and the inner diameter is slightly greater than the outer diameter of the collar 42. Multiple notches 83 are introduced into the periphery of the separating element 76 and are enclosed by projections (not shown in greater detail) on the housing wall 32. A rotation lock is therefore established.

[0054] In the assembled state, the openings 38 and the housing wall 32 are covered by the separating element 76 and, therefore, the phase connections 52 protrude through the separating element 76. To this end, the separating element 76 has three main slots 84, which are introduced into the separating element 26 by cutting or punching. Each of the main slots 84 extends substantially radially with respect to the longitudinal axis 28 and one of the phase connections 52 is assigned to each of the main slots 84. Therefore, one of the phase connections 52 in each case protrudes through each of the main slots 84. Two further slots 86 open into each of the main slots 84. The two further slots 86 are disposed at opposite ends of the main slot 84 and extend obliquely, i.e., not in parallel, to the main slot 84. A Z-shape is therefore realized by each of the main slots 84 and the associated further slots 86.

[0055] Due to the insulating layer 82, a short circuit to ground, i.e., a short circuit of the stator 44 by the housing wall 32, is also prevented when the stator 44 approaches the housing wall 32. Safety of the electric motor 26 is therefore increased. Since the openings 38 are partially covered by the separating element 76, a passage of particles out of the motor compartment 34 into the electronics compartment 36 is prevented or at least made difficult in the area of the phase connections 52. Therefore, a comparatively cost-effective electronics system 70 can be used. Tolerance compensation is also created by the flexible separating element 76. In order to avoid the passage of the particles, it is merely necessary to at least partially cover the openings 38 by the separating element 76. Provided that the openings 38 are selected to be comparatively large, it is possible to select comparatively large production tolerances for the housing 30 and for the phase connections 52 and the stator 44, wherein the passage of particles is nevertheless prevented. An electrical short circuit between the phase connections 52 and the housing wall 32 through the air gap which is formed in this way is also prevented due to the enlarged openings 38. In addition, air is permitted to pass due to the at least partial air permeability through the separating element 76, at least in the area of the main slots 84, which is why the motor compartment 34 can be ventilated.

[0056] FIG. 6 shows a modification of the separating element 76 in part. The main slot 84 shown, of which three are once again present, still extends radially. The two further slots 86 are located on opposite longitudinal sides of the main slot 84 and extend perpendicularly to the main slot 84. It is therefore made possible to guide through the separating element 76 without the separating element 76 tearing in an uncontrolled manner also for the case in which the phase connections 52 are not aligned with the main slot 84 prior to insertion. In further variants which are not shown in greater detail, the notches 83 are not present. Any other type of modification is advantageously not carried out.

[0057] FIG. 7 shows one further alternative in part. Four further slots 86 are now assigned to the main slot 84 shown, wherein two of the slots 86 are located on the same side, in each case, with respect to the main slot 84. The further slots 86 are disposed perpendicularly to the main slot 84.

[0058] FIG. 8 shows a modification of the variant shown in FIG. 7. The four further slots 86 are once again present, wherein the slots 86 are slanted, however, by 45° with respect to the main slot 84. A herringbone pattern is therefore realized.

[0059] FIG. 9 shows one further alternative. Four further slots 86 are assigned to each of the sides of the main slot 84, and so, overall, eight such further slots 86 are present.

[0060] The invention is not limited to the above-described exemplary embodiments. Rather, other variants of the invention can also be derived therefrom by a person skilled in the art without departing from the subject matter of the invention. In particular, all individual features described in conjunction with the individual exemplary embodiments are also combinable with one another in another way without departing from the subject matter of the invention.

[0061] The following is a summary list of reference numerals and the corresponding structure used in the above description of the invention.

LIST OF REFERENCE CHARACTERS

[0062] 2 adjustment drive [0063] 4 motor vehicle [0064] 6 steering wheel [0065] 8 steering track rod [0066] 10 toothed rack [0067] 12 pinion [0068] 14 front wheel [0069] 16 axis [0070] 18 rod [0071] 20 first sensor [0072] 22 second sensor [0073] 24 control unit [0074] 26 electric motor [0075] 28 longitudinal axis [0076] 30 housing [0077] 32 housing wall [0078] 34 motor compartment [0079] 36 electronics compartment [0080] 38 opening [0081] 40 cut-out [0082] 42 collar [0083] 44 stator [0084] 46 electrical coil [0085] 48 interconnection ring [0086] 50 circular structure [0087] 52 phase connection [0088] 54 copper sheet strip [0089] 56 mounting [0090] 58 rotor [0091] 60 motor shaft [0092] 62 B-side bearing [0093] 64 A-side bearing [0094] 66 A-side bearing shield [0095] 70 electronics system [0096] 72 printed circuit board [0097] 74 semiconductor switch [0098] 76 separating element [0099] 78 bonding layer [0100] 80 layer [0101] 82 insulating layer [0102] 83 notch [0103] 84 main slot [0104] 86 further slot