Drive mechanism for a brake system of a motor vehicle

Abstract

The invention relates to a drive mechanism (1) for a braking device of a motor vehicle, comprising an electric motor (2) with a housing (5), the electric motor having a rotor (4) rotatably mounted in the housing (5), and a rotor position sensor mechanism (7), the rotor position sensor mechanism having a printed circuit board (8) with at least one sensor element assigned to the rotor (4), wherein the printed circuit board (8) is designed in the form of an annular disk and is arranged coaxially with the axis of rotation of the rotor (4). According to the invention, it is provided that the printed circuit board (8) is fastened in or to the electric motor (2) by means of at least one latching connection (17).

Description

Technical Field

[0001] The present invention relates to a drive mechanism for a braking device of a motor vehicle, comprising an electric motor with a housing, the electric motor having a rotor rotatably mounted in the housing, and a rotor position sensor mechanism having a printed circuit board with at least one sensor element assigned to the rotor, wherein the printed circuit board is designed in the form of an annular disk and is arranged coaxially with the axis of rotation of the rotor. Background Art

[0002] Precise control of electrically commutated electric motors requires the ability to determine the rotor angular position of the motor's rotor at all times so that one or more phases of the drive winding can be controlled based on the current rotor angular position. This requires the sensor element, which is used to detect the rotor angular position, to be permanently fixed in the correct position. When using inductive sensor elements, such as those used in resolvers, the use of metallic conductive fastening elements is disadvantageous because these fastening elements can negatively affect the function and angular accuracy of the sensor element. Furthermore, the motor's ambient temperature can sometimes fluctuate significantly during operation. These temperature fluctuations can affect the material and, if sensor components are made of materials with different coefficients of thermal expansion, lead to deformations of the rotor angular position sensor. Summary of the Invention

[0003] The drive mechanism according to the invention, having the features of claim 1, has the following advantages: a particularly simple installation of the rotor position angle sensor on the motor is provided in a cost-effective and advantageous manner, which also allows compensation for different coefficients of expansion in a simple manner. According to the invention, the printed circuit board of the drive mechanism is fastened in or on the motor by at least one latching connection, in particular made of a synthetic material. The latching connection allows the printed circuit board to be mounted particularly simply on the drive mechanism or the motor, and the latching connection is also releasable when necessary. The latching connection is in particular designed as a latching connection that can be releasable without destruction. Alternatively, the latching connection is designed as a latching connection that can be releasable only by destruction, which ensures a particularly high degree of reliability against unintentional release. The latching connection preferably creates a play between the printed circuit board and the motor, which ensures that changes in length due to different coefficients of thermal expansion during temperature fluctuations do not lead to mechanical stresses in the motor.

[0004] For this purpose, the printed circuit board is preferably pre-mounted on an annular carrier element, and the carrier element and the motor are provided with a latching connection. Pre-mounting allows for simple and reliable fastening of the printed circuit board to the carrier element, and the latching connection allows for simple installation of the carrier element with the printed circuit board in or on the motor. During pre-mounting, the printed circuit board is, for example, screwed, glued, or clamped to the carrier element, particularly outside the motor, thereby further simplifying installation.

[0005] The carrier element preferably has at least one axially protruding, elastically deformable retaining lug, which, in the installed state, engages the retaining section of the motor from behind. During installation, the retaining lug is pushed through the opening of the retaining section due to its elastic deformation, so that after passing through the opening, the retaining lug returns to its original shape due to its inherent elasticity and thus engages the retaining section of the motor from behind, thereby securing the carrier element to the motor in a form-fitting manner.

[0006] The electric motor preferably has a bearing shield, by which the motor's rotor is rotatably supported in the housing, and which forms a retaining section. To provide a rotating bearing arrangement for the motor's shaft, in particular for the motor's rotor shaft, it is known to use one or more bearing shields. These bearing shields are fastened, for example, clamped or screwed, to the motor's housing, thereby creating a wall in the housing that is particularly oriented perpendicular to the rotor's axis of rotation. An opening is particularly formed in the bearing shield, through which the rotor shaft is guided, and in which a rolling element bearing is typically retained. The inner ring of the rolling element bearing is held rotationally fixed to the rotor shaft, and the outer ring of the rolling element bearing is fixedly held relative to the housing on the bearing shield. The retaining section is preferably designed to be integrated into such a bearing shield, so that a latching connection acts between the carrier element and the bearing shield. This allows for an advantageous arrangement of the rotor position sensor mechanism close to the motor, directly on the bearing shield.

[0007] According to a preferred refinement of the present invention, the carrier element has three locking lugs, which are arranged evenly distributed over the circumference of the carrier element. The bearing cap has three retaining sections that interact with the locking lugs. The respective retaining sections, in particular, have a depression or recess for the respective locking lug, into which the locking lug can be introduced under elastic deformation to engage the respective retaining section from behind. The carrier element preferably has only three locking lugs, which are arranged evenly distributed over the circumference of the carrier element. Optionally, the carrier element may have more than three locking lugs.

[0008] The retaining lugs are preferably mounted radially displaceably on the corresponding retaining sections, in particular, in the respective recesses of the respective retaining sections, relative to the rotor's axis of rotation. This allows the retaining lugs to be radially displaceable in the bearing shield, which is arranged coaxially with the rotor shaft. This displacement prevents temperature-induced length differences from mechanically clamping or over-clamping the carrier element and the bearing shield during temperature fluctuations. Conversely, if, for example, the material of the carrier element experiences a greater increase in size than the bearing shield due to its coefficient of thermal expansion, the respective retaining lugs can be displaced radially outward. This radial displacement ensures that the rotor position sensor assembly remains centrally or centered on the bearing shield. The retaining lugs and retaining sections are arranged evenly distributed on the bearing shield or carrier element, so that they are each oriented at an angle of 120° relative to one another. This allows the carrier element to undergo an increase or change in diameter without being displaced or twisted in the circumferential direction. This ensures that the rotor position sensor assembly always maintains its optimal orientation relative to the rotor of the electric machine.

[0009] For this purpose, the respective retaining sections preferably have recesses each configured as elongated holes, which extend radially or are radially oriented in their longitudinal extent. This results in the advantages mentioned above. Due to the elongated hole shape, the retaining lugs are guided radially displaceably. In particular, the radial guidance reliably prevents the carrier element and, therefore, the rotor position sensor assembly from twisting or tilting.

[0010] The locking lug preferably has a rectangular or circular cross-section for radial displacement over the corresponding recess, wherein the cross-section has a long side and a short side, and wherein the long side is oriented parallel to the radial direction. In this way, the locking lug interacts with the recess as a centering element, which has radial play. This allows the diameter of the carrier element to be varied without thereby changing the orientation of the rotor position sensor relative to the motor.

[0011] The carrier element is preferably made of a synthetic material. This allows for a cost-effective design of the carrier element, particularly allowing for an integral design of the retaining lug and the carrier element, thereby further simplifying assembly. The corresponding retaining section of the bearing cap, in particular the entire bearing cap, is preferably made of metal to ensure a particularly robust design.

[0012] According to a preferred refinement, the respective locking lugs are slit-shaped in their radial longitudinal extension, so that each locking lug has two locking lug sections that can be moved toward each other under elastic deformation when engaged in the retaining section. The locking lug sections thus support each other, ensuring a particularly secure locking connection. In particular, each locking lug is thus held in a self-supporting manner on the respectively assigned retaining section. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The present invention will be described in detail below with the help of the accompanying drawings, wherein:

[0014] Figure 1 A simplified diagram shows an advantageous drive mechanism for a braking system of a motor vehicle,

[0015] Figure 2 A perspective exploded view of the bearing cap of the drive with the carrier element,

[0016] Figure 3 A detailed view of the bearing cap and the carrier element is shown and

[0017] Figure 4 A schematic top view of the bearing cap is shown. DETAILED DESCRIPTION

[0018] Figure 1 The simplified diagram shows an advantageous drive mechanism 1 for a consumer (not shown in detail here) of a braking system of a motor vehicle. The braking system is, for example, a parking brake of the motor vehicle, and the consumer is an axially displaceable brake piston that cooperates with a brake disk of a motor vehicle wheel.

[0019] To operate a consumer, a drive mechanism 1 includes an electric motor 2 with a drive shaft 3, wherein a rotor 4 is arranged on the drive shaft in a rotationally fixed manner, and the drive shaft 3 is rotatably supported in a housing 5, which is only schematically shown here. The rotor 4 is associated with a stator 6, which is arranged fixedly relative to the housing. The stator 6 or rotor 5 has, in particular, a multi-phase drive winding that can be supplied with voltage via power electronics (not shown here) to generate a rotating magnetic field. Through this rotating magnetic field, the electric motor 2 generates a torque that is transmitted by the drive shaft 3 to the consumer 2. To this end, the drive shaft 3 is coupled to the consumer, for example permanently or for desired time intervals.

[0020] The rotor 4 of the electric motor 2 is equipped with a rotor position sensor assembly 7 that continuously monitors the rotor angular position of the rotor 4 during operation by means of induction. To this end, the rotor position sensor assembly 7 includes a printed circuit board 8, which, according to the present embodiment, is designed in the form of an annular disk and is assigned to the end face of the rotor 4 coaxially with the drive shaft 3. The printed circuit board 8 carries a rotor angular position sensor 12 on its front side 9 facing the rotor 4. This rotor angular position sensor preferably includes one or more transmitter coils and a receiver coil, as well as a control unit or computing unit, particularly an electronic evaluation unit 11, such as an analog ASIC, arranged on a rear side 10 of the printed circuit board 8 facing away from the front side 9, which operates the coils. According to the present embodiment, the evaluation unit 11 is also arranged on the front side 9 of the printed circuit board 8 facing the rotor 4, next to the coils of the rotor angular position sensor 12. The transmitter coil is applied with a modulated signal, which is induced into the rotor 4 and then conducted back from the rotor 4 to the receiver coil. The received signal is demodulated and evaluated by the evaluation unit 11 to determine the current rotor angular position. Rotor position sensor 8 is therefore designed as a resolver.

[0021] Printed circuit board 8 is fastened to a carrier element 13, which is annular in shape. Carrier element 13 is coaxially assigned to the end face of rotor 4 with respect to drive shaft 3 and is held on a bearing cap 14. Bearing cap 14 extends radially inward from a housing wall 15 of housing 5 toward drive shaft 3. Arranged between drive shaft 3 and bearing cap 14 is at least one rotary bearing 16, in the present case in the form of a rolling element bearing, the inner ring of which rests on drive shaft 3 and the outer ring of which is fastened to bearing cap 14. Drive shaft 3 is thus advantageously rotatably supported on housing 5.

[0022] The carrier element 13 is fastened to the bearing cover 14. For this purpose, there are a plurality of latching connections 17 which, when referring to Figures 3 to 4 This is described in detail below.

[0023] Figure 2 For this purpose, the bearing cap 14 and the carrier element 13 are shown in a perspective exploded view. The carrier element 13 has, on its end face 3 facing the bearing cap 14, axially protruding locking lugs 18, which are arranged evenly spaced apart on the circumference of the carrier element 13. The bearing cap 14 has three retaining sections 20 on the end side 19, which are formed in the bearing cap 14 corresponding to the locking lugs 18. A recess 21 is formed in each retaining section 20, which is used to receive one of the locking lugs 18.

[0024] Figure 3For this purpose, the functioning principle of the corresponding latching connection 17 is shown in a simplified detail view. Figure 3 The figure shows a cross-section of one of the latching connections 17 in the still unconnected state. Each latching nose 18 of the carrier element 13 has a rectangular cross section and has two laterally protruding latching projections 22 on its free end sides. The respective latching nose 18 is designed to be slotted so that the longitudinal cut 23 is located between the latching projections 22. The slots 23 are designed to be wide enough so that the latching nose sections created by the slots 23 can move towards each other, e.g. Figure 3 Indicated by arrow 24. The spacing of the locking projections 22 relative to each other is greater than the clear width of the corresponding recess 21 in the bearing cover 14. If the locking nose 18 is now pushed into the associated recess 21, the locking projections 22 move toward each other under elastic deformation via their corresponding starting bevels 25 (which hit the holding section 20 of the bearing cover 14), so that the locking nose 18 can completely penetrate the recess 21 until the locking projection 22 completely penetrates the recess 21, so that it can then be re-springing radially outwards, whereby the bearing cover 14 is engaged from behind on the holding section 20 via the corresponding locking nose 18 in a form-fitting manner. Alternatively, the locking nose 18 is designed to have a rectangular cross section, as in Figure 2 According to a further exemplary embodiment, it is provided that the retaining nose has a circular cross section or a circular contour.

[0025] Figure 4 A top view of the end face of the bearing cap 14, specifically the face facing away from the carrier element 13, is shown. It can be seen that the recesses 21 are each configured as elongated holes or rectangles, with their longitudinal extension extending radially relative to the center Z of the bearing cap 14 or the axis of rotation of the drive shaft 3. Since the recesses 21 are also arranged evenly distributed over the circumference of the end face of the bearing cap 14, they are each located at an angle of 120° relative to one another, corresponding to the latching projections 18.

[0026] By the rectangular cross section of the stop projection 18, as in Figure 4 As can also be clearly seen in the figure, and by the elongated hole-shaped structure of the recess 21, the locking nose 18 is in this case supported radially displaceably in the associated recess 21, as shown in FIG. Figure 4 This is indicated by the double arrow 26. Thus, even when the carrier element 18 is locked on the bearing cap 14, there is a radial play, which does not change the orientation of the carrier element 13 on the bearing cap 14 despite the different coefficients of thermal expansion of the carrier element 13 and the bearing cap 14. In particular, a rotation about the center Z is advantageously avoided by the advantageous locking device.

[0027] By using the advantageous locking geometry described above, rotor position sensor 8 is held in position such that it permanently maintains a stable, accurately positioned position relative to electric motor 2 and ensures adequate tolerance compensation in the radial direction. Preferably, carrier element 13 is made of plastic, and bearing shield 14 is made of metal. The plastic carrier element 13 reliably prevents electrically conductive connections between the rotor position sensor and bearing shield 14. Furthermore, the locking device provides a durable secure position over the entire life of drive mechanism 1, even under the most diverse temperature conditions. The advantageous orientation of recess 21 and locking projection 18 ensures that carrier element 13 remains fixed in the rotational center of drive shaft 3 or rotor 3 over the entire temperature range. Drive mechanism 1 is easily assembled by joining carrier element 18 to bearing shield 14 under elastic deformation of the locking projection. The locking lugs 18 ensure that even with varying thermal expansion of the materials used, slight radial sliding of the locking lugs 18 in the respective recesses 21 is possible.

Claims

1. A drive mechanism (1) for a braking device of a motor vehicle, comprising an electric motor (2) with a housing (5), the electric motor having a rotor (4) rotatably mounted in the housing (5), and a rotor position sensor mechanism (7), the rotor position sensor mechanism having a printed circuit board (8) with at least one sensor element assigned to the rotor (4), wherein: The printed circuit board (8) is designed in the shape of an annular disk and is arranged coaxially with the axis of rotation of the rotor (4), characterized in that the printed circuit board (8) is fastened in or on the motor (2) by means of at least one locking connection (17), wherein the printed circuit board (8) is pre-mounted on an annular carrier element (13), wherein the carrier element (13) has at least one axially protruding and elastically deformable locking nose (18), which in the mounted state engages from behind an associated retaining section (20) of the motor (2), wherein the locking nose (18) is supported radially displaceably in a recess (21) of the retaining section (20).

2. The driving mechanism according to claim 1, wherein: The carrier element (13) forms the locking connection (17) together with the electric motor (2).

3. The driving mechanism according to claim 1, wherein: The electric motor (2) has a bearing cover (14) by which a drive shaft (3) of the electric motor (2) carrying the rotor (4) is rotatably mounted and which forms a corresponding retaining section (20).

4. The driving mechanism according to claim 3, characterized in that: The carrier element (13) has three retaining noses (18) which are arranged evenly distributed over the circumference of the carrier element (13), and the bearing cover (14) has three retaining sections (20) which cooperate with the retaining noses (18).

5. The driving mechanism according to claim 4, characterized in that: The respective recess (21) is designed in the form of an elongated hole and is oriented radially in its longitudinal extension.

6. The driving mechanism according to claim 4, characterized in that: The retaining nose (18) has a rectangular cross section for radial displacement in a corresponding recess (21), wherein the cross section has a long side and a short side, and wherein the long side is oriented parallel to the radial direction.

7. The driving mechanism according to claim 1, wherein: The carrier element (13) is made of plastic and / or the holding section (20) is made of metal.

8. The driving mechanism according to claim 4, characterized in that: The respective locking lugs (18) are slit-shaped in their radial longitudinal extension so that the locking lug sections can be moved toward each other under elastic deformation when they are engaged in the retaining section (20).

Images