Electric motor for motor vehicle

Abstract

The invention relates to an electric motor (10) of a motor vehicle (2), comprising a housing (18) on which a bearing shield (26) is fastened, on which a bearing (28) is held, by means of which a shaft (30) is rotatably mounted about an axis of rotation (16), and comprising a sensor system (50) for determining the position of the shaft (30). The sensor system (50) has two sensor units (58), each including a contact transmitter (56), and a sensor transmission (62), which includes a gear (61) fastened to a shaft (30), which meshes with another gear (70) fastened to another shaft (63), which is rotatably supported about another axis of rotation (66). The sensor system (50) is designed in such a way that, when the shaft (30) rotates, the two contact emitters (56) move, the rotational speeds of which differ, and the sensor transmission (62) comprises a mechanical backlash compensation element (72). The invention also relates to an auxiliary unit (8) of a motor vehicle (2).

Description

[0001] This invention relates to an electric motor having a housing including a bearing guard on which a bearing is held. The electric motor is a component of a motor vehicle. The invention also relates to an auxiliary unit of a motor vehicle.

[0002] Motor vehicles, such as passenger cars, typically have a steering system by means of which the direction of travel is adjusted. Typically, the steering system includes a steering wheel located inside the vehicle and connected to the steering column. At its end is a gear that meshes with a rack, which is supported on the vehicle's pivotable front wheels (and possibly the rear wheels). Therefore, when the steering wheel is rotated, the rack moves laterally, and the steering angle of the wheels changes.

[0003] To enhance comfort, a steering motor designed as an electric motor is often provided. This motor supports the driver's steering movements, reducing the force required to operate the steering wheel while still achieving proper wheel alignment. To reduce weight and improve safety in accidents, steering systems without mechanical coupling between the steering wheel and the front wheels are known. In this case, sensors detect the angular position of the steering wheel or other operating elements, and based on this position, a steering motor driving a rack is actuated. This system is also known as a "steer-by-wire" system.

[0004] In this scenario, the angular position predetermined by the operating element / operating device must always be translated to the corresponding angular position of the wheel, where minimizing tolerances is paramount. For this purpose, it is also necessary to determine the position of the motor shaft with relatively high precision so that the motor can be properly energized. Sensor systems are typically used to determine the shaft position. In this case, the contact transmitter of the sensor system, such as a permanent magnet, is usually fixed to the shaft. Hall sensors are fixed to the sensor system, and by means of the Hall sensors, the change in the supplied magnetic field over time is detected as the shaft rotates. However, in this case, only a relatively imprecise determination of the shaft position is permissible. This is insufficient, at least for applications in this type of steering system.

[0005] Another option is to use multiple magnetic poles and / or multiple Hall sensors in the case of permanent magnets. Therefore, the rotating magnetic field is detected several times per revolution of the shaft, which in principle improves resolution. However, in this case, for example, time-varying magnetic fields generated during motor operation may also have a greater impact on the operating mode of the Hall sensor, or the Hall sensor may be too inertial to correctly detect all changes. Therefore, the generated sensor data may contain at least slight errors. Consequently, relatively expensive Hall sensors are required.

[0006] Another option is to distribute the sensor system onto the rack. However, this requires additional assembly steps, thus extending manufacturing time. Furthermore, the rack is relatively unprotected, necessitating precautions to protect the sensor system, which increases manufacturing costs.

[0007] The object of the present invention is to provide a particularly suitable electric motor for a motor vehicle and a particularly suitable auxiliary unit for a motor vehicle, wherein manufacturing costs and / or manufacturing time are advantageously reduced.

[0008] According to the invention, with respect to the electric motor, this objective is achieved by the features of claim 1, and with respect to the auxiliary unit, this objective is achieved by the features of claim 13. Advantageous improvements and designs are the subject of the respective dependent claims.

[0009] An electric motor is a component of a motor vehicle. In other words, an electric motor is suitable, particularly for being provided and configured as a component of a motor vehicle in its assembled state. Motor vehicles are particularly land-connected and are preferably designed as multi-lane vehicles. In this case, the motor vehicle can be positioned substantially freely, particularly on the corresponding road. For this purpose, the motor vehicle conveniently has corresponding wheels. In short, preferably, the motor vehicle can be positioned substantially independently of other conditions on land. In other words, the motor vehicle is preferably not track-guided. Preferably, the motor vehicle is a passenger car or commercial vehicle, such as a truck or bus.

[0010] An electric motor is, for example, a component of the main drive system of a motor vehicle, thus driving the vehicle during operation. However, it is particularly preferred that the electric motor is a component of an auxiliary unit of the motor vehicle, thus not directly driving the vehicle. Specifically, the electric motor is a component of an adjusting drive, such as an electric seat adjuster or an electric window regulator. Alternatively, the electric motor is, for example, a component of a pump, such as a water pump or an oil pump. In another alternative, the electric motor is, for example, a component of a transmission actuator, and the auxiliary unit is particularly the transmission. In yet another alternative, the electric motor is, for example, a component of an air conditioning compressor.

[0011] However, it is particularly preferred that the auxiliary unit including the electric motor is the steering system. For example, the electric motor forms a steering motor. In this case, for example, when operated by means of the electric motor, the steering motion performed by the driver is supported. In other words, the steering system is mechanically designed, wherein there is mechanical coupling between the operating device such as the steering wheel and the wheels configured as controllable / steerable. However, it is particularly preferred that the steering system is configured as a so-called "steer-by-wire" system, and in particular, there is no direct mechanical operating connection between the operating device and the wheels configured as controllable / steerable. The electric motor preferably acts on the controllable / steerable wheels via a rack or the like. The gear meshing with the rack is conveniently driven by the electric motor. Preferably, a sensor is associated with the steering wheel or other operating device, which is connected to the electric motor, particularly electrically and / or by signal. In this case, the connection is, for example, direct or via a control unit, by means of which the operation of the electric motor is performed based on signals / data provided by the sensor. At least, the electric motor preferably operates according to data and / or signals generated / provided by means of the sensor.

[0012] The electric motor includes a housing, which may be designed as a single piece or multiple pieces. In particular, the housing is substantially hollow and cylindrical, and advantageously cup-shaped. The housing is preferably made of a metal such as aluminum, and advantageously made by aluminum die casting or extrusion. The housing extends particularly along the axis of rotation and / or is particularly concentrically arranged with the axis of rotation, at least in sections. A bearing housing is fastened to the housing. In this case, the housing is preferably closed on at least one side by the bearing housing. The bearing housing is particularly arranged substantially perpendicular to the axis of rotation. For example, the bearing housing is an A-side bearing housing. However, the bearing housing is particularly preferably a B-side bearing housing.

[0013] The bearing is held in a bearing housing. The bearing is preferably fastened to the bearing housing, or, for example, loosely inserted into a bearing housing. For example, the bearing is a sliding bearing. However, the bearing is preferably a roller bearing, such as a ball bearing or a needle roller bearing. The shaft of the motor is rotatably supported about the axis of rotation by a bearing. In this case, the shaft is preferably connected to the bearing housing by a bearing. For example, the inner ring of the bearing is fastened to the shaft, provided the shaft is designed as a roller bearing. The shaft is advantageously cylindrical and, for example, made of steel. The shaft advantageously extends along the axis of rotation and is preferably concentric with the axis of rotation. The rotor of the motor is suitably torsionally fastened to the shaft. The rotor is preferably arranged concentrically with the axis of rotation and includes, for example, multiple magnets. The motor suitably includes a stator also arranged concentrically with the axis of rotation. The stator is preferably substantially partially hollow cylindrical and, for example, surrounds the rotor circumferentially. In particular, the stator is fastened to a housing.

[0014] The electric motor also includes a sensor system for determining the position of the shaft. For this purpose, a sensor system is suitable, particularly provided and configured. The sensor system further comprises two sensor units, each including a corresponding contact emitter. Specifically, each sensor unit also includes a sensor operatively connected to the correspondingly associated contact emitter. In this case, only non-contact coupling exists. Each sensor can conveniently detect the position of the corresponding contact emitter. Specifically, at least one sensor is a Hall sensor. In this case, the contact emitter is specifically designed in a magnetic manner. Therefore, the manufacturing cost is relatively low. Alternatively or in combination, one of the sensor units is, for example, a so-called non-contact inductive position sensor. The latter specifically has a leaf-shaped or flower-shaped contact emitter, which is formed, for example, from a magnetic material or a conductor ring forming a closed profile. The sensor includes excitation coils, specifically arranged parallel to each other and spaced apart vertically from the axis of rotation. For example, the two sensor units operate in the same manner and are specifically designed to have identical structures. Therefore, the same components can be used. Alternatively, the two sensors may have different structures relative to each other, or particularly operate according to different principles. Therefore, robustness is increased, and adverse environmental conditions, such as those affecting the two sensor units, will not cause them to fail.

[0015] The sensor system also includes a sensor drive, comprising a gear fastened to a shaft. In this case, the gear is specifically positioned relative to the bearing on the side opposite to the possible rotor. Therefore, the gear does not obstruct the rotor and stator. The gear meshes with another gear, which is fastened to another shaft. This other shaft is rotatably supported about a different axis of rotation. Thus, when the shaft rotates, the other shaft also rotates. In this case, the other axis of rotation is parallel to the axis of rotation but laterally offset relative to it. In this case, the distance is predetermined, particularly by means of two gears. For example, the other gear and / or this gear is made of metal or plastic. For example, the gear is made of a metallic material, for example, by means of sintering. This increases robustness. For other purposes, the other gear is made of plastic, thereby improving acoustic characteristics.

[0016] The sensor system is designed such that two contact emitters move as the shaft rotates. In other words, the contact emitters are arranged such that they rotate as the shaft rotates. However, in this case, their rotational speeds are different from each other. Therefore, when the angular position of the shaft changes by a certain amount, the positions of the two contact emitters also change, and the changes between the two contact emitters are different. In particular, the different movements of the contact emitters occur due to the sensor drive mechanism. In short, the sensor system is therefore designed at least in part based on the vernier principle. Therefore, the position of the shaft can be determined relatively accurately with only two sensor units.

[0017] The sensor drive also includes a mechanical backlash compensation element. This backlash compensation element is used to compensate for the clearance between two rotating axes and / or two shafts. Specifically, it compensates for manufacturing tolerances and / or operational deviations. Therefore, the backlash compensation element is used to compensate for changes in distance / tilt between two shafts / gears / rotating axes, such as those caused by different thermal expansion. For this purpose, a backlash compensation element is suitable, and is specifically provided and installed. The backlash compensation element also specifically ensures that the two gears always mesh with each other, even if slight movement (e.g., tilting) occurs between the two rotating axes. Because the backlash compensation element is mechanically designed, the structure is simplified. Furthermore, for this purpose, no setting or adjustment of the backlash compensation element is required during motor operation.

[0018] Suitably, the motor includes electronics or at least one printed circuit board, specifically arranged perpendicular to the axis of rotation. At least one, preferably two, corresponding sensor units are conveniently fastened to the printed circuit board, keeping the latter stationary. In this case, the two sensors are conveniently assigned to the same printed circuit board, thus simplifying assembly. The printed circuit board is preferably arranged within the electronics compartment of the motor. Therefore, the infiltration of foreign particles is avoided, thereby preventing failure of the two sensor units. For example, another electronic device, or preferably electronic device, is also used specifically to energize other components of the motor (preferably the stator). In this case, the electronic device relies particularly on data provided by the sensor system for operation. Preferably, the electronic device includes a bridging circuit, such as a B6 circuit. For example, the motor is a brushed commutator motor. However, particularly preferably, the motor is brushless, and advantageously a brushless DC motor (BLDC). Advantageously, the electronic device includes a B12 circuit, and the motor has twice the phase, each phase connected in a star configuration.

[0019] Preferably, the retainer is connected to another shaft, specifically fastened to another shaft. The retainer holds one of the contact emitters. For example, the retainer is designed as a sleeve, with the contact emitter positioned at one end of the sleeve. The other end of the sleeve is fitted onto another shaft, for example, and secured there with adhesive. Alternatively, the sleeve is also pressed against the other shaft.

[0020] Therefore, in the case of an electric motor, the shaft position can be determined relatively accurately using only two sensor units. This reduces the number of required components, thus lowering manufacturing costs and space requirements. Since the sensor system is secured to the bearing housing, no additional assembly steps are needed, as is the case when electronics are associated with components driven by an electric motor (e.g., possibly a rack). This reduces manufacturing time. Furthermore, the sensor system is stabilized by the bearing housing and is therefore at least partially enclosed by the motor housing, thus providing relative protection. This increases robustness. Due to the mechanical backlash compensation element, the two gears remain meshed even under motor vibration and / or various environmental conditions, ensuring a repeatable arrangement between the contact emitters corresponding to predetermined positions on the shaft. Therefore, the shaft position can be determined relatively accurately. When the gears wear in the tooth region, the backlash is preferably compensated by the backlash compensation element, which appropriately fills / reduces the "gaps" created by wear, thereby reducing backlash throughout the service life. For this purpose, the backlash compensation element is particularly suitable, provided, and configured to achieve this objective.

[0021] For example, another gear employs a ring design. For example, another tooth is rigidly fastened to another shaft on this gear. Due to the ring design, inertia is reduced. In particular, the other gear is substantially concentrically arranged with the other axis of rotation. It is particularly preferred that the other gear is fastened to the other shaft by means of a clearance compensation element. Therefore, if the center point of the gear is not directly located on the other axis of rotation, compensation is specifically provided by means of a clearance compensation element. Due to the use of the clearance compensation element, the meshing between the other gear and this gear is maintained. Therefore, both gears can use relatively high manufacturing tolerances, thereby reducing manufacturing costs while still maintaining the functionality of the sensor system. For example, the center point of the other gear is intentionally chosen to be slightly offset from the other axis of rotation, particularly towards the axis of rotation. Therefore, even when the degree of expansion differs, such as during cooling that causes a reduction in the diameter of the other gear, meshing with the gear still exists. In other words, in this case, the clearance compensation element specifically preloads the other gear in the gear direction.

[0022] For example, the clearance compensation element comprises one or more springs. Particularly preferred is that an annular clearance is formed between the other gear and the other shaft, and the clearance compensation element is disposed within this clearance. Therefore, the required space is relatively small. Specifically, the clearance compensation element is here made of an elastomer. Preferably, a material-fit connection is formed between the other gear and the other shaft by means of the clearance compensation element, and to establish a mechanical connection, the clearance compensation element is injection molded onto the other shaft and / or the other gear. This achieves a connection that prevents loss of connection and improves robustness. It also reduces the number of assembly steps required.

[0023] In an alternative design, the other gear is preferably rigidly fastened to another shaft. A retainer holds the contact emitter in place. However, the retainer is connected to the other gear via a gap-compensating element. Specifically, the gap-compensating element is made of an elastomer and is preferably injection-molded onto the other gear and / or the retainer. This achieves a connection that prevents loss of connection. The gap-compensating element can also be designed to be at least partially encapsulated, increasing robustness. In an alternative embodiment, the gap-compensating element is implemented as a plug-in component. This has the advantages of allowing selection of different gap-compensating elements based on application and load requirements, such as gap-compensating elements with different Shore hardness. Here, the gap-compensating element is conveniently an elastomer gasket.

[0024] For example, the retainer is generally designed as an annular or cup-shaped device. Particularly preferably, the retainer has circumferential teeth that also mesh with a gear. This reduces the load on the backlash compensation element, since the retainer is also driven by a gear. Here, in particular, the teeth of the retainer differ from those of the other gear; for example, the tooth dimensions are changed. During normal operation, the retainer is appropriately driven directly by the gear. Only under unfavorable operating conditions may the retainer disengage from the gear, or only when the mechanical contact area between them is relatively reduced. In this case, the rotational motion of the shaft is primarily transmitted to the retainer through the other gear and the backlash compensation element, thus reducing its load.

[0025] For example, the retainer is mechanically spaced from another gear and makes mechanical contact only through a clearance compensation element. However, it is particularly preferred that the retainer engages or clamps with the other gear. Here, in particular, the other gear has a locking pin that extends into a recess in the retainer. During assembly, the retainer is specifically fitted onto the shaft and engaged with the corresponding locking pin or multiple corresponding locking pins of the other gear. This allows for tool-free assembly. The locking mechanism specifically stabilizes the position of the retainer relative to the other gear parallel to another axis of rotation. Furthermore, due to the locking mechanism, radial and / or tangential movements relative to the other axis of rotation can also be conveniently achieved, at least within a certain range. This reduces the requirements for the locking mechanism, simplifying its structural design and manufacturing.

[0026] For example, these gears are designed as wheels (spur gears), and the sensor drive is particularly a spur gear drive. This reduces manufacturing costs. Here, the gears are specifically spur gears. Therefore, the design is simplified. Alternatively, the two gears mesh with each other by means of helical gear teeth. Due to the use of helical gear teeth, the two gears, especially in the corresponding gear drive, have spur gears with variable tooth profile offset. In particular, one of the gears is truncated conical. A backlash compensation element is formed by means of the helical gear teeth. This eliminates the need for additional components, thereby reducing material costs and improving robustness. In particular, the two gears are rigidly fastened to their respective associated shafts, thus improving robustness.

[0027] Particularly preferably, the other shaft is rotatably supported by another bearing held on a bearing housing. During the manufacture of the bearing housing, a bearing housing is specifically made for both the bearing and the other bearing. Here, particularly to reduce manufacturing tolerances, the bearing housing can be easily reworked, whereby the bearing housing can be reworked for both the bearing and the other bearing in a single work step. This does not significantly extend manufacturing time. The other bearing is, for example, a sliding bearing or, more preferably, a roller bearing, such as a ball bearing or a needle bearing. Therefore, the starting torque is relatively low when the other shaft rotates, thus allowing for relatively reliable detection of even minute changes in shaft position using a sensor system.

[0028] For example, on the side where the sensor system or at least the sensor actuator is arranged, the bearing housing is covered by an electronic device housing, etc. In particular, in this case, the electronic device housing houses any printed circuit boards, by virtue of which, for example, it provides any electronic device compartments and / or is designed, for example, in a cup shape and closed by means of the bearing housing. Particularly preferably, a cap covering the sensor actuator is fastened to the bearing housing. In this case, the cap is particularly made of plastic. Advantageously, the cap is glued or snap-locked to the bearing housing. Alternatively, for example, the cap is screwed onto the bearing housing. However, particularly preferably, the cap is non-removably attached to the bearing housing, for example, by rivets. For assembly, a wobbly rivet process is preferred.

[0029] For example, the entire sensor system, especially except for any sensors in each sensor unit, is covered by a cap. This reliably prevents dust particles from penetrating into the sensor system. Alternatively, another shaft is connected to the cap by means of an additional bearing, which conveniently guides the other shaft, simplifying the structural design. In other words, the other shaft is rotatably supported about another axis of rotation by means of an additional bearing connected to the cap. Here, for example, any other bearing is provided, such that the other shaft is rotatably supported integrally by means of two bearings. This relatively precisely defines the other axis of rotation, and the other shaft is stable. Alternatively, for example, the other shaft is rotatably supported only by means of an additional bearing. Thus, a component or module is particularly provided, having a cap, an additional bearing, another shaft, and at least one of the contact transmitters. It can be assembled, in particular, in one working step. Particularly preferably, the component also has an auxiliary bearing by means of which the shaft extension is rotatably supported. For this purpose, it is nail-shaped and, in the assembled state, is inserted, in particular, into the corresponding short shaft receiving portion of the shaft. An inherent gear is fastened on the shaft extension. Therefore, apart from arbitrary sensors, the sensor system is essentially a single component (module) that can be fastened to the bearing housing in a single working step during assembly and is manufactured independently of the bearing housing. The shaft is intact in this case, i.e., the shaft extension is inserted into the short shaft. The component here is particularly independent of clearance compensation elements and is considered a standalone invention.

[0030] An additional retainer is conveniently fastened to the shaft, thereby holding one of the contact emitters in place. Therefore, as the shaft rotates, these contact emitters also rotate, such that their rotational speed equals that of the shaft. Specifically, another contact emitter can be driven by another shaft, for example, by means of a retainer fastened to that shaft. Thus, relatively fewer components are required, reducing manufacturing costs and space requirements.

[0031] In the improved embodiment, the sensor drive specifically includes a second additional shaft to which a second additional gear is fastened. This second additional shaft is rotatably supported about a second additional axis of rotation, conveniently parallel to the other axis of rotation. Specifically, the sensor system, preferably the sensor drive, is configured such that when the shaft rotates, the second additional shaft also rotates. For this purpose, for example, the second additional gear meshes with a gear or only with the other gear. Specifically, one contact emitter is associated with the second additional shaft, and the other contact emitter is associated with the other shaft. In this case, for example, when the shaft rotates, the contact emitters rotate, wherein, for example, the rotational speed of one of the two other contact emitters is equal to the rotational speed of the axis of rotation of the shaft. Alternatively, all contact emitters rotate at a speed different from the rotational speed of the shaft, thereby allowing for relatively accurate determination of the shaft's position. The two additional shafts, the two additional gears, and the associated contact emitters are conveniently structurally identical to each other, and are correspondingly held on the respective additional shafts by means of corresponding retainers. Thus, two structural units are formed, particularly those that are structurally identical or at least similar to each other. Specifically, they differ only in the number of teeth on the corresponding additional gears, thus achieving different rotational speeds. Therefore, at least some of the same components can be used, which reduces manufacturing costs.

[0032] In the improved design, additional gears are provided, wherein, in particular, a corresponding contact transmitter is associated with each gear. In this case, the sensor transmission is preferably designed as a planetary transmission. Specifically, during operation, the other gears rotate at different speeds.

[0033] In its assembled state, the auxiliary unit is a component of a motor vehicle and is specifically provided and configured for this purpose. The motor vehicle is, for example, land-based, and such as a truck, bus, or preferred passenger car. The auxiliary unit has an electric motor with a housing on which a bearing guard is fitted, holding a bearing, rotatably supported by its shaft about a rotational axis, and has a sensor system for determining the position of the shaft. The sensor system has two sensor units (each including a contact transmitter) and a sensor drive comprising a gear fastened to the shaft, which meshes with another gear fastened to a different shaft rotatably supported about another rotational axis. The sensor system is designed such that as the shaft rotates, the two contact transmitters move at different speeds, and the sensor drive includes a mechanical backlash compensation element.

[0034] Specifically, another component of the auxiliary unit, such as an adjustment component, is driven by an electric motor. For example, the electric motor is a component of an electric pump, such as a water pump, coolant pump, or lubricant pump, such as an oil pump. For example, the auxiliary unit is a transmission. However, particularly preferably, the auxiliary unit is a steering system. In this case, the electric motor acts as a support during operation, for example, by force applied manually by the driver. However, the steering system is particularly preferably configured as a "steer-by-wire" system. In this case, the electric motor specifically drives a component by means of which the steering angle of the vehicle's wheels is predetermined. Specifically, in this case, a rack connected to at least one wheel of the vehicle is driven by the electric motor, thereby pre-determining the steering angle of the associated wheel by the position of the rack. For example, in this case, the rack is a component of the auxiliary unit, or the latter is driven by the auxiliary unit. Specifically, the steering system includes an operating device such as a steering wheel, by means of which, particularly the driver of the vehicle, can pre-determine the steering angle. In this case, signal coupling / connection between the electric motor and sensors assigned to the operating device is preferably present. Alternatively or in combination, the electric motor is coupled to the vehicle's onboard computer or another auxiliary system by means of which the vehicle can move forward, particularly autonomously. The present invention also relates to a motor vehicle having such an auxiliary unit.

[0035] The improvements and advantages explained by combining electric motors will also be transferred accordingly to auxiliary units / vehicles / components and between them, and vice versa.

[0036] Embodiments of the present invention will now be explained in more detail with reference to the accompanying drawings. Wherein:

[0037] Figure 1 The illustration schematically depicts a motor vehicle with a steering system, which includes an electric motor.

[0038] Figure 2 A schematic cross-sectional view of an electric motor, including a sensor system, is shown.

[0039] Figures 3 to 6 Different implementations of the sensor system are shown in a partial perspective sectional view, and

[0040] Figure 7 Perspective shows according to Figure 6 Another gear in the sensor system shown.

[0041] In all figures, the corresponding parts use the same reference numerals.

[0042] Figure 1A simplified schematic representation of a motor vehicle 2 in the form of a passenger car is shown. The motor vehicle 2 has a total of four wheels 4, which stand in their intended state on a road (not shown in detail) and are connected to the body 6 of the motor vehicle 2 via a chassis. Two of the wheels 4, namely the two front wheels in this example or optionally the rear wheels, are coupled to an auxiliary unit 8, i.e., a steering system, by means of which the steering angle of these wheels 4 relative to the body 6 can be adjusted. For this purpose, the auxiliary unit 8 is operatively connected to these wheels 4. The auxiliary unit 8 includes an electric motor 10, by means of which drives a rack (not shown in detail), which is supported on the two front wheels. During operation of the electric motor 10, the rack moves laterally, i.e., in a horizontal plane and perpendicular to the longitudinal axis of the motor vehicle 2, wherein, due to the connection of the front wheels, the steering angle of the front wheels relative to the body 6 is changed.

[0043] The auxiliary unit 8 also includes a sensor 12 associated with the operating device 14, wherein the position of the operating device 14 is detected by means of the sensor 12. The operating device 14 is configured as a steering wheel and is arranged in the interior space of the motor vehicle 2 provided by the body 6. The sensor 12 is signal-connected to the electric motor 10 via a control device / control unit (not shown in more detail). There is no direct mechanical coupling between the operating device 14 and the front wheels of the motor vehicle 2, therefore the steering system is configured as a so-called "steer-by-wire" system.

[0044] Figure 2 A schematic cross-sectional view of an electric motor 10 along a rotation axis 16 is shown. The electric motor 10 includes a cup-shaped housing 24 made of aluminum, thus having a hollow cylindrical portion 20 arranged concentrically with the rotation axis 16. The cup-shaped housing 18 has a bottom 22 arranged perpendicular to the rotation axis 16, to which an A-type bearing 24 is connected.

[0045] On the side opposite to the bottom 22, the housing 18 is enclosed by a bearing housing 26 fastened to it. A bearing 28, designed as a ball bearing, is held in the bearing housing 26. A shaft 30, concentrically arranged and extending along the axis of rotation 16, is rotatably supported about the axis of rotation 16 by type A bearings 24 and 28. A rotor 32, concentrically arranged with the axis of rotation 16 and torsionally fastened to the shaft 30, is disposed between the type A bearings 24 and 28. The rotor 32 includes multiple permanent magnets (not shown in detail). The rotor 32 is circumferentially surrounded by a stator 34, which includes multiple electromagnets (not shown in detail). The stator 34 is fastened to a hollow cylindrical portion 20. In this configuration, the motor 10 is designed as a brushless direct current motor (BLDC), and the electromagnets of the stator 34 are connected in several phases, i.e., two three-phase systems (a six-phase system).

[0046] The electromagnets of the stator 34 are energized through several phase terminals 36, which pass through corresponding channels 38 of the bearing housing 26 and extend into the electronics compartment 40 located on the side of the bearing housing 26 opposite to the rotor 32. In this case, the electronics compartment 40 is defined by the electronics housing 42, which is cup-shaped, with its opening closed by the bearing housing 26.

[0047] Electronic device 44 is arranged within electronic device compartment 40, and includes a printed circuit board 46 arranged vertically to the rotation axis 16. Connected to the printed circuit board 46 is a bridging circuit 48, which is electrically contacted with phase terminals 36 and includes multiple semiconductor switches (not shown in detail). Electronic device 44 also has a drive circuit (not shown in detail), controller, regulator, and / or similar device for controlling the bridging circuit 48. A sensor system 50 for determining the position of shaft 30, i.e., its angular position, is arranged between the printed circuit board 46 and the bearing housing 26. In this case, with the help of other components of electronic device 44, stator 34 is also energized according to the position of shaft 30, so that it is always in the desired position. Therefore, the steering angle of wheel 4 always corresponds to a preset position by means of operating device 14.

[0048] exist Figure 3 A portion of the perspective sectional view shown along the axis of rotation 16 reveals a sensor system 50 with an additional retainer 54 disposed on the side of the bearing housing 26 opposite to the rotor 32, which is fitted onto the end of the shaft 30 there. The additional retainer 54 is designed as a sleeve and is pressed against the end of the shaft 30. A contact emitter 56 of the sensor unit 58, arranged vertically to the axis of rotation 16, is positioned with the aid of the additional retainer 54. It also has a sensor 60, which is fastened to the side of the printed circuit board 46 facing the bearing housing 26. Therefore, when the shaft 30 rotates, the contact emitter 56 also rotates relative to the sensor 60, which is detected by the sensor 60. In this case, the sensor unit 58 operates, for example, according to the principle of inductance, and is specifically configured as a CIPOS unit (Contactless Inductive Position Sensor). Therefore, relatively accurate position determination can be achieved by means of this sensor unit 58. The additional retainer 54 is thus fastened to the shaft, thereby holding one of the contact emitters 56.

[0049] Gear 61 is disposed between bearing 28 and additional retainer 54, sleeved on shaft 30 and torsionally fastened thereto. Thus, gear 61 is rigidly fastened to shaft 30. Gear 61 is a spur gear and is a component of sensor drive 62 of sensor system 50. For example, gear 61 is made of a metallic material, for example, by means of sintering. Furthermore, another shaft 63 of sensor drive 62 is driven by gear 61, which is connected to bearing housing 26 by means of another bearing 64. Here, the other shaft 63 is rotatably supported by means of another bearing 64 (which is a ball bearing) about another axis of rotation 66, which is parallel to the axis of rotation 16 and radially outward relative to it. Thus, the other shaft 63 is rotatably supported by another bearing 64 held on bearing housing 26.

[0050] The retainer 68 is fitted onto and pressed against the end of the other shaft 63 opposite to the bearing housing 26. The retainer 68 is designed as a sleeve, thereby circumferentially surrounding the other shaft 63. The retainer 68 also holds the contact transmitter 56, so that the sensor system 50 as a whole has two corresponding sensor units 58. Each sensor unit 68 also includes a sensor 60, which is fastened to the printed circuit board 46 on the side facing the bearing housing 26 and located on another axis of rotation 66. In this case, the two sensor units 58 are structurally identical or operate according to different principles, wherein one sensor unit 58 is a Hall sensor and the other is a CIPOS unit.

[0051] The sensor drive 62 also includes another gear 70, which is designed to be annular and surrounds another shaft 63, creating a gap between them. In this case, the other gear 70 is torsionally secured to the other shaft 63 by means of a mechanical backlash compensation element 72 made of an elastomer that fills the gap. Here, the backlash compensation element 72 compensates for the following: the center point of the annular other gear 70 may not be completely located on the other axis of rotation 66 due to manufacturing tolerances or different thermal expansion, so that the meshing between the other gear 70 and the gear 61 is still maintained.

[0052] In this configuration, the sensor drive 62 is designed such that the two contact emitters 56 move during the rotational motion of the shaft 30, but at different rotational speeds. In this configuration, the contact emitter 56 associated with the shaft 30 moves with the rotational speed of the shaft 30 due to rigid coupling. The contact emitter 56 associated with the other shaft 63 moves at a lower speed due to the teeth of the two gears 61, 70. Evaluation of the data provided by the sensor 60 is performed using other components of the sensor system 50, which are provided, for example, in part by means of the electronics 40, where a vernier principle is used. Therefore, the position of the shaft 30 can be determined relatively accurately.

[0053] In general, gear 61 of sensor drive 62 meshes with another gear 70. Sensor system 50 is designed such that two contact transmitters 56 move at different speeds as shaft 30 rotates, and sensor drive 62 includes a mechanical gap compensation element 72. Furthermore, gear 70 is annular and fastened to another shaft 63 by means of gap compensation element 72, forming a circumferential gap between the other gear 70 and the other shaft 63, within which gap compensation element 72, made of elastomer, is arranged. In this case, gap compensation element 72 is injection molded onto shaft 63 and fastened to the other gear 70 by means of adhesive (not shown in detail).

[0054] Furthermore, the cap 74, as a plastic injection-molded component, is fastened to the bearing housing 26. The sensor drive 62 is covered by the cap 74. In other words, the sensor drive 62 is arranged in the space formed between the cap 74 and the bearing housing 26. The two retainers 54, 68 and the two contact transmitters 56 are also located in the space surrounded by the cap 74. The electronics 44 is arranged outside the cap 74. Therefore, with the help of the cap 74, any wear particles generated during the operation of the sensor drive 62 are blocked by the electronics 44, thereby protecting the sensor drive. In addition, any particles that penetrate from the side of the rotor 32 through the bearing 28 are kept away from the electronics 44 by means of the cap 74. Therefore, the connection between the electronics compartment 40 and the space provided by the housing 18 exists only in the area of ​​the channel 38, whereby the channel 38 is closed by the sealing element (not shown in detail) and the phase terminal 36. Therefore, the electronics compartment 40 is relatively securely sealed.

[0055] Figure 4 Modifications to the sensor system 50 are shown, in which the cap 74, shaft 30, bearing housing 26, bearing 28, additional retainer 54, two contact emitters 56, and another bearing 46 remain essentially unchanged. The same applies to the others. The retainer 68 is slightly modified, but its functional principle remains essentially the same. Furthermore, the two contact emitters 56 are also covered by the cap 74.

[0056] Now, another shaft 63 is also rotatably supported by an additional bearing 76 connected to the cap 74, which has the same structure as the other bearing 46 and is arranged concentrically with the axis of rotation. Another gear 70 is further fastened to the other shaft 63, now directly and mechanically pressed against and against it. Further, a gear 61 is fastened to the shaft 30, which meshes with the other gear 70. In this case, there is direct meshing, with a clearance compensation element 72 formed by the helical gear teeth, by which the two gears 61 and 70 mesh. In other words, the two gears 61 and 70 no longer mesh with straight teeth, but have a beveled profile on their circumferential sides, making the two gears 61 and 70 conical. If different thermal expansion occurs during heating, clearance compensation is performed by the helical gear teeth, ensuring that the meshing of the two gears 61 and 70 is always present. The sensor system 50 also operates on the vernier principle.

[0057] exist Figure 5 Another modification to the sensor system 50 is shown, wherein it further includes a cap 74 to which an additional bearing 76 is attached, and another shaft 63 is rotatably supported about another axis of rotation 66 by means of the additional bearing. The other bearing 64 is absent, and the other shaft 63 extends through the cap 74. A retainer 68 and substantially corresponding to... Figure 3 The associated contact emitter 56 of the variant shown is thus located outside the space formed by the cap 74 and the bearing cover 26.

[0058] The additional retainer 54 and the contact emitter 56 held therein correspond to Figure 3 The variant shown is as follows. However, the shaft 30 has now changed, featuring a short shaft 78, which is shortened relative to the integral shaft 30 and connected to the bearing 28. The short shaft 78 has a receiving portion 80 concentrically constructed with the rotation axis 16, into which a nail-shaped shaft extension 82 is inserted or pressed. A gear 61 is fastened to the shaft extension 82, which, along with another gear 70 and corresponding to... Figure 3 The clearance compensation element 72 in the variant shown is exactly the same. Therefore, gear 61 and another gear 70 also mesh. The shaft extension 82 is secured to the cap and passes through the cap 74 by means of an auxiliary bearing 84. In other words, gear 61 and the additional retainer 54 are located on different sides of the cap 74. The sensor system 50 also operates on the vernier principle.

[0059] Assembly 86 is formed by a cap 74, bearings 76 and 84 fastened thereto, and a sensor drive 62 (with two gears 61 and 70 and another shaft 63) fastened thereto, a gap compensation element 72, two retainers 54 and 68, a shaft extension 72, and a contact transmitter 56. This assembly can be manufactured independently of other components of the motor 10. Assembly 86 is a pre-assembled module and is fitted onto and fastened to the bearing housing 26 after the housing 18 is closed by the bearing housing 26. The cap 74 is fastened to the bearing housing 26 by means of fasteners (not shown in detail), such as rivets or screws, and the shaft extension 32 is inserted into the receiving portion 80 of the short shaft 78. This allows for relatively quick assembly.

[0060] exist Figure 6 Another modification to the sensor system 50 is shown, which also operates based on the vernier principle. The shaft 30 is now integral and rotatably supported on the bearing housing 26 by means of bearing 28. The gear 61 is also fitted onto the shaft 30, but the contact transmitter 56 is no longer associated with the shaft 30. The sensor system 50 now has two structural units 88, which have substantially the same structure. In this case, each of the two structural units 88 includes another bearing 64 fastened to the bearing housing 26, with each associated other shaft 63 rotatably supported by the bearing housing about its respective other axis of rotation 66. Therefore, there are a total of two other shafts 63.

[0061] Each of the other shafts 63 has a separate gear 70 rigidly fastened to it, which meshes with gear 61, resulting in a spur gear mesh. The two other axes of rotation 66 and the axis of rotation 16 are located on the same straight line. Because the two other gears 70 have different numbers of teeth, the distances between the two other axes of rotation 66 and the axis of rotation 16 are different. However, this essentially corresponds to the only difference between the two structural units 88. For this purpose, the other gears 70 are made of plastic, thereby improving acoustic characteristics. Due to the double-sided load caused by the other gears 70, gear 61 is designed using a metallic material (sintered metal).

[0062] Each structural unit 88 also includes one of the corresponding contact emitters 56, which are held and connected to their respective other gears 70 by means of their respective associated retainers 68. In this case, each retainer 68 is connected to its respective associated other gear 70 by a corresponding gap compensation element 72 made of an elastomer. Overall, each other gear 70 is thus rigidly fastened to its respective associated other shaft 63, and each other gear 70 is connected to one of the corresponding retainers 68 by its respective associated gap compensation element 72, thereby holding one of the corresponding contact emitters 56. Overall, the sensor drive 62 thus has two other shafts 63, on which one of the other gears 70 is fastened, and each other shaft 63 is rotatably supported about one of its respective other rotation axes 66. The sensor system 50 is designed in such a way that when the shaft 30 rotates, the two other shafts 63 move, but at different speeds.

[0063] exist Figure 7 A mid-perspective view shows one of the two other gears 70. An associated clearance compensation element 72 is injection molded onto it, forming a hollow cylindrical structure. In an alternative embodiment, the clearance compensation element 72 is implemented as a plug-in element with a Shore hardness matched to the application. Here, the clearance compensation element 72 is an elastomer gasket.

[0064] Clearance compensation element 72 is arranged on the circumferential surface of three latches (tongues) 90, which are connected to another gear 70 and extend parallel to another axis of rotation 66. In the assembled state, the latches 90 engage with the plastic recesses 92 of retainers 68. In other words, retainers 68 are thus engaged with the other gear 70. During assembly, each retainer 68 is fitted onto another shaft 63 parallel to the other axis of rotation 66 until the latches 90 engage with their respective associated recesses 92. In this case, by means of each retainer 68 surrounding its respective associated other shaft 63 on one side, the retainer 68 is only fitted onto the free end of the corresponding other shaft 63, but is not directly fastened to it, thus simplifying assembly. Due to the snap-fit ​​engagement, the retainers 68 are prevented from detaching from their respective associated other gears 70, and they can move relative to each other, at least to a limited extent.

[0065] Each retainer 68 has its own circumferential teeth 94, which also mesh with gear 61. Thus, retainers 68 are driven directly, not just through another gear 70. This reduces the load 34 on the clearance compensation element 72, which ensures that the other shaft 63 is driven or at least in contact with the transmitter 56 even under high manufacturing tolerances or deformation.

[0066] This invention is not limited to the exemplary embodiments described above. Rather, those skilled in the art can derive other variations of the invention therefrom without departing from its subject matter. Furthermore, in particular, all the various features described in connection with the embodiments can be combined with each other in other ways without departing from the subject matter of the invention.

[0067] List of reference numerals

[0068]

[0069]

[0070]

Claims

1. An electric motor (10) of a motor vehicle (2) having a housing (18) on which a bearing guard (26) is fixedly fitted, the bearing (28) being held on the bearing guard, a shaft (30) being rotatably supported by the bearing guard about a rotation axis (16), and having a sensor system (50) for determining the position of the shaft (30), wherein, The sensor system (50) includes two sensor units (58), each of which includes a contact emitter (56) and a sensor drive (62). The sensor drive includes a gear (61) fastened to the shaft (30) and meshing with another gear (70) fastened to another shaft (63), which is rotatably supported about another axis of rotation (66). The sensor system (50) is designed such that the two contact emitters (56) move when the shaft (30) rotates, wherein their rotational speeds are different, and wherein the sensor drive (62) includes a mechanical clearance compensation element (72).

2. The electric motor (10) according to claim 1. Its features are, The other gear (70) is of a ring design and is fastened to the other shaft (63) by means of the clearance compensation element (72).

3. The electric motor (10) according to claim 2. Its features are, A circumferential gap is formed between the other gear (70) and the other shaft (62), and the gap compensation element (72) made of an elastomer is arranged in the circumferential gap.

4. The electric motor (10) according to claim 1. Its features are, The other gear (70) is rigidly fastened to the other shaft (63), and the retainer (68) is connected to the other gear (70) via the clearance compensation element (72) and holds one of the contact emitters (56) via the retainer (68).

5. The electric motor (10) according to claim 4. Its features are, The retainer (68) has circumferential teeth (94) that mesh with the gear (61).

6. The electric motor (10) according to claim 4 or 5. Its features are, The retainer (68) engages with the other gear (70).

7. The electric motor (10) according to claim 1. Its features are, The two gears (61, 70) mesh by means of helical gear teeth, thereby forming the clearance compensation element (72).

8. The electric motor (10) according to any one of claims 1 to 7. Its features are, The other shaft (63) is rotatably supported by another bearing (64) held on the bearing housing (26).

9. The electric motor (10) according to any one of claims 1 to 8. Its features are, The cap (74) is fastened to the bearing cover (26) to cover the sensor drive (62).

10. The electric motor (10) according to claim 9. Its features are, The other shaft (63) is connected to the cap (74) by means of another bearing (76).

11. The electric motor (10) according to any one of claims 1 to 10. Its features are, An additional retainer (54) is fastened to the shaft (30) to hold one of the contact emitters (56).

12. The electric motor (10) according to any one of claims 1 to 10. Its features are, The sensor drive (62) has a second gear (70) fastened to a second shaft (63) which is rotatably supported about a second axis of rotation (66). The sensor system (50) is designed such that the sensor system moves as the shaft (63) rotates.

13. An auxiliary unit (8) of a motor vehicle (2), particularly a steering system, having an electric motor (10) according to any one of claims 1 to 12.

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