Electric motor-operated drive unit, brake actuator

#The present application claims priority under 35 U.S.C. § 119 to DE 10 2018 219 979.5 filed in the Federal Republic of Germany on Nov. 22, 2018, the content of which is hereby incorporated by reference herein in its entirety.

#The present invention relates to an electric motor-operated drive unit, in particular for a brake actuator of a motor vehicle, including: a rotor shaft rotatably mounted in a housing; and a rotor position sensor that includes a transmitter wheel situated on the shaft in a rotatably fixed manner and a sensor fixed to the housing and assigned to the transmitter wheel, where a front face of the transmitter wheel is positioned opposite a housing wall section of the housing, axially spaced apart therefrom. The present invention further relates to an electric motor-operated brake actuator, in particular a parking brake actuator, for a motor vehicle, including a displaceable brake element, in particular a brake piston or a hydraulic piston, and including the electric motor-operated drive unit coupled to the brake element for displacing the brake piston.

#Drive units and brake actuators are already known from the related art. The increasing electrification of motor vehicles also increasingly affects the braking systems. Meanwhile, for example, parking brakes of motor vehicles are increasingly operated using electric motor-operated actuators. These include a brake element, for example, a brake piston, which is pressed onto a brake disk of the motor vehicle in order to fix the affected wheel. In order to move the brake element, a drive unit is provided, which includes an electric motor, which is mechanically coupled to the brake element using a spindle gear unit and/or a planetary gear unit in order to ensure a high drive force or contact force. For the regulation of the electric motor, a rotor position sensor is provided, which monitors the instantaneous rotation angle position and/or the rotational speed of the electric motor. Usually, such a rotor position sensor includes a transmitter wheel fixedly connected to the rotor shaft, as well as a sensor fixed to the housing, which is assigned to the transmitter wheel in order to detect the transmitter wheel. For example, the transmitter wheel is designed as a pole wheel, which includes one or multiple permanent magnets, whose magnetic fields are detectable by the sensor, in order to recognize the rotation angle position or the rotary motion of the electric motor. The rotor position sensor is generally integrated into a housing of the drive unit or of the gear unit. For reasons of installation space, a small clearance is frequently provided between the transmitter wheel and a housing wall section of the housing assigned to a front face of the transmitter wheel.

#The FIGURE shows a simplified longitudinal sectional representation of a brake actuator for a motor vehicle according to an example embodiment of the present invention.

#The FIGURE shows a simplified longitudinal sectional representation of a brake actuator 1 for a motor vehicle, which is not represented here in greater detail. Brake actuator 1 includes a displaceable brake element 2 in the form of a hydraulic piston, which is mounted in a hydraulic cylinder 3. Hydraulic cylinder 3 includes an outlet, through which hydraulic medium, in particular brake fluid, is expellable from hydraulic cylinder 3 using brake element 2, in order to apply a braking force, for example, on a parking brake unit. Alternatively, brake element 2 is a brake piston, which is pressable against a brake disk of a wheel brake unit of the motor vehicle, in order to generate a braking torque or a friction torque of the parking brake.

#A drive unit 4 is assigned to brake element 2, which includes an electric motor 5 and a gear unit 6 coupling electric motor 5 to brake element 2. Gear unit 6 is designed, in particular, as a combined planet wheel-spindle gear unit in the present case, which, in particular, converts a high rotational speed of electric motor 5 into a low rotational speed using great force in order to displace brake element 2.

#A rotor position sensor 7 is also provided for the activation of electric motor 5. Rotor position sensor 7 includes a transmitter wheel 8, which is designed, in particular, as a pole wheel including one or multiple permanent magnets and which is situated on a rotor shaft 9 of electric motor 5 in a rotationally fixed manner. Transmitter wheel 8 is situated between gear unit 6 and electric motor 5 on rotor shaft 9. A sensor element 10 is also assigned to transmitter wheel 8, using which the magnetic field or magnetic fields of transmitter wheel 8 are detected in order to determine the rotor position. In principle, such rotor position sensors are known, so that the specific design and evaluation of the sensor signal is not explained in greater detail at this point.