ONE-PIECE THREAD ROTOR, ELECTRIC MOTOR, ACTUATOR AND PARKING LOCK

Description

[0001] The invention relates to a rotor for an electric motor according to the preamble of claim 1. Furthermore, the invention relates to an electric motor with such a rotor, an actuator with such an electric motor and a parking lock with such an actuator.

[0002] It is known to use a rotor for an electric motor, for example, in a parking lock for an automatic transmission in a motor vehicle. DE 10 2017 102 804 A1 describes a parking lock in which an electric motor drives a spindle with which a spindle nut engages. The spindle nut is guided in a guide groove for rotation. When the electric motor is rotated, the spindle nut is moved, thereby actuating the parking lock.

[0003] To save space, it is common practice to integrate the mechanical transmission, which converts rotary motion into translational motion, into the electric motor. Typically, a spindle nut is pressed into the rotor of the electric motor and connected to a spindle shaft in a form-fitting manner. The rotary motion of the spindle nut, which rotates with the rotor, is thus converted into translational motion of the spindle shaft, which, for example, activates a parking lock.

[0004] EP2873891A1 discloses in its Fig.4 a rotor for an electric motor according to the preamble of claim 1.

[0005] The object of the present invention is to improve a rotor in an electric motor. The installation space, assembly effort, and manufacturing costs of a rotor are to be reduced.

[0006] At least one of these objects is achieved by a rotor for an electric motor having the features of claim 1. Accordingly, a rotor for an electric motor is proposed, wherein the rotor is rotatable about an axis of rotation and has a first outer circumference and a magnetic field element arranged in the region of the first outer circumference for generating a magnetic field to effect a rotary movement of the rotor, wherein the rotor is assigned a thread for positive connection to a translationally movable actuating element, wherein the thread is formed as one piece from the rotor.

[0007] This makes the rotor easier to construct and install. Manufacturing costs and assembly effort are reduced. The rotor can be smaller. The installation space required and the number of components can be reduced.

[0008] The magnetic field element can be a permanent magnet or a wire coil. The permanent magnet can be sintered. The permanent magnet can be attached to the rotor inside the rotor in an IPM (Interior Permanent Magnet) arrangement or on the outer circumference in an SPM (Surface Permanent Magnet) arrangement. The magnetic field element can be firmly connected to the rotor, for example, by a form-fitting, friction-fitting, or material-fitting connection. The magnetic field element can be bonded to the rotor.

[0009] At least two magnetic field elements distributed around the circumference can be arranged in the region of the outer circumference.

[0010] The thread can form a spindle nut, which can be positively connected to the translationally movable actuating element, which is designed as a spindle shaft. The thread can be designed as an internal thread. The rotor can be made of a ferromagnetic material.

[0011] In a preferred embodiment of the invention, the rotor has a recess radially inwardly defining an inner circumference of the rotor, with the thread being formed on the inner circumference. The recess can be concentric with the rotational axis. The recess can be a central bore.

[0012] According to the invention, the rotor is designed as a formed part, having a radially outer first bent section defining the first outer circumference, and a radially inner second bent section, wherein the first and second bent sections are integrally connected to one another on a first axial side of the rotor, and the thread is integrally formed from the second bent section. The formed part can be a sheet metal component. The formed part can be a deep-drawn part. The second bent section can define an inner circumference of the rotor, wherein the thread is formed on the inner circumference. The first bent section can define the first outer circumference of the rotor. The magnetic field element can be firmly connected to the first bent section.

[0013] In an advantageous embodiment of the invention, the rotor has a bearing receiving area formed integrally with the rotor for accommodating a bearing. The bearing can be a rolling bearing.

[0014] In a special embodiment of the invention, the bearing receiving area is arranged on a second outer circumference of the rotor that is different from the first outer circumference. The second outer circumference can be smaller or larger than the first outer circumference. The bearing is connected to the rotor by a rolling process. The bearing can be connected to the rotor in a form-fitting manner. The rolling process can secure the bearing by deforming the rotor.

[0015] In a preferred embodiment of the invention, the rotor has a sensor receiving area formed in one piece with the rotor for receiving a sensor component of a sensor. The sensor can be a rotary sensor. The sensor component can be a sensor magnet. The sensor can be effective for detecting a rotational position of the rotor. The sensor component can be directly connected to the rotor. The sensor component can be round. The sensor component can be attached to the rotor concentrically with the axis of rotation. The sensor receiving area can be arranged on a first side of the rotor. The sensor receiving area can be concentric with the axis of rotation. The sensor component can be pressed into the sensor receiving area.

[0016] To achieve at least one of the aforementioned objects, an electric motor comprising a stator and a rotor with at least one of the above features is further proposed. The electric motor can be a brushless direct current (BLDC) motor. The rotor can be arranged to rotate radially within the stator. The electric motor can be an internal rotor motor.

[0017] To achieve at least one of the aforementioned objects, an actuator with a spindle drive and a previously described electric motor is further proposed, wherein the actuating element is designed as a spindle shaft and the thread forms a spindle nut which can be positively connected to the spindle shaft.

[0018] To achieve at least one of the aforementioned objects, a parking lock in a vehicle with a previously described actuator is further proposed, wherein the actuating element is operatively connected to a pawl and can effect a release position or a locking position through the translational movement. The parking lock can limit or prevent a rotational movement of a rotating component, for example, a locking ring. The rotating component can be arranged in a transmission of the vehicle.

[0019] Further advantages and advantageous embodiments of the invention emerge from the description of the figures and the illustrations.

[0020] The invention will be described in detail below with reference to the figures, where only the Fig.6 shows a rotor according to the invention, i.e. a rotor which falls within the wording of claim 1.

[0021] They show in detail: Figure 1: A cross-section through a parking lock which does not fall under the wording of claim 8. Figure 2 : A cross-section through an actuator which does not fall under the wording of claim 7. Figure 3 : A cross-section through a rotor which does not fall within the wording of claim 1. Figure 4 : A three-dimensional view of a rotor not falling within the wording of claim 1. Figure 5 : Another spatial view of the rotor in Figure 4 . Figure 6 : A cross section through an electric motor in a special embodiment of the invention.

[0022] Figure 1 shows a cross-section through a parking lock 10, which does not fall under the wording of claim 8.

[0023] The parking lock 10 is installed in a vehicle to limit the rotational movement of a locking ring 12, for example, in a transmission. The locking ring 12 has a locking toothing 14 on its outer circumference. The parking lock 10 comprises a pawl 16, which can be positively connected to the locking ring 12 via a pawl tooth 18, thereby limiting or preventing the rotational movement of the locking ring 12.

[0024] The pawl 16 is rotatable and preloaded by a tension spring. When the parking lock 10 is in a release position, the pawl tooth 18 is located outside the locking teeth 14. In a locked position, the pawl tooth 18 engages the locking teeth 14 in a positive-locking manner. The pawl tooth 18 moves toward or away from the locking ring 12 with a rotation of the pawl 16.

[0025] The parking lock 10 is actuated by an actuating carriage 20, which has a first roller 22 and a second roller 24 and is translationally displaceable in an axial direction 26. In the release position, the actuating carriage 20 is in a left-hand position and in the locked position, it is in a right-hand position. A ramp 28 on the locking pawl 16 aligns the pawl in the left-hand position away from the locking ring 12 by the tension force of the tension spring. If the actuating carriage 20 is moved to the right to initiate a locked position, the first roller 22 rolls on the ramp 28 and rotates the locking pawl 16, whereby the pawl tooth 18 is brought into engagement with the locking toothing 14 of the locking ring 12 and the parking lock assumes a locked position.

[0026] The axial displacement of the actuating carriage 20 is effected by an actuator 30 comprising an electric motor 32. The electric motor 32 has a rotor 36 rotatable about a rotational axis 34, which is assigned a thread 38 for positive connection to an actuating element 40 movable in translation in the axial direction 26. The actuating element 40 is designed as a spindle shaft, and the thread 38 as a spindle nut, which together form a spindle drive 42 that converts a rotational movement of the rotor 36 into a translational movement of the actuating element 40, thus effecting a mechanical transmission.

[0027] The actuating element 40 is connected to the actuating slide 20, and a movement of the actuating element 40 leads to a corresponding movement of the actuating slide 20, which in turn deflects the pawl 16. The translation of the rotational movement of the rotor 36 into the axial movement of the actuating element 40 is realized within the electric motor 32, thereby saving installation space for a mechanical transmission arranged separately from the electric motor 32.

[0028] The installation space can be further reduced, and manufacturing costs and assembly effort can be lowered by making the thread 38 a single piece from the rotor 36. A spindle nut separate from the rotor 36 for achieving the mechanical transmission can thus be dispensed with. The number of parts required to implement the mechanical transmission can be reduced.

[0029] In Figure 2is a cross-section through an actuator 30, which does not fall under the wording of claim 7. The actuator 30 comprises an electric motor 32 designed as a brushless direct current (BLDC) motor, which has a stator 44 and a rotor 36 rotatable about a rotational axis 34. A stator 44 arranged radially outside the rotor 36 has circumferentially distributed grooves in which a wire winding 37 for commutation of the electric motor 32 is arranged. The stator 44 is preferably designed as a laminated core and is firmly connected to an actuator housing 46, which accommodates control electronics 48 with which the electric motor 32 can be controlled. The rotor 36 has a first outer circumference 50. In the region 52 of the first outer circumference 50, a plurality of magnetic field elements 54 are arranged circumferentially distributed, each for generating a magnetic field for causing a rotational movement of the rotor 36 about the rotation axis 34.The magnetic field elements 54 are each sintered permanent magnets mounted on the first outer circumference 50 in an SPM (surface permanent magnet) arrangement. The magnetic field elements 54 can be bonded to the rotor 36.

[0030] The electric motor 32 is an internal rotor motor in which the rotor 36 is arranged radially inward of the stator 44. The rotor 36 is a sintered part made of fine-grained ceramic or metallic material sintered by applying pressure and heating to a predetermined production temperature. The production temperature is preferably below the melting temperature of the material or at least one of the materials forming the sintered part. This allows the shape of the rotor 36 to be retained and the mechanical load capacity to be increased. The material from which the rotor 36 is made is preferably ferromagnetic in order to increase the efficiency of the electric motor 32.

[0031] The rotor 36 has a recess 58, for example a central bore, arranged radially inwardly and concentric with the rotational axis 34, which defines an inner circumference 60 of the rotor 36. On the inner circumference 60, a thread 38, here an internal thread, is formed integrally from the rotor 36 and is positively connected to an actuating element 40. The actuating element 40 has an external thread 62 corresponding to the thread 38, and a rotary movement of the rotor 36 is converted by this mechanical transmission into a translational movement of the actuating element 40, for example, for actuating a parking lock. The actuating element 40 is designed here as a spindle shaft of a spindle drive 42.

[0032] The rotor 36 has, on a second outer circumference 64 of the rotor 36, which is different from the first outer circumference 50, a bearing receiving area 66 formed integrally with the rotor 36 for receiving a bearing 68. The bearing 68 is designed as a rolling bearing and can be positively connected to the rotor 36 by a rolling process. For example, the bearing 68 can be secured by the rolling process via a deformation 70 of the rotor 36.

[0033] The rotor 36 further comprises a sensor receiving area 72 formed integrally therewith for receiving a sensor component 74 of a sensor 76. The sensor 76 is a rotary sensor for detecting a rotational position of the rotor 26, and the sensor component 74 is a round sensor magnet attached to the rotor 36 concentrically to the rotational axis 34 and directly connected to the rotor 36.

[0034] The rotor 36 is designed to save space by integrating a bearing support area 66, a sensor support area 72, and a spindle nut into the rotor. This also reduces the assembly effort required to manufacture the electric motor 32.

[0035] Figure 3 shows a cross-section through a rotor which does not fall under the wording of claim 1.

[0036] A plurality of magnetic field elements 54 are attached to a first outer circumference 50 of the rotor 36, distributed along the circumference. The magnetic field elements 54 are bonded to the first outer circumference 50 in an SPM arrangement. On a second outer circumference 64, which is preferably smaller than the first outer circumference 50, a bearing receiving area 66 is formed integrally with the rotor 36, on which a bearing (not shown here) can be received and firmly connected to the rotor.

[0037] Furthermore, a sensor receiving area 72 is formed integrally with the rotor 36. A sensor component 74 of a sensor 76 for detecting a rotational position of the rotor 36 is accommodated therein concentrically to the rotational axis 34. The sensor component 74 can be a sensor magnet that is pressed into the rotor 36.

[0038] The rotor 36 is a sintered part, and a thread 38 is formed integrally with the rotor 36 in a recess 58 arranged radially inwardly of the rotor 36. The thread 38 is an internal thread. An actuating element 40 with a corresponding external thread 62 is positively received in the internal thread. This allows a rotational movement of the rotor 36 to be translated into an axial movement of the actuating element 40.

[0039] In Figure 4 a spatial view of a rotor which does not fall under the wording of claim 1 is shown. Figure 5 shows another spatial view of the rotor in Figure 4The rotor 36 has magnetic field elements 54 arranged circumferentially distributed on a first outer circumference 50. The magnetic field elements 54 can be permanent magnets attached to the rotor 36 in an SPM arrangement.

[0040] The rotor 36 has, on a second outer circumference 64, which is in particular smaller than the first outer circumference 50, a bearing receiving area 66 for receiving a bearing, for example a rolling bearing.

[0041] In Figure 6 A cross-section through an electric motor 32 in a specific embodiment of the invention is shown. A stator 44, arranged radially outside the rotor 36, has circumferentially distributed grooves in which a wire winding 37 is arranged for commutation of the electric motor 32. The stator 44 is designed as a laminated core.

[0042] The rotor 36 of the electric motor 32 is designed as a formed part, in particular as a deep-drawn part, and comprises a radially outer first bent section 78 defining the first outer circumference 50, and a radially inner second bent section 80. The first and second bent sections 78, 80 are integrally connected to one another on a first axial side 82 of the rotor 36. The thread 38 for connection to an actuating element 40 is integrally formed from the second bent section 80. The second bent section 80 defines an inner circumference 60 of the rotor 36, with the thread 38 being designed as an internal thread on the inner circumference 60.

[0043] The first bending section 78 defines the first outer circumference 50 of the rotor, to which the magnetic field elements 54 arranged distributed around the circumference are firmly connected. On a second outer circumference 64 of the rotor 36, here at the first bending section 78, a bearing receiving area 66 for receiving a bearing 68 is formed integrally from the rotor 36. The second outer circumference 64 is larger than the first outer circumference 50. List of reference symbols

[0044] 10Parking lock 12Locking ring 14Locking toothing 16Pawl 18Pawl tooth 20Actuating slide 22First roller 24Second roller 26Axial direction 28Ramp 30Actuator 32Electric motor 34Rotational axis 36Rotor 37Wire winding 38Thread 40Actuating element 42Spindle drive 44Stator 46Actuator housing 48Control electronics 50First outer circumference 52Area 54Magnetic field element 58Recess 60Inner circumference 62External thread 64Second outer circumference 66Bearing receiving area 68Bearing 70Forming 72Sensor receiving area 74Sensor component 76Sensor 78First bending section 80Second bending section 82Axial side

Claims

1. A rotor (36) for an electric motor (32), wherein the rotor (36) can be rotated about a rotational axis (34) and has a first outer circumference (50) and a magnetic field element (54) arranged in the region of the first outer circumference (50) for generating a magnetic field for effecting a rotational movement of the rotor (36), and the rotor (36) is assigned a thread (38) for form-fitting connection with a translationally moveable actuation element (40), wherein the thread (38) is integrally formed with the rotor (36), characterised in that the rotor (36) is designed as a formed part, having a radially outer first bending section (78) defining the first outer circumference (50) and a radially inner second bending section (80), and the first and second bending sections (78, 80) are integrally connected to one another on a first axial side (82) of the rotor and the thread (38) is integrally formed from the second bending section (80).

2. The rotor (36) according to claim 1, characterised in that the rotor (36) has a radially inwardly arranged recess (58) that defines an inner circumference (60) of the rotor (36), and the thread (38) is formed on the inner circumference (60).

3. The rotor (36) according to any one of the preceding claims, characterised in that the rotor (36) has a bearing receiving region (66) integrally formed therewith for receiving a bearing (68).

4. The rotor (36) according to claim 3, characterised in that the bearing receiving region (66) is arranged on a second outer circumference (64) of the rotor (36) which is different from the first outer circumference (50).

5. The rotor (36) according to any one of the preceding claims, characterised in that the rotor (36) has a sensor receiving region (72) integrally formed therewith for receiving a sensor component (74) of a sensor (76).

6. An electric motor (32) having a stator (44) and a rotor (36) according to any one of the preceding claims.

7. An actuator (30) having a spindle drive (42) and an electric motor (32) according to claim 6, wherein the actuation element (40) is designed as a spindle shaft and the thread (38) forms a spindle nut that can be form-fittingly connected to the spindle shaft.

8. A parking lock (10) in a vehicle with an actuator (30) according to claim 7, wherein the actuation element (40) is operatively connected to a pawl (16) and a release position or a locked position can be effected by the pawl (16) during a translational movement of the actuation element (40).