Locking device, electric motor drive unit, and vehicle
Patent Information
- Application Number
- EP2023738693
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-07-15
- Filing Date
- 2023-07-04
- Publication Date
- 2025-05-21
AI Technical Summary
Existing locking devices for electric motor drive units in vehicles lack an efficient and compact mechanism for locking the shaft, requiring high actuation forces and additional components, which complicates assembly and increases space requirements.
A locking device with a form-fitting element that undergoes an axial lifting movement, pre-tensioned by elastic means, engages with a shaft-side complement to lock the shaft, featuring a housing with a multifunctional shaft adapter and integrated contacting means like slip rings, allowing for energy-saving actuation and compact design.
The solution provides a compact, energy-efficient locking mechanism that requires low actuation forces, reduces component count, and simplifies assembly, while ensuring secure locking and torque transmission, even in emergency scenarios like motor failure during incline braking.
Smart Images
Figure 1.1
Abstract
Description
[0001] Description
[0002] Locking device, electric motor drive unit and vehicle
[0003] The invention relates to a locking device, an electric motor drive unit with such a locking device and a vehicle with such an electric motor drive unit.
[0004] The locking device proposed in this disclosure represents a further development of the locking devices described in the German patent applications with the file numbers 10 2021 213 737.7 and 10 2021 213 739.3.
[0005] An object underlying the invention is to provide an improved locking device, in particular for a vehicle.
[0006] This object is achieved by a locking device proposed and protected according to claim 1.
[0007] A locking device for an electric motor drive unit is proposed. The locking device comprises a locking mechanism for locking a lockable shaft of the electric motor drive unit and an electric drive for actuating the locking mechanism, which is accommodated in a housing of the locking device next to the locking mechanism.
[0008] The locking mechanism comprises a form-locking element which can be actuated in an axial stroke movement and longitudinally to the shaft and which can be joined in a form-locking manner at least in sections with a shaft-side complement within a form-locking area in order to lock the shaft.
[0009] This actuatable form-locking element is, in a state in which it rests on the shaft-side complement at its end face, preloaded or clamped longitudinally to the shaft by means of at least one elastic force transmission means in a defined manner against the shaft-side complement. In a locked state of the shaft, in which the actuatable form-locking element and the shaft-side complement engage in the form-locking area of the locking mechanism, the actuatable form-locking element rests against a housing section of an electric motor drive unit to which the locking actuator is attached.
[0010] The locking mechanism has a play of movement between the actuatable form-locking element and the shaft-side complement in the form-locking area and in the circumferential direction of the shaft, which, in conjunction with the said or previously mentioned pre-tension / tensioning of the actuatable form-locking element against the shaft-side complement, enables the actuatable form-locking element to engage in the shaft-side complement or the actuatable form-locking element to join with the shaft-side complement.
[0011] A shaft-side complement is understood to be a shaft-side counterpart to the actuatable form-locking element, which is designed or shaped in a manner complementary to the actuatable form-locking element in the form-locking area. This can be a correspondingly shaped section of the shaft itself or a separate and correspondingly shaped element joined to the shaft, which interacts positively with the actuatable form-locking element.
[0012] An elastic force transmission means is understood to mean a mechanical energy storage device for elastically preloading / bracing the actuatable form-locking element against the shaft-side complement, for example in the form of at least one separate spring or a separate spring element and / or in the form of at least one spring element section integrated into the actuatable form-locking element.
[0013] This energy storage device preloads the actuatable form-locking element against the shaft-side complement until the shaft assumes or achieves a suitable alignment for a form-locking engagement relative to the actuatable form-locking element. As soon as such an alignment is achieved, this energy storage device pushes the actuatable form-locking element into the shaft-side complement, locking or blocking the shaft.
[0014] In addition, the locking mechanism can be actuated in an energy-saving manner, as neither the aforementioned actuation nor the aforementioned preloading requires high actuating forces. When the actuable form-locking element is joined to the shaft-side complement, only the actuable form-locking element is moved, and not the drive train element to be locked.
[0015] The locking mechanism has a first form-locking element with an internal toothing and a second, shaft-side form-locking element with an external toothing, against which the first form-locking element can be actuated in an axial stroke movement and longitudinally to the shaft.
[0016] On the shaft-side form-locking element, a centering tapered section is formed on the front side and facing the first form-locking element, against which the internal toothing can be abutted in order to align the two form-locking elements with each other.
[0017] This ensures an even distribution of force across the circumference of the two form-locking elements in the joined state.
[0018] In one embodiment, the housing of the locking device also accommodates a multifunctional shaft adapter for connection to the lockable shaft. This multifunctional shaft adapter is made essentially of a plastic and in which contacting means for externally exciting a rotor of a synchronous machine of the electric motor drive unit, connected to the shaft, are embedded. The plastic of the shaft adapter is integrally bonded to the shaft-side form-locking element. These contacting means comprise at least two slip rings for contacting an associated slip brush, as well as at least one conductor track associated with the respective slip ring, which extends from the associated slip ring through the plastic of the shaft adapter.
[0019] The housing of the locking device also accommodates a separate arrangement of at least two grinding brushes for the aforementioned external excitation.
[0020] This proposed functional integration advantageously saves components and thus installation space. This also advantageously simplifies assembly work.
[0021] In one embodiment, the electric drive is arranged transversely to the shaft. Such a transverse arrangement advantageously creates space for accommodating the contacting means through the housing of the locking device.
[0022] Transverse means either an orthogonal arrangement of the electric drive to the shaft or an arrangement in which a longitudinal axis of the electric drive forms an acute or obtuse angle with a longitudinal axis of the lockable shaft.
[0023] In another design, the grinding brushes are arranged radially to the shaft. This radial arrangement also facilitates a compact design of the locking device.
[0024] It is proposed that the grinding brushes be spring-loaded and contacted against a corresponding slip ring of the contacting device. This ensures that grinding brushes, which wear out over time, are guided against the corresponding slip rings.
[0025] Furthermore, an electric motor drive unit is proposed, in particular for driving a vehicle, with a locking device of the type described above, which is attached to a housing of the electric motor of the electric motor drive unit (claim 4).
[0026] In addition, a vehicle with an electric motor drive unit of the type described above is proposed (claim 5).
[0027] A vehicle is defined as any type of vehicle or motor vehicle powered by an electric motor, particularly passenger cars and / or commercial vehicles. These are preferably semi-autonomous and, in particular, fully autonomous vehicles.
[0028] The invention will be explained in detail below with reference to the figures. Further advantageous developments of the invention will become apparent from the dependent claims and the following description of preferred embodiments. These are shown in:
[0029] Fig. 1 is a perspective view of an electric motor drive unit with a proposed locking device (left) and, in addition, a separate, perspective and enlarged view of a part of the locking device (right);
[0030] Fig. 2 shows the locking device shown in Fig. 1 in a planar sectional view;
[0031] Fig. 3 shows a locking mechanism of the locking device together with an arrangement of contacting means;
[0032] Fig. 4 shows the arrangement of the locking mechanism and the contacting means shown in Fig. 3 in a perspective view;
[0033] Fig. 5 a multifunctional shaft adapter of the locking device;
[0034] Fig. 6 a form-fitting area between a lockable shaft and the
[0035] Locking device in a sectional view; Fig. 7 is a perspective and enlarged view of the locking device shown in Fig. 6
[0036] Form-locking area and
[0037] Fig. 8 is a perspective sectional view of the locking device.
[0038] The proposed locking device SV is mounted on an electric motor drive unit EM-AE, in particular for driving a vehicle. The electric motor drive unit EM-AE comprises an electric motor EM in the form of a separately excited synchronous motor and a reduction gear RG connected to it. The locking device SV is arranged on a housing EM-G of the synchronous motor.
[0039] The locking device SV comprises a locking mechanism and an electric drive EA for actuating the locking mechanism, which is housed next to the drive EA in a housing SV-G of the locking device. Figure 2, for example, clearly illustrates that a housing section EM-G of the synchronous machine also forms the housing SV-G of the locking device.
[0040] The drive EA is arranged transversely and orthogonally to the shaft W or shaft axis X - X. In an embodiment not shown here, the drive EA can also be arranged relative to the shaft such that a longitudinal limb of the drive EA forms an acute or obtuse angle with the longitudinal axis X - X of the shaft W.
[0041] The drive EA drives a helical gear shaft 8, which in turn interacts with a gear segment 10 of a spindle nut SM with an internal thread. This spindle nut SM is joined longitudinally displaceably to a spindle S with a corresponding external thread, which together with the spindle nut SM forms a so-called helical drive or a so-called helical gear, which converts a rotational movement of the spindle nut SM (left or right rotation) into a translational movement of the spindle nut SM along the spindle S and in the longitudinal direction X - X or along the shaft W. The spindle S is arranged stationary relative to the housing SV-G and is supported against the housing SV-G (Fig. 2).
[0042] On the shaft side, the spindle nut SM is elastically preloaded by a ring element RE, which is received in a low-friction manner by the spindle nut SM itself via a rolling bearing, and individual springs, for example in the form of helical springs 18, against a form-locking element 4 which can be actuated in the longitudinal direction X - X or along the shaft W (Fig. 3, Fig. 4).
[0043] This form-locking element 4 is thus elastically connected via these - approximately three helical springs 18 arranged distributed over the circumference of the ring element RE - to a movement mechanism of the locking device SV which effects the axial lifting movement of the form-locking element 4.
[0044] This form-locking element 4 is metallic and high-strength and designed in the form of a closed, circumferential, annular element with an internal toothing IV and an external toothing 5. While the internal toothing IV can be moved in a form-fitting manner into an external toothing AV of a shaft-side, high-strength metallic complement 6 to lock the shaft W, the external toothing 5 always interacts in a form-fitting manner with a complementary section of the electric motor housing EM-G. This latter form-fitting arrangement ensures that the form-locking element 4 is guided and supported relative to the electric motor housing EM-G. This external toothing 5 enables a favorable and even force distribution over the circumference of the form-locking element 4 and, at the same time, a favorable and even force introduction into the electric motor housing EM-G. Fig.Figure 7 illustrates the section on the EM-G electric motor housing, which is complementary to the external gearing 5, with its internal gearing. For the sake of simplicity, the form-locking element 4 is not shown, hidden, or omitted.
[0045] When the shaft W is locked, both static and dynamic torque loads of the drive train are thus introduced into the electric motor housing EM-G via this external toothing 5. As an alternative to the external toothing 5, an external profiling of the form-locking element 4 in the form of individual, radial, claw-like projections can also be provided. In this regard, reference is made to the German patent applications with the file numbers 10 2021 213 737.7 and 10 2021 213 739.3 mentioned above, which describe and illustrate this.
[0046] The locking device SV further comprises a multifunctional shaft adapter 12, which extends through the spindle S and into a region of the hollow shaft W. This shaft adapter 12 is essentially made of a plastic material, in which two metallic slip rings 14a, 14b and a metallic conductor or contact track 16 associated with the respective slip ring 14a, 14b are embedded. The conductor track 16 extends from the associated slip ring 14a, 14b toward the hollow shaft W through the plastic material of the shaft adapter 12.
[0047] Furthermore, the plastic of the shaft adapter 12 is injection-molded or materially bonded to the shaft-side complement 6, which is in the form of a metallic adapter ring. Fig. 6 illustrates, by way of example, an annular projection of the adapter ring or form-locking element 6, which is formed in the form of a dovetail on the end face of the adapter ring 6 and facing the form-locking element 4 and is enclosed by a plastic flange of the shaft adapter 12. This adapter ring 6 has an external toothing AV complementary to the internal toothing IV and also an internal profiling or internal toothing, via which the adapter ring 6 and thus the shaft adapter 12 is pressed onto a correspondingly complementary external profiling or external toothing of the hollow shaft W.
[0048] The proposed locking device SV can be advantageously adapted to different shaft diameters using the adapter ring 6.
[0049] Arranged radially to the shaft adapter 12, two grinding brushes 2a, 2b, 3a, 3b are assigned to each of the two slip rings 14a, 14b and accommodated by the SV-G housing. The grinding brushes 2a, 2b, 3a, 3b are spring-loaded against or contact the associated slip rings 14a, 14b. The grinding brushes 2a, 2b, 3a, 3b assigned to a slip ring 14a, 14b and forming a pair are arranged relative to each other such that they form an angle while being at the same height (Fig. 3, Fig. 4).
[0050] For the purpose of aligning the two form-locking elements 4, 6 with each other, a centering tapered section 7 is formed on the end face of the form-locking element 6 and facing the form-locking element 4 (Fig. 6, Fig. 7). In the event of an axial offset between the form-locking element 4 and the form-locking element 6 or the hollow shaft W, the internal toothing IV can strike against this tapered section or centering section 7 during a longitudinal displacement of the form-locking element 4 in the direction X - X in order to be aligned with the external toothing AV and thus with the hollow shaft W. The form-locking element 6 therefore has not only a locking function but also a centering function, which ensures a coaxial alignment of the two form-locking elements 4, 6 with each other. This ensures a uniform force distribution over the circumference of the two form-locking elements 4, 6 in the joined state.
[0051] The locking device SV further comprises, for example, an inductively acting position sensor arrangement for detecting a position of the rotor of the synchronous machine connected to the shaft W in order to enable efficient electronic commutation of the synchronous machine. Fig. 8 illustrates, by way of example, a position sensor arrangement in the region of the outer end of the shaft adapter 12 or the end of the shaft adapter 12 facing away from the shaft end.
[0052] A signal generator with a coil arrangement is provided, which is fixed to the SV-G housing and integrated into a circuit board 20 and interacts with a sensor component in the form of a metallic, disc-like element 18, which is fixed to the hollow shaft. This element 18, which is arranged opposite the circuit board, is held by the plastic of the shaft adapter 12 and is fixed to the shaft adapter 12. This element 18 has individual radial, claw-like projections on its circumference, which, as such, cause a detuning of a magnetic field acting on them. At least these radial, claw-like projections can be magnetic, for example ferromagnetic. In a simple embodiment, this disc-like element 18 is made entirely of a non-magnetic metal, such as aluminum.
[0053] Alternatively, such a position sensor arrangement can also be provided in the area of the said form-locking elements 4, 6 or on the shaft side.
[0054] In addition to the said signal generator, sensor electronics for the position sensor arrangement and motor electronics for controlling the electric drive EA are also integrated into the circuit board 20.
[0055] The proposed locking device represents a compact, space-saving and cost-effective solution within a drive train, in particular of a vehicle in the sense of a parking lock or a locking actuator, according to which the locking mechanism is integrated into the electric motor EM and the locking device into the electric motor housing EM-G.
[0056] In a vehicle with such a locking device, this means that the vehicle can be locked or blocked in a parking situation in which the vehicle is stationary, for example at the request of the driver.
[0057] If, in this parking situation, the alignment of the shaft W is not such that it enables locking by the form-locking element 4, the form-locking element 4, in a state in which its end face rests against the shaft-side complement or form-locking element 6 or against the external toothing AV, can be pre-tensioned or clamped longitudinally to the shaft W and with a definable force against the shaft W via the aforementioned screw drive - formed by the spindle S and the spindle nut SM - and the aforementioned coil springs 18 to engage. If the shaft W is then twisted or turned just a little further, the form-locking element 4 engages with the form-locking element 6 and thus with the shaft 6 as soon as a corresponding alignment of the shaft W is achieved, which enables engagement. Such further rotation of the shaft W in the parking situation can be initiated by the vehicle system.
[0058] The said play of movement between the two form-locking elements 4, 6 and in the circumferential direction of the shaft W also enables the following emergency scenario in the event of a vehicle failure, in which the electric motor EM of the electric motor drive unit EM-AE fails.
[0059] If the electric motor EM fails while driving and the vehicle is then braked to a standstill on a road with an incline, the proposed locking device SV enables the vehicle to be locked or blocked as it rolls from a standstill, up to a maximum rotational speed of the shaft W or the maximum speed of the vehicle, which depends on the play.
[0060] In this case, the positive locking element 4 is engaged with the positive locking element 6 and thus with the shaft W by utilizing the movement play and up to the maximum rotational speed of the shaft W or the maximum speed of the vehicle, which depends on the movement play, and thus the vehicle is brought to a standstill.
[0061] By pre-tensioning or clamping the form-locking element 4 in a state in which the end face of the form-locking element 6 or the external toothing AV is resting, via the screw drive and the coil springs 18 and longitudinally to the shaft W, with a definable force against the shaft W and until it engages, the engagement finally takes place as soon as the shaft W is aligned accordingly with the form-locking element 4.
[0062] Although exemplary embodiments are explained in the foregoing description, it should be noted that a multitude of modifications are possible. Furthermore, it should be noted that the exemplary embodiments are merely examples and are not intended to limit the scope of protection, applications, or structure in any way. Rather, the foregoing description provides the skilled person with a guide for implementing at least one exemplary embodiment, whereby various changes, particularly with regard to the function and arrangement of the described components, can be made without departing from the scope of protection as it results from the claims and equivalent combinations of features.
Claims
Patent claims: 1 . Locking device (SV) for an electric motor drive unit (EM-AE), wherein the locking device (SV) has a locking mechanism for locking a lockable shaft (W) of the electric motor drive unit (EM-AE) and an electric drive (EA) for actuating the locking mechanism, which is accommodated in addition to the locking mechanism by a housing (SV-G) of the locking device (SV), wherein the locking mechanism has a first form-locking element (4) with an internal toothing (IV) and a second, shaft-side form-locking element (6) with an external toothing (AV), against which the first form-locking element (4) can be actuated in an axial stroke movement (X - X) and longitudinally to the shaft (W), wherein a centering-acting tapered section (7) is formed on the end face of the shaft-side form-locking element (6) facing the first form-locking element (4), against which the internal toothing (IV) can be abutted in order to Form-locking elements (4,6) to align with each other.
2. Locking device (SV) according to claim 1, wherein the housing (SV-G) also accommodates a multifunctional shaft adapter (12) for connection to the lockable shaft (W), which is made essentially of a plastic and in which contacting means for externally exciting a rotor of a synchronous machine of the electric motor drive unit (EM-AE) connected to the shaft (W) are embedded, wherein the plastic of the shaft adapter (12) is materially connected to the shaft-side form-fitting element (6).
3. Locking device (SV) according to claim 2, wherein the contacting means comprise at least two slip rings (14a, 14b) for contacting with an associated grinding brush (2a, 2b, 3a, 3b) and at least one each slip ring (14a, 14b) associated conductor track (16) which extends from the associated slip ring (14a, 14b) through the plastic of the shaft adapter (12).
4. Electric motor drive unit (EM-AE), in particular for driving a A vehicle with a locking device (SV) according to one of the preceding claims, which is mounted on a housing (EM-G) of an electric motor (EM) of the electric motor drive unit (EM-AE).
5. A vehicle with an electric motor drive unit (EM-AE) according to claim 4.