Drive device

Abstract

A drive device, comprising a first housing part and a second housing part which can be displaced with respect thereto, and comprising a motor assembly, which comprises a rotor, two mounting elements and two permanent magnet shells, and if desired comprising a transmission assembly and/or a sensor unit associated with the motor transmission.

Claims

1. A drive device, comprising: a first housing part having a connector configured to connect to one of a stationary base part and a movable component, a second housing part arranged substantially coaxial with the first housing part, configured to connect to the respective other of the stationary base part and the movable component, and directly or indirectly displaceably guided on the first housing part in an axial direction relative thereto, and a drive unit received in the first housing part and comprising a motor assembly for bringing about a relative displacement movement of the first housing part and the second housing part, the motor assembly comprising a rotor having a rotor shaft, two mounting elements for mounting the two ends of the rotor shaft, and two permanent magnet shells held on the mounting elements, wherein the motor assembly is received directly in the first housing part, and the first housing part is made of a magnetisable material at least in a length portion associated with the motor assembly, wherein at least one of the mounting elements comprises a holding recess holding at least one of the permanent magnet shells, and a wedge face cooperating with an associated counter wedge face on an axial longitudinal end of the at least one permanent magnet shell to hold the at least one permanent magnet shell in a defined radial position on the mounting element, and wherein the wedge face is inclined such that a radially outer edge of the wedge face is closer to the other respective mounting element than a radially inner edge of the wedge face extends increasingly radially outwards in a direction pointing towards a respective other axial longitudinal end of the at least one permanent magnet shell.

2. The drive device according to claim 1, wherein at least one of the mounting elements comprises at least one axial shoulder that projects in between the permanent magnet shells.

3. The drive device according to claim 1, wherein the holding recess and the wedge face are on an end face of the at least one mounting element.

4. The drive device according to claim 1, wherein the holding recess and the wedge face cooperate in an interlocking manner, at least in the radial direction, with a permanent magnet shell associated therewith.

5. The drive device according to claim 1, further comprising a compensation element that is resiliently compressible in the axial direction and is provided on at least one axial longitudinal end of the at least one permanent magnet shell between the permanent magnet shell and the mounting element.

6. The drive device according to claim 5, wherein the compensation element is in the form of a ring extending over the entire circumference.

7. The drive device according to claim 6, wherein two adjacent undulating portions of the compensation element are connected by means of a circumferential portion of the ring that projects in the radial direction over circumferential portions of the ring that are adjacent thereto.

8. The drive device according to claim 1, wherein a damping element is associated with at least one mounting element.

9. The drive device according to claim 1, wherein electrical connecting lines for the motor assembly are led away from the drive device in an axial or radial direction.

10. The drive device according to claim 1, wherein at least one of the permanent magnet shells comprises at least two permanent magnet elements.

11. The drive device according to claim 1, wherein the drive unit further comprises a transmission assembly connected to an output side of the motor assembly, the relative displacement movement of the first housing part and the second housing part being derived from a rotational movement of an output shaft of the transmission assembly, and wherein the mounting element of the motor assembly closest to the transmission assembly simultaneously forms a housing cover of the transmission assembly.

12. The drive device according to claim 11, wherein the internal diameter of a central opening, for passing the rotor shaft through, of the mounting element closest to the transmission assembly is dimensioned at least as large as the external diameter of an input pinion of the transmission assembly.

13. The drive device according to claim 11, wherein a damping element is provided on the end of the transmission assembly remote from the motor assembly.

14. The drive device according to claim 11, wherein the motor assembly further comprises a brush-commutator arrangement, wherein the brush-commutator arrangement is arranged on the side of the motor assembly facing the transmission assembly.

15. The drive device according to claim 11, wherein the motor assembly further comprises a sensor unit having a sensor sub-unit fixed to the rotor and a sensor sub-unit fixed in an axial recess of one of the mounting elements.

16. The drive device according to claim 15, wherein the sensor unit is arranged on the end of the motor assembly remote from the transmission assembly.

17. The drive device according to claim 15, wherein the sensor unit is arranged between the motor assembly and the transmission assembly.

18. The drive device according to claim 15, wherein the sensor sub-unit fixed in the axial recess of one of the mounting elements is arranged radially outside the sensor sub-unit fixed to the rotor.

Description

(1) In the following, the invention is explained in greater detail by way of embodiments, with reference to the appended drawings, in which:

(2) FIG. 1 is a perspective view of the tail of a vehicle equipped with drive devices according to the invention;

(3) FIG. 2 is a longitudinal section of a part of a first embodiment of a drive device according to the invention;

(4) FIG. 3 is a side view of the embodiment in accordance with FIG. 2, but with the first housing part removed;

(5) FIG. 4 is a view similar to FIG. 2 of a variant embodiment of the first embodiment;

(6) FIG. 5 is a view similar to FIG. 2 of a second embodiment of the drive device according to the invention;

(7) FIG. 6 is a view similar to FIG. 3 of the second embodiment;

(8) FIG. 7 is a view similar to FIG. 2 of a variant embodiment to the second embodiment;

(9) FIG. 8 is a longitudinal section of the motor assembly of a third embodiment of a drive device according to the invention;

(10) FIG. 9 is a perspective view of a compensation element as used in the third embodiment;

(11) FIG. 10 is a perspective view of the motor assembly in accordance with FIG. 8; and

(12) FIG. 11 is a perspective view of one of the mounting elements of the motor assembly of the third embodiment.

(13) FIG. 1 shows the tail of a vehicle 10. A tailgate 12 of the vehicle 10, which is pivotably articulated to the vehicle 10 about a transverse axis Q, is shown open, and thus reveals two drive devices 18 and 20. The drive device 18 may for example be formed by a gas spring, whilst the drive device 20 is a drive device of the type according to the present application, which can be motor-adjusted between a retracted state and an extended state.

(14) In particular the drive device 20 is provided for adjusting the tailgate 12 between a closed state and the open state shown in FIG. 1, it also being possible for the tailgate 12 to take on intermediate positions between these two positions if desired. For this purpose, the drive device 20 comprises a first housing part 22, which is articulated to the tailgate 12 via a connecting part 24, and a second housing part 26, which is guided telescopically in the first housing part 22 and which is articulated to the body 14 of the vehicle 10 via a connecting part 28. In the context of the claims, the tailgate 12 forms the movable component and the body 14 forms the stationary base part.

(15) FIG. 2 shows a first embodiment of a drive device 20 according to the invention in detail. Since the present invention relates mainly to the formation of the motor assembly 30, but also to the formation of the transmission assembly 32 of the drive device 20, and these two components are received in the first housing part 22, only this part of the drive device 20 is shown in FIG. 2.

(16) FIG. 2 also illustrates the rotor 34, which is formed as an armature of the motor assembly 30 and of which the rotor shaft 36 is rotatably mounted in two mounting elements 38 and 40, specifically via rotary bearings 36a and 36b which are received in associated recesses 38a and 40a of the mounting elements 38, 40. The mounting elements 38 and 40 further serve to retain the two permanent magnet shells 42 and 44 of the motor assembly 30. For this purpose, the permanent magnet shells 42, 44 are formed with axial projections 42a, 44a which engage in recesses 38b and 40b respectively of the bearing elements 38, 40. In this context, the recesses 38b, 40b also retain the permanent magnet shells 42, 44 in the radial direction, in such a way that the rotor 34, the bearing elements 38 and 40, and the two permanent magnet shells 42 and 44 form a pre-assembled motor assembly 30. However, this motor assembly 30 only forms a functioning electric motor when it is arranged in the first housing part 22, which is for example formed as a steel tube and which according to the invention takes on the function of the magnetic back iron.

(17) So as to prevent the development of noises which result from the motor assembly 30 stoking internally against the first housing part 22, in particular in applications which are susceptible to vibrations, a damping element 46 or 48 is associated with each of the two mounting elements 38 and 40. The damping element 46 which is associated with the mounting element 38 closest to the connecting part 24 is in the form of a disc, which is preferably made of a resilient material, for example rubber, and the end face of which comes to be positioned against the bearing element 38. By contrast, the damping element 48 associated with the other mounting element 40 is in the form of an O-ring, which is laid in a circumferential groove 40c of the mounting element 40. The O-ring 48 too is preferably made of a resilient material, for example rubber. Further, the external diameters of the mounting elements 38, 40 and the permanent magnet shells 42, 44 when the motor assembly 30 is assembled and the internal diameter of the first housing part 22 are matched to one another in such a way that a gap 50 of a predetermined size is left between the motor assembly 30 and the first housing part 22. The damping elements 46, 48 thus make some movement of the motor assembly 30 in the first housing part 22 possible without resulting in noise-producing contact between the two, and simultaneously damp this relative movement.

(18) At this point, it should be noted that the nominal torque losses of the electric motor due to this gap do not exceed a tolerable level. Equally, embodiments are also conceivable in which the motor assembly 30 is inserted into the first housing part 22 with a lower tolerance, in such a way that there is no corresponding gap between the two. An embodiment which is modified in this way is shown in FIG. 4. It is suitable for example for applications which are not very susceptible to vibrations, and has a higher nominal torque at otherwise identical dimensions.

(19) In connection with the motor assembly 30, it should further be noted that the brush-commutator arrangement 52 is also received in the mounting element 38 closest to the connecting part 24, and if required an interference suppressor 54 may additionally be provided.

(20) It should further be noted that, for detecting the direction of rotation of the rotor 34 and/or for detecting the respective rotational position of the rotor 34 and/or for detecting the number of rotations already performed by the rotor 34, in each case with respect to the first housing part 22, a sensor unit 56comprising a sensor sub-unit 58 fixed to the rotor, which is formed for example by a Hall magnet, and a sensor sub-unit 60 fixed to the stator, which is formed for example by a Hall plate comprising at least one Hall probemay be associated with the motor assembly 30. As is shown in FIG. 2, the sensor sub-unit 60 fixed to the stator may be centred by means of a shoulder 60a in a recess 62a of a housing cover 62.

(21) FIG. 2 further illustrates a wire harness 64, which contains not only the lines for the sensor unit 56 but also the supply lines for the motor assembly 30.

(22) A further aspect of the invention relates to the cooperation of the motor assembly 30 and the transmission assembly 32. As can be seen from FIG. 2, the transmission assembly 32 comprises a housing 66 in which the components of a two-stage planetary transmission are received, specifically the sun gear or input pinion 68 of the first stage, the planet gears 70 of the first stage, the planet carrier 72 of the first stage, which is formed integrally with the sun gear or input pinion 74 of the second stage, the planet gears 76 of the second stage and the planet carrier 78 of the second stage, which is formed integrally with the output pinion 30 of the transmission assembly. The housing 66 additionally forms the ring gears of both stages of the transmission assembly 32. However, according to the invention, the transmission assembly 32 does not have a separate housing cover. This function is instead taken on by the mounting element 40 of the motor assembly 30 which is remote from the connecting piece 24.

(23) After the pre-assembly of the motor assembly 30, the transmission assembly 32 can be pre-assembled next, the final assembly step involving placing the motor assembly 30 on the transmission assembly 32 as the housing cover. In this state, the motor assembly 30 and the transmission assembly 32 together form a drive unit 82 of the drive device 20.

(24) So as to be able to facilitate the joining of the motor assembly 30 and the transmission assembly 32, in a first step of assembling the motor assembly 30 the input pinion 68 of the transmission assembly 32 can be fastened to the shaft 36 of the rotor 34. However, so as subsequently to be able to place the mounting element 40 on the rotor shaft 36, the internal diameter of the recess 40a has to be dimensioned slightly larger than the external diameter of the input pinion 68.

(25) In principle, it is conceivable also to associate a separate damping element with the transmission assembly 32, for example on the end thereof remote from the motor assembly 30, as is shown highly schematically at 84 in FIG. 2. In accordance with a first embodiment, this damping element 84 may be formed in a disc shape or cup shape. However, it is also possible to form it as an O-ring which is received in a circumferential groove of the transmission housing 66. Preferably, a resilient material is also used for the damping element 84, for example rubber. In this case, if desired, the damping element 48 can be omitted if the damping element 84 is provided.

(26) It should also be added that an adjustment assembly 86 of the drive device 20 follows the thread assembly 32 in the output direction, and may be formed for example by a spindle drive, which is known per se and is therefore merely shown in dashed lines in FIG. 2. The adjustment assembly 86 takes the rotational movement, reduced by the transmission assembly 32, of the rotor 34 of the motor assembly 30 from the output pinion 80 of the transmission assembly 32, and derives therefrom the relative displacement movement of the first housing part 22 and the second housing part 24.

(27) FIG. 3 illustrates that the mounting elements 38 and 40 comprise axial projections 38c and 40d, which extend in between the permanent magnet shells 42, 44 and hold them at a distance from one another in the circumferential direction in the respective operating positions thereof.

(28) FIGS. 5 and 6 show a second embodiment of a drive device according to the invention, which substantially corresponds to the embodiment in accordance with FIGS. 2 and 3. Analogous parts are therefore provided with the same reference numerals as in FIGS. 2 and 3, but increased by 100. Further, the drive device 120 in accordance with FIGS. 5 and 6 will only be described in the following in so far as it differs from the drive device 20 of FIGS. 2 and 3, to the description of which reference is otherwise explicitly to be made.

(29) The drive device 120 in accordance with FIGS. 5 and 6 differs from the drive device 20 of FIGS. 2 and 3, on the one hand, in that the sensor unit 156 comprising the sensor sub-unit 158 fixed to the rotor and the sensor sub-unit 160 fixed to the stator is arranged between the motor assembly 130 and the transmission assembly 132. As a result, although the drive unit 182 cannot necessarily be formed shorter, this facilitates the arrangement of the lines in the interior of the drive device 120.

(30) As can be seen in FIG. 2, only a little constructional space is available for the lines which proceed from soldering points on the circuit board of the sensor sub-unit 60 fixed to the stator, so as to be able to divert them in the desired direction, on the one hand, and provide them with the necessary strain relief, on the other hand. This problem is encountered increasingly the more the soldering material not only wets the line wires at the soldering point, but also wets the wires over some distance away from the soldering point as a result of capillary forces, when the lines are soldered in place on the circuit board. After cooling, this soldering material solidifies the wires, and this makes them not only less flexible, but also more likely to break.

(31) This problem does not occur in the embodiment of FIGS. 5 and 6, since the lines are guided over a greater path length in the drive device 120. Therefore, sufficient distance from the welding points can be maintained before the lines are diverted in the desired direction. Further, sufficient line length is available to provide the required strain relief.

(32) In addition, no additional radial constructional space has to be provided for the additional line portions which extend inside the first housing part 122. The lines can, in a simple manner, be laid where the axial projections 138c and 140d of the mounting elements 138 and 140 project in between the permanent magnet shells 142, 144 (see also FIG. 6). Here, the axial projections 138c and 140d are not of the same radial thickness as the permanent magnet shells 142, 144, but instead merely provide a protective covering, which ensures that the lines cannot come into contact with the rotor 134. For this purpose, they advantageously extend far enough in between the permanent magnet shells 142, 144 that the end faces thereof are virtually positioned against one another.

(33) On the other hand, however, the drive device 120 in accordance with FIGS. 5 and 6 also differs from the drive device 20 of FIGS. 2 and 3 in that the rotor 134 is received in the reverse orientation in the first housing part 122, in other words the brush-commutator arrangement 152 thereof is arranged on the side facing the transmission assembly 132. This similarly fails to save constructional length. However, the same considerations apply to the supply lines leading to the brushes (not visible in FIG. 5 because of the sectional view) as to the lines leading to the sensor sub-unit 160 fixed to the stator.

(34) However, as can be seen from FIG. 7, which shows a modification of the embodiment of FIGS. 5 and 6, some constructional length can be saved if the sensor sub-unit 160 fixed to the stator is arranged radially outside the sensor sub-unit 158 fixed to the rotor.

(35) It should be noted that other embodiments are also conceivable in which merely the sensor unit or merely the brush-commutator arrangement is arranged on the side of the motor assembly facing, the transmission assembly.

(36) FIGS. 8 to 11 show a third embodiment of a drive device according to the invention, which substantially corresponds to the embodiment in accordance with FIGS. 2 and 3. Analogous parts are therefore provided with the same reference numerals as in FIGS. 2 and 3, but increased by 200. Further, the drive device 220 in accordance with FIGS. 8 to 11 will only be described in the following in so far as it differs from the drive device 20 of FIGS. 2 and 3, to the description of which reference is otherwise explicitly to be made.

(37) More precisely. FIG. 8 shows the motor assembly 230 of the drive device 220.

(38) A first difference from the motor assembly 30 in accordance with FIG. 2 is that the recesses 238b, 240b of the mounting elements 238, 240 are formed in a wedge shape, and in particular comprise a wedge-shaped boundary face 238b1, 240b1 radially outwards. Whilst the wedge face 238b1 is positioned directly against a counter wedge face 242c of a permanent magnet shell 242, the wedge face 240b1 is only positioned indirectly against the counter wedge face 242c of the permanent magnet shell 242, specifically by way of a compensation element 288 which is discussed in greater detail in the following. The radial position of the permanent magnet shell 242 is fixed by positioning it on support faces 238b2, 240b2 of the recesses 238b, 240b. Analogous counter wedge faces may also be provided on the other permanent magnet shell 244.

(39) The aforementioned compensation element 288 provides the second difference from the motor assembly 30 in accordance with FIG. 2. One function of the compensation element 288 is to provide an axial length compensation between the spacing of the mounting elements 238, 240 and the length of the permanent magnet shell 242, which may differ from one another as a result of manufacturing tolerances. For this purpose, the compensation element 233 is formed so as to be compressible in the axial direction.

(40) In accordance with the embodiment shown in FIG. 9, the compensation element 288 is formed in an annular shape, with an annular body 288a extending over the entire circumference and a plurality of undulating portions 288b, four in the embodiment shown, which are formed on the inner face of the annular body 288a and provide the compressibility of the compensation element 288.

(41) A third difference is that the two permanent magnet shells 242, 244, which each extend over a circumferential angle of approximately 180, are not formed in a single piece, as can be seen from FIG. 10, but instead each comprise two permanent magnet elements 290 which extend over a circumferential angle of approximately 90. In this context, both the two permanent magnet shells 242, 244 and the two permanent elements 290 of a permanent magnet shell 242, 244 are separated from one another by projections 238c, 240d of the mounting elements 238, 240. In the drawing, it would also be possible to neglect completely to refer to the permanent magnet shells 242, 244, since, as is known to the person skilled in the art of electric motors, the functionality of the electric motor ultimately merely depends on the rotor 234 (see FIG. 8) being surrounded by permanent magnetic material over substantially the entire circumference thereof, and this is ensured by the four permanent magnet elements 290 in the present case.

(42) FIG. 10 further illustrates two circumferential portions 288a1 of the annular body 288a of the compensation element 283, which project over the mounting element 240 in the radial direction. In accordance with FIG. 8, two circumferential portions 288a1 of this type, which are adjacent in the circumferential direction, are connected by a further circumferential portion 288a2 of the annular body 288a. The undulating portions 288b are formed on the inner face of the further circumferential portions 288a2, whilst breaks 238c, through which the projections 240d of the mounting element 240 pass when mounted, are provided on the inner face of the radially projecting circumferential portions 288a1. As a result, the compensation element 288 is secured on the mounting element 240, in such a way that the circumferential portions 288a1 which project in the radial direction can serve to centre the mounting element 240 and thus the entire rotor 234 in the first housing part.

(43) A fourth difference is shown in FIG. 11. Specifically, the directions in which the brushes 252a of the brush-commutator arrangement are orientated with respect to the axis A form an angle of substantially 90. Accordingly, the commutator of the brush-commutator arrangement and the rotor 234 are formed with six poles.

(44) It should be noted that the four differences mentioned in the above are completely independent of one another. Thus, a compensation element could advantageously be used even if the permanent magnet shells or the permanent magnet elements and the mounting elements are not formed with cooperating wedge faces, but for example stepped, as is shown in FIG. 2, or even with continuous end faces extending orthogonal to the axis of rotation.

(45) Further, a compensation element of this type and/or the wedge face of the cooperating end faces can advantageously be used even if the two permanent magnet shells are each formed in a single piece.

(46) The 90 arrangement of the brushes and the six-pole formation of the commutator and the rotor can likewise be used in the first and/or the second embodiment.