Electromotive drive unit for motor vehicle applications

Abstract

An electric motor drive unit for motor vehicle applications, which is equipped with an electric motor having an output shaft substantially circular in cross-section and with a drive element mounted on the output shaft, preferably made of plastic. The output shaft engages a receiving hole of the drive element defining at least one vent hole. According to the invention, the output shaft has, in one variant, at least in the engagement area of the receiving bore, two ridges that are spaced apart from one another and extend axially. A protrusion of the drive element engages between the ridges for rotational coupling. Furthermore, the two ridges each describe a vent hole on the outer edge.

Claims

1. An electric motor drive unit for motor vehicle technical applications, the drive unit comprising: an electric motor with an output shaft circular in cross-section, and a drive element mounted on the output shaft wherein the output shaft engages a receiving bore of the drive element, and wherein the output shaft has, at least in an engagement region of the receiving bore, two ridges which are spaced apart from one another, and extend axially and are chord-like in cross-section, between which a protrusion of the drive element engages for rotary coupling of the output shaft and the drive element, and each of the two ridges and an inner wall of the receiving bore defines a vent hole on an outer edge side of each of the two ridges, wherein the two ridges are connected to one another at a foot end by an arc to form a composite U-shaped ridge extending around at least a portion of a midpoint of the circular cross section of the output shaft, and wherein the protrusion of the drive element is inserted into the ridge.

2. The drive unit according to claim 1, wherein the two ridges extend parallel to one another.

3. The drive unit according to claim 1, wherein the two ridges extend in an axial direction at equal distances from the midpoint of the circular cross section of the output shaft.

4. The drive unit according to claim 1, wherein the two ridges terminate at a head end at a circumference of the output shaft.

5. The drive unit according to claim 1, wherein the protrusion engages the U-shaped ridge in a friction locking manner.

6. The drive unit according to claim 1, wherein the vent holes are formed as a circular-segment in cross section.

7. The drive unit according to claim 1, wherein the vent holes are of equal size in cross section.

8. The drive unit according to claim 1, wherein the vent holes are arranged in mirror symmetry with respect to an axis extending through a center of the circular cross section of the output shaft.

9. A motor vehicle lock comprising a drive unit according to claim 1 and a locking mechanism that is operated by the drive unit.

10. The drive unit according to claim 1, wherein the drive element is made of plastic.

11. The drive unit according to claim 1, wherein the drive element is made of plastic and the output shaft is made of metal.

12. The drive unit according to claim 1, wherein the drive element is a worm gear and/or a worm wheel.

13. The drive unit according to claim 1, wherein the protrusion has a complementary U-shape relative to the composite U-shaped ridge.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) The invention is explained in greater detail below with reference to a drawing which shows only one exemplary embodiment. In the drawing:

(2) FIG. 1 shows schematically and exemplarily an electric motor drive unit for motor vehicle technical applications according to the invention,

(3) FIG. 2 shows the drive element designed as a worm in a perspective view,

(4) FIG. 3 shows a section through the subject matter shown in FIG. 2,

(5) FIG. 4 shows an alternative output shaft of the electric motor in perspective and

(6) FIG. 5 shows a section through the subject matter shown in FIG. 4.

DETAILED DESCRIPTION

(7) The figures show a representation of an electric motor drive unit for automotive applications. In fact, in the context of the embodiment example, the electric motor drive unit is used in connection with a motor vehicle lock and in particular a motor vehicle door lock. In fact, within the scope of the embodiment example according to FIG. 1 and not restrictively, the electric motor drive unit is designed as an opening drive for a locking mechanism 1, 2 schematically shown there, consisting of a rotary latch 1 and a pawl 2. For this purpose, the electromotive drive unit operates on a release lever 3. To open the locking mechanism 1, 2, the release lever 3 is acted upon by means of the electric motor drive unit such that the release lever 3 pivots about its axis in a clockwise direction.

(8) The clockwise movement of the release lever 3 results in the release lever 3 engaging the locking mechanism 1 which is in the closed position, 2 engaged with the rotary latch 1 pivots about its axis 2 in a counterclockwise direction. This releases the rotary latch 1 and in turn allows it to swing open about its axis in a clockwise direction, releasing a previously captured locking bolt that is not explicitly shown. The same applies to a motor vehicle door carrying the locking bolt and not specifically illustrated.

(9) For this purpose, the electromotive drive unit according to the invention has an electric motor 4 and an output shaft 5 which is substantially circular in cross-section, is provided on the output side of the electric motor 4 and is set into high-speed rotations with its aid. A drive element 6 is mounted on the output shaft 5.

(10) According to the embodiment example, the drive element 6 made of plastic is a worm 6, as shown in detail in the perspective representation according to FIGS. 2 and 4. The worm 6 or drive element 6 made of plastic meshes with a worm wheel 7 also made of plastic. The worm wheel 7 has an actuating pin 8. In this manner a gearbox 6, 7, 8 connected to the electric motor 4 is realized.

(11) On the basis of FIG. 1, it can be understood that a counterclockwise movement of the worm wheel 7 causes the actuating pin 8 to act on the release lever 3 in the sense that the release lever 3 performs the clockwise movement about its axis described earlier. This lifts the pawl 2 from its engagement with the rotary latch 1 and effectively releases the motor vehicle door. Of course, the electric motor drive unit to be described in detail below can also be used for other purposes and applications as already described in the introduction.

(12) On the basis of FIGS. 2 to 5, it is clear that the drive element or worm 6 made of plastic is not only a component of the gearbox 6, 7, 8. But the drive element or worm 6 is also mounted on the output shaft 5, according to the embodiment example, plugged onto the output shaft 5 and, if necessary, additionally axially secured thereon. This can be done, for example, by additionally applying adhesive or by other means.

(13) For this purpose, the output shaft 5 engages a receiving bore 9 inside the drive element or worm 6. According to the exemplary embodiment, the receiving bore 9 is arranged in the center of the cylindrical screw 6 and extends in the axial direction.

(14) On the basis of the schematic diagram in FIGS. 2 and 4, it can be seen that the output shaft 5 engages in the worm 6 as seen over a certain axial length, namely under definition of an engagement area E. Moreover, when the output shaft 5 engages the receiving bore 9 of the worm 6, bilateral vent holes 10 are defined, which can best be understood by reference to the representation in FIGS. 2 to 4.

(15) In fact, according to the invention, the formation of the output shaft 5, which is substantially circular in cross-section, in the engagement region E of the receiving bore 9 of the worm 6 is substantially designed and pronounced in such a manner that at this location two ridge 11, which extend axially and are chord-like in cross-section, are realized in the first variant according to FIGS. 2 and 3 are realized. This is particularly clear from the sectional view in accordance with FIG. 3. In this sectional view, one can see a center point M of the output shaft, which is substantially circular in cross-section 5.

(16) Relative to this midpoint M, the two ridges 11 extend along a circular chord. In this case, the two ridges 11 each end at the head end of the circumference of the relevant output shaft 5 and are connected to one another at the foot end by an arc 12. Thus the two ridges 11 in connection with the arc 12 describe a compound U-bridge 11, 12.

(17) Furthermore, according to the embodiment, the two ridges 11 extend parallel to one another and are equally spaced from the center point M in question. A protrusion 13 of the drive element 6 engages between the two ridges 11. Thus, a rotary coupling or rotary connection between the output shaft 5 and the drive element 6 is realized and converted. Furthermore, the two ridges 11 on the outer edge each describe a vent hole 10. In fact, the ridge 11 acts as a boundary of the respective vent hole 10 along with an inner wall of the receiving bore 9.

(18) The protrusion 13 generally engages the U-shaped ridge 11, 12 in a force and form closure. In fact, the protrusion 13 is complementary designed like the U-shaped protrusion 11, 12, is consequently designed as a U-shaped protrusion 13. The vent holes 10 are designed to be circular in cross-section. Furthermore, according to the embodiment example, the two vent holes 10 have the same cross-section and are incidentally arranged in mirror symmetry with respect to an axis A extending through the center M of the output shaft 5.

(19) The drive element or worm 6 (and also the worm wheel 7) is generally made of a thermoplastic material. Plastics, such as polyamide and, in particular, homopolyamides, have proven particularly advantageous here. In contrast, the output shaft 5 of the electric motor 4 is usually metallic. To unite the worm 6 with the output shaft 5, the latter is pushed onto the output shaft 5 in such a manner that there is a form closure in the direction of rotation of the output shaft 5. The two ridges 11, resp. the U ridge 11, 12 in the engagement area E of the receiving bore 9 of the worm 6 is usually produced on the output shaft 5 by forming the output shaft 5.

(20) Comparable advantages and effects are also observed for the second variant according to FIGS. 4 and 5. Here, the output shaft 5 engages in the engagement area E with a D-shaped extension 14 in the receiving bore 9. This again provides a torsional coupling to the screw 6. The vent holes 10 realized at the outer edge of the D-shaped extension 14 again provide for eventual cooling.

LIST OF REFERENCE SIGNS

(21) TABLE-US-00001 1, 2. Locking mechanism 1 Rotary latch 3 Release lever 2 Pawl 4 Electric motor 5 Output shaft 6, 7, 8 Drive element 6 Worm 7 Worm gear 8 Actuating pin 9 Receiving bore 10 Vent hole 11, 12. U-bridge 11 Webs 12 Arc 13 Protrusion 14 D-shaped extension A Axis E Engagement region M Midpoint