WO2005043719A1

WO2005043719A1 - Electromotive auxiliary drive

Info

Publication number: WO2005043719A1
Application number: PCT/EP2004/012071
Authority: WO
Inventors: Dietmar Seitz; Andreas Saum
Original assignee: Valeo Motoren Und Aktuatoren Gmbh
Priority date: 2003-10-28
Filing date: 2004-10-26
Publication date: 2005-05-12
Also published as: DE10350187A1

Abstract

An electromotive auxiliary drive used in vehicles, e.g. a drive for a window lifter system, comprising an armature shaft (3) which is rotationally mounted in a housing (2), a worm (6) which is provided on the armature shaft (3) and which forms a worm gear in conjunction with a worm wheel (7), also comprising at least one axial stop (10) for the armature shaft (3) in order to transfer axial forces from the armature shaft (3) to the housing (2). The at least one axial stop (10) comprises at least one stop part (11) which forms a stop surface which is arranged concentrically in relation to the axis of the armature shaft (3) and which is rotationally secure and shaped in the form of a ring or partial ring. The stop surface is located directly opposite a counter surface concentrically surrounding the axis of the armature shaft (3) and is provided with a reverse-rotation lock function. By selecting a combination of material for the armature shaft (3) in the region of the counter surface and material for the stop part (11) in the region of the stop surface and/or by specially configuring the surface of the counter surface and /or stop surface and/or selecting the size of the stop surface or average radius of the stop surface, it is possible to adjust the friction force or friction moment between the armature shaft (3) and stop part (11) such that rotation of the armature shaft (3) can be prevented by said friction force when an external torque acts upon the worm wheel (7).

Description

Electromotive auxiliary drive

The invention relates to an electric motor auxiliary drive according to the preamble of claim 1.

For example, electrical auxiliary drives for window lift systems in vehicles have to perform a wide variety of tasks. Among other things, the opening and closing of the respective window must be ensured, but it must also be ensured that, when the drive is at rest with the window fully or partially open, its pane cannot be forced open by the application of an external, generally downward force. This is guaranteed by the auxiliary drive designed as an electric window motor with gear. This is designed so that when an external force acts on the disk, the reverse torque thus generated on the output shaft of the electromotive auxiliary drive does not result in the armature shaft spinning and thus in opening the window pane.

In known electromotive auxiliary drives for window lift systems, this backstop is solved in detail in that the worm of the gear designed as a worm gear has a small pitch angle, so that the self-locking of the worm gear which takes up the reverse torque is achieved. The small lead angle, however, requires a relatively large diameter for the worm, since this is the only way that sufficient strength can be achieved for this worm, inter alia, to prevent the worm tooth from breaking out, especially with the high ones Loads that occur with window regulator systems. In known electromotive auxiliary drives, a reduction in the diameter of the armature shaft or the worm on the armature shaft means that the self-locking is lost and the motor turns under the action of an external return torque, so that burglary protection is no longer guaranteed, particularly in the case of drives for window regulator systems. Due to the design of the worm necessary for self-locking, the freedom of design for the worm gear is also severely restricted.

The object of the present invention is to show an electromotive auxiliary drive which avoids the aforementioned disadvantages and in which the backstop is not, or at least not exclusively, achieved by the self-locking of the transmission. To solve this problem, an electric motor drive is designed according to claim 1.

In the simplest case, the invention uses a single component, namely the start-up part of the axial start-up, to absorb the axial forces of the armature shaft during normal operation and to transmit them to the housing, in which the start-up part is held free of play and in a rotationally secure manner. If an external reverse torque is exerted on the output shaft of the electromotive drive, for example when trying to open the window of a vehicle window by force, the force applied to the window is transmitted to the drive or worm wheel of the electromotive drive, with the result that that a torque is generated on this drive wheel. This causes a translational or axial movement of the armature shaft via the worm, in such a way that the at least one counter surface of the armature shaft comes to rest against the thrust surface of the thrust part and is supported against this thrust surface with a high force corresponding to the return torque. The armature shaft is prevented from spinning by the static friction between the contact surface and the counter surface or by the resulting frictional moment. This frictional torque depends on several parameters, with which the friction torque can be set to a certain size, namely among other things

- from the mean radius of the ring-shaped or partially circular contact surface,

the material combination of the material of the thrust part on the thrust surface and the armature shaft on the counter surface,

- The surface quality of the contact surface and / or the counter surface.

With these parameters, the friction torque is set so that during normal operation of the drive there are low losses within the motor and the highest possible efficiency for the motor is achieved, i.e. in normal operation, the frictional torque caused by sliding friction between the motor shaft and the starting part is as small as possible.

The start-up part is, for example, in one piece from a wear-resistant sintered material, e.g. Sintered metal manufactured. Other materials are also conceivable. However, high wear resistance is required in every case, especially in order to be able to absorb the axial forces that occur during normal operation.

Developments of the invention are the subject of the dependent claims. The invention is explained in more detail below with reference to the figures using an exemplary embodiment. Show it:

1 shows the open housing of an electric motor drive of a window lifter system for a vehicle, together with the armature shaft with armature mounted in the housing and with an axial start-up acting as a backstop for the armature shaft;

2 shows a simplified schematic illustration of the armature shaft with the worm provided on the armature shaft, the worm wheel interacting with the worm and the starting part of the axial start-up acting as a backstop; Fig. 3 in an enlarged detail that arranged in the housing

Abutting part;

Figure 4 is a section along the line I - 1 of Figure 1;

5 shows the start-up part in a perspective individual illustration;

6 is an enlarged partial representation of the end of the armature shaft provided with a groove for the starting part; 7 shows a perspective view of the start-up part and the end of the armature shaft interacting with this start-up part; 8 is a plan view of one side of the thrust part with the effective sliding or thrust surface between the thrust part and the armature shaft which is highlighted by hatching.

In the figures, 1 is an electrical auxiliary drive, for example the electrical auxiliary drive for a window lifter system for vehicles, for example for cars. This auxiliary drive 1 essentially consists of an electric motor and a worm gear.

Shown is a shell-shaped housing part 2 of a two-part or multi-part housing and the armature shaft 3 of the electric motor with the armature 4 rotatably mounted in this housing part 2. On the armature shaft 3 there is between the free end 3.1 of this armature shaft and the armature 4 or the commutator 5 the worm 6 is provided which, together with the worm wheel 7 (FIG. 2), forms the worm gear. The worm wheel 7 is provided on a shaft 9 rotatably mounted in the housing part 2 at 8, which forms the output shaft of the electromotive drive 1 and which is oriented with its axis perpendicular to the axis of the armature shaft 3.

In order to absorb forces acting in the axial direction of the armature shaft 3 and in particular also to avoid the axial play of the armature shaft, for example due to production-dependent tolerances and / or due to different thermal expansions of the housing part 2 and the armature shaft, the armature shaft 3 is in the region of the free end 3.1 an axial start is provided, which in 1 is generally designated 10, and in particular also acts as a backstop.

This axial run-up 10 includes from a run-on part 11, which, in the embodiment shown, is made like a horseshoe from a suitable sintered material, in one piece with two legs 12 and with an arcuate yoke section 13 connecting these legs.

Due to the U-shape or horseshoe shape, the casserole part 11 forms a recess 14, which is open on one side, but is otherwise limited by the legs 12 and the yoke section 13 is oriented perpendicular to the axis of the armature shaft 3 with the planes of its front side 11.1 and rear side 11.2 and with the open side of its recess 14 towards the open side of the shell-like housing part 2. In addition, the receptacle 15 is designed such that the casserole part 11 is accommodated in this receptacle 15 only at its outer edge region, but is otherwise also free in particular on the front 11.1 facing the screw 6 and on the rear 11.2 facing away from the screw 6.

The armature shaft 3 is provided at its end 3.1 with a groove 16 concentrically enclosing the axis of the armature shaft and open on the circumference, the width of which is equal to or only slightly greater than the thickness of the run-on part 11 (distance from the front 11.1 / rear 11.2) and its lateral boundary surfaces 16.1 and 16.2, which are each arranged in planes perpendicular to the axis of the armature shaft 3, form axially contact or support surfaces with which the armature shaft 3 bears against the front 11.1 or rear 11.2 of the starting part 11. At the bottom 16.3 of the groove 16, the armature shaft 3 has an outer diameter which is the same or slightly smaller than the width of the recess 14. After the start-up part 11 has been inserted into the receptacle 15, in which this start-up part is held by a press fit, the armature shaft 3 with its groove 16 inserted into the recess 14 such that it with the side surface 16.1 of the front 11.1 and with the side surface 16.2 of the rear 11.2 of the start-up part 11 is immediately adjacent, so that forces acting on the armature shaft 3 in the axial direction, depending on the direction of rotation of the armature shaft 3, via the side surface 16.1 on the front side 11.1 or via the side surface 16.2 on the rear side

11.2 of the casserole part 11 are transmitted.

On the one hand, this compensates for the axial play of the armature shaft 3. Among other things, by the selection of the material combination between the material of the armature shaft 3 and the material of the start-up part 11, it is also achieved that with a return torque acting on the worm wheel 6, for example in the direction of the arrow M in FIG. 2, the armature shaft 3 with the side face 16.1 the groove 16 is pressed against the front 11.1 of the thrust part or against the thrust surface 18 formed there and hatched in FIG. 8 in such a way that a sufficiently high friction torque and thus a backstop is achieved by a correspondingly high friction between the armature shaft 3 and the thrust part 11 that prevents the armature shaft 3 from spinning despite the return torque M.

Relevant parameters for the friction torque between armature shaft 3 and thrust part 11 include the size of the thrust surface 18 or the average radius of this part-circular thrust surface, the surface formation of the thrust part 11 on the thrust surface 18 and the side surfaces 16.1 and 16.2 of the groove, etc. By appropriate Forming the chamfer 17 on the groove 16 of the armature shaft 3 and / or a chamfer 19 on the recess 14 and within the contact surface 18, the inner and outer radius of this contact surface 18 and thus also the mean radius and the effective area dimension of the contact surface 18 can be set , The frictional force or the frictional torque are adjusted by these parameters in particular also taking into account the design of the worm gear and in particular taking into account the pitch of the worm 6 such that an effective backstop is still achieved at the maximum expected reverse torque acting on the worm wheel 7. on the other hand, in normal operation of the electromotive auxiliary drive 1, friction losses between the armature shaft 3 and the ramp part 11 are low. The invention has the advantage, inter alia, that the backstop or the backturn torque is not, as was previously customary, generated by the geometry of the worm 6 of the worm gear, but via the start-up part 11. This results, inter alia, in greater design freedom for the worm gear or the worm 6, ie it is no longer necessary to pay attention to the return torque when forming the worm 6, in particular also when choosing the pitch angle of the worm.

Since, in the embodiment according to the invention, larger helix angles are also possible for the worm 6, the armature shaft 3 can be formed in the region of the worm 6 with a diameter which is reduced in comparison to known electromotive drives, with a sufficiently high strength of the tooth of the worm 6.

Another decisive advantage of the invention is that a single component, namely the starting part, combines several functions in the motor, namely acting both as an axial start-up to compensate for or avoiding the axial play, and as a backstop. The reduction in the diameter of the armature shaft 3 or the worm 6 has, inter alia, a positive influence on the manufacturing costs of the armature shaft.

A wear-resistant sintered material or sintered metal, for example, is suitable as the material for the starting part 11.

The invention has been described above using an exemplary embodiment. It goes without saying that changes and modifications are possible without departing from the inventive idea on which the invention is based. LIST OF REFERENCE NUMBERS

1 electromotive auxiliary drive 2 housing 3 armature shaft 3.1 end of the armature shaft 4 armature 5 commutator 6 worm 7 worm wheel 8 bearing 9 shaft

10 axial start

11 start-up part

11.1 Front of the start-up part

11.2 Rear of the start-up part

12 legs of the U-shaped start-up part

13 yoke section of the U-shaped thrust part

14 Recess of the start-up part

15 recording

16 Groove of the armature shaft

16.1, 16.2 boundary or side surface of the groove 16

16.3 Bottom surface of the groove 16

17 chamfer

18 contact surface

19 chamfer

M reverse torque

Claims

claims

1. Electromotive auxiliary drive for use in vehicles, for example drive for a window lifter system, with an armature shaft (3) rotatably mounted in a housing (2), with a worm (6) provided on the armature shaft (3), which together with a worm wheel ( 7) forms a worm gear and with at least one axial run-up (10) for the armature shaft (3) for transmitting axial forces from the armature shaft (3) to the housing (2), the at least one axial run-up (10) at least one start-up part (11 ), which forms a ring-shaped or partially ring-shaped thrust surface (18) which is arranged in a rotationally secure manner concentrically to the axis of the armature shaft (3) and which is directly opposite a counter surface (16.1, 16.2) which concentrically surrounds the axis of the armature shaft (3), characterized in that Choice of the material combination of the material of the armature shaft (3) in the area of the counter surface (16.1, 16.2) and the material of the thrust part (11) in the area d he contact surface (18) and / or by the surface design of the counter surface (16.1, 16.2) and / or the contact surface (18) and / or by selecting the size of the contact surface (18) or the average radius of the contact surface the frictional force or the frictional torque between the armature shaft (3) and the start-up part (11) are set such that this frictional force prevents the armature shaft (3) from rotating when the external torque acts on the worm wheel (7).

2. Auxiliary drive according to claim 1, characterized in that the at least one contact surface (18) and the associated counter surface (16.1, 16.2) extend in planes perpendicular to the armature shaft.

3. Auxiliary drive according to claim 1, characterized in that the start-up part (11) has a recess (14) open towards an edge of this start-up part, in which the armature shaft (3) is received with an armature shaft section (16), and that the at least a counter surface (16.1, 16.2) from one to the Armature shaft section adjacent annular and in a plane perpendicular to the axis of the armature shaft (3) arranged surface (16.1, 16.2) of the armature shaft is formed.

4. Auxiliary drive according to claim 3, characterized in that the armature shaft section is a groove (16) and the at least one counter surface is formed by a side surface (16.1, 16.2) of the groove.

5. Auxiliary drive according to one of the preceding claims, characterized in that the starting part (11) is U-shaped or horseshoe-shaped with a recess (14).

6. Drive according to claim 5, characterized in that the start-up part (11) is received with no play or almost no play in the groove (16).

7. Auxiliary drive according to one of the preceding claims, characterized in that the starting part is held without play or almost without play in the housing (2) or in a receptacle there (15).

8. Auxiliary drive according to one of the preceding claims, characterized in that the starting part (11) in one piece from a wear-resistant material, for example from a sintered material, e.g. is made of a metallic sintered material.