DE102018221914B4 - Worm gear with mechanical stop - Google Patents

Abstract

Worm wheel (1) for converting a rotational movement of the worm wheel (1) into a translational movement of the worm wheel (1), characterized in that the worm wheel (1) has at least one mechanical stop (10) for limiting its rotational movement, the limiting of the rotational movement prevents over-rotation of the worm wheel.

Description

The present invention relates to a worm wheel with a mechanical stop for limiting a rotational movement of the worm wheel. Corresponding worm gears are used in particular, but not exclusively, for actuating parking locks. Accordingly, the present invention further relates to a parking lock arrangement with a corresponding worm wheel.

Out DE 10 2015 206 157 A1 a parking lock arrangement with an actuating element for actuating a pawl is known. The parking lock pawl can lock or release a parking lock wheel depending on the operating state. A drive device has a curve contour by means of which a rotary movement can be converted into an axial movement of the actuating element for locking or releasing the parking lock gear. The parking lock arrangement also has a drive / worm wheel. It is also known from the cited prior art to provide an emergency actuator.

The present invention is based on the object of providing an improved worm wheel or an improved parking lock arrangement. In particular, an even more reliable detection of the end positions of the worm wheel should be made possible by the embodiment according to the invention.

The object is achieved with a worm wheel according to patent claim 1. Furthermore, the object is achieved by the parking lock arrangement according to the invention according to one of claims 8 or 9 and by the method according to claim 10.

The worm wheel converts a rotational movement into a translational movement. In order to limit its rotational movement, the worm wheel according to the invention has at least one mechanical stop. It is also conceivable that the worm wheel has more than one, in particular two, mechanical stops. A mechanical stop is then provided to limit a rotational movement in a first and a second direction of rotation.

A mechanical stop is to be understood as meaning, in particular, a contour of the worm wheel which can come into contact with a contact contour that is complementary thereto. Depending on the design, the mechanical stop and the complementary or corresponding contact contour form positive and negative to one another. In particular, limiting the rotational movement is intended to prevent over-rotation, for example beyond a critical point.

The worm wheel advantageously has a partially circumferential toothing area, for example with external toothing. A first radius of the worm wheel is larger than a second radius of the worm wheel. The first radius is assigned to a section of the worm wheel which has a toothed area. In contrast, the second radius of the worm wheel is assigned to a section which has no toothing area. The transition between the first radius and the second radius advantageously forms the at least one mechanical stop. In particular, the transition is designed in the form of an edge.

The at least one mechanical stop of the worm wheel is preferably formed by an edge running parallel to an axis of rotation of the worm wheel. The corresponding surface for providing the at least one mechanical stop can be formed, for example, by a cut in a vertical orientation along the toothing of the toothed area or by a vertically oriented beginning of the toothed area.

In an alternative embodiment, the at least one mechanical stop is formed by an edge running parallel to the toothing of the toothed area. This is particularly applicable when the worm wheel has a helical toothing in the toothing area. The at least one mechanical stop thus runs parallel to the first tooth flank of the toothing of the toothed area. Configurations are also conceivable in which the at least one mechanical stop is formed neither by an edge running parallel to the toothing of the toothed area nor by an edge running parallel to an axis of rotation of the worm wheel.
In other words, the at least one mechanical stop according to the aforementioned embodiments results from the provision of at least two sections with different radii. These sections are partially arranged with respect to the circumference.

As an alternative or in addition to the aforementioned embodiments of the at least one mechanical stop, provision can be made for an elevation to be provided on a first end face of the worm wheel which forms the at least one mechanical stop. The elevation can be provided in the form of an application of material (thickening), as a pin, bolt, angle or the like.

An elevation as on a second end face of the worm wheel is further preferred mechanical stop arranged. The first and second end faces of the worm wheel are arranged diametrically to one another.

More preferably, the worm wheel has a helix contour in which the at least one mechanical stop can be integrated. The helix contour is arranged on one of the two end faces of the worm wheel. In this context, an integrated arrangement is to be understood to mean that, for example, a sudden rise in the helix contour is provided so that, for example, an actuator or emergency actuator cannot travel over the sudden rise generated thereby and thus a mechanical stop is formed.

In a further development, a helix contour can advantageously be provided which extends over the full circumference of the face of the worm wheel. Then a first and a second mechanical stop are formed by the non-traversable, abruptly rising helix contour. The first mechanical stop is located at a starting point of the helix contour and the second mechanical stop is located at the end point of the helix contour. The first and second mechanical stops act in opposite directions of rotation of the worm wheel. The same effect can also be achieved if two or more helical contours are provided partially circumferentially on the end face. In this way, an angle of rotation of the worm wheel can be influenced which it passes through from the first to the second stop.

According to a further aspect of the present invention, a parking lock arrangement is proposed which has a worm wheel according to the invention, a contact contour for the mechanical stop of the worm wheel being provided on a stationary element of the parking lock arrangement. In particular, the stationary element can be a housing or an element that is immovable in some other way with respect to the worm wheel. The contact contour and the mechanical stop form mutually complementary contact surfaces or contact contours.

According to a further development of the parking lock arrangement according to the invention, the at least one mechanical stop of the worm wheel represents a redundancy for a first determination of the position of the worm wheel. In particular, this means that the position of the worm wheel is determined by sensors. In the event of an error, the at least one mechanical stop can produce a safe state at any time.

According to a further aspect of the present invention, a method for determining an end position of a worm wheel in a parking lock arrangement according to the invention is claimed. Blocking of the rotational movement of the worm wheel when it reaches the at least one mechanical stop is detected by sensors. Blocking the rotational movement of the worm wheel is understood to mean that the mechanical stop and the corresponding contact contour counteract a sufficient force so that the worm wheel does not continue to rotate. The sensor-based detection of the reaching of the at least one mechanical stop can take place, for example, by a contact sensor which is actuated as soon as the mechanical stop comes into contact with the system contour. Alternatively, a change in current or a changed power consumption of an actuating element of the worm wheel can also be sensed when the at least one mechanical stop of the worm wheel comes into contact with the contact contour. Optical position detection can also take place, in particular since the at least one mechanical stop of the worm wheel provides a clearly delimited contour which is also suitable, for example, for image detection.

• 1: eine perspektivische Darstellung eines erfindungsgemäßen Schneckenrads;
• 2: eine schematische Darstellung des Schneckenrads;
• 3: eine perspektivische Darstellung einer weiteren Ausführungsform des erfindungsgemäßen Schneckenrads;
• 4: in einer perspektivischen Darstellung eine mögliche Anordnung des Schneckenrads in einem Gehäuse;
• 5: eine weitere Ausführungsform des erfindungsgemäßen Schneckenrads.

The present invention is explained in more detail with reference to the following figures. Show it:

• 1 : a perspective view of a worm wheel according to the invention;
• 2 : a schematic representation of the worm wheel;
• 3 : a perspective view of a further embodiment of the worm wheel according to the invention;
• 4th : in a perspective view a possible arrangement of the worm wheel in a housing;
• 5 : Another embodiment of the worm wheel according to the invention.

1 shows schematically the worm wheel according to the invention 1 . This is around an axis of rotation 2 rotatable. By a rotational movement around the axis of rotation 2 an actuator not shown here rolls 13th along a helix contour 3 of the worm wheel 1 away. Since the actuator is arranged in a stationary manner in the parking lock arrangement, it rolls along the helical contour 3 a translational movement of the worm wheel 1 along the axis of rotation 2 .

The helix contour 3 is on a second face of the worm wheel 1 arranged, which has a first end face of the worm wheel 1 opposite. The helix contour 3 rises from a starting point 4th to an end point 5 steadily on. The slope values can vary.

It can also be seen that the worm wheel 1 not fully external toothing 6th having. Rather, this is partially arranged circumferentially over a first section. Furthermore, the worm wheel 1 accordingly also a tooth-free section 7th on. The section of the worm wheel 1 with the external toothing 6th has a first radius 8th on, while the serration-free section 7th of the worm wheel 1 a second radius 9 having. It can be seen that the first radius 8th larger than the second radius 9 is.

In the embodiment of the worm wheel shown here 1 the transition takes place from the section with external teeth 6th to the gear-free section 7th of the worm wheel by leaps and bounds. This means that by changing the radius immediately 8th , 9 one edge or one surface on the external toothing 6th is formed, which in the present case has a first and a second mechanical stop 10 form.

In the embodiment of the worm wheel shown here 1 is due to the presence of a first and a second mechanical stop 10 a rotational movement of the worm wheel 1 limited both in a first direction of rotation and in a second direction of rotation opposite thereto. In particular, the rotational movement is limited when the corresponding actuator (not shown here) has a starting point 4th or an endpoint 5 the helix contour 3 has reached.

2 shows in a plan view the in 1 described worm wheel 1 . In the present case, the axis of rotation protrudes 2 vertically into the picture surface. In particular, the illustration according to FIG 2 the edges in the contour of the external toothing 6th caused by the sudden change in the first and second radius 8th , 9 are caused and thus the first and second mechanical stop 10 form.

3 shows an alternative embodiment to the worm wheel described above 1 . In contrast to what has been described above, the mechanical stop runs here 10 not parallel to the axis of rotation 2 , but rather across or diagonally to it. Thus, the mechanical stop 10 parallel to the tooth flanks of the toothing area of the external toothing 6th educated. In principle, it is also conceivable to use the embodiments of 1 and 2 with mechanical stops 10 according to the embodiment according to 3 to combine.

4th shows a possible arrangement of the worm wheel in a perspective view 1 , for example in a housing 11 . With the exception of an (emergency) actuator 13th The representation of the other elements of a parking lock arrangement was dispensed with. In the present case, however, it can be clearly seen that the worm wheel 1 a first and second mechanical stop 10 having. In the illustration shown here, there is a first stop 10 for placement on a placement contour 12th , which as a thickening or material application of the housing 11 is executed. The actuator is also located 13th at the end point 5 the helix contour 3 .

In the present case, there is a rotary movement about the axis of rotation 2 clockwise not possible. Correspondingly, such a rotary movement is blocked or the possibility of rotation is limited. Accordingly, only a counterclockwise rotation is possible. The actuator moves through this 13th at the helix contour 3 along. Because the actuator 13th stationary in the housing 11 is arranged, leads along the helix contour 3 to the fact that the worm wheel 1 towards the actuator 13th emotional. A corresponding rotary movement around the axis of rotation 2 is possible until the mechanical stop 10 now on the other side of the system contour 12th comes to the plant. So here are the first and second mechanical stops 10 on one and the same system contour 12th , but on opposite sides to the system. It is also possible to have different system contours 12th to be provided so that every mechanical stop 10 one system contour each 12th assigned.

5 shows a further embodiment of the mechanical stops 10 . In the present case, these are radially offset as pins arranged in pairs on the first end face of the worm wheel 1 intended. The pairwise arrangement has the consequence that every mechanical stop 10 is redundant. The system contour 12th is also designed as a pin in this exemplary embodiment and is stationary in the housing 11 arranged. Furthermore, in the embodiment shown here, there is a spring 14th represented by the worm wheel depending on the position (starting point 4th or endpoint 5 ) is preloaded or relieved.

List of reference symbols

1

Worm wheel

2

Axis of rotation

3

Helix contour

4th

Starting point

5

End point

6th

External gearing

7th

gear-free section

8th

first radius

9

second radius

10

mechanical stop

11

casing

12th

System contour

13th

(Emergency) actuator

14th

feather

Claims (10)

Worm wheel (1) for converting a rotational movement of the worm wheel (1) into a translational movement of the worm wheel (1), characterized in that the worm wheel (1) has at least one mechanical stop (10) for limiting its rotational movement, with the limiting of the rotational movement prevents over-rotation of the worm wheel. Worm wheel (1) Claim 1 , characterized in that the worm wheel (1) has a partially circumferential toothing area with external toothing (6), a first radius (8) of the worm wheel (1) in the toothing area being greater than a second radius (9) of the worm wheel (1) outside of the toothed region, and wherein at least one mechanical stop (10) is formed by the transition between the first radius (8) and the second radius (9). Worm wheel (1) Claim 2 , characterized in that the at least one mechanical stop (10) is formed by an edge running parallel to an axis of rotation (2) of the worm wheel (1). Worm wheel (1) Claim 2 , characterized in that the at least one mechanical stop (10) is formed by an edge running parallel to an external toothing (6) of the toothed area, the external toothing of the toothed area (6) being designed as a helical toothing. Worm wheel (1) according to one of the preceding claims, characterized in that an elevation is arranged as a mechanical stop (10) on a first end face of the worm wheel (1). Worm wheel (1) according to one of the preceding claims, characterized in that an elevation is arranged as a mechanical stop (10) on a second end face of the worm wheel (1). Worm wheel (1) according to one of the preceding claims, characterized in that the at least one mechanical stop (10) is integrated into a helical contour (3) of the worm wheel (1). Parking lock arrangement with a worm wheel (1) according to one of the preceding claims, characterized in that a contact contour (12) to the mechanical stop (10) of the worm wheel (1) is provided on a stationary element (11) of the parking lock arrangement. Parking lock arrangement according to Claim 8 , characterized in that the at least one mechanical stop (10) represents a redundancy to a first position determination, whereby a safe state can be established at any time in the event of an error in the first position determination by the at least one mechanical stop (10). Method for determining an end position of a worm wheel in a parking lock arrangement according to Claim 8 or 9 , characterized in that a blocking of the rotational movement of the worm wheel (1) when the at least one mechanical stop (10) is in contact with a contact contour (12) is detected by sensors.

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