EP3190254B1 - Scissors drive - Google Patents

Description

The present invention relates to a scissors drive according to the preamble of claim 1.

Such scissor drives are known from applications in which the angle between two pivotally connected components should be adjustable. For example, scissor drives are used to automatically tilt windows in buildings or to open and close tailgates in automobiles. In known scissor drives, however, the actual drive of the pivoting movement, i. H. a motor, such as an electric motor, is designed separately from the two legs of the scissors drive and is seated, for example, on the hub of the scissors drive that corresponds to the pivot axis of the scissors drive, in which case, in the case of a rotary motor, its axis of rotation is perpendicular to the plane formed by the two legs.

Such scissor drives therefore require more space, especially outside the pivoting plane of the two legs, since, as mentioned, the motor of the drive extends out of this plane.

the DE 29 23 421 A1 and the FR 2 689 171 A1 show a scissor drive From the DE 20 2011 106054 U1 , which is considered to represent the closest prior art, a scissors drive according to the preamble of claim 1 is known, comprising two relatively pivotable legs, one of the legs being hollow for receiving a drive assembly therein. Furthermore, at this point on the documents DE 29 23 421 A1 , FR 2 689 171 A1 , WO 01/42608 A1 , DE 10 2008 063571 A1 and DE 10 2004 058114 A1 referred.

It is therefore the object of the present invention to provide an improved scissors drive which, compared to scissors drives known from the prior art, requires less space and, due to its increased integration, is also lightweight and inexpensive to produce.

This object according to the invention is achieved by a scissors drive according to claim 1.

According to the invention, the first leg comprises a housing that is hollow at least in sections, with a cavity defined in the hollow housing extending at least in sections along the longitudinal axis of the first leg and the motor-gear assembly at least in sections in the section of the first leg that extends along the longitudinal axis of the first leg Cavity is accommodated in the housing of the first leg. This structural measure makes it possible to minimize the installation space required by the scissor drive, in particular outside the pivot axis of the two legs. Furthermore, due to the integration of the motor-gear assembly in the housing of the first leg, a separately designed motor housing can be dispensed with, which leads to a weight reduction compared to known scissor drives. In addition, the motor-gear assembly in the configuration according to the invention is better protected against damage and/or dirt than if it were designed separately from the two legs, for example on the hub of the scissor drive.

In one embodiment of the scissors drive according to the invention, the motor-gear assembly can comprise a rotary motor whose axis of rotation runs essentially parallel to the longitudinal axis of the first leg. Such a configuration allows on the one hand an optimal utilization of the available space, since the longitudinal extension of the first leg for receiving the corresponding Motor is used and on the other hand, such rotary motors are particularly inexpensive and reliable. Alternatively, however, other motors, such as linear motors, can also be used depending on the application. The term "motor-transmission assembly" is also not to be understood in such a way that a transmission is absolutely necessary, but the transmission can also be dispensed with entirely if a suitable motor with sufficient torque is selected.

In a development, the motor-gear assembly can include a reduction gear, which is preferably provided with a reduction ratio of between 1:20 and 1:100, more preferably about 1:50. The use of such a reduction gear allows the use of commercially available rotary electric motors, which usually have a relatively high speed but a comparatively low torque. The use of the reduction gear then allows the relative pivoting speed of the two legs to be reduced while at the same time increasing the applied torque to provide sufficient force to pivot the external components connected to the two legs.

Furthermore, the scissors drive according to the invention can be designed in such a way that it comprises a worm gear which is set up to convert a rotary movement of the rotary motor into a relative pivoting movement between the two legs. Worm gears of this type are known per se and represent a robust and reliable way of converting a rotational movement about a first axis into a rotational movement about a second axis perpendicular to the first axis.

In a development, the planetary gear of the scissors drive according to the invention, which reduces the relative pivoting movement of the two legs, can be set up with a reduction ratio of between 1:3 and 1:10, preferably about 1:7.5. Here it can Planetary gear can be provided in addition or as an alternative to the already mentioned reduction gear of the motor-gear assembly. In particular, if both gears are used, very large reduction ratios of 1:300 or more can be achieved.

In order to achieve the desired reduction in the planetary gear, this comprises, according to the invention, two sets of concentrically arranged planet gears, which are connected to one another in pairs in a rotationally fixed manner. Such stepped planet wheels, which are carried concentrically by the planet carrier wheel of the planetary gear, represent a possibility of being able to realize the desired reduction ratio in a robust and space-saving manner.

In a preferred development, the scissors drive according to the invention can also include overload protection, which can prevent damage to the mechanical parts and the motor of the scissors drive, particularly in the event of improper use, such as the action of a large external torque.

For this purpose, the overload protection can be formed, for example, by a gear wheel and a ring gear engaging with the gear wheel, with the teeth of the gear wheel being arranged in such a way that when a predetermined maximum torque is exceeded, they can slide over the teeth of the ring gear in such a way that between the ring gear and the Gear a reduced torque is transmitted. For this purpose, recesses can be provided in the gear wheel, for example, which allow the areas of the circumference of the gear wheel provided with teeth to be pivoted out of engagement with the teeth of the hollow gear wheel in the event of an overload. Such overload protection devices are simple and inexpensive to produce and are easy to integrate into the scissor drive according to the invention, with the space requirement increasing only minimally, if at all.

In a likewise preferred development, the worm gear and/or the planetary gear and/or the overload protection can also be accommodated at least in sections in the housing of the first leg. This structural measure can also reduce the installation space required for the scissors drive, and the encapsulation of the respective mechanical components achieved in this way can also ensure that they are neither damaged nor soiled.

In a second aspect, the invention relates to a vehicle, for example a limousine, which comprises at least one scissor drive according to claim 1, wherein one of the two legs of the scissor drive is fixedly connected to the body of the vehicle and the other of the two legs is pivotably connected to the body of the vehicle, the element pivotally connected to the body being a tailgate, trunk lid, door or similar element of the vehicle. Here, the person skilled in the art is free to assign either the first leg, in which the engine-transmission assembly is accommodated, or the second leg to the body.

Figur 1:

eine Explosionsansicht eines Ausführungsbeispiels eines erfindungsgemäßen Scherenantriebs;

Figur 2:

eine Seitenansicht des Scherenantriebs aus Figur 1 in montiertem Zustand; und

Figur 3:

eine Schnittansicht durch die Ausführungsform aus den Figuren 1 und 2 entlang der Pfeile A in Figur 2.

Further features and advantages of the present invention are explained below by way of example with reference to the accompanying figures, which show in detail:

Figure 1:

an exploded view of an embodiment of a scissors drive according to the invention;

Figure 2:

a side view of the scissors drive figure 1 in assembled condition; and

Figure 3:

a sectional view through the embodiment of FIGS figures 1 and 2 along the arrows A in figure 2 .

In figure 1 11 is an embodiment of a scissors drive according to the invention, shown here in an exploded view, denoted generally by the reference numeral 10. FIG. The scissors drive comprises a first leg 20 and a second leg 30, which can be pivoted relative to one another about a pivot axis 12 indicated by dashed lines and each have a longitudinal axis L1 or L2, which is figure 1 are also indicated by dashed lines. The two legs 20 and 30 each have through-holes 22 and 32 on their side opposite the pivot axis 12, by means of which they can be connected to external components, for example with the aid of bolts or the like. The first leg 20 consists of a first housing part 24 and a second housing part 26, which are connected to one another by a plurality of screws 40 when the scissor drive is in the assembled state. Alternatively or additionally, however, other connection techniques known to those skilled in the art, such as gluing, welding, snapping etc., could also be used for the two housing parts.

The two housing parts 24 and 26 are hollowed out in sections and, when assembled, form a housing in which a cylindrical first cavity 28a, which extends along the longitudinal axis L1 of the first leg 20, and a second cavity 28b connected thereto, which extends in a circular shape, are defined about the pivot axis 12 extends. The connection between the first cavity 28a and the second cavity 28b is formed by a cylindrical section 28c. In the assembled state of the scissors drive 10, a motor-gear assembly 42 is fitted into the first cavity 28a, which assembly comprises a rotary electric motor and a reduction gear at its output.

When the scissors drive 10 is in the assembled state, an output shaft 44 is flanged to the output of the reduction gear of the motor-gear assembly 42 and extends through the cylindrical section 28c from the first cavity 28a into the second cavity 28 . Operational of the scissors drive 10, the output shaft 44 rotates according to the speed of the motor and the reduction ratio of the reduction gear about an axis 46, again indicated by dashed lines. On the outer circumference of the output shaft 44 there is a helical toothing 44a, which allows the output shaft to be used as a worm shaft in a worm gear serve. A worm wheel 48 engages with this toothing 44a and has a corresponding ring gear 48a on its outer circumference and converts the movement of the output shaft 44 about the axis of rotation 46 into a rotation about the pivot axis 12 .

Also located on the outer circumference of the worm wheel 48 is an inwardly directed ring gear, which is shown in FIG figure 1 however is hidden, however in figure 3 denoted by reference numeral 48b. An overload protection toothed wheel 50 with its toothed sections 50a now in turn engages with this inwardly directed toothed ring 48b. These toothed sections 50a are formed in such a way that they comprise a web which forms part of the outer circumference of the overload protection gear 50 and which is undercut in such a way that the respective section 50a with the teeth located thereon can be pressed against the overload protection gear from the outside 50 acted, a maximum torque exceeding torque can pivot radially inward, so as to pivot out of engagement with the inwardly directed ring gear 48b of the worm wheel 48. In this way, the gear wheels 48 and 50 act together as overload protection, for example in the event of an improper external torque acting on the second leg 30.

The hub of the overload protection gear 50 extends through the hub of the worm gear 48, in which extension a toothed portion 50b is provided. First planet gears 52a of a planetary gear 52 in turn engage with this toothed area 50b. Here, the planetary gear 52 is designed as a stepped planetary gear, the first planetary gears 52a coaxial with second planetary gears 52b are firmly connected, the second planetary gears 52b compared to the first planetary gears 52a have a reduced diameter and correspondingly a reduced number of teeth.

The second planet gears 52b run on the internal teeth of a ring gear 54, which is firmly fitted into the cavity 28b and is thus connected to the first leg 20 in a torque-proof manner. A toothed ring 56a of an axle 56 acts as the sun wheel in this planetary gear 52, which ring gear is also in engagement with the second planet wheels 52b. The selected proportions of the teeth 56a, the ring gear 54 and the respective diameters of the planetary gears 52a, 52b achieve an additional reduction in the rotational movement. The axle 56 extends from its area of engagement with the toothing 56a in the assembled state of the scissors drive 10 between the first planet gears 52, further through the hub of the worm gear 48 and the overload protection gear 50 and passes through an opening 28d from the second cavity 28b of the first leg 20 to the outside. The second leg 30 can be attached there to the second end 56b of the axle 56 .

In the embodiment shown, the rotational movement of the motor-gear assembly 42 is accordingly first deflected by the worm gear formed by the elements 44a and 48a, then passed on via the overload protection formed by the elements 48 and 50, reduced again by the planetary gear 52 and then transferred to the second leg 30.

In figure 2 the scissors drive 10 is now off figure 1 shown in assembled condition in side view. Here, a sectional plane is indicated, which runs through the pivot axis 12 of the two legs 20 and 30, the view from figure 3 is to be understood in the direction of the arrows A.

This view in figure 3 now shows the elements arranged around the pivot axis 12 of the scissors drive 10 in the assembled state. The output end 56b of the axle 56 is firmly connected to the second leg 30 . At its other end 56c, the axle 56 is rotatably received in a recess 28e in the first housing part 24 of the first leg 20. Furthermore, seated on the axle 56 is the ring gear 56a, which engages with the second planet gears 52b.

On the other hand, these second planetary gears 52b also engage with the ring gear 54 and are rotatably seated on a planetary axle 52c, indicated by dashed lines, which is connected to the planetary carrier 52d of the planetary gear. The planetary gears 52a are also carried by the planetary axle 52c in a concentric and non-rotatable manner with the second planetary gears 52b. These engage on their radial inside with the teeth 50b of the overload protection gear 50, which has the engagement sections 50a at its other end. These mesh with the internal teeth 48b of the worm wheel 48 in the manner described above, while the external teeth 48a of the worm wheel 48 mesh with the worm shaft 44 which is driven by the motor-gear assembly 42 in the manner described above.

Claims (9)

1. Scissor drive, comprising:

   two legs (20, 30) which can be pivoted relative to one another about a pivot axis, each comprise a longitudinal axis (L1, L2) and are designed to be connected to an external component;

   a motor/gear assembly (42) that drives the relative pivoting movement of the two legs (20, 30),

   which comprises a motor and a gear

   wherein the first leg (20) comprises a housing (24, 26) that is hollow at least in portions, a cavity (28a-c) defined in the hollow housing extending at least in portions along the longitudinal axis (L1) of the first leg (20),

   and the motor/gear assembly (42) being received in the housing (24, 26) of the first leg (20) at least in portions in the portion (28a) of the cavity (28a-c) that extends along the longitudinal axis (L1) of the first leg (20),

   wherein the scissor drive comprises a planetary gear train (52),

   characterized in that the planetary gear train (52) comprises two sets (52a, 52b) of concentrically arranged planet gears which are interconnected for conjoint rotation in pairs.
2. Scissor drive according to claim 1, characterised in that the motor/gear assembly (42) comprises a rotary motor, the rotational axis (46) of which extends substantially in parallel with the longitudinal axis (L1) of the first leg (20).
3. Scissor drive according to either of the preceding claims, characterised in that the motor/gear assembly (42) comprises a reduction gear, which preferably has a reduction ratio of between 1:20 and 1:100, more preferably approximately 1:50.
4. Scissor drive according to either claim 2 or claim 3, characterised in that it comprises a worm gear (44a, 48a) which is designed to convert a rotational movement of the rotary motor into a relative pivoting movement between the two legs (20, 30).
5. Scissor drive according to any of the preceding claims, characterised in that the planetary gear train (52) which is designed having a reduction ratio of between 1:3 and 1:10, more preferably approximately 1:7.5.
6. Scissor drive according to any of the preceding claims, characterised in that it also comprises an overload protection means (48, 50).
7. Scissor drive according to claim 6, characterised in that the overload protection means is formed by a gearwheel (50) and a hollow gearwheel (48) which meshes therewith, the teeth (50a) of the gearwheel (50) being arranged such that, when a predetermined maximum torque is exceeded, said teeth can slip over the teeth (48b) of the hollow gearwheel (48) such that a reduced torque is transmitted between the hollow gearwheel (48) and the gearwheel (50).
8. Scissor drive according to any of the preceding claims, characterised in that the worm gear (44a, 48a) and/or the planetary gear train (52) and/or the overload protection means (48, 50) are also received at least in portions in the housing (24, 26) of the first leg.
9. Vehicle, for example a limousine, comprising at least one scissor drive according to claim 1, wherein one of the two legs (20, 30) is rigidly connected to the body of the vehicle and the other of the two legs (20, 30) is connected to an element which is pivotally attached to the body of the vehicle,
   wherein the element which is pivotally attached to the body is a tailgate, a boot lid, a door or the like.

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