Door Drive

The present invention relates to a friction wheel drive for a sliding door, especially for a lift door, consisting of at least one door leaf, which is moved rectilinearly or curvilinearly and which is supported by means of guide rollers and guided at a guide.

A drive of the above-mentioned kind for door leaves of a sliding door is known by Swiss patent specification No. 636 162. This drive comprises a rotating shaft, which is parallel to the door guide, with at least one roller head, which operates as an entrainer of the door leaf suspended at a guide by means of guide rollers. The roller head comprises three rollers, which are distributed about the inner circumference of the roller head, and which are in frictionally-coupled connection with the rotating shaft. The roller axes are so arranged that when the shaft is rotating a lateral movement of the roller head on the shaft results in analogous motion of a screw nut on a rotating threaded spindle. Opposite movements of for example, two roller heads on the same shaft can be achieved with an appropriately different arrangement of the roller axes. The shaft itself is driven by a motor.

This drive does not particularly distinguish itself from conventional drives with either a crank drive or a belt drive from the viewpoint of construction and assembly cost. Moreover, for reasons of rigidity the rotating shaft must be supported at a plurality of points.

Swiss patent specification No. 384 404 describes a further "electrical drive device for opening and closing of lift doors". A drive similarly operating with a friction couple is shown in this disclosure, wherein the drive device works as a tractive drive, has a separate guide and the drive take-off thereof is formed as a conical friction wheel, which is disposed in operative connection with a special cam with chamfers at both sides. The chamfers effect an axial displacement of the friction contact point on the conical friction wheel, whereby a corresponding speed profile for the sliding door results from the cam geometry.

Due to the tractive drive principle, substantial space is needed for this drive, which precludes its use for lift applications. Furthermore, the friction contact with punctiform support seems to yield a somewhat limited friction couple.

It is therefore the task of the present invention to create a simple and compact friction wheel drive, which is economic to produce and universally usable, for a sliding door.

The invention is distinguished inter alia in that the guide roller itself is constructed as a motor of the outside rotor form, thus as a motor roller. The outside rotor has the form of a guide roller which runs along on a guide rail. The outside rotor is mounted for rotation about a stationary shaft and is equipped with permanent magnets at its inner circumference. The stationary shaft is connected to the door leaf to be entrained, and carries a wound inner stator stack. The winding connections are guided outwardly through the interior of the shaft. The roller motor is advantageously realized as a permanent pole direct current motor with electronic commutation.

As a further type of motor, an synchronous polyphase induction motor with frequency regulation, can be used wherein the outside rotor then comprises an annular lamination stack with short-circuited squirrel cage and the static inner stator comprises a polyphase alternating current winding.

A feedback signal for speed regulation and travel regulation can be obtained by means of a revolution transmitter at the motor roller and/or linear transmitter at the guide each with a respective opto-electronic reader at the door leaf. A force transfer from a motor roller to a running roller is possible by means of a is transmission.

The invention is more closely explained in the following by reference to an example of embodiment and is illustrated in the drawings, in which:

FIG. 1 shows the front view of a door leaf with motor roller and running roller;

FIG. 2 shows a cross-section through a roller motor;

FIG. 3 shows a plan view of a telescopic sliding door with motor roller and running roller; and

FIG. 4 shows the roller motor as a three-phase induction synchronous motor.

A door leaf of a sliding door is designated by 1 in FIG. 1. The door leaf 1 is suspended by means of rollers 3 at a guide 2. Of the rollers 3, that designated by 3' is a motor roller, and that designated by 3" is a running roller. Externally, the difference between motor roller 3' and running roller 3" as seen from this side is not recognizable. Drawn in by dotted lines is a possible transmission cord 18 for transmission of the motor force from the motor roller 3' to a running roller 3".

The roller 3' comprise a roller body with rim gear 19 at both ends and a running surface 20 is designated by 4 in FIG. 2. The forward rim gear 19 has a groove 17 for the laying in of the transmission cord 18. Respective roller bearings 9 and 10, each running on a stationary shaft 8, are incorporated in the forward and rearward end face of the roller body 4. In the illustrated exemplary form, the motor incorporated in the roller body 4 is a direct current motor with permanent magnet poles 5 upon the circumference of the inner cylindrical roller surface and a laminated inner stator 6 with a winding 7 on the stationary shaft 8, wherein an electronic commutator circuit, which is not illustrated, is provided instead of a mechanical commutator.

The right hand end part of the shaft 8 is provided with a screw thread 14 beyond the exit from the roller body 4. The shaft 8 is firmly screw-connected at the thread end with the upper part of the door leaf 1 by means of flat nuts 11 and 12. The winding connections 13 of the winding 7 are guided out through an axial bore in the shaft 8. For the purpose of signalling back the roller speed to a motor regulation regulator of known kind, a code strip 15 in a circularly annular form is mounted externally on the rearward end face of the roller body 4 and is electronically scanned by a reader 16, for example of a known opto-electronic-type, mounted on the door leaf 1. For the signalling back to a travel regulator of known kind a further code strip 21 is mounted on the guide 2 and is scanned by an analog reader 22, similarly preferably opto-electronic, on the door leaf.

FIG. 3 is an example of use of the invention in connection with a telescopic door. In classic mechanical drives having an entraining lever, different speeds for the two door leaves 1a and 1b is achieved through different lever translations and is thus unchangeably defined. With the individual controllable and regulable motor rollers 3', as depicted in FIG. 3, the first speed of the door leaf 1a and a second, typically double speed of the door leaf 1b can be preset solely by the motor control and regulating devices. As an alternative, the roller motors in the two motor rollers 3' may be constructed to be appropriately different, for example with respect to the number of poles, whereby the precise movement synchronization or movement relationship of the two door leaves 1a and 1b relative to one another can be additionally monitored by the two travel and speed regulators associated with the door leaves 1a and 1b.

The power requirements for the door drive varies according to the respective mass and required speed of the sliding door. A doubling of the drive power can be accommodated, for example, by utilizing motor rollers 3' for both door rollers for a particular door leaf. In the case of very light door leaves the drive power of a motor roller 3' can additionally be transmitted to a running roller by a cord 18, whereby the friction coupling with the guide 1 is improved. Moreover, the running surface 20 of a motor roller 3' can also be provided with a coating having a higher friction value, whereby the friction couple with the guide is similarly strengthened.

An synchronous polyphase induction motor can be provided as depicted in FIG. 4. If such a motor is incorporated into the roller body 4, it may consist of a lamination stack outside rotor 23 with a short circuit winding 24 consisting of short-circuit rods pushed into grooves and short-circuit rings connected at the end faces with the short-circuit rods. A similarly laminated inner stator on the shaft 8 includes a known polyphase winding with, for example, two or more poles formed by the winding layout. Control and regulation of such a polyphase induction motor can be expediently effected by means of a variable voltage, frequency and amplitude control, as known in the art.

Other modifications and adaptations to the invention a described herein are intended to be embraced thereby. For example, the profile of the door roller 2 is not limited to that of the shown example. Concave or convex running surfaces, which then run on guides with a correspondingly matched shape, can also be employed. Instead of a cord 18, the use of a light chain or a flat belt is also possible. The latter can run on the running surface 20 and thus replace an additional friction coating. In such a case, however, one of the door rollers should be fastened in an elongate hole or a slot, or provided with other adjustment means, for the tensioning of the belt.