Holding brake with locking mechanism

A holding brake is designed for use in an elevator installation, the installation comprising an elevator cage, a drive and a drive control, wherein a support is movable by way of the drive and the elevator cage is movable by way of this support. The holding brake is designed for application of a mechanical braking action relative to a guide rail of the elevator installation so that the elevator cage after actuation of the holding brake retains its vertical position. The holding brake comprises a locking mechanism which is designed so that it acts from two opposite sides on the guide rail.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to European Patent Application No. 10166041.3, filed Jun. 15, 2010, which is incorporated herein by reference.

FIELD

The disclosure relates to a holding brake for an elevator installation.

BACKGROUND

Elevator systems of a conventional kind generally comprise a drive, a drive control associated with the drive and a braking system.

Holding brakes, which usually must fulfill prescriptions with regard to safety regulations, are employed at the elevator cages.

A hydraulically actuable disc brake is known from patent specification EP 0 648 703 B1, in which, in the case of braking, brake plates engage a guide rail and the elevator cage is secured at a story stop against impermissible upward movements and downward movements.

A locking device which is engageable from outside and which in company with the movement in upward direction or downward direction of the elevator cage builds up the necessary braking force in order to stop the elevator cage is known from patent application EP 0 999 168 A2/A3.

An elevator installation with a cage brake has become known from EP 1 840 068 A1, in which brake wedges slide on tracks extending obliquely with respect to a guide rail. In the case of braking a respective hydraulic actuator pushes a respective brake wedge along the track against the travel direction of the elevator cage. As soon as the brake wedge comes into contact with the guide rail the brake wedge moves further on the track and wedges between the guide rail and the track in brake-amplifying manner.

SUMMARY

At least some embodiments of the disclosed technologies comprise a holding brake which combines a simple construction with a safe function. In particular embodiments, the holding brake can exert a direct braking action.

At least some embodiments are equipped with a locking mechanism, possibly a double-acting locking mechanism, for holding a elevator cage in a fixed shaft position.

The holding brake can exert a form of symmetrical clasping action. The clasping action can arise due to unilaterally acting traction elements of the locking mechanism.

In one embodiment the holding brake comprises a double-acting brake which acts symmetrically. In that case, two opposite brake shoes act as active brake shoes and produce a braking force at a guide rail.

Use can be made of a holding brake which is designed specifically for use in an elevator installation comprising an elevator cage. The holding brake is designed for application of a mechanical braking action relative to a guide rail of the elevator installation so that the elevator cage or the counterweight, after actuation of the holding brake, keeps its vertical position. For this purpose the holding brake can comprise a locking mechanism, possibly a double-acting locking mechanism, which is so designed that it acts on the guide rail from two mutually opposite sides and amplifies the braking force.

In some embodiments, a minimum vertical movement of the elevator cage or of the counterweight is sufficient in order to trigger an amplified or self-amplifying locking function of the holding brake. This locking function can be triggered by use of the locking mechanism not only if the elevator cage or the counterweight should move a small amount upwardly (here termed impermissible movement), but also if the elevator cage or the counterweight should move a small amount downwardly (here termed impermissible movement).

In further embodiments, the holding brake has a self-locking function, since sometimes even in the case of a small undesired movement of the elevator cage the braking action increases quasi-automatically.

In additional embodiments, the locking mechanism is equipped with at least one actuator in order to be able to so adjust, in an initial movement or adjusting movement, brake bodies that in the activation case they only have to execute a small closing movement (engagement movement) in order to more firmly fix the elevator cage.

DETAILED DESCRIPTION

FIG. 1shows a first exemplary embodiment in a schematic overall illustration. An elevator installation10is shown in strongly schematic form. The elevator installation10comprises an elevator cage12and a corresponding counterweight19, which are guided to be vertically movable in opposite sense in a elevator shaft. The elevator cage12can serve several stories (here two stories A and B are shown). The elevator cage12can be moved by a drive11which, by way of example as indicated inFIG. 1, is disposed at the upper shaft end. Apart from the drive11, the elevator installation10comprises a drive control15, which is associated with the drive11, and a braking system13. The elevator cage12is here connected with the counterweight19by way of a support means18which runs around a drive pulley of the drive11. The linking, in terms of control, of the drive control15with the elements of the elevator installation10is schematically indicated by a double arrow16, which symbolizes a connection between the drive11and the drive control15. The drive control15typically receives signals by way of, for example, the control link16. These signals are converted into control magnitudes. If the drive11sets the elevator cage12in motion, at least one holding brake20, which is arranged at the elevator cage12and mechanically interacts with at least one guide rail17in the elevator shaft14, is released.

On reaching a destination story (for example story B inFIG. 1) the speed of the drive11is slowed down and the braking system13is activated. When the correct vertical position in the elevator shaft14has been reached, the holding brake20comes into action in order to hold the elevator cage12exactly at the correct vertical position.

The holding brake20, which is described in more detail in two different forms of embodiment with reference toFIGS. 2 and 3, is designed for use in an elevator installation10. The holding brake20serves for application of a mechanical braking action relative to a stationary guide rail17of the elevator installation10. The elevator cage12is held in its vertical position in the elevator shaft14by the holding brake20after actuation thereof.

The holding brake20comprises a locking mechanism21, possibly a double-acting locking mechanism21. The locking mechanism21is so designed and constructed that it acts on the guide rail17from two mutually opposite sides S1, S2.

A view of the holding brake20is shown in each ofFIGS. 2 and 3, in which the double-acting locking mechanism21acts from the left (side S1) and from the right (side S2) on the guide rail17. In the case of action on the guide rail17the locking mechanism21exerts, for example, an advancing force BK1and an oppositely directed advancing force BK2on the guide rail17.

The locking mechanism21can comprise a first brake body22.1and a second brake body22.2. These brake bodies22.1,22.2are opposite one another. The first brake body22.1has a first brake shoe23.1on a side facing the second brake body22.2. The second brake body22.2has a second brake shoe23.2on a side facing the first brake body22.1. The first brake body22.1presses together with the first brake shoe23.1by the advancing force BK1or by a force proportional to the advancing force BK1from the side S1against the guide rail17. The second brake body22.2presses together with the second brake shoe23.2by the advancing force BK2or by a force proportional to the advancing force BK2from the side S2against the guide rail17.

The first brake body22.1and the second brake body22.2can be so movably mounted at a guide body26that they are movable towards and away from one another.

The locking mechanism21can be designed that the two advancing forces BK1and BK2are of equal magnitude. It is thereby achieved that the double-acting locking mechanism21is constructed/arranged to be symmetrical mechanically and/or in terms of force with respect to the longitudinal axis L of the guide rail17.

The locking mechanism21can be coupled to a traction device24acting from the sides S1, S2, as is shown inFIGS. 2 and 3.

This traction device24is so constructed/arranged symmetrically with respect to the first brake body22.1and the second brake body22.2that two traction elements24.1,24.2of the traction device24are connected with the first brake body22.1and two further traction elements24.3,24.4of the traction device24are connected with the second brake body22.2

The traction device24can comprise a traction cable (for example a steel cable) which is arranged so that four cable sections24.1,24.2,24.3,24.4of the traction cable result, as shown inFIG. 2. The four cable sections24.1,24.2,24.3,24.4can form a form of lozenge or parallelogram with lateral corner points or lateral points UL, UR at the two distal ends of the brake bodies22.1,22.2and with an upper distal point or upper deflection point UO at a fastening element25of the holding brake20and with a lower distal point or lower deflecting point UU at the fastening element25of the holding brake20.

The traction cable of the traction device24can be fixedly connected at the lateral deflecting points UL, UR with the respective brake body22.1or22.2. Possibly provided at the upper deflecting point UO and at the lower deflecting point UU are (deflecting) rollers27(as shown inFIG. 2) or slide posts, so that the traction cable can run around or slide around these deflecting points UO and UU. The axes R1, R2of these rollers27or slide posts are perpendicular to the plane E (which here coincides with the plane of the drawing).

The holding brake20can comprise a fastening element25and a guide body26, as shown inFIGS. 2 and 3. The fastening element25is designed for fastening the holding brake20to the elevator cage12and the guide body26is mounted to be displaceable along the fastening element25. The corresponding displacement movement is indicated inFIG. 2andFIG. 3by the double arrow P1.

The guide body26can have two mutually parallel extending rails or slide surfaces28, which in the mounted state run parallel to the longitudinal axis L. In addition, the guide body26comprises a cross member29which is fixedly connected with the rails or slide surfaces28.

The fastening element25and the cross member29can be arranged perpendicularly to one another and form a kind of cross.

The cross member29can carry (horizontal) guides30for horizontal guidance of the brake bodies22.1,22.2. The two brake bodies22.1,22.2can be mounted to be so movable in, at or between the guides30that they can execute an advancing movement in the direction of the guide rail17.

In some embodiments at least one active actuator is employed in order to be able to actively execute initial movements or advancing movements. These movements serve the purpose of bringing the locking mechanism21into a position in which this can build up the holding force with a minimum advance travel. In the case of the form of embodiment shown inFIG. 2, use can be made of a total of three actuators31.1,31.2,31.3. The actuator31.1advances the brake body20.1in the direction of the guide rail17so that the first brake shoe23.1presses, when required, against the guide rail17. The actuator31.2advances the brake body22.2in the direction of the guide rail17so that the second brake shoe23.2presses, also when required, against the guide rail17. Use can be made of a middle (restoring) actuator31.3in order to be able to urge the brake shoes23.1,23.2apart for release of the holding brake20. The position of the brake shoes23.1,23.2can be optimally preset and in the case of need also re-adjusted by co-operation of the actuators31.1,31.2,31.3. The actuators31.1,31.2trigger a first braking action. The actuator31.3releases the holding brake20again.

The presetting of a minimum braking force by one or more actuators can also be employed so that the holding brake20does not automatically open in the case of a corresponding transition through the zero position when a load change from an empty elevator cage12to a full elevator cage takes place.

InFIG. 3only a central actuator32is employed, which extends parallel to the longitudinal axis L and is seated between the upper deflecting point UO and the lower deflecting point UU. This central actuator32combines the braking action and the release of the holding brake20in one. The actuator32thus replaces the actuators31.1,31.2,31.3.

In at least some embodiments, the locking mechanism21is equipped with at least one actuator in order to be able to so advance the brake bodies22.1,22.2in an initial movement that they exert a braking action in order to fix the elevator cage12.

In at least some cases, the actuators comprise a spring and an active actuator element which expands or contracts by, for example, application of a voltage. An actuator in the sense of the present disclosure is a component or an element which converts a signal of a regulating means into mechanical work or movement. The signal can be an electrical, a hydraulic or a pneumatic signal.

The locking mechanism21can comprise a traction cable with several sections24.1to24.4, as shown inFIG. 2. The rollers27serve as deflecting rollers around which the traction cable is guided. The traction cable is fastened at the points UL and UR so as to be able to build up a traction force which by virtue of the symmetrical disposition/path of the traction cable acts at the points UL and UR perpendicularly in the direction of the guide rail17.

However, the locking mechanism21can also comprise, instead of the traction cable, a linkage33with several rods34.1to34.4loadable in tension and compression, as shown inFIG. 3. In order that this locking mechanism21according toFIG. 3is equivalent in effect to the locking mechanism according toFIG. 2, a short length of a traction cable35is attached at each of the deflecting points UO and UU. These traction cables35are tensioned between the points UO1and UO or between UU1and UU.

The traction cable ofFIG. 2and the linkage33inclusive of the short traction cables35constitute a so-termed traction element acting from one side. The action of this unilaterally acting traction element is as follows:

When the elevator cage12is located at a story (for example story B inFIG. 1), the holding brake20comes into play as follows:

The brake bodies22.1,22.2are advanced by the actuators31.1,31.2and the brake shoes23.1,23.2come into interaction with the guide rail17. A first braking action thereby results. If the elevator cage12should now drop a small amount, for example because a large load is contained in the elevator cage12, the fastening element25, which is fixed to the elevator cage12, displaces downwardly in company with the elevator cage12a few millimeters. At the same time the traction elements24.2and24.3pull obliquely downwardly at the points UL and UR. By virtue of this symmetrically acting traction force the brake bodies22.1,22.2are further advanced and the brake shoes23.1,23.2press even more firmly from both sides symmetrically against the guide rail17.

In at least some embodiments, by virtue of their unilateral character, the traction elements24.1and24.4do not exert any pressing force on the brake shoes23.1,23.2, which would impair the braking action.

The converse takes place if the elevator cage12should move upwardly a small amount, for example if a large load is removed from the elevator cage12. Here the traction elements24.1,24.4come into play.

In a form of embodiment according toFIG. 3in which the unilaterally acting traction element comprises a linkage33with traction cables35the manner of effect is in principle the same. In the case of a downward movement of the elevator cage12the lower cable length35pulls at the point UU and the rods34.2,34.3symmetrically pull at the points UL, UR. Through this symmetrically acting traction force the brake bodies22.1,22.2are further advanced and the brake shoes23.1,23.2press even more firmly from both sides symmetrically against the guide rail17.

The converse takes place if the elevator cage12should move a small amount upwardly. Here the upper cable length35pulls at the point UO and the rods34.1,34.4pull symmetrically at the points UL, UR.

As a result, in at least some embodiments, every smallest positional deviation of the elevator cage12is immediately converted into an amplified braking action of the holding brake20. In the embodiment according toFIG. 2, the (deflecting) rollers27guarantee that the respective traction elements24.1to24.4pull with the same forces symmetrically at the points UL, UR. In the case of a form of embodiment according toFIG. 3, the short traction cables35ensure a uniform traction effect as long as the lengths of the rods34.1to34.4are identical and the positions of the points UO and UU are central.

In order to release the braking action of the holding brake20, use can be made of the actuator31.3or32which urges the brake shoes23.1,23.2apart. The release of the holding brake20typically takes place only when the drive11has applied sufficient torque (termed pre-torque) for driving the elevator cage12.

Some embodiments eliminate a load measurement in the elevator cage12, since the actuator can open the holding brake20only when there is sufficient pre-torque. For this purpose the pre-torque can be increased until the actuator is in a position of releasing the holding brake20. In the case of incorrect pre-torque, release of the holding brake20is generally hardly possible, which can lead to improved safety. In the embodiment ofFIG. 3, the actuator32is shortened and thereby urges, due to the stiffness of the rods of the linkage33, the brake bodies22.1,22.2outwardly. Release of the holding brake20takes place here in this manner.

The holding brake20is thus a braking device which symmetrically engages a stationary guide rail17on both sides.

Such a holding brake20can be mounted on the elevator cage12and/or the counterweight19.

The holding brake20can prevent drifting of the elevator cage12away from the story level. Re-regulations by the elevator drive11can be eliminated.

Having illustrated and described the principles of the disclosed technologies, it will be apparent to those skilled in the art that the disclosed embodiments can be modified in arrangement and detail without departing from such principles. In view of the many possible embodiments to which the principles of the disclosed technologies can be applied, it should be recognized that the illustrated embodiments are only examples of the technologies and should not be taken as limiting the scope of the invention. Rather, the scope of the invention is defined by the following claims and their equivalents. I therefore claim as my invention all that comes within the scope and spirit of these claims.