Patent Application
20080135345
The present invention relates to an elevator installation, to a guide rail of an elevator installation, to brake equipment of an elevator installation and to a method for guiding, holding and braking an elevator installation.
An elevator installation substantially serves for vertical transport of goods or persons. The elevator installation includes for this purpose an elevator car for reception of the goods or persons, which elevator car is movable along a guide path. As a rule, the elevator installation is installed in a building and the elevator car transports goods or persons from and to various floors of this building. In a customary construction the elevator car is installed in a shaft of the building and it contains, apart from the car, support means which connect the car with the counterweight. The elevator car is moved by means of a drive, which acts selectably on the support means or directly on the elevator car or the counterweight. The guide path for guidance of the elevator car is usually a guide rail which is fixedly arranged in the building or in the shaft. From time to time an elevator installation of that kind is also arranged outside a building, wherein then the guide path can be part of a structure. Elevator installations of that kind are equipped with brake systems which on the one hand can hold the elevator car in a stopping position and/or can brake and hold the elevator car in the event of a fault.
An elevator installation with brake equipment is known from patent document EP 1 213 249, in which holding and braking is achieved in that a brake part is brought into mechanically positive contact with a stationary part. The brake part is for that purpose pressed against the stationary part by a small force. In this connection a defined sliding movement, which enables braking, is brought about at the brake part. The brake equipment requires, in particular, low brake actuating forces and thus also low brake release forces.
The problem with this solution is now to be seen in the fact that the brake equipment has to include sliding equipment so as to make possible, in the case of braking, a gentle stopping of the elevator car. This requires, above all in the case of higher speeds, long slide paths and associated elements defining braking force, such as, for example, springs. This necessitates much constructional space and is expensive.
The present invention is based on the object of providing brake equipment of an elevator installation which can hold an elevator car in an elevator installation at standstill with low actuating forces, but in the case of emergency is also in a position of braking the elevator car. In addition, it shall demand little constructional space.
The elevator installation according to the present invention comprises an elevator car and brake equipment for braking and holding the elevator car. The brake equipment comprises a brake lining which co-operates with a brake surface for the purpose of the holding and braking.
Moreover, the present invention relates to a guide rail of an elevator installation. The brake rail brakes and holds the elevator car by means of brake equipment. In that case the brake rail has a brake region as a brake surface for interaction with the brake equipment.
Equally, the present invention relates to a method for guiding, holding and braking the corresponding elevator installation.
According to the present invention the brake surface has at least one longitudinal wedge groove or wedge elevation which is oriented in braking direction and on which the brake lining acts in case of need. This longitudinal wedge groove or longitudinal wedge elevation can be a groove or elevation of appropriate width or several wedge grooves can lie adjacent to one another. The advantage of this construction is to be seen in that the wedge groove shape effects an amplification of a normal force and that with this normal force a high braking force can thus be achieved, wherein a possibility of sliding is additionally given.
The normal force FN is that force which presses the brake lining towards the planar brake surface in the case of need. The planar brake surface is oriented perpendicularly (90°) relative to the normal force FN. This normal force FN produces a braking force FB which is defined by the coefficient of friction μ between brake lining and brake surface:
F
B
=F
N×μ
If the brake equipment in relation to the brake surface is disposed at standstill, a coefficient of static friction μH is to be used as the coefficient of friction μ and in the case of a relative movement between brake equipment and brake surface a coefficient of sliding friction μG is used. A braking force amplification in correspondence with a wedge plane form results with use of a wedge groove. In the case of a wedge plane inclination in correspondence with an angle α, wherein the angle α denotes the plane deviation of the wedge plane from the planar brake surface, a braking force amplification of 1/cos α results. The resulting braking force FBK is:
F
BK=(1/cos α)×FN×μ
A significant amplification of braking force can thus be achieved by means of the longitudinal wedge groove or wedge elevation. It is clear that as a rule there is selection of a symmetrical wedge shape so that lateral forces mutually cancel.
Advantageously, the brake lining has a counter-shape adapted to the longitudinal wedge groove or wedge elevation of the brake surface. Wear of the brake lining can thereby be kept small, since the wedge surfaces rest or rub on one another. Obviously it is to be ensured that in the case of wear the brake lining can be appropriately urged forward. In this connection it is to be noted that current items of brake equipment are increasingly employed for sole holding of the elevator car at a floor. This holding force FH results from, for example, a maximum load difference between car and counterweight. In inversion of the above-mentioned formula for calculation of the braking force, there accordingly results a required normal force FNH for holding a car at a floor of:
F
NH
=F
H×cos α/μH
Analogously, a required normal force FNB for braking a car results:
F
NB
=F
B×cos α/μG
In this connection, the required braking force FB is used instead of the holding force FH and the coefficient of sliding friction μG is used instead of the coefficient of static friction μH.
A pressing device for holding and braking the car can be designed, in correspondence with the wedge angle α, with lower pressing forces FN. This enables use of smaller drive units or brake release units, which is correspondingly more favorable.
Advantageously, in the design of the brake equipment the number of brake linings and/or items of brake equipment which co-operate is to be taken into consideration.
In a preferred embodiment the brake equipment is arranged in the region of the elevator car and the brake surface is integrated in a guide rail, which guide rail at the same time guides the elevator car. Advantageously at least one brake equipment is used per guide rail. This is advantageous, since the car can thereby be directly held at a stop. Stretchings of support means thereby do not influence a loading or unloading process.
A further advantage of this solution according to the present invention is to be seen in that the brake lining and thus the brake equipment is at the same time laterally guided by the longitudinal grooves. Derailing of the braking lining and thus failure of the braking action are effectively prevented.
An embodiment in which the guide rail has a guide region for interaction with the guide means and a brake region as brake surface for interaction with the brake equipment is particularly advantageous, wherein the guide region and brake region have different surfaces and the guide region is geometrically separated from the brake region. This embodiment allows an optimum and functionally appropriate design of the respective regions.
Advantageously the guide rail is a T-shaped guide rail, which has a rail web, and this rail web has both the guide region for interaction with the guide means and the brake region for interaction with the brake equipment. Other forms of brake rails are obviously also possible, such as, for example, guide rails in the form of an angle profile member or any other shapes. T-shaped guide rails are widely known in elevator construction and manufacture thereof is possible in simple manner.
In an embodiment of particularly elevated quality the guide region is provided with a slide means for reducing friction or it is furnished with a slide coating, wherein the slide coating is a profile member, preferably a synthetic material profile member which contains “Teflon” (registered trademark of E. I. Du Pont de Nemours and Company, Wilmington, Del.) and which, for example, is plugged onto the relevant web of the guide rail.
Nano-composites, for example homogeneously formed nickel-fluorpolymer coatings, are, for example, also particularly suitable as the slide means coating, since they enable unchanging slide characteristics in conjunction with good chemical and mechanical properties. This construction enables provision of a guide rail which does justice to high demands on comfort.
The brake region can be formed directly in the basic structure of the brake track. The brake track or the corresponding guide rail is, for example, drawn, rolled or mechanically processed. Alternatively, the brake region can also be produced by means of a brake profile member mounted on the basic structure of the guide rail. The brake region can obviously be provided with a friction-influencing means, for example nano-composite, or with a surface structure for increasing friction. An advantage of this embodiment is that a coefficient of friction can be selected to be as high as possible, whereby the required normal force is in turn reduced. This makes possible creation of economical brake equipment.
In an advantageous embodiment the separation between the guide region and the brake region is constructed in such a manner that a transmission of lubricants such as, for example, oil or other slide means from the guide region to the brake region is prevented or reduced. A functional reliability of the brake equipment is thereby significantly increased, since no substances which reduce the coefficient of friction can easily pass into the brake region.
In an alternative embodiment the brake equipment is arranged in the region of a drive motor and the brake surface is disposed in direct connection with a drive pulley or a drive shaft of the drive motor. In this connection the braking and holding action of the brake equipment is transmitted to the elevator car by way of supporting and drive means. A holding brake in the drive can thereby be provided economically, since as a consequence of the wedge action a reduced braking force is possible.
The above, as well as other advantages of the present invention, will become readily apparent to those skilled in the art from the following detailed description of a preferred embodiment when considered in the light of the accompanying drawings in which:
The following detailed description and appended drawings describe and illustrate various exemplary embodiments of the invention. The description and drawings serve to enable one skilled in the art to make and use the invention, and are not intended to limit the scope of the invention in any manner. In respect of the methods disclosed, the steps presented are exemplary in nature, and thus, the order of the steps is not necessary or critical.
One possible overall arrangement of an elevator installation is illustrated in
In the illustrated example the items of brake equipment 10 are arranged below the car 3. An attachment 10a above the car 3 is obviously also possible, as optionally illustrated in
The holding force is thus calculated as: FH=FN×2×μH [1]
The braking force is correspondingly calculated as: FB=FN×2×μG [2]
For release of the brake equipment 10, i.e. when the car 3 is to be moved, the brake levers 10.1 are drawn together at the rearward ends thereof by means of an actuator force FA, whereby the brake linings 12 are relieved and a braking or holding force thereby removed.
As schematically illustrated in
holding force: FH=(1/cos α)×FN×2×μH [1.1]
braking force: FB=(1/cos α)×FN×2×μG [2.1]
This holding or braking force in turn relates to brake equipment 10 with two brake surfaces 11 as illustrated in principle in
The following table gives an overview of achievable braking force amplification in dependence on the selected wedge angle α:
In the case of use of a wedge angle α of 30° a braking force amplification of approximately 15% or an amplification factor of 1.15 thus results. With consideration of the resulting braking force amplification and the loading, which increases therewith, of the brake linings 12, a proposed optimum wedge angle α in the region of 30° to 60° results.
A correspondingly reduced pressing force FN can also now be selected for achieving a desired holding force, which in turn enables use of brake equipment 10 with small actuator forces. A longitudinal wedge groove further has the advantage that the brake lining 12 is laterally guided. Derailing of the brake lining 12 is thereby prevented. It is obviously conceivable to provide a longitudinal wedge groove primarily for the purpose of lateral guidance. In this connection, longitudinal grooves of other shapes, such as, for example, a curved groove could be used or also flat wedge angles in an angular range below 30° could also be used. In addition, these grooves produce, in correspondence with the above embodiments, as before an amplification of the resulting braking force.
The solutions shown by way of
The illustrated solutions are obviously also translatable to counterweight guide rails or to a brake disc of the drive and the production methods of the longitudinal wedge grooves are selected by the web manufacturer.
In accordance with the provisions of the patent statutes, the present invention has been described in what is considered to represent its preferred embodiment. However, it should be noted that the invention can be practiced otherwise than as specifically illustrated and described without departing from its spirit or scope.
| Number | Date | Country | Kind |
|---|---|---|---|
| 06125624.4 | Dec 2006 | EP | regional |
