ELEVATOR BRAKE

The present invention relates to an elevator brake as de- scribed in the preamble of claim 1.

Elevators are generally provided with a holding brake, which is used to hold the elevator car stationary when the car is standing at a landing. This same brake is also often used as an emergency brake, which is required by elevator regulations and which is activated in the event of emergencies, such as electric power failures. The brake used may be e.g. a drum brake or a disc brake.

Traditionally, elevators use a drum brake, which comprises an active part provided with at least a brake block and an actuator for moving the brake block and, as a passive part, a brake drum attached to and rotating with the rotor of a hoisting motor comprised in the elevator hoisting machine, a braking surface being provided on the outer circumference of the brake drum. The operation of an elevator drum brake is generally such that, when the brake is in a closed position, a spring comprised in the active part of the brake presses a brake shoe and the brake block attached to it against the braking surface of the brake drum, thereby keeping the elevator car stationary. During travel, an electromagnet comprised in the active part of the brake is in an energized state and the magnet pulls the brake shoe and brake block clear of the braking surface of the brake drum, keeping the brake open and permitting the elevator car to move up or down in the elevator shaft. The elevator brake may be implemented e.g. by using a design that comprises two brakes serving as active parts, placed outside the circumference of the brake drum, on mutually opposite sides of the brake drum circumference as seen from the front in the direction of the axis of rotation of the brake drum.

When the brake is engaged, the force acting on the brake drum of the drum brake is relatively great, and consequently the

brake wheel absorbs a great deal of kinetic energy. This produces a loud noise when the brake block hits the brake drum. An attempt to solve this problem has been to minimize the air gap between the brake block and the brake drum. In such a brake, the brake block can not reach a very high speed and kinetic energy by the moment it hits the brake drum, and consequently the impact is weaker. However, an air gap that is sufficiently small is difficult to implement and adjust, and such a solution leads to a quite sensitive construction and requires very accurate manufacturing tolerances. Another problem encountered in drum brakes is a defective orientation of the brake shoe and the movable parts of the electromagnet, which produces skewness in the air gap and additionally a load straining the other parts of the brake. This problem is par- ticularly pronounced in the case of narrow brake drums.

The object of the present invention is to eliminate the above- mentioned drawbacks and to achieve an elevator brake that is easily and quickly adjustable, takes up as little space as possible and is as quiet as possible in operation. A further object is to achieve an elevator brake in which an adjustment has a substantially identical effect on the behavior of the brake regardless of the traveling direction of the elevator. The elevator brake of the invention is characterized by what is disclosed in the characterizing part of claim 1. Other embodiments of the invention are characterized by what is disclosed in the other claims.

Inventive embodiments are also discussed in the description part of the present application. The inventive content disclosed in the application can also be defined in other ways than is done in the claims below. The inventive content may also consist of several separate inventions, especially if the invention is considered in the light of explicit or implicit sub-tasks or with respect to advantages or sets of advantages achieved. In this case, some of the attributes contained in the claims below may be superfluous from the point of view of

separate inventive concepts. Correspondingly, different details described in connection with each example embodiment of the invention can be used in other embodiment examples as well .

The solution of the invention has the advantage that even a small brake air gap can be adjusted easily and quickly. A further advantage is that the adjustment has the same effect regardless of the traveling direction of the elevator. Another advantage is that the stop faces in the brake body which are relevant to the size of the air gap can be made during manufacture by the same attaching operation, with the result that the stop faces are mutually parallel with a high accuracy. This permits more accurate adjustment while at the same time reducing the noise produced by operation of the brake, because the brake blocks hit the brake drum surface more smoothly. Yet another advantage is that the brake elements are substantially simple, from which it follows that the brake solution is economical to implement.

In the following, the invention will be described in detail by referring to different embodiment examples and the attached drawings, wherein

Fig. 1 presents a diagrammatic and simplified front view of an elevator hoisting machine in which a brake solution according to the invention is used,

Fig. 2 presents a lateral view of an elevator brake system according to the invention, Fig. 3 presents a partially sectioned front view of the elevator brake system according to Fig. 2, Fig. 4 presents a lateral view of a second preferred elevator brake system according to the invention, Fig. 5 presents a lateral view of a third preferred ele- vator brake system according to the invention, and

Fig. 6 presents a lateral view of a magnified detail of one end of the brake system according to Fig. 5

In Fig. 1, an elevator hoisting machine 1 which uses a solution according to the invention is presented in a diagrammatic and simplified front view, i.e. as seen from the direction of the axis of rotation of the brake drum. The machine comprises at least a hoisting motor, which in the figure is hidden behind other components, a frame part 2 and a traction sheave 3 rotated by the hoisting motor. Attached to the traction sheave is a brake drum 4 provided with a cylindrical braking surface 5 and fitted to rotate with the traction sheave 3. The hoisting machine 1 additionally comprises at least brakes 6 fitted to produce a braking effect on the brake drum 4 by friction and disposed on the outer circumference of the brake drum 4 on mutually opposite sides of the brake drum 4 as seen in the direction of the axis of rotation of the brake drum 4. Each brake 6 is hingedly secured at least by one of its mounting brackets 9 or 10 e.g. to the frame part 2 of the hoisting machine 1. The securing and adjustment of the brake 6 are implemented using eccentric shafts 11, which serve as eccentric adjustment elements and are substantially parallel to each other, each brake 6 having two such shafts, disposed substantially symmetrically on either side of the brake 6 as seen in the direction of the center axis of the eccentric shafts 11. The center axis of the eccentric shafts 11 is substantially parallel to the axis of rotation of the brake drum 4.

Inside the body of the brake 6 are one or more compression springs, which have been fitted to press a brake block 8 of the brake, said brake block being provided with a braking sur- face, against the braking surface 5 of the brake drum 4 when the brake is engaged and is e.g. holding the elevator car immovable. Correspondingly, placed inside the body of the brake 6 is also one or more electromagnets, which have been fitted to pull the brake block 8 away from the braking surface 5 against the spring force pressing the brake block 8 and thus to release the brake when the elevator car is starting to move .

Figs. 2 and 3 are diagrams representing an elevator brake system 6 according to the invention in a simplified and partially- sectioned view. In Fig. 2, the brake is shown as seen from the front of the hoisting machine and turned through 90 ² relative to Fig. 1, and in Fig. 3 the brake is shown as seen from the side of the hoisting machine and turned through 90 ^s relative to Fig. 1. In Figs. 2 and 3, the frame part 2 of the hoisting machine is partially visible, and likewise the brake drum 4 and the braking surface 5 of the brake drum 4, whereas the hoisting motor and traction sheave are not shown in the figures .

The brake 6 comprises at least a hollow body 6a and mounting brackets 9 and 10, which are attached to the body 6a on mutually opposite sides of the body 6a and extend outward from the body 6a substantially in the direction of the plane of rotation of the braking surface 5 of the brake drum 4. When the brake is engaged, the brake block 8 is pressed against the braking surface 5 of the brake drum 4, but otherwise the brake block 8 and the braking surface 5 are separated by an air gap 8a. The brake 6 is hingedly secured by its first mounting bracket 9 to the frame part 2 of the hoisting machine 1 by means of an eccentric joint 11. Similarly, the second mounting bracket 10 of the brake 6 is provided with a substantially identical eccentric joint 11, which has been fitted in the through hole 14 of the second mounting bracket 10, the diameter of said hole being substantially larger than the diameter of the eccentric shaft 11. In addition, the brake comprises a spring element 15, which in this case is a draw-spring attached to the second mounting bracket 10 and arranged to pull the brake in a direction away from the braking surface 5 of the brake drum 4.

The two eccentric shafts 11 are mutually substantially identical. Provided at the first end of each eccentric shaft 11 is a flange 11a having a diameter larger than that of the shafts,

the flange being fitted e.g. by threads to the first end of the first cylindrical part lib of the eccentric shaft 11. The flange 11a serves to lock the eccentric shafts 11 and at the same time the brakes 6 in position. As an extension of the first cylindrical part lib, the eccentric shaft has a second cylindrical part lie, which is substantially parallel to the first cylindrical part lib but whose center axis is, however, located at a distance from the center axis of the first cylindrical part lib, so that the cylindrical parts lib and lie together form an eccentric shaft. In this example, the cylindrical parts lib and lie are equal in diameter, but they may just as well have unequal diameters. In addition, the second end of each eccentric shaft 11 has a hex head Hd or an equivalent form-locking element which can be used to rotate the eccentric shafts 11 about their center axis to adjust the size of the air gap 8a.

The frame part 2 of the hoisting machine 1 is provided with mounting holes 12 , whose diameter has been adapted to corre- spond to the diameter of the first cylindrical part Hb of the eccentric shafts 11, so that the mounting hole 12 receives the first cylindrical part Hb. The first cylindrical part Hb fits in the mounting hole 12 as tightly as possible and substantially without clearance, but the cylindrical part Hb can still be rotated about its center axis by the hex head Hd when the eccentric shaft 11 is being rotated.

The first mounting bracket 9 of the brake 6 has a mounting hole 13, whose diameter has been adapted to correspond to the diameter of the second cylindrical part Hc so that the mounting hole 13 receives the second cylindrical part Hc. In this embodiment of the invention, the second cylindrical part Hc fits in the mounting hole 13 as tightly as possible and substantially without clearance, but still so that it can be ro- tated about the center axis of the _. first cylindrical part Hb by the hex head Hd when the eccentric shaft H is being rotated. This causes the mounting bracket 9 and consequently the

brake 6 as a whole to be displaced by an amount corresponding to the rotated eccentricity of the eccentric shaft 11, while the frame part 2 remains immovable. The center axis of the mounting hole 13 lies substantially in the tangential plane of the point of contact between the brake block 8 and the braking surface 5, and consequently the braking force is substantially the same in both directions of rotation of the brake drum 4.

In another embodiment of the invention, a sleeve (not shown in the figure) is provided between the cylindrical part lie and the mounting hole 13, so that the second cylindrical part lie can be rotated in the mounting hole 13 by means of the sleeve.

Correspondingly, the diameter of the through hole 14 in the second mounting bracket 10 is substantially greater than the diameter of the second cylindrical part lie of the eccentric shaft 11. The through hole 14 is so disposed in the mounting bracket 10 that the lowest point along its periphery, i.e. the point closest to the braking surface 5, is substantially level with the lowest point along the periphery of through hole 13, in other words, in each hole 13 and 14, the point closest to the braking surface 5 is located at a substantially equal distance from the braking surface 5. The brake drum-side portion of the periphery of through hole 14 forms a stop face 16, which has been fitted to be pressed against the second cylindrical part lie of the second eccentric shaft 11 by the spring force of the spring element 15 acting substantially in a direction away from the braking surface 5. Correspondingly, the distance between the centers of holes 13 and 14 is substan- tially equal to the distance between the centers of the mounting holes 12 in the frame part 2 of the hoisting machine 1.

The brake 6 additionally comprises a releasing element 7 fitted to be mechanically operable, by means of which the brake can be released manually when no electricity is supplied to the brake .

Fig. 4 represents another elevator brake system 6 according to the invention as seen in lateral view. In this solution, all other parts of the brake 6 except for the second mounting bracket 10 are substantially identical to those in the solu- tion represented by Figs. 2 and 3. Instead of a through hole 14, the second mounting bracket 10 now has only a stop face 16 which opens in a direction away from the brake drum 4 and whose distance from the braking surface 5 has been adapted to be substantially equal to the distance of the closest point along the periphery of the mounting hole 13 of the first mounting bracket 9 from the braking surface 5 of the brake drum 4.

Figs. 5 and 6 represent a third preferred elevator brake sys- tern 6 according to the invention as seen in lateral view. In this solution, too, all other parts of the brake 6 except for the second mounting bracket 10 and the associated auxiliary components are substantially identical to those in the solution represented by Figs . 2 and 3. The second mounting bracket 10 is now provided with a separate, carriage-type or similar supporting element 17 arranged to be substantially linearly movable and functioning as a slipper pad, which has been fitted to be movable between the second eccentric shaft 11 and the second mounting bracket 10. The supporting element 17 has a substantially curved stop face 16 opening in a direction away from the brake drum 4. The distance of the closest point of said stop face from the braking surface 5 has been adapted to be substantially equal to the distance of the closest point along the periphery of the mounting hole 13 of the first mounting bracket 9 from the braking surface 5 of the brake drum 4. The stop face 16 of the supporting element 17 is so shaped that the surface pressure between the second eccentric shaft 11 and the supporting element 17 will be as small as possible in all adjustment positions of the eccentric shaft 11.

The second mounting bracket 10 is provided e.g. with guide tracks 18, along which the supporting element 17 has been fitted to slide in mutually opposite directions as indicated by- arrow 19 due to the force exerted by the eccentricity of the second eccentric shaft 11 when the second eccentric shaft 11 is being rotated in connection with adjustment of the air gap 8a.

The air gap 8a of the brakes 6 presented in Figs. 2-6 is ad- justed in the same way in all the brake types according to the example. All these brake solutions have at least in the mounting hole 13 at the first end a substantially clearance- free eccentric shaft 11, which is rotatable about its center axis and serves as a means of adjusting the size of the air gap 8a, and at the second end a stop face 16, which has been fitted to be pressed by a spring element 15 against that surface of the second cylindrical part lie of the second eccentric shaft 11 which faces towards the braking surface 5. Adjustment of the size of the air gap 8a has been adapted to be effected by ro- tating the eccentric shafts 11 by the hex head Hd. On the side of the first mounting bracket 9, the brake 6 is moved farther away from the braking surface 5 and closer towards the braking surface 5 by the force exerted by the eccentric motion of the second cylindrical part Hc of the eccentric shaft 11. Similarly, on the side of the second mounting bracket 10, the brake 6 is moved farther away from the braking surface 5 by the spring force of the spring element 15 when permitted by the eccentric motion of the second cylindrical part Hc of the eccentric shaft 11 and likewise moved closer towards the brak- ing surface 5 when forced by the eccentric motion of the second cylindrical part Hc of the eccentric shaft 11 against the spring force of the spring element 15. In each brake solution, the brake 6 comprises two eccentric shafts H functioning as eccentric adjusting devices, one eccentric shaft being placed on either side of the brake block 8 as seen in the direction of the axis of rotation of the brake drum 4, i.e. relative to

the direction of the plane of rotation of the braking surface 5.

It is obvious to a person skilled in the art that the inven- tion is not exclusively limited to the example described above but that it may be varied within the scope of the claims presented below. Thus, for example, the fastening and structure of the adjusting elements may differ from those described above .

It is also obvious to a person skilled in the art that the first and second cylindrical parts of the eccentric shafts may differ from each other in diametric size, for example so that the second cylindrical part going through the mounting bracket is smaller in diameter than the first cylindrical part in the mounting hole of the frame part of the hoisting machine.

It is further obvious to a skilled person that the first and second cylindrical parts of the eccentric shafts may also dif- fer from each other in diametric size so that the second cylindrical part going through the mounting bracket is larger in diameter than the first cylindrical part in the mounting hole of the frame part of the hoisting machine.

It is likewise obvious to a skilled person that the structure of the eccentric shaft may also differ from the structure described above so that the shaft itself is straight and has a substantially uniform thickness throughout its length but is provided with an eccentric sleeve placed on the cylindrical part going through the mounting bracket or on the cylindrical part in the frame part of the hoisting machine.

It is additionally obvious to a skilled person that, instead of an eccentric shaft, it is also possible to provide a wedge- shaped adjusting element or equivalent in conjunction with the second mounting bracket to allow adjustment of the air gap of the brake .