One of the objectives in elevator development work is to achieve an efficient and economical utilization of building space. In recent years, this development work has produced various elevator solutions without machine room, among other things. Good examples of elevators without machine room are disclosed in specifications EP 0 631 967 (A1) and EP 0 631 968. The elevators according to these specifications are fairly efficient in respect of space utilization as they have made it possible to eliminate the space needed for the ma- chine room in the building without a need to enlarge the elevator shaft. The machine used in the elevators according to these specifications is compact in at least one direction, but in other directions it may be much larger than conven- tional elevator machines.

In these basically good elevator solutions, the space and placement of the hoisting function limits the freedom of choice in elevator lay-out solutions. As the aim is to achieve elevators of a more compact construction, the size of the hoisting machine is a factor that encourages the search for new solutions in the construction of the machine or parts of it. When hoisting ropes that are thinner than the hoisting ropes conventionally used in elevators, ropes of a thickness below 8 mm or otherwise flexible ropes or equivalent are used, there is no problem in using a traction sheave of a smaller diameter. This permits the use of a smaller hoisting machine as the torque requirement is smaller. Likewise, the brakes holding or braking the trac- tion sheave can be made smaller due to the smaller braking moment required. Thus, the concept of an elevator with a small traction sheave, i. e. a traction sheave clearly below 330 mm, even only 100 mm in diameter, enables a reappraisal of the various features associated with the hoisting ma-

chine. The results of such reappraisal may of course be ap- plicable to other elevators besides those with a small trac- tion sheave.

Elevators without machine room generally use gearless ma- chines. The conventional brake solution in the machines is a shoe brake in which a brake shoe has been arranged to be pressed against a braking rim by a spring in braking situa- tions and in which the brake is released by lifting the brake shoe from the braking rim by means of an electromagnet or a similar coil solution. A known method of adjusting the shoe brake, in other words the air gap of the brake, is to move the entire brake in relation to the machine by utiliz- ing the adjustment tolerance provided in the fastening screws of the brake. For example, if the brake has been secured to the machine frame with four screws with distance adjustment provided in conjunction with them, then in prac- tice it may be difficult to perform a successful adjustment because it is difficult to tighten the screws evenly, and thus an unsuccessful adjustment has the result that the brake and the machine are incorrectly positioned relative to each other and further that a"wedge-shaped"air gap appears between the brake shoe and the braking rim, which means that the air gap is clearly larger at one edge than at the other edge of the air gap. A"wedge-shaped"air gap leads to un- even stress on the brake shoe and indefinite operation of the brake. Thus, if the machine has several brakes, the operation of each brake may differ from that of the others, and consequently one of the brakes undergoes greater wear than the others.

The object of the present invention is to overcome the above-mentioned drawbacks and create a mechanically simple and reliable brake and a method of adjusting the brake. It is an object of the invention to achieve an elevator hoist- ing machine that has a lighter construction at least in respect of the brake. A further object is to achieve a com-

pact machine or at least a compact brake structure.

The brake of the invention is characterized by what is dis- closed in the characterization part of claim 1, and the method of the invention for adjusting a brake is character- ized by what is disclosed in the characterization part of claim 4. Other embodiments of the invention are character- ized by what is disclosed in the other claims.

The brake and method of the invention, in short the solution of the invention has the advantage of simplicity of the adjustment function. By applying the invention, it will be easy to achieve a compact and quiet brake structure that is well suited for use in elevators without machine room. The brake is reliable in operation, easy to maintain and a clearly defined construction. The compact and clear con- struction comprising a relatively small number of components also means a reasonable manufacturing cost of the brake. The brake of the invention is easy to install in conjunction with an elevator machine and simple to adjust so as to make it ready for operation. As the adjustment does not substan- tially change the orientation of the brake shoe relative to the braking rim, the brake wears evenly.

In the following, the invention will be described in detail with reference to an embodiment example and the attached drawings, wherein Fig. 1 represents a hoisting machine according to the invention with two brakes, and Fig. 2 presents a brake according to the invention.

Fig. 1 presents a hoisting machine unit 100, which comprises an actual hoisting machine 91 provided with a traction sheave (the traction sheave is not shown in the figure) and an auxiliary pulley 92 guiding the passage of the ropes, which pulley can also be used to rig the machine as a so-

called"double wrap"machine. The hoisting machine 91 and auxiliary pulley 92 are mounted on a supporting frame 93, whereby the hoisting machine unit is secured in place in the elevator. The supporting frame 93 also forms part of the stiffening structure of the actual machine 91. The hoisting machine 91 is provided with two brakes 94, in which a brake shoe 95 has been arranged to be pressed against a braking rim 96 rotating with the traction sheave. Connected to the hoisting machine unit 100 is a switch box 98, through which the control of the brakes and hoisting machine has been arranged either as electric current feeds only or as a com- bination of current feeds and control and/or monitoring functions. The brake has a release lever 7, by means of which the brake can be released without electric control.

For operating this lever 97, it is possible to connect an operating wire rope or some other power transmission means.

If emergency release of the brake is implemented using an electric arrangement actuated e. g. by a stand-by battery, then no lever 97 is needed.

Fig. 2 illustrates the structure of the brake 94 in a sec- tioned view. The brake frame 14 is secured by a rigid fas- tening arrangement to the body of the hoisting machine 91.

Placed in an opening in the brake frame is an adjusting nut 7, which is pressed against the brake frame via a washer 6 and engages a magnet body 4 by an external thread. Between the magnet body and the brake frame are cup springs 3, which tend to push the brake frame and the magnet body apart from each other. In this way, a screw adjustment is achieved wherein the force of the cup springs 3 ensures that the mutual clearances of the assembly consisting of the magnet body 4, the washer 6 and further the brake frame 14 remain small and unchanging in direction, so that the adjustment thus achieved and performed by means of the nut 7 is accu- rate and easy to manage. To compensate the wear of the brake shoe, the functional assembly consisting of the magnet body 4 and a moving frame 9, which preferably is a structure

mainly or completely made of iron or steel, is moved by means of the adjusting nut 7 closer to the braking rim 96.

The adjusting nut 7 is also used in connection with manufac- ture or installation of the brake or renewal of the brake shoe to adjust the clearance between the brake shoe and the braking rim to a suitable size. The magnet body 4 is a bob- bin type structure, preferably mainly or completely made of iron or steel, which is provided with a magnetizing coil 15, to which is connected a conductor 16 that contains the elec- tric conductors and is introduced into the brake via a lead- through 13. Through the adjusting nut 7 goes a sleeve 10 and a shank 17. Under the nut 19 at the end of the shank 17 is a plate 20, by which the brake release lever 97 lifts the brake shoe to release the brake. The other end of the shank 17 is connected to the moving frame 9 of the brake, to which the brake shoe 95 is secured. A brake spring 21 is provided between the brake frame 4 and the moving frame 9 to keep the brake frame and the moving frame apart from each other when the electromagnet consisting of the coil 15 and the magnet body 4 is not attracting them towards each other. The force of the cup spring stackup 3 between the magnet body and the brake frame is greater than the force generated by the brake spring stackup 21, so the force of pressure of the brake shoe 95 against the braking rim 96 is in practice determined by the dimensioning of the brake spring stackup, and on the other hand, due to the stiffness of the cup spring stackup, the adjustment settings do not significantly depend on whether the brake is engaged or not. The sleeve 10 is de- signed to prevent adjustment of the brake in a way such that brake would remain permanently released, in other words, to prevent the gap between the plate 20 and the nut 17 from being reduced so much that the shank 17 would be supported by the nut 7 via the brake release lever 17. Pin 5 prevents rotation of the brake frame 14 and the magnet body 4 rela- tive to each other, and pin 8 similarly prevents rotation of the moving frame 9 and the magnet body 4 relative to each other. The mutual motion occurring between the moving frame

9 and the magnet body 4 when the brake is being released and closed and in connection with adjustment is controlled by means of a sliding bearing 2. The control of the sliding bearing 2 contributes towards allowing the adjustment to be made using only one adjusting nut 7. As the force effect produced when the brake is on is passed via the sliding bearing 2 to the brake frame over a very short distance, in other words, as the sliding bearing is very close to the braking rim, the brake structures can be made fairly light.

With wear of the brake shoe 95, the distance of motion or the air gap between the brake shoe and the braking rim 96 increases, and so naturally does the air gap between the moving frame 9 and the magnet body 4. The adjusting nut 7 is locked by means of a locking plate 18 to ensure that the position of the adjusting nut and thus the position of the magnet body 4 relative to the brake frame 14 can not change by themselves between adjustments. This leads to a greater kinetic energy of the moving frame 9 when the brake is re- leased and engaged, because the force of the electromagnet or brake spring is allowed to act for a longer time and further the stroke energy becomes greater, causing harder release and engagement noises. A longer stroke also has other disadvantages, such as increased wear of the brake shoe and somewhat longer brake operating times. The stroke noise produced upon release of the brake is damped by using a damping ring 33 made of a damping medium, e. g. rubber or silicone, which is placed in a space reserved for it between the moving frame 9 and the magnet body 4. This gap reserved for the damping ring is, even after the damping ring has been compressed, preferably larger than the suitable rema- nence air gap to be left between the energized electromagnet and the moving frame 9, which will allow easy dimensioning of the damping ring as it is possible to maintain a reason- able relative compression of the thickness.

The skilled person understands that the invention is not limited to the description presented by way of example, and

that the embodiments of the invention may be varied within the scope of the inventive concept and especially the claims below. Within the framework of the inventive concept, the features of different conceivable embodiments may also be applied within the limits of technical feasibility to re- place features of other embodiments. The skilled person also understands that the machine on which the brake is mounted may be different and that the number of brakes used in con- junction with the machine may be other than two as described by way of example.