Technical Field

This invention relates to an automotive friction- -type wheel brake, comprising relatively rotative ele¬ ments and friction material to be applied between said elements, said friction material containing a fiber structure such as asbestos fibers or substitutes there¬ for bound together by a binder. Background Art

It is very well known that asbestos provides envi¬ ronmental danger and therefore should not be used in the working life. Accordingly, efforts have been made to replace asbestos with other materials providing less danger as to the health of people working therewith. In most countries the use of asbestos is minimized by law and regulations, and rigorous measures must be taken when asbestos or materials containing asbestos are being handled or worked. One field wherein it has not been possible so far to generally replace asbestos material by another lessrisky material is the automobile industry where friction lin¬ ings for brakes practically without exception contain asbestos fibers. Usually, the material of such linings comprises asbestos fibers as friction and reinforcing material, and friction-modifying materials such as metal powders, metal oxides, and carbon, especially graphite, the fibers and the friction-modifying materials being held together by a binder system comprising a thermo- setting plastics material such as phenolic resins and synthetic rubber. The content of asbestos fibers in friction linings may comprise as much as 50 to 60 per cent by volume.

In order to protect people handling new linings for brakes in equipment shops and automobile repair work¬ shops against the injuries associated with asbestos pro¬ ducts it is common to have a coating on such linings, which prevents detachment of the asbestos fibers there-

from. However, when repairs have to be made on brakes wherein dust containing asbestos fibers has been col¬ lected, people performing such repairs are facing a considerable danger of inhaling air containing such fibers, particularly when repairs are made on trucks, buses and other large vehicles. It is therefore nec¬ essary to use breathing protection when such repairs are made or to bind the dust and the fibers entrained therein, by means of water. The asbestos fibers detached from the friction lining in a brake due to abrasio of such lining when the brake is engaged are not all of them collected in the brake. Although it has been maintained by manu¬ facturers of brake linings that the asbestos fibers are converted by the heat developed in the brake into a- modified for -which is not injurious to health when inhaled, investigations made have shown that the air around big traffic routes in towns has a high content of asbestos fibers emanating from the vehicles passing on the traffic route. Disclosure of Invention

The purpose of the invention is to reduce the environmental danger to the health associated with the use of friction linings containing asbestos or sub- stitutes therefor.

For this purpose, a brake of the kind initially referred to is characterized, according to the inven¬ tion, in that the annular space defined between the wheel rim and the shaft rotatably mounting the wheel is closed on the inner side of the relatively rotative elements by a ring forming an annular collecting chamber for catching material detached from the fric¬ tion material during braking, means being provided for directing such material towards said collecting chamber. Said means for directing the friction material towards the collecting chamber according to one embodi¬ ment of the invention can comprise an annular disc mounted for rotation together with the wheel, such disc

possibly being formed as a fan to force an air flow towards the collecting chamber.

In another embodiment the collecting chamber is made of magnetic or permanently magnetized material to attract the detached friction material by exerting a magnetic attraction force on magnetic metal or metal oxide particles, which form a constituent of the fric¬ tion material and is adhered or nested to detached fibers or clusters thereof. It is to be noted that although the purpose of the invention is said to be the reduction of asbestos dan¬ gers, the inventive idea is equally applicable for any component in the friction material which is desirable to collect. Brief Description of the Drawings

The invention will be described in more detail below with reference to the accompanying drawings, in • which Fig. 1 is an axial sectional view of an auto¬ motive wheel provided with a disc-type brake and ar- ranged according to the invsntion, Fig. 2 is a broken perspective view of an annular element forming the col¬ lecting chamber in the arrangement according to Fig. 1, Fig. 3 is an axial sectional view of an automotive drum-type brake arranged according to the invention, Fig. 4 is a broken perspective view of an annular element forming the collecting chamber in the arrange¬ ment according to Fig. 3 in one embodiment thereof, Fig. 5 is a view similar to that in Fig. 4 of the collecting chamber element in another embodiment there- of, and Fig. 6 is a fragmentary enlarged detail view of the arrangement in Fig. 3. Description of the Preferred Embodiments

In the drawings, there is shown in Fig. 1 an automotive wheel having a wheel rim 1 and a wheel disc 2, the wheel being mounted on a shaft 3. Mounted to the shaft for rotation therewith is a brake disc 4, and a conventional brake mechanism not shown in the

the drawings comprises brake pad holders with friction pads for co-operation with the brake disc in braking the rotational movement of the wheel. It is to be under¬ stood that the brake throughout can be of conventional design and construction. On the inne.r side of the brake disc 4 there is provided a fixedly mounted non-rotating splash shield 5.

An annular element 6 also shown in Fig. 2 is located on the inner side of the splash shield 5. The element 6 is formed as a channel open axially towards the annular space formed between the wheel rim 1 and the shaft 3, and the element forms an annular, axially projecting skirt 7 at which it is connected to the wheel rim 1 for rotation together with the wheel. As shown in Fig. 2, the annular channel formed by the element 6 can be divided by uniformly spaced trans¬ verse walls 8 into a plurality of individual pockets.

On the inner side of the wheel disc 2 forming conventional ventilation openings 9 there is mounted a ring 10 covering said openings but spaced therefrom, and this ring preferably is formed as a fan wheel for directing an air flow towards the element 6 when the wheel is rotating.

During rotation of the wheel friction material, which is detached from the friction pads, is collected in the pockets of the annular element 6 as well as on the inside surface of the skirt 7. Friction material initially landing on the skirt 7 may later on be de¬ tached therefrom and then will be caught by the pock- ets formed in element 6. This element can be made of a non-magnetic material, but the collecting effect can be increased by the element being made of a magnetic or permanently magnetized material. *-' The purpose of the ring 10 is to preventthe detached friction material from escaping to the.surroundings

through the openings 9 and to direct the friction material towards the element 6 where it is to be col¬ lected. This ring can be made of non-magnetic material and it may be formed as a flat ring, but the effect exercised on the friction material by said ring can be increased by the ring being formed as a fan element as mentioned above, or being made of a magnetic or perma¬ nently magnetized material. Also a combination of the fan construction and the magnetized material is con- ceivable.

In a modification of the embodiment disclosed in Figs. 1 and 2 the element 6 is stationarily mounted on the splash shield 5. However, this arrangement may involve constructive difficulties not encountered in the arrangement disclosed in Figs. 1 and 2 and in¬ cluding a rotating element 6.

Figs. 3 to 6 show the invention when applied to an automotive drum-type brake. With reference to Fig.3 this brake includes a drum 11 and brake blocks 12 mounted to be engaged with the inside cylindrical sur¬ face of the drum by actuating means 13 in the conven¬ tional way. On the inner side of the wheel there is provided a conventional stationary back plate 14, and mounted to this back plate is the collecting chamber element 6 which as shown in Fig. 4 can be constructed in a similar way as the element shown in Fig. 2. However, according to Fig. 5, said element designated 6' in Fig. 5, can form an unobstructed channel, i.e. a channel without transverse walls, a collector box 15 being provided at the lower end of the element 6'. The collector box communicates with the channel and may be detached therefrom. Preferably, the opening of the collector box through which the box communicates with the channel of the element 6' is provided with means for automatically closing-off said opening when the collector box is separated from the element 6 ' .

However, it is also possible to have a collector box 15 which is permanently attached to or is integral with the element 6' .

On the inner annular end face of the brake drum 11 there is mounted a ring 16, which is rotatable with the brake drum and is more clearly shown in Fig. 6. It appears that this ring is of conical form, and the purpose thereof is the same as that of the ring 10 disclosed in Fig. 1, i.e. to direct friction material detached from the friction lining of the brake blocks 12 during braking, into the annular element 6 or 6' forming the collecting chamber. As will be seen from Fig. 3, the brake blocks- 12 have bevelled ends to operate as scrapers which deflect friction material adhering to the brake drum 11 towards the collecting chamber when the wheel is rotating.

Also in the embodiment disclosed in Figs. 3 to ^' 6, element 6 or 6' may be made of non-magnetic material or of. magnetic or permanently magnetized material so as to attract in the latter case magnetic friction material entrained in the fibers or clusters of fibers originat¬ ing from the lining of friction material on the brake blocks 12.. Moreover, the ring 16 may be constructed to provide a fan action for forcing air towards the col- lecting chamber, and/or may be made of a magnetic or permanently magnetized material.

The embodiments of the invention as described herein can be modified within the scope of the follow¬ ing claims. Some modifications have already been en- tioned and further modifications present themselves to a man skilled in the art as far as the constructive details of the means for collecting and retaining the particles detached from the friction material are con¬ cerned. In case of electrically driven vehicles running on rails, collection of the particles detached from

the friction material of the brakes may be advantageous also from the point of view that such material other¬ wise may be deposited on electrical equipment on the vehicle and along the track for the vehicle and if it is electrically conducting may cause flash-overs in such equipment. This is a secondary advantage obtained by the invention.

( OMPI