Signal generator

In a signal generator with a magnetic rest, consisting of a ferromagnetic studded disk (13) with a U-shaped part (6) consisting of a permanent magnet (3) and lateral ferromagnetic small plates (4,5), two brackets (7, 8) are provided for on a support (1) between which the permanent magnet (3) and the small plates (4, 5) are capable of being clampingly inserted. This permits an easy assembly and adjustment of the permanent magnet (3) as well as of the small plates (4, 5).

BACKGROUND OF THE INVENTION 
The present invention relates to an adjustable apparatus for use in a 
signal generator of the type used with a machine having a rotatable disk 
that includes a plurality of teeth. 
A signal generator with a magnetic support structure is known from DE-GM 81 
30 371. This magnetic support structure along with a U-shaped magnetizable 
member are arranged along the outside of a rotatable magnetic ring (that 
includes alternate north and south poles at defined angular distances) so 
that a narrow airgap is formed between the magnetizable member and the 
ring. The U-shaped member is inserted in a small plastics block likewise 
of U-shaped design. In this way, the position of the U-shaped member is 
predetermined. Therefore, the U-shaped member must be manufactured with a 
relatively high accuracy because its effectiveness strongly decreases as 
the distance increases, and because in the case of a smaller distance, 
owing to the already very small airgap, a sliding on the ring may occur, 
thus likewise reducing its effectiveness and increasing the torque. 
SUMMARY OF THE INVENTION 
It is the object of the present invention to design a magnetic support 
structure in such a way that a simple and reliable adjustment of the 
U-shaped member becomes possible. This object is achieved by the 
combination of a housing including a mounting bracket adapted to 
adjustably receive the U-shaped member, and clamping means for securing 
that member in the desired position with respect to a rotatable disk 
having a plurality of teeth.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The reference numeral 1 indicates a support, such as the cover of a housing 
having a peripheral rim portion 2. It may also be designed as the 
baseplate for a signal generator. Two vertically projecting mounting 
brackets 7 and 8 are provided on the support 1 in order to fix the 
position of U-shaped member 6, which includes a permanent magnet 3 
(preferably having a square or rectangular shape) and laterally attached 
magnetizable small plates 4 and 5 part 6 designed as a permanent magnet 3 
of preferably square or rectangular shape with laterally attached 
magnetizable small plates, 4, 5, each time two vertically projecting 
post-like brackets 7 and 8 are provided. Within the latter, the permanent 
magnet 3 together with its lateral small plates 4, 5, is clampingly 
inserted. 
The inwardly projecting ends 9, 10 of the small plates 4, 5, are positioned 
so far apart from each other that they are located opposite the end faces 
11 of respective teeth 12 of a studded disk 13 and, by leaving a small 
airgap therebetween, serve a signal generating function. The studded disk 
13 consists of a magnetizable material. 
In the support 1 there is provided a central borehole 15 which is 
preferably designed as a blind hole. Into this there may be inserted the 
shaft of an adjusting disk 16 whose radius RJ is by the airgap 14 larger 
than the radius RZ of the studded disk 13. For adjusting the small plates 
4, 5 and the permanent magnet 3 there is inserted the adjusting disk 16, 
and the permanent magnet 3 together with the small plates 4, 5 is pressed 
with the aid of a plunger 17 from the outside towards the inside until the 
ends 9, 10 of the small plates 4, 5 meet against the oppositely arranged 
teeth 12. This completes the adjustment, and the adjusting disk 16 is 
replaced by the studded disk 13 or else the support , e.g. designed as the 
cover of a housing, is placed onto a bottom part of the housing provided 
with the studded disk 13. In the latter case, therefore, the adjustment 
can be carried out independently of the assembly of the studded disk 13, 
in a separate mounting support. 
For securing the adjusted position, the brackets 7, 8 may be joined to one 
another by a web 18. In this web 18 there is provided a borehole 19 with a 
headless screw 20 screwed therein. The end 21 of the headless screw 20, 
when being screwed-in, presses against the permanent magnet 3, thus 
securing the adjusted position thereof. If so required, a pressure plate 
may still be provided for between the headless screw 20 and the permanent 
magnet 3, and the small plates 4, 5. 
The brackets 7, 8 appropriately have a hollow inside, for example, are 
designed as tubular sections. In this way there is obtained an elastic 
deflection of the sidewall members cooperating with the small plates 4, 5 
by simultaneously maintaining a high mechanical stability of the brackets 
7, 8. 
The brackets 7, 8 and the web 18 are suitably made of an elastic plastics 
material. In particular, they form one structural unit together with the 
support 1 consisting of such a material. 
Preferably, the support 1 is square or rectangular in outline and the 
brackets 7, 8 are each provided for within the area of a corner 22. 
For adjusting both the permanent magnet 3 and the small plates 4, 5 an 
opening 23 may be provided for within the marginal area or rim portion 2 
of the support 1 through which the plunger 17 may be inserted and the 
adjustment may be carried out.