Modular camshaft with removable cams, particularly for circuit breakers and electrical changeover switches or the like

A modular camshaft comprises at least two modular elements or modules removably coupled together; each module carries at least one cam and comprises two cylindrical elements disposed on the same axis and projecting in opposite directions from opposing faces of said cam, a first cylindrical element acting as a hub and the second being hollow and acting as a seat, the seat of one modular element being arranged to receive the hub of the other module so as to define the camshaft, on each hub there being provided means which cooperate with counter-means provided in each seat to torsionally lock said two modular elements together. According to the invention the camshaft comprises, between two consecutive cams, at least one annular element spaced from said cams and removably mounted on one of the two cylindrical elements of each module, said annular element comprising in its outer edge at least one recess so as to act as an additional cam, and comprising in its inner edge means for torsionally locking it to the cylindrical element on which said element or removable cam is mounted.

BACKGROUND OF THE INVENTION 
This invention relates to a camshaft, particularly for use in circuit 
breakers electrical changeover switches or the like. In particular, the 
present invention relates to a camshaft comprising at least two modular 
elements or modules coupled together. Each module carries at least one cam 
and comprises two cylindrical elements disposed on the same axis and 
projecting in opposite directions from opposing faces of said cam, a first 
cylindrical element acting as a hub and the second being hollow and acting 
as a seat, the seat of one modular element being arranged to receive the 
hub of the other module so as to define the camshaft, on each hub there 
being provided means which cooperate with counter-means provided in each 
seat to torsionally lock said two modular elements together. 
These modules can in particular be made hollow to allow them to be mounted 
on a further shaft generally of square of polygonal cross-section, 
connected to a knob or the like. In this manner, by rotating the knob the 
camshfat rotates to cause said cams to act on known contacts associated 
with the electrical changeover switch or the like. 
Such a system generally involves the use of modules with cams arranged in 
predetermined positions. This is very convenient if camshafts of standard 
type are required, but creates problems if the positions of the cams on 
the shafts do not correspond with the positions of the electrical 
contacts. 
Again, if a camshaft is used in known measuring devices comprising 
proximity sensors, the use of camshafts consisting of modules with cams in 
predetermined positions is often impossible. In this respect, there is 
often not sufficient space to arrange the sensors at the cams, and it is 
not even possible to bring them close because of the predetermined 
positioning of the cams on said camshaft. 
Camshafts of the aforesaid type can, with obvious particular modifications, 
also be generally used in the mechanical field, where the problems due to 
the predetermined positioning of the cams on the camshaft are even more 
apparent. 
SUMMARY OF THE INVENTION 
An object of the present invention is therefore to provide a camshaft in 
which the position of the cams can be varied at will, or rather to provide 
a camshaft on which additional cams can be arranged according to 
requirements. 
A further object is to provide a camshaft which is simple to construct and 
use, and is of very versatile application so enabling it to be used in the 
most diverse situations and in the most different fields with consequent 
reduction in the cost of the electrical or mechanical equipment in which 
it is used. A further object is to provide a camshaft of the aforesaid 
type which is of low cost and of considerable reliability in use. These 
and further objects which will be apparent to one skilled in the art are 
attained by a camshaft of the aforesaid type, comprising, between two 
consecutive cams, at least one annular element spaced from said cams and 
removably mounted on one of the two cylindrical elements of each module, 
said annular element comprising in its outer edge at least one recess so 
as to act as an additional cam, and comprising in its inner edge means for 
torsionally locking it to the cylindrical element on which said element or 
removable cam is mounted.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In FIGS. 1 and 2 the reference numeral indicates overall a camshaft. This 
is composed of a series of modular elements or modules 2, each comprising 
a cam 3. A first and a second cylindrical element project from opposing 
faces 4 and 5 of each cam 3, and are indicated by 6 and 7 respectively. 
Specifically, the first cylindrical element 6 acts as a hub and is 
arranged to cooperate with the second element 7, which for this purpose 
comprises a cavity 8 arranged to receive the element or hub 6. The second 
element 7 therefore acts as a seat for the hub 6. 
It should be noted that both the hub 6 and the respective seat 7 are 
provided with a series of longitudinal grooves 9 (only those of the hubs 6 
are shown in the figures) so that when two consecutive modules 2 are 
coupled together they become torsionally locked to each other. 
According to the invention, at least one additional removable cam, disposed 
between two consecutive cams 3, can be associated with the camshaft 1. 
More specifically, the additional cam 10 consists of a removable annular 
element provided in its outer edge 11 with at least one recess 12 and 
provided in its inner edge 13 with toothing 14 arranged to cooperate with 
the grooves 9 of a hub 6. In at least one face 15 of said element or cam 
10 there can be provided a collar 16 to act as a spacer if two cams 10 are 
to be disposed on a single hub 6. 
For this purpose. i.e. to form the seat for the additional cam 10, 
according to one embodiment of the invention each hub 6 has a length D 
(see FIG. 2) greater than the depth d of each cavity 8 in the seats 7. In 
this manner, on inserting each hub into the respective seat a space K for 
housing the annular element or cam 10 is formed between the free edge 18 
of this latter seat and a step 19 provided at that end 20 of said hub 
close to the cam 3. It will now be assumed that cams 10 are to be added to 
the camshaft 1. 
To achieve this, a first cam 10 (that to the extreme left in FIGS. 1 and 2) 
is placed on the hub 6 of a module 2 and the hub inserted into the seat 7 
of another module (the central one in said figures). 
In this manner the cam 10 is clamped between the step 19 of the first 
module and the end 18 of the seat 7 of the second modular element 2. If 
this latter is chosen with a hub 6 having a dimension D much greater than 
the dimension d of the cavity 8 in the seat 7, then on fitting said 
modular element to another similar one (that to the extreme right in FIGS. 
1 and 2) a space K of relatively large dimensions is created to house two 
annular elements or cams 10. 
In this case at least one of said cams is provided on that face 15 with the 
collar 16 to keep the cams 10 spaced apart in the desired manner. 
By such means, two cams 10 can be mounted on the hub 6 of a module 2 (the 
central one in the figures). These cams are locked axially by the step 19 
of said modular element 2 and by the end 18 of the seat 7 of the other 
modular element (that on the extreme right in FIGS. 1 and 2). 
The invention also covers an arrangement in which in place of the collar 16 
associated with the cam 10, a ring acting as a spacer is provided having 
an inner edge shaped so that it can be mounted rigidly on a module 2. By 
interposing several rings between two cams 10 and choosing a module 2 in 
which the hub 6 has a sufficient dimension D, several adjacent removable 
cams can be removably arranged on said hub. 
FIGS. 3 and 4 show part of a different embodiment of a camshaft 1 according 
to the invention. In these figures, parts corresponding to those of FIGS. 
1 and 2 are indicated by the same reference numerals. 
In the figures under examination the module 2 is of the type suitable for 
forming a camshaft for mounting on the shaft of a changeover switch (or 
switching shaft) operated by a knob (not shown). For this reason the 
module is provided with a through bore 30 for receiving said switching 
shaft. 
In the embodiment shown in FIGS. 3 and 4 the removable additional cam 10 is 
mounted on the seat 7 of the module 2. This cam 10 is provided in its 
inner edge 13 with recesses 31 to receive ribs 32 provided on said seat 7, 
the cooperation between said recesses and ribs providing the torsional 
locking between the cam 10 and module 2. 
Finally, the removable cam 10 comprises at least on one face 33 a collar 34 
to act as a spacer between said cam and that of the module 2. 
The use of the camshaft constructed in accordance with this latter 
embodiment of the invention is identical to that of FIGS. 1 and 2 and will 
therfore not be described. 
It should be noted that if the invention is used in electrical changeover 
switches or the like, the camshaft 1 and its components can be 
advantageously of molded plastics construction. This makes it simple to 
obtain different forms of torsional locking elements between the removable 
cams and the modules 2. A camshaft according to the invention is of 
considerable versatility of application, is of low construction cost and 
is very reliable in use.