[0001] The invention relates to an improved mechanism for driving turning shafts, the said
mechanism being of the type that comprises a chamber within which a pair of opposite
pistons are movable, the latter being provided with a toothed arm forming a gear with
a turning shaft that crosses the said chamber, the walls of which are provided with
several holes in order to allow the circulation of a fluid designed to alternatively
hit against both the faces of the piston plates, with which the latter perform their
stroke in one or other direction.
[0002] Up to the present it occurs that in mechanisms of the described type, in order that
the chamber could be as smaller as possible, and at the same time the pistons could
perform a stroke as long as possible, the plates of the latter had to have the smallest
possible thickness. Although this condition involved an improvement in the length
of the stroke, prejudicial vibrations have simultaneously appeared, in damage to the
working and duration of the mechanism.
[0003] To avoid these disadvantages it has been proposed to widen the circular contour of
the plates, but in such a manner that the thickness of their walls is smaller than
that of the conventional ones, so that it results in a diminution of weight, and,
in the other hand, the shape of the said plates is such as to include several helicoidal
springs in case that the fluid under pressure that acts the mechanism is supplied
and evacuated from the center of the chamber.
[0004] The following is a detailed description of an embodiment of the invention, reference
being made to the accompanying drawings in which:
Figure 1 is a longitudinal section of the mechanism showing the piston plates in the
nearest position to each other, and
Figure 2 is a cross section of the same mechanism in coincidence with the shaft designed
to be driven by both the pistons.
[0005] The mechanism comprises a chamber 1 within which a pair of pistons are movable. These
pistons are provided with respective plates 2 integral with which respective hollow
arms 3 eccentrically protrude, a portion of the contour of same being adapted to that
of the chamber, whereas one of their faces is toothed in order to form a gearing with
the toothed surface 4 of the shaft 5, transversally mounted in the middle of the chamber
1.
[0006] Diametrically opposed to the arms 3, the plates 2 are provided with projecting portions
6, which contour also partially adapts to that of the chamber, whereas when the piston
plates reach the nearest position to each other, the said portions staggered engage
with corresponding hollow portions formed in the said arms.
[0007] The hollow spaces of the arms 3, as well as the projecting portions 6, are reinforced
by several equidistant vertically arranged walls 7. On the other hand, several hollow
spaces 8 are also formed in the opposite face of the piston plates, said spaces 8
being arranged for optative mounting of respective helicoidal springs. This arrangement
is specially devised for mechanisms of the described type in which the acting fluid
is only received, as previously indicated, through a point placed in the middle of
the chamber, but in case the mechanism is designed to receive the acting fluid upon
both the piston faces, i. e. the inner and the outer ones (making it unnecessary the
presence and action of said helicoidal sprin
fs), then the hollow spaces 8 serve to reduce the weight of the pistons, in spite of
the enlarged contour width of their plates. It is to be pointed out that the wall
of the piston plates is provided with an enlarged slot 9 in order to include the end
of the opposite toothed arm 3, with a substantial increasing in the length of the
piston stroke within the chamber.
1. An improved mechanism for driving turning shafts, the said mechanism being of the
type that comprises a pair of pistons which respective toothed arm, partially adapted
to the inner contour of the enclosing chamber, forms a gear with the pinion of a crossing
shaft laying in the chamber where the cited elements are mounted, characterised by
the fact that each toothed arm, as well as a diametrically opposed portion that projects
from the respective piston plate and is also partially adapted to the inner contour
of the enclosing chamber, have a hollow structure reinforced by equidistantly distributed
walls, the cited arms and projecting portions staggered engaging when the pistons
reach the nearest position to each other, whereas on the opposite face of the piston
plates several hollow spaces are opened for optative mounting of respective helicoidal
springs, all this being arranged to reduce the weight of the pistons and, at the same
time, to increase the width of the corresponding plates, being the wall of the latter
provided with an enlarged slot in order to include the end of the respective opposite
toothed arm in order to increase the length of the piston strokes.
