Improvements in Force Accumulators for the Compensation of the Acceleration Pressures of Moving Masses.
Year: 1889

page_text: Date of Application, 30th Apr., 1889-Accepted, 6th July, 1889
COMPLETE SPECIFICATION.
Improvements in Force Accumulators for the Compensation of the
Acceleration Pressures of Moving Masses.
We, OSOAR FLECK and RICHARD FLEOK trading as C. L. P. Fleck Sölme Manu-
facturers, and WOLFGANG SCHRADER, Engineer in the employ of said firm all of
31 Chaussee str. Berlin Prussia in the Empire of Germany, do hereby declare the
nature of this invention, and in what manner the same is to be performed,
to be particularly described and ascertained in and by the following statement :-
When a body A, figure 1, is moved to and fro by driving gear, for example, as
shown in the drawing, by a crank, forces are required for accelerating this body, and
also its connecting rod transmitting the motion between the continuously rotating shaft
and the body. The magnitude of these forces can be easily ascertained arithmetically
or geometrically for any position of the body A in its course, and is shown by the
diagram figure 2. In it, s designates the course which A passes from the upper dead
point to the lower one U, y the accelerating pressure required in the different
positions. The line of the diagram, approximated here by a parabola, shows that the
triangles are positive during the onset, become nought at a certain point of the way,
and are negative during the offset. For the same mass of body A and its connecting
rod, the acceleration pressures y increase in proportion to the number of revolutions of
the continuously rotating driving or driven shaft 1. The positive acceleration
pressures (+ y) decrease the driving forces for the value of its magnitude, but the
negative pressures (- y), acting in the direction of the driving forces, are to be
added to them. Both are injurious. In the first case, only the difference between
the driving forces (P) and the accelerating pressure (P y) can be counted for
effect. In the second case, the whole sum of the driving force and the accelerat-
ing pressure (P + y) exists, but it is a maximum at the dead point, and is to be
annihilated suddenly on reaching it, which, for comparatively high numbers of
rotation, causes considerable shocks, vibrations, and heatings, to be produced.
-
The object of the present invention is to insert into mechanism in which masses
are moved to and fro, force stores or accumulators in the form of tension devices,
which take up the momentum of the masses moved to and fro, i.e., the
negative (-) y s, during the offset, and give it off again effectively during the
onset, i.e. for overcoming the positive (+) y s.
These accumulators may be constructed in different ways, according to shape and
purpose of the mechanism used, such, for instance, as springs, air cushions, or
general tension devices, and their arrangement must be adapted to existing
circumstances.
For crank gear, which is the most important example, figure 3 shows the
arrangement of an air tension device as accumulator. With the body A is united,
by the piston rod b, the piston c, moving to and fro in the cylinder d, filled with
air.
When the ducts e are closed, the air in front of the piston will be compressed
during the motion, and that behind the piston will be expanded. The closing of the
ducts e is done by hand, or automatically by any suitable mechanism, in such a
manner that, when the piston has arrived at the end of its stroke, compressed air of the
total pressure y maximum, is to be found in front of it, but air of atmospheric pressure
behind it. Figure 4 shows the forces required for the compression of the air, or the
work of them. These forces become free again by the expansion of the air; the accu-
mulated or stored up work therefore is given back. It must be kept in mind that the
hatched area of figure 4 must be deducted, as the areas x = x and ßß reprosent
the compression work upon the back faces of the piston, which is to effected during
the expansion. Figure 5 shows the available surplus of force transferred graphically
in the diagram. This diagram proves that the compressed air can give off, during

page_text: the onset (from the dead point), a surplus of force, which is used up only at the
middle of the stroke, and that then the air behind the piston is loaded with the
surplus of force.
If, instead of the common crank gear; the oscillating slotted yoke gear is used for
moving the body A, the line of the diagram becomes, for the required acceleration
pressures f, g, h, a straight one, which, inserted into figure 5, shows that, in this case,
about the total work required for the acceleration during the onset f, g, and for the
retardation during the offset g, h, is given off by the before compressed air, and taken
up by the air to be compressed. Of the driving forces, in this case, there is still to
be performed only the small surplus of work, figure 6. It is the business of the
constructor to accommodate in each case, the curves of the compression to the curves
of the acceleration of the masses.
From the diagram figure 6 it is clear that the speed (numbers of revolutions)
of the devices furnished with the above described accumulator may be increased
quite at pleasure, without fear of blows, shocks, vibrations &c. It is only necessary
to make in each single case, the compensation of the acceleration pressure by the tension
devices, as complete as possible. At high speed however, it would occur that in starting
an engine or a machine provided with one of the new accumulators, the air would be
compressed to an extreme degree, i.e., to that which would correspond to the accelera-
ting pressure of the standard speed of the continuously rotating shaft. This woukl
render it nearly impossible to start the machine. For such cases, provisions are
made so that, at the start of the machine, the piston c, figure 3, moves freely in
its cylinder, i.e., without material effect. To attain this object, all three ducts e', e², e³
are opened at the start. After the machine has reached a certain speed, the two
extreme ducts el and e³ are closed and only when the machine has attained nearly the
normal speed, the middle duct e2 is finally closed.
The opening and closing of the ducts may be done by hand, or by a regulating
mechanism. As shown in figure 7, the latter is constructed as balanced valve gear.
The single valves are arranged in such manner that, for closing the ducts e¹ and e, the
joint valve bar has to travel the distance i=, but for closing the middle duct e², the
longer distance. The construction of the regulator itself is of no importance, and
may be made, according to circumstances, of any suitable design. In machines of a
very long stroke more than 3 ducts may be arranged in a similar way.
Instead of air tension devices, spring tension devices and other forms of apparatus,
may be employed as serviceable, but less qualified, force accumulators. In figure 8 is
shown a spring accumulator. Upon both faces of the piston are placed coiled screw
springs S.
The use of the invention extends to machines with fast moving masses, whatever
may be the object for which the machines are intended to be used.
Having now particularly described and ascertained the nature of our said
invention, and in what manner the same is to be performed, we declare that what we
claim is
1. The employment of force accumulators in form of tension devices, in which
elastic means, as air, gas, springs, etc., take up the surplus of work during the offset,
and give it off again during the onset, for compensating the acceleration pressures in
apparatus in which moving masses are reciprocated.
2. The particular arrangement of the air tension device with ducts furnished with
valves e¹, e²,
e", which are actuated by hand or automatically, in such manner that
at first the two extreme ones e¹ and eª are closed, and afterwards the intermediate
ones, substantially as explained and for the purpose set forth.
Dated thi 20th dow of A: 1000
OSCAR FLECK, RICHARD FLECK, WOLFGANG SCHRADER.
By Harris & Mills, 23, Southampton Buildings, Agents.