Improvements in Compound Engines.
Year: 1894

page_text: Date of Application, 4th May, 1894
Complete Specification Left, 28th Jan., 1895-Accepted, 23rd Mar., 1895
Improvements in Compound Engines.
1 CORNELIS JOHANNES WILTON VAN REEDE, Engineer, of Rotterdam, in the
Kingdom of Belgium, do hereby declare the nature of this invention to be as
follows:-
This invention for improvements in compound engines has for its object to utilize
the pressure of steam in the boiler in such manner as to obtain maximum efforts of
useful force on the shaft without its being necessary to have recourse to forced draft
with all its disastrous consequences to the boilers and the engines and the wasteful
expenditure of fuel.
These results are obtained by the special arrangement of compound engines
which forms the object of this invention and by which the steam is able to exert
approximately all its action in useful work contrary to what takes place in engines
at present in use in which the action of the steam is absorbed in a considerable
proportion by the internal reactious such as counter pressure of the receivers and
excessive compression notably in engines of triple and quadruple expansion.
The reactions mentioned and consequently the reduction in the output of the
present compound engines are still further increased by the faulty proportions of
the volumes of the cylinders or in other terms, the dimensions of the latter, the
high pressure cylinder being always much too large in comparison to the others, so
that the steam works with a great loss in the high pressure cylinder itself as also
in the intermediate cylinder or cylinders in the case of engines having graduated
expansion and in the low pressure cylinder in the case of a simple compound
machine, the result being that forced draught must be employed and large volumes
of steam used in order to obtain the desired amount of useful work.
a
The new arrangement of the compound engines which obviates all these incon-
veniences and permits of a larger useful effect being obtained whilst maintaining
constant pressure in the boiler, with a much smaller expenditure of fuel even with
the maximum expenditure of steam, is characterised in principal by the utilization
of the working steam with normal admission to 60% in two phases only that is to
say at high and low pressure, and in such proportions that the phase of the high
pressure comprises 40 % and the phase of the low pressure 60 % of the total work,
the low pressure phase preferably exerting itself, and simultaneously, in two or more
cylinders.
For every engine of whatever power constructed on the principle mentioned the
relation between the volume of the high pressure cylinder and the volume of the
low pressure cylinders is calculated from an empirical formula in which the pressure
in the boiler and the length of the distance travelled by the pistons enter as
variables and the work or the forces exerted by the new engine will be divided as
follows:-
follows:-
For a three cylinder engine
High pressure cylinder
Low pressure cylinder 2 × 30
=40% total 100.
60%

page_text: In arranging compound engines in accordance with these details, the volume of
the high pressure cylinder is much smaller, and the volume of the low pressure
cylinders determined exactly by the high pressure volume in the proportions
indicated, is much larger than the volume of the corresponding cylinders of present
engines, the engine thus accomplishing equal useful work for a much less expenditure
of steam and in consequence with an expenditure of fuel reduced in the same
proportion and contrary to previous engines the high pressure cylinder develops
force greater than that developed by one of the other cylinders.
a
This is easily understood when it is considered that in accordance with the
dimensions of the high pressure cylinder and the intermediate cylinders in present
engines the sum of the counter pressures in the receivers exceeds the useful force
effected, diminished furthermore by the compression in the cylinders and the
receiver at the moment of closing the exhausts towards the end of the piston stroke,
a compression the more considerable as the exhaust is closed earlier and the pressure
of which often equals the pressure in the boiler.
Contrary therefore to the old systems, the present engine is arranged in such
manner that it is the high pressure cylinder which attacks the last crank and thus
better equalises the work of the machine on the shaft, the cranks on which are
placed at 120° for three cylinders and at 90° for four cylinders, the engine having
thus all the advantages of a triple or quadruple without having a single disadvantage
and without having also the disadvantage of the bad division of forces on the shaft
as in the case of an engine having two cylinders only.
In the new engine the seats of the slide valves of the low pressure cylinders
constitute the extreme part of the receiver so that the discharge steam from the
high pressure cylinder is in direct contact with the slide valve of the low pressure
cylinders. Nevertheless it is rational to arrange them so that each of the valve
seats can be isolated separately from the receiver so that in case of accident
one of the low pressure cylinders could be cut out and the engine worked with the
remainder. According to the space at disposal and the general arrangement of the
engine the seats of the slide valves may be applied between the cylinders or outside
on one or the other side thereof.
The advantages resulting from the use of the new engine, particularly for
navigation are of the highest importance from the point of view both of the output
and of easy working, of less wear, and of the economy permitting either a reduced
charge, or longer voyages without renewing the fuel.
Dated this 4th day of May 1894.
WHEATLEY & MACKENZIE,
40, Chancery Lane, London, W.C., Agents.
I CORNELIS JOHANNES WILTON VAN REEDE, Engineer, of Rotterdam, in the
Kingdom of Belgium, 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:—
The present invention has for its object a construction of compound engine by
means of which these motors utilise to the utmost the force of the steam and
consequently are capable of a considerably greater output than any other construction
of this class of engines having the same object.
With compound engines having only two cylinders it has been necessary for the
purpose of attaining regular speed to make the low pressure cylinder of such size

page_text: that it exerts about the same power as the high pressure cylinder on the crank
shaft. Under these conditions however the full utilisation of the power cannot be
attained, since, with the greatest possible expansion of the steam leaving the high
pressure cylinder, that is to say, with the largest possible dimensions of the low
pressure cylinder, the power of the latter becomes greater than that of the:
high pressure cylinder, and thus such dimensions for the low pressure cylinder must
be adopted as allow of the steam acting therein being only partially utilised, whilst
the remainder goes to waste.
It has been sought to remove these defects by using 3 or 4 cylinders of increasing
dimensions in which the expansion takes place step by step from the highest to the
lowest pressures. There arises however herein, both in the high pressure and
intermediate pressure cylinders, so much back pressure and compression that not
only is the work of the intermediate cylinders almost nullified by counteraction but
the high pressure cylinder also loses a large part of its useful effect.
These disadvantages are now removed by the steam being exclusively brought
into action at its highest and lowest pressure, the cylinder intended for the low
pressure being divided into several separate cylinders into which the steam has
simultaneous inlet and expands to the lowest possible pressure point. The division
of the low pressure cylinder can herein be so proportioned that each one of them
exerts about the same power as the high pressure cylinder and engages with a
special crank, by which means a still greater regularity of speed is attained than
with triple expansion engines, whilst the output is considerably greater, since each
low pressure cylinder exerts its full power, and no back pressure or compression
takes place.
An especially suitable subdivision of the working output of the steam is chosen
if, for example, with two low pressure cylinders, each one of them utilises 30%
and the high pressure 40%, since the latter as receiving cylinder has always to
overcome a slightly greater resistance.
For the purpose of accurately fixing the described respective conditions of
volume of the cylinders I have reckoned that for expanding the steam to the lowest
possible pressure with engines of two cylinders the volumes of the high pressure
cylinder must be so many more times that of the high pressure one as the pressure
of the steam expressed in atmospheres; in other words in order to fix the correct
area of the piston of the low pressure cylinder the area of the high pressure piston
must be multiplied by the number of atmospheres. Example.-If the area of the
high pressure piston equals 6 and the pressure in atmospheres equals 5, the figure
for the area of the low pressure piston equals 30. If the latter is divided into two
cylinders of equal volumes, the area will be
increased from 5 to 10, and if it is desired to still retain the same low pressure
cylinder, the area of the high pressure piston must be correspondingly decreased
and its correct area is found by the division of the area of the low pressure piston
by the figure of the atmospheres, that is
2 x 15
10
30
2
=
15. If the atmospheres are
= 3. If the pressure is less the
high pressure cylinder becomes larger, for example,
2 x 15
4
=
7, and if the lowest
pressure with condensation is taken, viz. 2 atmospheres, for the high pressure
cylinder the figure is obtained of
2 x 15
2
= 15. In this single case the three
cylinders have equal diameters, that is volumes.
According to the principle described the steam pressure is expanded from the
highest point directly to the lowest by the method described and consequently, not
only is the highest capacity of output obtained, but also smaller dimensions of the
engine are made possible with considerable economy in fuel; in other words,
compound engines are enabled to give out the highest useful effect, which has
hitherto been prevented.

page_text: Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
With compound engines the reduction of the steam pressure of the high pressure
cylinder to the smallest corresponding low pressure by simultaneous transmission of
the steam from the high pressure cylinder into two or more equal low pressure
cylinders the total volumes of which are equal to that of a single cylinder producing
this reduction.
Dated this 28th day of January 1895.
WHEATLEY & MACKENZIE,
40, Chancery Lane, London, W.C., Agents.