Improvements in Gas and Petroleum Motors.
Year: 1890

page_text: Date of Application, 3rd Apr., 1890
Complete Specification Left, 5th Jan., 1891-Accepted, 3rd Apr., 1891
PROVISIONAL SPECIFICATION.
Improvements in Gas and Petroleum Motors.
I, ALFRED GEORGE MELHUISH, of 39, Grove Hill Road, Denmark Park, in the
County of Surrey, Engineer, do hereby declare the nature of this invention to be as
follows:-
My invention relates to certain improvements in gas and petroleum engines,
and has for its objects the attainment of greater economy in the working of said
engines than can be attained in the case of those engines as hitherto made and
used.
In carrying my invention into effect I employ a method and means analogous to
the compounding of steam engines, but with a relatively greater economic effect in
the gas or explosive engine so arranged. Two cylinders are arranged side by side
or one above the other, and a port or passage is provided from one to the other in
such a manner that it is operated by a valve which closes said port at the same time
that one of the cylinders is open to the exhaust, the motion being synchronous.
Each cylinder is provided with a trunk or other piston, said pistons being each con-
nected, preferably by means of a rod, to a crank. The two cranks, each attached
to a separate shaft supported in bearings upon the bed plate, are arranged so that
one is approximately twice the stroke of the other. I prefer to attach the flywheel
to the crank shaft whereof the stroke is least, and attach the driving pulley, or
other means for transmitting power to the other shaft. I also cause the relative
motions of the unequally cranked shafts to correspond by means of geared wheels
or other equivalent device, whereby the ratio of the speeds is about 2 to 1. Con-
sequently one of the pistons makes two out-strokes and two return strokes to one
double stroke of the other piston. I arrange the position of the two cranks in such
a manner that they are both in the position of half stroke at the same time, in other
words, are both at the point of highest efficiency. Following the relative move-
ment of the two cranks geared in the manner hereinbefore described, when the short
crank, or that with least stroke, is right back to the end of its stroke, the other
crank, of greater stroke, is approximately 22 degrees advanced upon its outward
stroke. At that portion of the stroke of the piston corresponding to this, I arrange
the igniting device, which explodes the mixture of gas and air or hydrocarbon
vapor and air which has previously been forced into this cylinder by the back
stroke of the piston connected to the shorter of the two cranks. It is an essential
feature of my invention that one of the cylinders so arranged acts as a motive
power chamber and a pump alternately, while the other acts as
chamber only. Thus the mixture is drawn in by one piston, and exploded behind
both; the port or passage of communication between the cylinders being kept open.
The igniting device, whether this be a hot tube or an equivalent, is opened to the
mixture by the travel of the pistons only, thus any premature explosion is obviated,
and the action of the gearing between the two shafts is such as to cause both cranks
to be in the best position for receiving the impulse, and transforming it into rotary
motion and power with the least degree of loss.
I may describe the cycle as follows, that is to say ;-
motive power
The cylinder that performs the functions of a pump draws in a mixture of gas and
air through an automatic valve, the port or passage of communication between the two
cylinders being closed. The piston within the motive power cylinder is now upon
its instroke, expelling the products of combustion resulting from the previous
explosion, through the exhaust port, since, as herein before referred to, the port of
communication is closed at the same time that the exhaust is open to the motive
power cylinder, and vice versa. The piston in the cylinder acting as a pump, on its

page_text: instroke pushes the mixture previously drawn in 'into the motive power cylinder
when the port of communication is open, which occurs when the pump piston is half
way advanced on its return stroke. During the other half of the return stroke as
aforesaid, the motive power piston is moving upon its outstroke, and the crank in
connection therewith has reached approximately 22 degrees. Then I cause the
igniting device to be opened to the mixture behind both pistons, the pump piston,
owing to the arrangement of the cranks and the gearing thereof, having now com-
menced its second outstroke, which is completed by the time that the motive power
piston has moved the crank corresponding thereto, to a point approximately
22 degrees from the end of its stroke. The return stroke of the pump piston forces
the products of combustion resulting from its individual explosion into the motive
power cylinder, the return stroke of the piston of the latter completely expelling
said products by way of the exhaust in the manner before described.
From the foregoing description it will be seen that the method of, and means for
compounding a gas engine according to my invention, allows of a single charge of
gas, necessary to vitalize the volume of air drawn in, acts upon two pistons, one of
which is in the most favorable position for receiving an impulse, and transmitting
the power thereof as rotary motion with least loss, and the other piston is actuated
immediately afterwards. The power is taken from the shaft which receives an
impulse at each revolution, and is materially assisted, and uniformity and regularity
of motion procured, by the stored momentum of the fly wheel, which revolves at
twice the rate of the power shaft, and receives an independent impulse once in two
revolutions. I wish it to be understood that I do not confine myself to the employment
of separate shafts, but may arrange both cranks upon one shaft, or upon two equally
geared, and I may also arrange the cylinders oppositely, diagonally, or in fact in any
suitable position relatively to each other without departing from the principle of my
said invention.
Dated this 2nd dow of su 1000
A. G. MELHUISH.
COMPLETE SPECIFICATION.
Improvements in Gas and Petroleum Motors.
1, ALFRED GEORGE MELHUISH, of 39, Grove Hill Road, Denmark Park, in
the County of Surrey, Engineer, 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 :-
My invention relates to certain improvements in gas and petroleum engines, and
has for its objects the attainment of greater economy in the working engines than
can be attained in the case of those engines as hitherto made and used.
In order to render the subjoined description more clearly, I have appended two
sheets of drawings, in which
Figure 1 Sheet I is a sectional elevation of an engine constructed according to
my invention, and Figure 2 is an end elevation thereof.
Figures 1, 2, 3, 4, 5, 6, Sheet 2 are progressive diagrams illustrating the cycle of
operation.
In carrying my invention into effect, I employ_a_method-and-means analogous to
the compounding-of steam engines, but with a relatively greater economic effect in
the gas or explosive engine so arranged. Two cylinders,. .A. and B respectively,
Figures 1 and 2, are arranged either side by side, or one above the other as shewn
by the drawing, and a port or passage a is provided from one to the other in such a
manner that it is operated by a valve I which closes said port at the same time that
one of the cylinders is open to the exhaust. Two pistons or trunks C and D are
fitted to the cylinders A and B respectively and are connected by suitable rods to
two cranks E and F, each attached to separate shafts supported in bearings upon
the bed-plate. The principle adopted by me in carrying out my invention is to

page_text: arrange the cylinders, pistons and adjuncts so that both may perform an equal
amount of work upon the driving shaft c. I can effect this by constructing one
piston C of half the area of D, the stroke of each being equal, but gearing the
shafts b and c by geared wheels G and H so that these are in the proportion of
2 to 1 relatively to each other as shewn. Or both pistons may be of the same area,
the length of stroke being varied, or I may otherwise arrange the relative proportions
of areas, strokes and gearing to attain the same result. I prefer to attach the fly
wheel L to the shaft which in the example shewn, revolves at the highest rate
of speed, and attach the driving pulley K or other means for transmitting power to the
shaft c. By the arrangement of gearing as shewn, the piston C makes two outward
strokes and two return strokes to one double stroke of the piston D, and the cranks E
and F are placed so as to be at the position of half stroke at the same time, Figure 4
Sheet 2. I prefer to employ a double ported semi-rotary valve I, to which motion is
imparted by means of a cam, eccentric or other suitable means. The spindle J of
said valve is furnished with a screw thread of long pitch, so that the semi-rotary
movement before referred to also causes a lateral motion so that said valve is
rendered practically tight by the fitting of the conical end upon the seating d,
when the port of communication between the two cylinders is open, and opens the
exhaust to lower cylinder when said port of communication is closed, as shewn by
Figure 2 Sheet 1. I may however use any other form of valve for performing the
same functions, such as a drop plunger valve for instance.
It is an essential feature of my invention that one of the two cylinders A and B,
arranged as described and shewn, acts as a motive power chamber and a pump
alternately, while the other acts as a motive power chamber only. Thus the
mixture, in the example quoted is drawn into A by the piston C, and is exploded
behind both C and D, the port a between the two cylinders being kept open. The
igniting device, whether this be a hot tube, or an equivalent is opened to the
mixture by the travel of the pistons only, whereby a premature explosion is obviated,
and the action of the gearing between the two shafts is such as to cause both cranks
at the moment of explosion to be in the best position for receiving the impulse,
and transforming it into rotary motion and power with the least possible degree
of loss.
I may describe the cycle of operation as follows, with reference to the diagrams
on Sheet 2-
Figure 1 shews the commencement of an outward stroke, the mixture having
been compressed in B, behind the piston D, the port of communication being open,
and the ignition about to take place by the orifice being uncovered by D.
In Figure 2 the impulse has been imparted to both pistons.
Figure 3 shews the termination of the first outward stroke of C, and the con-
tinuation of that of D.
Figure 4 shews the completion of the return stroke of C, which is now ready to
draw in a fresh supply of explosive mixture, and the commencement of the return
stroke and exhaustion of D, the valve being suitably placed for this purpose at this
point of the cycle as shewn.
Figure 5 shews a fresh charge being drawn into A by C, and the completion of
exhaustion of B by the return stroke of D.
Figure 6 shews the compression of the charge of explosive mixture in A by the
return stroke of C, which is now ready to be expanded behind C and D when the
valve opens the port of communication between A and B as in Figure 1.
Thus, the cylinder A and its piston B performs the function of a pump, and
draws in a mixture of gas and air through a suitable automatic valve, as in
diagram Figure 4, the port or passage of communication being closed, and the
piston D being upon its instroke, completely expelling the products of com-
bustion resulting from the previous explosion throngh the exhaust port, diagram
Figure 6, since the port of communication before referred to is closed at the
same time that the exhaust is open to B, and vice-versa. The piston C on its
complete instroke, diagram Figure 1, has pushed the mixture previously drawu

page_text: in, into B, the port of communication having been opened when C was half
way advanced on said return stroke, during which time the piston D has moved
upon its outward stroke, and the crank in connection therewith has reached
When I
approximately 224 degrees from the neutral point or dead centre.
cause the igniting device to be uncovered by D, and explosion to take place,
giving an impulse to both pistons. The arrangement of the gearing and cranks
causes C at this time to have commenced the second outward stroke, diagram
Figure 2, which is completed by the time that D has moved the crank corre-
sponding thereto to a point approximately 22 degrees from the end of its
stroke, diagram Figure 3. The return stroke of C forces the products of com-
bustion resulting from the explosion through the open port of communication
into B, the return stroke of D completely expelling said products by way of the
exhaust in the manner hereinbefore described.
From the foregoing description it will be seen that the method of, and means for,
compounding a gas engine according to my invention allows a single charge of gas
necessary to vitalize the volume of air drawn in, to act upon two pistons one of
which is in the most favorable position for receiving an impulse, and transmitting
the power thereof as rotary motion with the minimum of loss, and the other piston
is actuated immediately afterwards. The power is preferably taken from the shaft
which receives an impulse at each revolution, and is materially assisted, and
uniformity and regularity of motion procured by the stored momentum of the fly-
wheel, which revolves at twice the rate of speed of the power shaft, and receives an
impulse once in two revolutions.
may arrange the cylinders oppositely, diagonally, side by side, or in any suit-
able position relatively to each other and further I may make the cylinders A & B,
and the pistons C and D of the same area, and also arrange the cranks to be of the
same length of stroke, as indicated by the dotted lines on the diagrams, Sheet 2 of
the drawings, without departing from the essential principles of my said invention.
I may summarise the advantages of my invention as follows,-
Firstly, both pistons exert an equal force upon the driving shaft or pulley, as
herein described. Secondly, the explosive charge is limited to the stroke area, or
capacity of the pump cylinder, but is expanded behind both pistons. Thirdly, the
explosive charge is expanded after ignition to the same volume as before ignition in
about one third of the time necessary to procure such expansion in other engines, as
hitherto made and used. Fourthly, the products of combustion are completely
expelled after explosion. Fifthly, the arrangement whereby the piston uncovers
the ignition device prevents premature explosion of the mixture, and if necessary,
the engine may be regulated by cutting off said explosion.
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 :-
First. In a gas or petroleum motor the employment of two cylinders with pistons
of unequal areas, in combination with two cranks of equal stroke upon separate
shafts, connected by gear wheels in the ratio of two to one, one of said cylinders
being used as a pump and both as motive power cylinders, substantially as herein
described with reference to Figures 1 and 2, Sheet-1-of-the appended drawings.
- - - Second. In a gas or petroleum motor, the employment of two cylinders with
pistons of equal areas, in combination with cranks of unequal length, upon separate
shafts connected by gear wheels in the ratio of two to one, substantially as
herein described with reference to Figures 1, 2, 3, 4, 5, and 6 Sheet 2 of the
appended drawings.
Third. The method of, and means for compounding gas engines of the ordinary
displacer type, so that the displacer performs the function of a "four cycle" motor,
and the working piston that of a "two cycle" motor, both however being of equal
power, substantially as herein described."
Fourth. In a compound gas or petroleum motor as referred to in the preceding

page_text: claims, the arrangement of one valve which closes the communication between the
two cylinders at the same time that the exhaust is opened, and vice versa, substan-
tially as herein described and set forth.
A. G. MELHUISH.