Improvements in or relating to Internal Combustion Engines.
Year: 1897

page_text: Date of Application, 13th Mar.,
1897
Complete Specification Left, 13th Dec., 1897-Accepted, 22nd Jan.,
1898
PROVISIONAL SPECIFICATION.
Improvements in or relating to Internal Combustion Engines.
I, JOHN REGINALD HARGREAVES, Witchingham Hall, Norwich, in the County of
Norfolk, Gentleman, do hereby declare the nature of this invention to be as
follows:-
My invention relates to internal combustion engines, and has for its object to
improve the construction of such engines by providing means whereby the entire
products of combustion will be swept out of the cylinder before a fresh charge is
drawn in.
Hitherto the pistons and cylinders of internal combustion engines have been in
general so proportioned that the piston does not at any period of the stroke reach
the end of the cylinder, that is to say, the internal capacity of the cylinder is never
reduced to zero at any part of the stroke. In consequence of this, at the end of the
exhaust stroke, and before the fresh charge is drawn into the cylinder, there still
remains a considerable volume of the products of combustion from the previous
explosion which mixes with the fresh charge of explosive mixture. Owing to the
dilution of the explosive charge by the waste products the energy of the explosion
is diminished, and the engine cannot work at its full capacity.
According to my invention I provide that the piston shall at every return stroke
after having fired completely sweep out the products of combustion of the previous
explosion, and for this purpose the piston is arranged to reduce the volume of the
working cylinder to nothing before drawing in the fresh explosive charge; when,
however, the explosive charge has been drawn in, it is compressed on the next
stroke of the piston, and since the charge cannot be compressed so far as to fill
no space I provide an auxiliary cylinder in connection with the working cylinder
to receive the explosive charge during the compression stroke. Said auxiliary
cylinder is preferably made with an internal capacity equal to the capacity to
which it is desired to compress the charge, and it is provided with a loose piston
furnished with a spring or weight which tends to maintain the piston at one end
of the cylinder and so reduce its internal capacity to its smallest dimensions. In
one method of carrying out my invention the auxiliary cylinder is placed with its
axis vertical, and is connected at the bottom with the main cylinder so that the
weight of the piston in the auxiliary cylinder tends to maintain the piston at the
bottom of the cylinder and reduce its internal capacity to zero.. Suitable cushion-
ing springs may be provided to avoid knocking and shock at the ends of the stroke
of the auxiliary piston.
"
The operation of an internal combustion engine working according to the
Otto" cycle and provided with my improvements is somewhat as follows:-
After the explosion stroke the working piston moves back to the rear end of its
cylinder sweeping out the entire products of combustion. It then moves forward
again drawing in a fresh explosive charge. During these two strokes the piston

page_text: of the auxiliary cylinder remains at the bottom of its cylinder. The main
cylinder now moves back compressing the charge and ultimately forcing it out of
the working cylinder into the auxiliary cylinder the piston of which moves out,
the charge being compressed because the capacity of the auxiliary cylinder is less
than that of the main cylinder, being the same as that of the combustion chamber
in the ordinary way. The charge is now fired in the auxiliary cylinder and the
explosion forces out the main piston which performs its working stroke. During
the next stroke the products of combustion are being swept out of the main
cylinder, and as the exhaust is open the piston of the auxiliary cylinder will move
back forcing out the products of combustion from the auxiliary cylinder also.
The main piston then draws a fresh charge, and the operation continues as before.
I have herein described my improvements as applied to an engine working with
the "Otto" cycle but I wish it understood that I do not restrict myself to this
particular class of engines, as iny improvements are obviously applicable to engines
working with other cycles in which the charge after being drawn into the cylinder
is compressed by the back stroke of the piston.
Improvements in or relating to Internal Combustion Engines.
I, JOHN REGINALD HARGREAVES, Witchingham Hall, Norwich, in the County of
Norfolk, Gentleman, 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 internal combustion engines, and has for its object to
improve the construction of such engines by providing means whereby the entire
products of combustion will be swept out of the cylinder before a fresh charge is
drawn in.
Hitherto the pistons and cylinders of internal combustion engines have been in
general so proportioned that the piston does not at any period of the stroke reach
the end of the cylinder, that is to say, the internal capacity of the cylinder is never
reduced to zero at any part of the stroke. In consequence of this, at the end of the
exhaust stroke, and before the fresh charge is drawn into the cylinder, there still
remains a considerable volume of the products of combustion from the previous
explosion which mixes with the fresh charge of explosive mixture. Owing to
the dilution of the explosive charge by the waste products the energy of the explo-
sion is diminished, and the engine cannot work at its full capacity.
According to my invention I provide that the piston shall at every return stroke
after having fired completely sweep out the products of combustion of the previous
explosion, and for this purpose the piston is arranged to reduce the volume of the
working cylinder to nothing before drawing in the fresh explosive charge, when,
however, the explosive charge has been drawn in, it is compressed on the next
stroke of the piston, and since the charge cannot be compressed so far as to fill
no space I provide an auxiliary cylinder in connection with the working cylinder
to receive the explosive charge during the compression stroke. Said auxiliary
cylinder is preferably, made with an internal capacity equal to the capacity to
which it is desired to comprèss the charge, and it is provided with a loose piston
furnished with a spring or weight which tends to maintain the piston at one end
of the cylinder and so reduce its internal capacity to its smallest dimensions.

page_text: In order that my invention may be clearly understood I will proceed to describe
the same with reference to the accompanying drawing which illustrates one method
of carrying out the same in practice.
A is the main cylinder of the engine, B. the valve box through which the working
charge is admitted to the cylinder, C is the auxiliary cylinder secured to the top
of the valve box B the interior communicating with interior of the valve box
through a port C and through said valve box with the main cylinder. The
cylinder C is provided with a piston D having packing rings D' and capable of
sliding freely up and in the cylinder, said piston is also furnished with an
extension D adapted to fill the port C¹ when the piston is at the bottom of its
cylinder. E is a valve in the top of the cylinder which permits air freely to enter
the same, but is provided with only a small orifice for the air to escape from said
cylinder, the movement in the piston D in the upward direction is thereby
cushioned. Knocking is further prevented by springs FF the inner one F pre-
venting concussion between the piston and cylinder cover and the outer one being
compressed between a collar D³ on the piston rod and the cylinder cover when the
piston reaches the bottom of the cylinder. G is a lubricator of any suitable type.
The operation of the apparatus is very simple and is as follows that is to say.
After the explosion stroke the main piston moves back to the rear end of its
cylinder sweeping out the entire products of combustion through the exhaust
orifice. It then moves forward again drawing in a fresh explosive charge. During
these two strokes the piston D of the auxiliary cylinder C remains at the bottom
of its cylinder as shewn in the drawings. The main piston now moves back com-
pressing the charge and ultimately forcing it out of the main cylinder into the
auxiliary cylinder C the piston D of which moves up, the charge being compressed
because the capacity of the auxiliary cylinder is less than that of the main cylinder,
being the same as that of the combustion chamber in the ordinary way. During
the movement of the piston D the air included above said piston slowly escapes
by the valve E and the spring F prevents jarring and knocking. The charge is
now fired in the auxiliary cylinder and the explosion forces out the main piston
which performs its working stroke. During the next stroke the products of com-
bustion are being swept out of the main cylinder, and as the exhaust is open the
piston of the auxiliary cylinder owing to its weight will move down forcing out.
the products of combustion from the auxiliary cylinder also. The main piston
then draws a fresh charge, and the operation continues as before.
In the drawing the auxiliary cylinder is secured to the top of the valve box but
it would in general require to be firmly bolted to the engine as the valve box would
not be strong enough to carry it for long. Said cylinder may obviously be located
in any suitable position where a free communication between it and the main
cylinder can be provided. It may further be placed in an inclined or horizontal
position in which case a spring would be furnished to force the piston to the end
of the cylinder during the exhaust stroke.
I have herein described my improvements as applied to an engine working with
the "Otto" cycle but I wish it understood that I do not restrict myself to this
particular class of engines, as my improvements are obviously applicable to engines
working with other cycles in which the charge after being drawn into the cylinder
is compressed by the back stroke of the piston.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is:--
1. An internal combustion engine having a main cylinder the piston of which
reduces the volume thereof to zero on the scavenging and compression strokes,
and an auxiliary cylinder connected with the main cylinder which receives the
charge from the main cylinder during the compression stroke and in which the
charge is compressed and fired.
2. An internal combustion engine provided with an auxiliary cylinder arranged

page_text: and operating substantially as described with reference to the accompanying
drawing, and for the purpose specified.
Dated this 13th day of December 1897
W. P. THOMPSON & Co.,
Of London, Liverpool, Manchester and Birmingham,
Patent Agents for the Applicant.