The accompanying engravings illustrate Edwards' patent gas engine, made
by Messrs. Cobham & Co., Stevenage, Herts, recently exhibited at York.
In our engravings, _a_ is the foundation plate of the engine, having
the bearing, _b_, in which the crank shaft, _c_, revolves; _d_, an
inclined plate upon the foundation, _a_, to which the cylinder, _e_,
and casing, _f_, are bolted; _g_ is a piston working in the cylinder,
_e_, and having a hollow rod or trunk, _h_, to which is jointed the
connecting rod, _i_, which drives the crank pin, _k_. The guide, _l_,
fits upon the hollow trunk, _h_, and is itself surrounded by the air
casing, _m_, which communicates with the casing, _f_, through openings,
_n n_, in the inclined plate, _d_. The guide, _l_, has openings, _o
o_, through which air enters the casing, _m_, when the hollow trunk,
_h_, is at the inner end of its stroke; _p_ is the exhaust pipe, and
_r_ is a casing round the cylinder, _e_, through which water may be
made to circulate by pipes at _s, t_. The valve seat, _v_, fits into
the cylinder, _e_, and has holes, _w_, for the admission of air, and
_x_ for the admission of gas through the central pipe, _y_. The valve,
_z_, consists of a disk of metal covering these holes and guided
by a spindle, A, the outer end of which is fitted with a metal or
India-rubber spring at B, and a regulating nut, C. The gas pipe, _y_,
is shown supplied from a flexible bag, D, the supply to which from any
convenient source is regulated by a cock or valve at E. The piston,
_g_, contains a disk exhaust valve, G, the spindle, H, of which is
fitted with a closing spring, I, and the end of the spindle is pressed
down during the inner stroke of the piston by a tail-piece, K, on the
inner end of the connecting rod, _i_. Holes, L, open from the hollow
piston above the exhaust valve, G, into the cylinder round the hollow
trunk, _h_, and thence to the exhaust pipe, _p_. At or near one-third
of the stroke of the piston a firing valve, P, is arranged, having an
inlet hanging valve of the usual kind, through which a flame burning
outside is drawn when the valve is uncovered by the piston, _g_. The
outer end of the casing, _f_, is closed by a cover, R, to which the
valve seat, _v_, and gas inlet pipe, _g_, are connected.
The operation of the engine is as follows: The piston, _g_, being at
the inner end of its stroke, the crank is turned round in the direction
of the arrow, and the piston draws air in through the holes, _w_, and
gas through the holes, _x_, the two mixing as they pass under the
inlet valve, _z_. When the piston has advanced far enough to uncover
the firing valve, P, the flame is drawn in and the inflammable mixture
exploded, the expansion of the air and gas closing the inlet valve,
_z_, and carrying the piston to the end of the stroke. The momentum
of the fly-wheel then carries the piston back through its return
stroke, during which the tail-piece, K, presses the spindle, H, and
opens the exhaust valve, G, through which expanded air and gas escape
to the exhaust pipe, _p_. It is claimed that this arrangement is very
effective in securing a complete clearance from the cylinder of the
products of combustion, which, when not wholly removed, vitiate the
incoming charge and reduce efficiency.
When the piston arrives at the inner end of its stroke, the exhaust
valve, G, is closed by the spring, I, and a fresh supply of air and
gas are drawn in through the inlet valve seat, _v_, as the piston
again commences its outer stroke. In order to keep the cylinder, _e_,
sufficiently cool, whether the water casing at _r_, be used or not,
the whole supply of air is drawn from the front end of the cylinder
through the openings, _n n_, and thence between the cylinder, _e_, and
the casing, _f_, and round the end of the latter to the inlet valve,
_v_. And in order to prevent or lessen the noise of the explosions, the
hollow trunk, _h_, is made of such length that its front edge closes
the openings in the guide, _l_, through which air is drawn into the air
casing _m_, and through the openings, _n n_, just before the explosion
takes place, the noise of which therefore cannot escape. For the same
purpose fibrous or porous material, such as mineral or slag wool, may
be placed loosely in the space between the cylinder and the casing, _f_.
The engine may be made to revolve in the opposite direction to the
arrow by turning the piston and connecting rod round so that the
tail-piece upon the latter is above instead of below, and instead of
the water casing, _r_, radial ribs may be formed upon the cylinder,
_e_, from which the air passing between them inside the casing, _f_,
absorbs the heat. The cylinder is arranged preferably in the inclined
position shown, but it may, of course, be fixed in any other convenient
position.--_Engineering._
[Illustration: IMPROVED GAS ENGINE.]
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