IMPROVEMENTS IN GAS ENGINES
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by Edward Sparshott Wastfield at the
Office of the Commissioners of Patents on the 10th February 1882.
EDWARD SPARSHOTT WASTFIELD of Bath in the County of Somerset Civil
Engineer. "IMPROVEMENTS IN GAS ENGINES."
This Invention relates to various improvements in the construction and general
arrangement of gas engines whereby economy of gas is obtained with greater
efficiency of action and reduction of noise in working.
According to my Invention I use in combination with a hollow or chambered
piston a peculiar arrangement of slide valve for the admission of the inflammable
inixture and for admitting a small charge of gas alone immediately before and after
the admission of the mixture. By first admitting pure gas 1 ensure a more ready
and certain ignition of the inflammable mixture in the cylinder and maintain &
more equable pressure during such time as the piston is making its out stroke.
My improved slide valve is provided with a gas inlet passage on the lower side
communicating direct with a mixing chamber formed inside the slide such chamber
being sufficiently prolonged and curved at each end to answer the purpose of the
ports for the admission of the gas and of the requisite supply of air to form the
mixture. The air port is opened subsequently to and is closed previously to the
gas port whereby I obtain the particular order of admissions already referred to.
On the lower edge of the slide valve I form an elongated port or channel one end
of which communicates with and supplies the burner for igniting the charge whilst
the opposite end is sufficiently extended to communicate at the required moment
with an equilibrium separate port in the bottom of the valvo box, which port is
connected by a pipe with an aperture made through the side of the cylinder and
which aperture is alternately opened and closed by a corresponding aperture in the
side of the chambered piston, during its traverse. By this arrangement I ensure
a supply of gas alone to the igniter at a pressure exactly equal to that of the
mixture inside the cylinder. This result may if desired be also obtained by the
employment of a small piston valve which is in connection with the before
mentioned equilibrium port and is further connected by a pipe with a separate
chamber or if preferred with the exhaust port of the engine the said piston valve
being actuated by the main slide valve. Or the said equilibrium port may be
D

page_text: made to open direct into the exhaust port through a passage cut in the slide valve
itself. Or I may employ a force pump.situate at and worked from any convenient
part of the engine for compressing a charge of pure gas and delivering the same by
a suitable pipe or passage into the equilibriúin port. In order to admit of the
piston traversing the entire length of the cylinder and thereby avoiding grooving I
employ a separate receiver or chamber in connection with the cylinder for
containing the charge of inflammable mixture.
In order to take up the wear on the edges of the slide valve I employ an
adjustable packing piece consisting of a strip or bar of metal resting on the top
edge of the slide and set up by adjusting screws passing down through the top of
the valve box. In order to facilitate the starting of the engine I provide a stop
cock on the side of the cylinder communicating by a pipe and valve opening
outwards with the exhaust pipe or with the atmosphere the said stop cock being so
situate on the cylinder as that the piston when moved inwards by hand shall first
partially expel the previously indrawn charge and thereby facilitate the rotation
of the shaft and by the time the piston has moved inwards a few inches further it
will close the communication with the stop cock and allow the remaining portion
of the charge to be slightly compressed.
In orde:
avoid the unpleasant noise of the exhaust in gas engines I cause the
exhaust Jucts to enter a closed chamber or vessel by a pipe entering some
distance th in and to escape quietly from such chamber or vessel by a separate
outlet pipe.