Heating Steam Engine Cylinders, Covers, and Pistons.
Year: 1895

page_text: Date of Application, 28th Aug., 1895
Complete Specification Left, 18th May, 1896-Accepted, 22nd Aug., 1896
PROVISIONAL SPECIFICATION.
Heating Steam Engine Cylinders, Covers, and Pistons.
WILLIAM ISAAC LAST 3 Balmuir Terrace Putney S.W. Engineer do hereby
declare the nature of this invention to be as follows:-
To economise steam by maintaining the cylinder or jacket, its covers, and its
piston, all or any of these parts, at a high temperature. Steam jacketing I
consider to be insufficient and, although I may use it, I supply heat by electrical
energy, obtained from a dynamo driven by the engine, or from any other
source.
If a continuous current is used, I may send it through insulated wire placed in
the spaces usually filled with steam when a cylinder or its piston is steam jacketed.
The spaces round the wires may be filled with steam, oil, mercury or other fluids
to assist in transmitting the heat, generated by the current flowing through the
wire, to the metal of the cylinder etc. Or the wire may be placed in grooves
formed in the surfaces to be heated, or it may take the form of metal tape which
when used on a cylinder cover or piston may be arranged as a spiral, and be attached
to an insulating plate or sheet secured to the inside of the cover. The electric
current passing through such wire or tape heats it and maintains the desired high
temperature.
It is much better however to use an alternating current to supply the heating
energy, and so arrange the wire conducting it that Foucault currents shall be
induced in the metal surfaces to be kept hot and so heat these surfaces.
To heat a cylinder by these Foucault currents it is only necessary to wind
insulated wire, through which passes an alternating current, outside the cylinder,
and the direction of winding is unimportant although helical winding is more
convenient. Or the insulated wire may be placed in a groove, preferably helical,
cut inside the cylinder and closed over the wire or cemented up so as to leave a
smooth surface. But it is hetter to employ a detached liner and wind it externally
with the conducting wire, while to bring the wire as near the concave surface of
the liner as possible, without making the liner too thin, the wire may be arranged
in helical grooves turned in the exterior of the liner. Outside this liner may be
placed a liner of insulating material such as cement or ware, and in this way the
production of Foucault currents in the true cylinder casting that contains the liner
be checked. By utilising the strength of the cylinder casting to support the liner
and winding the wire in a helical groove turned on the liner, a very thin liner may
be used and so the heating be concentrated near the surface that is to be kept
hot. In addition the cylinder may be also steam jacketed and lagged in the usual
manner, to reduce the external radiation from the liner. The liner may be of
steel, cast iron, copper alloys or other suitable material.
To heat a cylinder cover by an alternating current, recesses or spiral grooves
may be made in the inside face of the cover, and the insulated conducting wire be
fitted therein, and then a thin cover of copper added so that the Foucault currents
will be chiefly induced in this. copper plate while the ordinary or external cover
gives the requisite strength. The grooves may however be formed in the copper:
plate instead, and the plate be separated from the true cover by a sheet of asbestos
millboard, or marble or other poor conductor of heat or electricity.
To heat a piston by an alternating current each end of the piston may be treated.
as a cover, or else the body of the piston may contain. coils of insulated wire. To
convey the current to and from the piston windings, insulated conductors may be
:
1

page_text: placed within the piston rod. At the crosshead end these conductors may have
flexible ends, or they may each terminate in a metal brush that slides upon two
fixed terminal bars arranged' parallel with the piston rod. Where the piston has a
tail rod this may more convently be used, or else separate rods secured to the
piston and passing through glands in the cover may be used to contain the
conducting wires.
I may couple up the wires of the end covers circuits, the cylinder circuits, and
the piston circuits, all in series, but I may however put some or all in parallel
and may also introduce some adjustable resistances. Also to vary the heating I
may in places modify the windings of the wire, or may use a switch arrangement
that shall shut off certain circuits at particular portions of the stroke.
The insulation of the wires must be capable of withstanding high temperatures,
and may be of asbestos, or of cotton chemically impregnated, and in some
situations clay, porcelain, marble, glass, Portland cement or similar materials may
be used.
By employing powerful coils in the end covers I may by magnetic or by simple
induction from them, induce currents through the piston and cylinder walls, that
will of themselves give the necessary general heating, and such an arrangement
is most convenient for small cylinders or for those that are single acting.
Similarly I may use alone the coils in the piston, or those round the cylinder
or liner.
Another way of heating the parts is by forming a strong magnetic field within
the cylinder and so distributing the lines of force that the piston in its movements.
shall be heated by the currents so induced.
1007
I, WILLIAM ISAAC LAST of 3 Balmuir Terrace, Putney in the County of
London, 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 has for its object to economise steam by maintaining the cylinder
or jacket, its covers, and its piston, all or any of these parts, at such a high
temperature by electrical energy, as will prevent the steam exposed surfaces of
these parts, even at the close of the exhaust stroke, from falling so low in
temperature as to be lower than the initial temperature of the steam supplied to
the engine. In this way I prevent the condensation of the entering steam upon.
such steam exposed surfaces, and so avoid the heavy losses due to what is under-
stood by "cylinder wall action." Ordinary steam jacketting, even for the limited
surfaces treated, is quite inadequate for this purpose, owing to the temperature
in the jackets being too low to lieat the cylinder walls etc.. to the requisite degree.
To prevent the chilling, that takes place during the exhaust stroke, due to the
cooling of the surfaces to a point that is lower than that of the entering steam, I
find that the temperature of the metal immediately behind those surfaces must be
much higher than has before been anticipated. Taking the case of an engine.
supplied with steam at 55 lbs. per square inch above atmosphere and at a
temperature of 303° F. working without expansion and exhausting into a condenser
at 135° F., there is a difference of temperature in the two strokes of 168° F., and to
prevent the cylinder surfaces from falling at the end of the exhaust stroke below the
temperature of the entering steam i.e. 303° F., the metal behind those surfaces must
be maintained at a temperature of probably between 387 to 471° F., depending,
upon the speed and other conditions of the engine.

page_text: prepared according to my invention.
Figure 2 is an elevation of the piston.
Figure 3 is a sectional view of a modified cylinder cover.
Figure 4, is a detailed section of a cylinder and its liner.
Figure 5 is a detailed section of a modified cylinder and liner.
Figure 6 is a detailed section of a modified cylinder without a liner.
Figure 7 is a detailed section of a portion of a piston or cover.
Figure 8 is a modified form of Figure 7.
Figure 9 is another modification of Figure 7.
Figure 10 is a section of a modified piston, the construction of which is also
applicable to covers.
In Figure 1 the cylinder C is fitted with a liner / in the usual mauner, but the
exterior of the liner is provided with grooves cut in it as shewn more clearly in
Figure 4. These grooves may most easily be formed by cutting as a helix in a
lathe, but the pitch may be increased towards the centre of the length of the liner,
where less heating is required. In this groove insulated wire is laid of such
material and sectional area that it shall be so heated by an electric current sent
through it as to maintain the metal of the liner at the desired high temperature.
I have used wire at a temperature of from 1000° to 1500° F., but the actual
temperature required depends, amongst other things, upon the distance apart of
the wire coils. The insulation of the wire must necessarily be able to withstand a
high temperature, and I have found both asbestos and mica suitable, but porcelain
tubing in short lengths or in the shape of saddles may be used, or glass beads, or
similar refractory insulating material can be substituted. To keep the electrical
wire in position in the groove I find it convenient to stem into the groove, after
the insulated conductor is in place, a wire that is a tight fit into the groove as
shewn at Z Figure 4. This wire also assists in conducting the heat through the
insulation into the liner. Cement or similar filling may also be used instead. The
filling wire has another use, in that it can be made to compress the insulation and
so increase its heat conducting power.
Or, as shewn in Figure 5, a thinner liner may be used, and the groove and wire
be arranged within the metal of the cylinder.
Or, as shewn in Figure 6, where no liner is necessarily used, the groove is cut in
the bore of the cylinder, and of a terraced section so as to facilitate the securing
of a steam tight joint with the stemming-up wire, which may be of a suitable
section as shown. The groove and wire may also be arranged on the exterior
of the cylinder, and the direction may be to and fro longitudinally, but neither
In all cases
of these arrangements is generally as convenient as those drawo.
however the cylinder should be well lagged externally to prevent external
radiation.
It is however of far greater importance to heat in this way the cylinder ends and
both faces of the piston, as these surfaces do not remain bright or cleau, and also,
form so large a percentage of the exposed surfaces at the commencement of each
stroke, when the piston is moving slowly and the most serious condensation
of entering steam takes place. With short stroke engines 1 believe that by
putting an excess of heat into the covers and piston, sufficient heat may
escape into the cylinder barrel to render the separate heating of this part
unnecessary.
In Figure 1 and Figure 2, and in detail in Figure 7, a piston is shown, with its
faces, or the metal behind them, heated by an electric current, as described for a
cylinder, except that the grooves are preferably spiral as shown in Figure 2.
Figure 7 is shown a portion of a radial section of such a fitted piston, the means
In

page_text: for securing and protecting the electric wire being similar to those before explained
in connection with Figure 6. The means for supplying the electricity to the
piston circuit is described further on.
In Figure 8 is shown another arrangement of the wire etc., for heating a piston
face. To the face is secured a thin cover, in the back of which is a (preferably)
spiral groove, in which is placed the insulated wire as shown. Such cover plates
form a ready means of securing the insulated wire, and of protecting the insulation
from contact with steam or moisture.
In Figure 9 is shown another similar arrangement to Figure 8 except that no
groove is turned in the thin plate, but between the plate and the piston are inter-
posed two sheets of asbestos millboard or similar insulating material. Between
the sheets uncovered wire is placed and tied or stuck down in the desired
position, where it is afterwards firmly secured when the plates, etc., are attached
to the piston as indicated. This modification saves the expense of cutting the
groove.
In Figure 10 is shown a piston in which the insulated heated wires are wound
together into a chamber left in the piston body and then protected by a covering
plate, the heat from the wires distributing itself throughout the piston by
conduction. Two different shapes for the chamber are shown, that in the lower
half of the drawing being however rather the better. When alternating currents
are used, the heat given to the piston by this arrangement is to some extent due
to the heating of the wires, but also to the induced or Foucault currents in the
metal of the pistou. This method of winding is also suitable for the windings of
cylinder covers.
A cylinder cover may be heated by wire arranged as shown in the loose cover A
in Figure 1 the enlarged detail of which is similar to that for a piston face as
shown in Figure 7, a spiral course for the wire being also preferable as indicated
in Figure 2. Or a cylinder cover may be treated as shown in the front end B of
the cylinder in Figure 1, the detail of the covering internal plate being similar to
the piston plate shown and explained in connection with Figure 8. In Figure 3 is
shown a loose cover fitted with a modification of this arrangement, the added
heating plate being extended out into the cylinder cover joint
The piston
arrangements shown in Figure 9, and in Figure 10 are also equally applicable
to covers.
In all cases in which covers are heated, by added plates that are heated by
electric wires, it is economical to interpose between the plate and the true cover
a sheet of asbestos millboard or other suitable non-conductor of heat, so as to
reduce as far as possible the loss through heat radiation from the cover.
Such
sheets are shown in Figure 1, Figure 3 and Figure 9.
The terminals of the insulated wires of the various heating circuits may be
carried to the exterior of the engine, and then be coupled up in series, or
in parallel, and be connected to the leads of a dynamo or other source of
electricity.
Owing to the motion of the piston, the supply of its electricity requires special
arrangements and in Figure 1 the inculated terminals of the wire of its windings
are carried through an axial hole in the piston rod and then led out to separate
insulated sliding contacts or brushes attached to the crosshead. These brushes
slide on the fixed terminal bars, that are insulated from the surrounding metal but
connected with the dynamo terminals, or in the circuit as indicated One insulated
wire from the piston is however sufficient if the other end of the piston winding
is connected to the body of the piston, the circuit being completed through
the metal of the engine. The cover and barrel windings may be supplied by a
single wire and an "earth" return in this way, but I prefer complete insulated
circuits.
A tail rod may be used instead of the piston rod shown in Figure 1, to contain
the piston leads. Or one or two insulated rods may be carried through insulated
glands in the cylinder cover, as indicated in Figure 10.

page_text: The connection to the moving insulated conductors from a piston circuit, may be
made by sliding contacts or by swinging rods or by flexible wire conductors.
The connections from the various heating circuits may be brought to a common.
switchboard, with a switch arranged so as to place them in parallel or in series as.
desired, so that, when starting, a quick heating up may he obtained by the larger
current passed when the circuits or some of them are in parallel, and then the
normal current be restored by placing the circuits in series.
The electrical energy necessary to maintain the steam exposed surfaces at-
the desired high temperature may be reduced by using dry or superheated
Eteam.
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:-
1. In steam engines, heating the steam exposed surfaces of the cylinder, its.
covers and its piston by means of electrical energy to such a degree that the
temperature thereof at the end of the exhaust stroke shall be at least as high
as the initial temperature of the steam supplied to the engine, substantially as.
described.
2. In steam engines, heating the steam exposed surfaces of the cylinder
covers by electrically heated conductors for the purpose and substantially as
described.
3. In steam engines heating the steam exposed surfaces of the piston by
electrically heated conductors, for the purpose and substantially as described.
4. In heating steam engines by electrical energy in the manner referred to in
the first claim, the use of alternating currents for producing Foucault currents in.
the steam exposed surfaces substantially as described.
5. In steam engines heated by electrical energy, forming grooves in the cylinder
liner or cylinder face, the cover liner or face and the piston liners or faces into.
which grooves are introduced firstly the electrical wires and secondly above these
a covering wire of such size as to fit the groove tightly, substantially as described
with reference to Figures 4 to 8 of the drawings.
6. In steam engines beated by electrical energy, fitting layers of asbestos mill.
board in the cylinder, cylinder cover, or piston faces between or upon which layers.
are secured the electrical wires, which are then covered by plates, substantially
as described with reference to Figures 1, 3 and 9 of the drawings.
7. In steam engines heated by electrical energy, forming chambers in the body.
of the piston in which are fitted coils of electrical wire, substantially as described.
with reference to Figure 10 of the drawings.
8. Supplying electric current to the electric wires in the piston by connecting.
them to an insulated conductor passing up through the piston or tail rod and
connected at the outer end to the supply circuit either by means of a brush or
brushes sliding upon fixed conducting rods, or by flexible or telescopic conducting
connections that allow of the to and fro motion of the piston, substantially as.
described with reference to Figure 1.
9. Supplying electric current to the electric wires in the piston by connecting them.
to a conducting rod fixed to the piston that extends through an insulating stuffing
box in the piston cover and is connected externally to the supply circuit either
by a sliding contact or by a flexible or telescopic connection substantially as
described with reference to Figure 10..
10. The use in combination with a steam engine with electrically heated cylinder,.
covers, and piston, of a switch board to which the several electric heating wires of
the engine are connected by leads, the switches being so arranged that the said
electric heating wires can be connected to the supply circuit either in series.
or in parallel, according as a greater or less degree of heating may be required,
substantially as described.
11. When beating cylinder-ends by an electrically heated conductor, the use.

page_text: of an internal plate heated by such conductor, situated in or behind the said
plate, such plate being insulated from the cylinder cover or end by a sheet of
asbestos millboard or other suitable nonconductor of heat substantially as
described.
ABEL & IMRAY,
Agents for the Applicant.