A field which almost from the beginning of the oil engine industry had suggested itself as a promising one for the extensive use of engines of that class is that of agricultural engineering. Steam engines have for quite a number of years been largely employed in agriculture, and have demonstrated conclusively that something more than manpower has become necessary to economically carry on much of the farm work of the present day. For such work, however, steam engines have always carried with them the dangers of steam boilers, necessarily entrusted to the care of comparatively unskilled attendants, and it has become generally recognized that if some other, less dangerous source of power were available, it would be well worth having. Oil engines with their comparative simplicity and absence of complication in management appeared to exactly meet the requirements, and as a consequence portable outfits were built and are already much used for threshing and other similar purposes.
/fig. 63.jpg) Fig. 63— The Stationary Hornsby-Akroyd Gas Engine |
| /fig. 64.jpg) Fig. 64— The Portable Hornsby-Akroyd Gas Engine |
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One of the makes which has become prominent in this line is the Hornsby-Akroyd oil engine, of which a portable form is shown in Fig. 64, while Fig. 63 represents the stationary design. It is built by Messrs.
Richard Hornsby & Sons, Limited , of Grantham, England. The engine is horizontal and works on the well-known Otto cycle. It is constructed with a working cylinder closed at one end by a cover and open at the other. In this cylinder works the piston, which is formed like a plunger, being open at one end to receive the end of the connecting rod. Near the closed end of the cylinder a valve box is fitted, which contains two valves, one being the air valve and the other the exhaust valve. The air and the exhaust valves are operated by separate levers, each lever being moved by a cam mounted on a horizontal shaft, driven by the crankshaft through skew or bevel wheels. This horizontal shaft makes only one revolution while the crankshaft makes two, so that the air and exhaust valves are each opened only once in every two revolutions.
At the back of the cylinder is a cast iron box, called the vaporizer, which is always open to the cylinder through a neck. This vaporizer is heated, before starting the engine, by an external lamp blown by a small fan for a few minutes, so that the vaporizer shall be able to vaporize and explode the oil when it is pumped into it. After the engine has started running, the lamp is no longer required, the vaporizer being kept hot enough by the explosions, which take place in it.
A small oil pump worked by the air valve lever draws oil from the oil tank under the engine and forces it into the vaporizer; this takes place only during the outstroke of the piston, when it is drawing in air. The oil on its way from the pump to the vaporizer passes through a valve box attached to the vaporizer. This valve box has two valves in it, one kept closed by a spring which the oil forces open as it goes into the vaporizer. The other is also kept closed by a spring, and should the engine run too quickly, the governor opens it and allows some of the oil to flow back to the tank. This valve can also be opened by turning a little regulating handle, which will stop the supply of oil to the vaporizer, and thus stop the engine. The action of the engine may be explained as follows:
The vaporizer having been previously heated and the fly-wheel being pulled round, the first outstroke of the engine thus made will cause air to be drawn into the cyl1nder, and at the same time the pump will force oil into the vaporizer, which is immediately transformed into oil vapor. On the return stroke of the piston, the air is compressed into the vaporizer and thereby mixed with the oil vapor, and just as the piston gets to the end of its stroke, and the compression is, therefore, greatest, an explosion takes place, which forces the piston out on its second stroke. When the piston gets to the end of this stroke the exhaust valve opens, and the return stroke expels the gases, the same cycle of operations being repeated continuously.
The speed of the engine is governed by a small Porter governor which acts through levers on an overflow valve fitted in the valve box attached to the vaporizer, so that when the engine runs too quickly this valve is opened by the governor and the oil allowed to return to the tank instead of going into the vaporizer. The latter getting little or no oil, the speed of the engine is thus regulated.
The oil used for running these engines can be varied from oil of a specific gravity of .80 to one of .85 and even .88, with flashing points of from 200 to 250 degrees Fahrenheit.
/fig. 65.jpg) Fig. 65— Explanatory Diagram of the Hornsby-Akroyd Gas Engine |
The outline drawing, Fig. 65, will help to further explain the general construction and manner of working of the engine. In this,
P represents the exhaust valve lever;
Q is the oil pump, and
R is the small fan referred to, driven from the pulleys
S. The vaporizer lamp is shown at
T, the vaporizer itself being marked
V;
H is the cam shaft, and
K are the governor gear wheels;
B is a cylinder oiler;
M is the connecting rod from the governor to the vaporizer valve box
X. The water circulat1ng pipes for the cylinder jacket are marked
a and
b, and those for the vaporizer valve box are marked
c and
d The oil supply pipe f from the tank to the pump has a three-way cock
e with a fitter inside ;
g is the oil pipe from the pump to the vaporizer valve box, and
h is the overflow pipe from the vaporizer valve box to the oil tank.
The absence of all flame in this engine, after having started, is a striking feature, and is claimed to make the engine a peculiarly safe one. The engine is turned out in large numbers, and, like other engines of its class, is used for almost every purpose that power is required. The stationary motor is built in sizes of from one and one-half to nineteen actual horse-power, and the portable type, in sizes of from three and one-half to nineteen horse-power. In the portable type that which takes the place of the boiler is a water tank containing water for circulation through the engine cylinder jacket; that which takes the place of a smokestack is an exhaust silencing chamber, and that which takes the place of the fire-box is an oil tank. The outfit is thus remarkably independent and self-sufficing.
/fig. 66.jpg) Fig. 66— The Portable Robey Oil Engine |
A somewhat similar portable oil engine outf1t is that shown in Fig. 66, and built by Messrs.
Robey & Co., of Lincoln, England. The engine in this case also works on the vaporizer system, oil being injected under pressure into an annular vaporizer chamber, heated only by the heat of combustion in the working cylinder. The governor also acts by determining whether the supply of oil shall go into the vaporizer or back into the oil supply tank. A heavy oil of about 0.85 specific gravity is used, with a flashing point of about 243 degrees Fahrenheit. The water tank contains sufficient water for circulation through the engine cylinder jacket for a whole day, and the oil tank is made large enough to hold a week's supply of oil.
Robey & Co. make also a semi-portable engine of the same general design.
One of the American engines which has made rapid progress during the past few years is that built by the
Van Duzen Gas and Gasoline Engine Company, of Cincinnati, O., and of which a number of different forms are shown. Altogether this company turns out seven styles: a simple stationary gas engine, a stationary gas and gasoline engine combined, a stationary gasoline engine, a portable gasoline engine, a stationary gas engine and pump combined, a stationary gasoline engine and pump combined, and a portable gasoline engine and pump combined. The gas and gasoline engine combined, as will be understood, may be used with gas alone, but has a gasoline apparatus attached to prevent any delays in operation should the gas supply suddenly fail. The portable gasoline engine is mounted on trucks, as the illustration shows, and may be used for driving threshing machines, hay presses, etc. The gas and gasoline engines and pumps combined, both stationary and portable, need no special explanation as to the uses to which they are to be put; the name sufficiently indicates the purposes to which they can be applied. In addition to the types already mentioned, the company also builds a marine engine, which appears to have met with much favor.
/fig. 67.jpg) Fig. 67— The Stationary Van Duzen Gas Engine |
| /fig. 68.jpg) Fig. 68— The Portable Van Duzen Gas Engine |
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From the illustration of the horizontal stationary engine, Fig. 67, it will be observed that the cylinder, water jacket and pillow-blocks are all cast in one piece, and are supported by a cast-iron base. The four and five horse-power engines carry one balance wheel, but those from seven horse-power up carry two such wheels. The four-stroke or Otto, cycle of operation is followed. Between the cylinder and the base is a countershaft, worked by spur gearing from the crankshaft. On one end of this countershaft is mounted a cam for operating the exhaust valve, and on the other end are cams for similarly working the admission and ignition valves.
/fig. 69.jpg) Fig. 69— Side Elevation of a Horizontal Van Duzen Gas Engine |
| /fig. 70.jpg) Fig. 70— The Portable Van Duzen Gas Engine |
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The valves all are of the poppet type, and their stems are fitted with long guides. Figs. 69 and 70, which represent, respectively, side and end elevations of the engine, will help to explain the functions of the main parts.
To begin with, if the engine be below its normal speed, the governor rod
D will allow the vibrating stem
B to drop into such a position that the toe
A will come in contact with it as soon as the rocker arm, marked
4, is raised. This arm begins to raise when the piston is at the end of its in-stroke, or when it is in the same position as that shown in Fig. 69. The cam marked
1, it will be noticed, is first about to come in contact with the cam roller
5 and the rocker arm
4. When it actually comes in contact with it and raises the arm
4, the toe
A will be depressed, come in contact with the valve stem
B, and open the admission valve
C. By the time that the crank has come into the position
B, corresponding to the end of the out-stroke of the piston, the valve
C is again shut. The cams
1 and
3, working, respectively, the admission and the exhaust valves, are so designed as to effect quick opening and shutting of valves, and also to keep them wide open during a large portion of the piston travel.
During the next half-revolution of the crank, from the position
B back again to the position A, the mixture in the cylinder of the engine is compressed, and as the crank passes the inner centre, the cam, marked
2, comes in contact with the lower end of the two-armed lever
E, and though it opens the ignition valve
N. The opening of this valve allows part of the explosive mixture from the cylinder to pass up into the ignition tube
O. On the end of this tube is a ball
H, which is said to serve as a cushion, and to dispose of the waste gases which accumulate in the ignition tube. The mixture, being ignited, again forces the piston forward, bringing the crank once more into the position
B. By this time the cam
3 on the other end of the camshaft opens the exhaust valve, and allows it to close again when the crank finally resumes its initial position
A. This completes a full working cycle, and everything is then in readiness to resume the same series of operations.
The end elevation, Fig. 70, shows, among other things, a vertical section of the carburetor. It consists of an iron casing with an inner tube through which the air necessary for the working charge enters. On top of this inner tube is seated a flange valve. As the air enters, it necessarily raises this valve which, in turn, raises the fluted stem of the check valve above it. The gasoline is in the chamber above this valve, and as soon as the valve is lifted the gasoline flows down inside the flange valve and out through the laterally disposed holes, as indicated by the arrows. Thence the gasoline flows over the edges of the air valve and is caught up by the air current flowing downward through the inner chamber and through a number of gauze rings, being vaporized on its way. It will be observed that no gasoline is allowed to enter the carburetor until the engine calls for it. From the carburetor the mixture goes immediately to the cylinder through the admission valve. Should any premature explosions occur, they would have to take place in the carburetor, and this is made strong enough to withstand them. As soon as the admission valve on the engine cylinder is closed, the air valve in the carburetor drops back on its seat, thus, in turn, allowing the gasoline check valve to drop back also, and effectively shutting off the gasoline supply. The gasoline tank necessarily is placed above the level of the top of the carburetor in order to allow the gasoline to flow to the latter by gravity.
The main features of the governor with which the engine is supplied are shown in the side elevation. The governor is worked from the crankshaft by intermediate gear wheels, and can be set to run at any desired speed. Changes of speed can be easily and quickly made.
/fig. 71.jpg) Fig. 71— The Van Duzen Vertical Gas Engine |
| /fig. 81.jpg) Fig. 81— The Sintz Vertical Gas Engine |
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Another engine of American design, more recently put on the market, is the Sintz engine, shown in Fig. 81, and built by the
Sintz Gas Engine Company, of Grand Rapids, Mich. It is of the vertical type and is turned out both for gas and gasoline use. When gasoline is to be employed, the engine is provided with a small pump and is connected with a gasoline supply tank conveniently located. The operation of the engine is substantially as follows: When the piston makes its first upward stroke of the working cycle, it draws a charge of air into the crank casing with which, as will be noticed, the engine is fitted. On the following down-stroke, and when near the end of
its stroke, the piston passes a port in the side of the cylinder which communicates with the crank chamber.
Just as the piston begins to open this port, the small gasoline pump (when gasoline is used) begins its downward or discharge stroke, causing the gasoline to pass into the port in the form of fine spray, and it finishes its stroke at the same time that the main piston completes its downward stroke. In the meantime the air, which has been slightly compressed in the crank chamber, is rushing through the port, and is deflected to the top of the cylinder, carrying the gasoline with it, and forming an explosive mixture.
The piston, on its next upward stroke, compresses the charge in the upper end of the cylinder where it is ignited electrically at the proper moment and drives the piston down again, this time performing a working stroke. On reaching the end of this stroke an exhaust port is uncovered, about opposite the transfer port already mentioned, and the waste gases are enabled to escape before the fresh charge is transferred to the cylinder. The design is such that an impulse, or explosion, takes place at every revolution while gasoline or gas is supplied. The supply of the oil or gas is controlled by the governor by its action on either the gasoline pump or on the gas valve, depending upon the kind of fluid used.
A special marine engine outfit is made by the builders, the engine itself being of substantially the same design as that shown. Both the marine and the stationary engines are made in sizes of from one to fifteen horse-power.
/fig. 76.jpg) Fig. 76— The “Forward” Horizontal Gas Engine |
| /fig. 77.jpg) Fig. 77— The Double Flywheel “Forward” Horizontal Gas Engine |
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The “Forward” gas engine, an English design, built by Messrs.
T. B. Barker & Co. of Birmingham, is shown in Figs. 76 and 77, the former representing the type followed in engines up to nine horse-power, having a single fly-wheel, while the latter shows an engine with two fly-wheels of the kind
turned out in sizes of from twelve to twenty horse-power. The engine follows the Otto cycle in its operation, working ordinarily, with one explosion in every two revolutions, the number of explosions, however, being reduced, as in many other engines, by the action of the governor when the engine is running with a light load. The principal feature of interest in the engine is the application, to the larger sizes, of a starting gear invented by Mr. F. W. Lanchester, and which adds nothing to the bulk or complexity of the engine, at the same time answering its purpose admirably, and making the engine as easy to handle as an ordinary steam engine.
/fig. 78.jpg) Fig. 78— The “Forward” Vertical Gas Engine |
| /fig. 79.jpg) Fig. 79— Lanchester’s Starting Gear |
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A sectional view of this starting gear is given in Fig. 79 The method of operation of the attachment is extremely simple.
Gas is allowed to blow into and through the cylinder until an explosive mixture is created within it, the condition of the mixture being judged by the color of the flame produced by allowing it to blow through an external pilot jet. At the right moment the gas is shut off and the flame strikes back through the blow-off cock, causing an explosion which starts the engine. The back stroke of the piston exhausts the gases, and the next stroke draws in a charge in the usual way; it also sucks in the pilot flame through the blow-off-cock, and fires the charge, the engine thus temporarily working on the Lenoir cycle, explained in the first paper, with an explosion at each revolution. Under these conditions a speed of 120 revolutions per minute is gained in a few seconds. A certain speed, less than 120 revolutions, however, is needed to insure a compressed charge exploded by an incandescent tube. When the requisite speed is attained, the blow-off is closed, and the cam set to exhaust every second revolution; the engine then works compressively and fires its charge from the hot tube. In the diagram
j is the gas nozzle,
f the blow-through cock containing a lightly loaded non-return valve which closes at the explosion,
d the outlet,
c the pilot flame,
h the gas pipe,
e the exhaust valve, and
m the exhaust cam.
It is interesting to note that besides having been applied to the “ Forward " gas" engines for some time past, the apparatus has also been used with success on engines of other makers.
/fig. 72.jpg) Fig. 72— The Trent Horizontal Gas Engine |
| /fig. 75.jpg) Fig. 75— Sectional Views of the Trent Horizontal Gas Engine |
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The Trent gas engine, shown in perspective in Fig. 72, is a single acting engine, receiving one impulse for every revolution, and is made by the
Trent Gas Engine Company, Limited, of Nottingham, England. Sectional views of the cylinder are given in Fig. 75. The cylinder, as shown, is of two different diameters and contains the double-headed piston
B D. When this piston makes its outstroke, gas and air are drawn in through a simple steel valve
E. On the in-stroke of the piston this valve is closed mechanically and the mixture of gas and air is forced through the valve
O into the explosion chamber
M, where it is compressed, driving before it the exhaust gases remaining from the previous explosion which escape through the valve
R, and is then ignited. The resulting explosion drives the piston outward, and the acquired momentum of the fly-wheel performs the next in-stroke. The valves are worked by cams on the crankshaft, and the gas supply is regulated by a hit-and-miss device controlled by a centrifugal governor. Firing of the gas and air charge is effected by a tube igniter. The engine is built in sizes of from one-half to 100 horse-power, and has done some good work in electric lighting.
/fig. 80.jpg) Fig. 80— The Hicks Vertical Gas Engine |
A gas engine, somewhat unusual in appearance, reminding one of a steeple compound steam engine, is made by the
Hicks Gas Engine Works , of Cleveland, O., and is shown in Fig. 80. The two cylinders are set in line, one above the other, and are arranged to work alternately, so that practically there is one effective impulse for every revolution of the crankshaft, the Otto working cycle being followed in each cylinder. Compared with a single cylinder gas engine, therefore, we find in this case, for the same sets of conditions, that the power of the engine is doubled, while the additional weight consists only of the weight of one cylinder and its piston. Another advantage of the two alternately working cylinders is found in the circumstance that the weight of the fly-wheel may be reduced considerably without unfavorably affecting the regular running of the engine. The design and construction of the engine are very simple and call for little explanation. The illustration, in fact, tells almost the whole story.
The amount of the explosive charge admitted to the cylinders is controlled by a governor as in a steam engine, the governor either throttling the supply or opening the valve wide, according to the demand for power. All the valves used are of the lift type. The exhaust valves, shown on the left of the cylinders, are worked by rods and tappets, and these, in turn, are moved by suitable cams carried on a small shaft in back of the engine frame. The cam shaft is driven from the main shaft through intervening gear wheels of such diameters that its speed is reduced one-half. Gasoline as well as gas may be used in operating the engine, the former, however, naturally calling for the addition of a carburetting apparatus of some kind.
/fig. 73.jpg) Fig. 73— The “Rocket” Horizontal Petroleum Engine |
| /fig. 74.jpg) Fig. 74— End View of the Rocket” Horizontal Petroleum Engine |
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A petroleum engine, which by its name as by its builders, recalls the early days of the locomotive, is shown in Figs. 73 and 74. It is called the “Rocket,” and is made by Messrs.
Robert Stephenson & Co. of Newcastle-on-Tyne, England, under the patents of E. Kaselowsky. The engine works on the well-known four stroke cycle. The governing arrangement is such that the supply of explosive vapor is entirely cut off when the speed of the engine runs above the normal, and with the exercise of the governor in this way a lever acts simultaneously to relieve the compression of the waste gases in the cylinder, thus helping to make the speed more regular. Sufficient oil for a day’s work can be stored in a tank fixed above the cylinder, from which it is allowed to flow by gravity into a lower receiver. In this latter there is
a float regulating the supply. The firing of the charge is effected by an ignition tube with a timing valve worked by the lever
I and cam
O. Compression in the cylinder is diminished by keeping the exhaust open when the engine is being started, and one man can, therefore, easily turn the engine over. The oil used is ordinary lamp oil.
From the oil tank
A the oil, as just stated, flows to the lower receiver
B, and from the latter it passes through the regulator and into the top of the vaporizer
E. In this the oil is sprayed by an air current and passes through tubes in the vaporizer, which forms an enlargement of the exhaust pipe. The bottom of the vaporizer is heated by a lamp flame for starting, but after the engine is once in operation the exhaust gases perform the heating. The main air admission pipe is marked
F and is provided with a regulating cock,
F1. Air is also admitted to the vaporizer through the pipe
D, which, similarly, has a regulating valve.
The sprayed oil is converted into vapor in its downward travel through the vaporizer, and, in addition to the air of the spraying current, takes in a further supply through the pipe
D. It then passes into the pipe issuing from the bottom of the vaporizer and joins the main air inlet pipe at a point above the cock
F'. From this point it finds its way into the cylinder of the engine through a valve,
G, controlled by the governor
H, trip
P and notch piece
N. When the engine runs too fast the spindle of the admission valve
G is missed, and another valve, not shown in the illustration, is opened to allow the gas contents of the cylinder to escape. The exhaust valve lever is shown at
J;
W and
W1 are water circulating pipes for the cylinder jacket, and
X is the exhaust pipe. The ignition tube is surrounded by a case,
K, and
L is the oil and air admission pipe for the heating flame. The engine is made in sizes of from one to ten horsepower.
Information Sources
- Cassier's Magazine, V4, Jul 1893 pgs. 185-200