Part 1

[Transcriber's Note:

Italics denoted by underscores.

Bold text denoted by plus signs.]

Scientific American Supplement, Vol. XVI., No. 404. } Scientific American, established 1845. }

NEW YORK, SEPTEMBER 29, 1883.

{ Scientific American Supplement, $5 a year. { Scientific American and Supplement, $7 a year.

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BIETRIX'S VERTICAL AND HORIZONTAL COMPOUND ENGINE.

Compound engines are tending to come more and more into use, inasmuch as they present many advantages over other kinds, especially as regards the saving they effect in fuel, and their great regularity, due to the adjusting of the cranks at right angles.

It is not surprising, then, to see our large manufacturers, who desire to maintain a reputation, seeking to create new types based upon this principle. But, in multiplying the parts, as is done in these motors, the engine is rendered more complicated, and the cost of installation is increased. Hence the difficulty of placing these motors, notwithstanding the saving in fuel that is gained by employing them.

Messrs. Bietrix & Co., of St. Etienne, however, have devised a type in which these two inconveniences seem to have been in a great measure overcome, and which we illustrate in the annexed engraving.

_Description of the Engine._--The engine as a whole is represented in longitudinal elevation in Fig. 1, in plan in Fig. 2, and in side view in Fig. 3. Fig. 4 shows the condenser in transverse section.

The motor consists of a small vertical cylinder, A, and of a large horizontal one, C, both projecting over a strong hollow frame, B, which connects them and carries the guides, _g g'_, and the pillow block, P, of the driving shaft, _p_. The condenser, D, is in a line with the large cylinder, and the piston, D², of its pump is mounted upon the prolongation, _d'_, of the piston rod, _a_, of the cylinder, C. The expansion gear is controlled by the regulator, and the admission may vary from 1/19 to 1/85. Steam is admitted into the small cylinder through the pipe, _s_, and its entrance may be regulated at will by acting upon the hand wheel, _s'_, which controls the maneuvering rod, _s²_. After expanding, the steam, in escaping from the smaller cylinder, passes through the pipe, _r_, into the feed-water heater, R, and then acts in the larger cylinder, _c_, in order to pass afterward to the condenser, D, through the pipe, _d_.

The frame, B, is in two parts, the vertical part being adjusted by keys upon the horizontal one, and strong bolts concurring with such a coupling to make the whole strong and solid. This frame carries plane slide bars, _g g'_, with beveled counter guides.

The pistons are of the Swedish type, of hollow iron, with steel rods. The segments are of cast iron. The horizontal connecting rod, M', is connected directly with the crank pin, _m_, but the vertical one is fixed to the head of the former, as may be seen in Figs. 3, 8, and 9.

The bearing of the horizontal connecting rod is in three parts, each having an anti-frictional bushing, and their play being regulated by bolts, _m²_. Friction being slight in the bearing of the vertical rod, M, inasmuch as the latter's axis has but a short travel at each revolution of the driving shaft, it is not provided with an anti-frictional bushing.

_The Small Cylinder_ (Figs. 5 and 6).--The small cylinder is shown in detail in Figs. 5 and 6, the valve box cover being removed in the latter. The diameter of this cylinder is 380 millimeters, the stroke of the piston is 650 millimeters, and the thickness of the sides is 25 millimeters. It is provided with a steam jacket; and the two ports are 45 millimeters in width by 200 in length. The exhaust is effected through an orifice 84 millimeters in diameter.

The distribution is a variable one, according to the Meyer system, the expansion being caused to vary automatically in the small cylinder, by means of a regulator, so as to proportion the motive to the resistant power.

The distributing slide valve, _t_, contains two steam inlets, whose orifices facing the cylinder are formed by two horizontal, parallel rectangles, while the inlets debouch toward the opposite surface (in contact, consequently, with the expansion slide valve, _t'_), according to two parallelograms, whose larger sides are oblique, and form between them a sharp angle, as may be seen in Fig. 6. These inlet conduits are therefore out of true. The slide-valve, _t_, is moved by an eccentric, E.

The expansion slide-valve, _t'_, has the form of a trapezium, whose two like sides are parallel with the inclined openings in the slide-valve, _t_. It is held by a piece, _q_, which carries it along in its backward and forward motion, but does not prevent it from being moved in a horizontal direction under the action of the regulator. This piece, _q_, is keyed upon a rod, _q'_, which is itself jointed at its lower extremity with the rod, _e'_, of a second eccentric, E', which causes its vertical motion.

The backs of the valve, _t_, and the piece, _q_, are provided with grooves, which are designed for giving passage to the steam, the pressure of which on these surfaces partially balances that that it exerts in an opposite direction.

_Automatic Regulation_ (Figs 5 and 6).--The upper part of the rod, _e'_, carries a cam, _f_, that plays freely between two connecting rods, _f¹_, and the travel of which is limited by two rollers, _f²_ and _f³_, situated between the rods, _f_, which latter are themselves suspended from a rod, F. The latter slides in a support, F², which serves likewise as a guide to the rods, _q'_ and _t²_, of the slide-valves, and which is fixed upon a projection cast in a piece with the frame, B, and is suspended from the short arm of a bent lever, F', whose longer arm carries a roller that runs in a vertical groove, _t³_, in the back of the expansion slide-valve. The lower extremity of the connecting rods, _f'_, is connected with the sleeve of the regulator, Q, by a lever, _f^{4}_, and a bent lever, Q'. This latter revolves on an axis passing through its elbow and mounted at the extremity of a projection that is cast in a piece with the support of the regulator. This bent lever is prolonged beyond the sleeve, and carries suspended from its extremity a small piston-rod that plays in a dash pot, Q³, and limits the too abrupt motions of the apparatus. The regulator is driven by a belt and through the intermedium of the bevel pinions, _u_.

It is easy now to understand the purpose and the _modus operandi_ of the mechanism that permits the regulator to act upon the expansion gear. When running normally the connecting-rods, _f'_, occupy a vertical position, and the rollers, _f²_ and _f³_, are placed exactly at the two extremities of the travel of the cam, _f_.

When the velocity exceeds the normal, the sleeve of the regulator rises and the lever, Q', tips to the right and forces the rods, _f'_, to oscillate in the same direction around their upper joint. After that, the lower roller, _f²_, being situated on the line of travel of the convex part of the cam, will be carried along by the latter and cause an oscillation to the right of the bent lever, F. The piece, _t'_, will then be pushed back in such a way as to partially close the inlet orifices of the slide-valve, _t_, and, as the steam will thereupon enter into less quantity, the engine will quickly resume its normal velocity. If the velocity becomes less that the normal the action will be just the opposite of that just described.

_The Large Cylinder_ (Figs. 1 and 2).--The two eccentrics, E and E', which control the distributing gear of the small cylinder, A, actuate at the same time that of the large one, C, through two rods, _e²_ and _e³_; such distribution is also effected by means of a sliding-plate valve. The two steam ports are 45 millimeters and the exhaust port 84 millimeters in diameter.

The large cylinder is 650 millimeters in diameter, and 930 in length. The stroke of the piston is 650 millimeters.

_The Feed-Water Heater_ (Figs. 1 and 2).--The exhaust from the small cylinder enters the heater through a pipe, _r_, 140 millimeters in diameter. This feed-water heater consists of a large cast iron cylinder, 400 millimeters in internal diameter, and 1.15 meters in length, connected with the pipe, _r_, on the one hand, and with the cylinder, C, on the other, by means of two couplings, R' and R². In its interior are arranged 60 copper tubes, of 29 millimeters internal, and 31½ millimeters external diameter. These tubes are fixed at their extremities into two circular supports that are riveted to the interior of the cylinder. The exhaust from the small cylinder passes into these tubes, around which circulates steam coming directly from the boiler through the tube, _r'_, and escapes toward the bottom, with the condensed water, through the tube, _r²_. The heater is surrounded with a 2 mm. plate iron jacket.

A communication, _r³_, with a valve-cock, R³, permits of the introduction, into the large cylinder, of the steam from the heater. The exhaust steam from the large cylinder goes directly to the condenser, but there is likewise provided a pipe through which it may make its exit into the open air, in case, for example, the condenser needs repairing or there is a failure of water.

_The Condenser_ (Figs. 1, 2, and 4).--The condenser is represented, half in section and half in external view and in elevation in Fig. 1, and in plan in Fig. 2; Fig. 4 is a transverse view of it. It consists of a large cast iron chest, D, bolted by means of its flanged base to a masonry support. This chest is cast in a piece with a pump chamber, D', in which works a piston mounted on the prolongation, _d'_, of the piston-rod of the cylinder, C. The diameter of this piston is 210 millimeters, and its stroke is 650. The condensing jet, whose flow is regulated by the cock, _d²_, is brought into contact with the steam by a rose, _d³_, which divides it into small drops.

The pump is a double acting one. Its valves are of rubber, and the passage-way allowed the water is, in each of them, in section, one-half that of the piston. The rod, _d'_, slides in a stuffing-box, with metallic lining, which is shown in Fig. 10.

_Lubrication._--The lubrication of the crank-pin presents some peculiarities. Two stationary cups, _z_, are placed at the upper part of the guides, as seen in Fig. 3. These distribute their oil, drop by drop, into two reservoirs, _z'_, fixed to the upper axis of the vertical connecting-rod. Two small brass tubes, resting against the connecting-rod, lead the lubricator into cavities in the head of the horizontal connecting-rod, M'. One of these cavities corresponds to the crank-pin and the other to the lower axis of the vertical connecting-rod. The lubrication of the cylinders is effected automatically by means of a Consolin apparatus (Fig. 1), based upon the condensation of the steam and upon the difference between the density of the oil and condensed water.

_Diagram of Distribution_ (Fig. 11).--We shall first examine that which relates to the small cylinder. The eccentric of the distributing slide-valves is adjusted to 123° with respect to the crank, and that of the expansion slide-valves to 170°, that is to say, so that the angles of advance are respectively 55 and 57 millimeters for these two cylinders.

Let us trace two axes, _o x_ and _o y_, at right angles, and a semi-circumference of any radius whatever, _o m_, which shall represent the travel of the crank-pin. Let us draw the line, _o_ A, making with _o y_ an angle of advance of 33°, and the length of which is equal to the eccentricity of the distributing slide-valve, say 55 millimeters, and let us describe a circumference on this length taken as a diameter. Let us trace in the same way the line, _o_ B, making with _o y_ an angle of advance of 80°, and let us describe upon this line a circumference equal in diameter to the eccentricity of the distributing slide-valve, say 57 millimeters.

Finally, let us trace points, _o_ and _c_, as centers of arcs of circles having respectively for radii the distance between the centers of the circumferences just mentioned and the eccentricity of the expansion slide-valve. These two arcs will intersect each other at a point, _c²_, which is thus the fourth angle of a parallelogram whose other angles are the points, _c_, _c'_, and _o_. From the point, _c²_, as a center let us describe a circle passing through _o_.

In short, we obtain three circles that are such that the vector radii, starting from the point, _o_, and limited at the said circles, represent, for the first, the deviations to the right of the distributing slide-valve beginning at the middle of its travel, the second the deviations of the expansion slide-valve, and the third the relative deviations of the distributing with respect to the expansion slide-valve.

Let us complete the diagram by describing, from the point, _o_, as a center, circumferences having for respective radii the length, _o e_, of the external overlap of the distributing slide-valve, and the lengths, _o i_ and _o i'_, corresponding to the minimum and maximum of the interval between one of the edges of the expansion slide-valve and the external edge of the corresponding inlet orifice of the distributing slide-valve, when the axes of these two valves coincide.

These radii have the values: _o e_ = 25 mm.; _o i_ = 8 mm.; and _o i'_ = 42 mm. Let us now prolong the radii, _o d_, _o d'_, _o d²_, and _o f_, until they meet the crank circle, and let us then project these points of intersection upon a line, M M', parallel with _o x_, and we shall have all the elements that are necessary to study the different phases of the distribution in the small cylinder.

Let us complete this diagram in such a way as to study also the distribution in the large cylinder:

In this cylinder the distribution cannot be modified, that is to say, the active length of the expansion slide-valve is invariable. The interval comprised between one of the edges of this valve and the internal edge of the corresponding inlet orifice is equal, then, to 28 mm. when the axes of the two valves coincide.

Let us describe, from _o_ as a center, a circle having this length for a radius, and let us again project the intersections of the radius, _o k_, with the crank circle upon a parallel at M M'. The external overlap, being the same as in the small cylinder, say 25 millimeters, the circle, _o e_, already traced for the distribution in the small cylinder, will serve for the distribution in the large one. Let us join its intersection with the circle, _c_, and the center, _o_, and let us trace also the circle of the internal overlap and the radii, _o g_, and _o h_, and we shall have all the elements of the distribution.

_Advantages of the Engine._--The engine that we have just described presents all the advantages possessed by horizontal motors and double cylinder vertical ones without their many inconveniences. It, in fact, takes up less space than the former, while it possesses more stability than the latter. Its operation is as regular as that of an engine having two cranks adjusted at right angles.

The cranked shaft, a costly member of an engine, and one whose duration is always uncertain, despite the care that has been taken in making it, is here done away with.

The kind of distribution adopted is well adapted to the great variations in expansion, and, notwithstanding the two superposed slide-valves in each cylinder, two eccentrics suffice to operate them.

The regulator, thanks to the mechanism that connects it with the expansion plate, is freed from all exaggerated resistance, the eccentric rod alone supporting the entire stress. The regulator is consequently very sensitive, and is capable of giving a coefficient of regularity which is more than sufficient in most cases. The condenser, with its wide apertures, is capable of operating with great speed without shock.

We may add to this that the engine is simple and compact; the number of parts is few, and all can be easily got at; the bearings are long, and the wear is consequently reduced; the dimensions of the steam ports are wide and permit of great velocities being reached without counter-pressures; the mode of lubrication has been well studied, and requires but little attention on the part of the engine man; and, finally, the cylinder jackets and the superheating of the steam after it has begun to expand make this an economical motor aside from all the advantages that we have enumerated.--_Publication Industrielle._

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IMPROVED GAS ENGINE.

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._

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METERS FOR POWER AND ELECTRICITY.[1]

By MR. C. VERNON BOYS.

The subject of this evening's discourse--"Meters for Power and Electricity"--is unfortunately, from a lecturer's point of view, one of extreme difficulty, for it is impossible to fully describe any single instrument of the class without diving into technical and mathematical niceties which this audience might well consider more scientific than entertaining. If, then, in my endeavor to explain these instruments and the purposes which they are intended to fulfill, in language as simple and untechnical as possible, I am not as successful as you have a right to expect, I must ask you to lay some of the blame on my subject and not all on myself.

I shall at once explain what I mean by the term "meter," and I shall take the flow of water in a trough as an illustration of my meaning. If we hang in a trough a weighted board, then, when the water flows past it, the board will be pushed back; when the current of water is strong, the board will be pushed back a long way; when the current is less, it will not be pushed so far; when the water runs the other way, the board will be pushed the other way. So by observing the position of the board, we can tell how strong the current of water is at any time. Now suppose we wish to know, not how strong the current of water is at this time or at that, but how much water altogether has passed through the trough during any time, as, for instance, one hour. Then if we have no better instrument than the weighted board, it will be necessary to observe its position continuously to keep an exact record of the corresponding rates at which the water is passing every minute, or better every second, and to add up all the values obtained. This would, of course, be a very troublesome process.