Exhaust system

“ The exhaust gases of the ordinary two-cycle motor pass out of the exhaust port as it is uncovered by the descent of the piston. Those that remain are forced out by the sudden admission of the fresh charge, which is deflected upward and is intended to scavenge the top of the cylinder. But it is claimed that thus employing the fresh mixture as a scavenging agent is162 wasteful of the fuel-permeated charge and does not conduce to efficient running. The system is simple in the extreme, however, and does its work well in small installations in which fuel economy is not of vital importance. ”

“ 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. ”

“ So far as the admission and exhaust valves are concerned, the wearing of the cams, rollers, and lever-pivots is evidenced by a retardation in the opening of these valves and an acceleration in their closing.
The ignition, whatever may be the system employed, is affected by lost motion and is retarded. The engine appreciably loses in power, and its consumption becomes excessive. ”

“ The simplest method, and the one usually employed in exhaust-steam heating, consists in dividing the main exhaust pipe, which receives the exhaust steam from all engines and pumps about the steam plant, into two branches, one leading to the atmosphere, the other being connected to the heating system. On the pipe to the atmosphere is placed a back-pressure valve, the object of which is to automatically maintain a uniform pressure upon the exhaust and upon the heating system, so that the steam may flow into the heating system as fast as it condenses in the radiators. ”

“ Where this system is adopted, a throttle is also used, which enables the operator to regulate the quantity of mixture, and thus alter the power of the explosion. For example, when the maximum power is required, the throttle is open to the fullest, and the sparking advanced to the utmost that the engine will take.
(2) Exhaust-Valve Lifter.—This operates by preventing the exhaust valve from closing after the exhaust gases have escaped. When the exhaust valve is held fully up, no explosive charge is taken into the cylinder. ”

“ But an excess amount of oil fed to the cylinders120 will result in so much less harm than will an insufficient supply, that we are treading on rather dangerous ground when we warn the amateur to cut down his lubricant to the point where there will be no smoke. As there are no ordinances that absolutely prohibit the slightest appearance of smoke at the exhaust, and as a faint blue trail is an excellent indication that the motor is receiving sufficient lubrication in the cylinders, it forms a satisfactory test by which the novice can determine the condition of the oiling system. ”

“ In this [43] system the exhaust and the admission valves are operated by separate eccentrics on opposite sides of the engine, and all the valves have the amount and rapidity of their opening and closing movements increased by the intervention of wiper cams, those for the admission valves being very long and giving a correspondingly greater enlargement of opening. The valves were double poppet valves, moving nearly in equilibrium in directions vertical to their seats. This cut-off was found to be capable of improvement in one important respect. ”

“ If when the ignition system is in good order, the carburettor properly adjusted and the compression cocks closed, there is a lack of power, it may be due to carbon or some foreign substance on the seats of the exhaust or inlet valves. Even so small a thing as a flake of metal or of emery left from a former grinding may lodge on the valve seat or under the valve stem and cause loss of power, or a crack in the head of the piston or cylinder or a broken or worn piston ring may give the same result. ”

“ Again we make large exhaust valves and provide a free escape through the silencer for the exhaust gases, so that when we have snatched our useful one-third of the heat supply we may throw the remainder away into the atmosphere as rapidly as possible.—this part is of no use to us, we cannot turn it into work, then why let it stay here and heat our cylinder walls and piston still further? ”

“ Exhaust.—For the exhaust, cast-iron or drawn pipes as short as possible should be used. Not only the power of the engine, but also its economic consumption, can be markedly affected by the employment of long and bent pipes. Resistance to the exhaust of the products of combustion not only causes an injurious counter-pressure, but also prevents the clearing of the cylinder of burnt gases, which contaminate the aspired mixture and rob it of much of its explosiveness. ”

“ It is easy to tell by the sound of the exhaust if the ports are rightly proportioned, and whether running at high or low speed, the engine should give a clear and distinct exhaust at every stroke of the piston. ”

“ Some engineers never touch their flues with a cleaner, but when they choke the exhaust sufficiently to create such a draught as to clean the flues, they are working the engine at a great disadvantage, besides being much more liable to pull the fire out at the top of smokestack. If it were not necessary to create draught by reducing your exhaust nozzle, your engine would run much nicer and be much more powerful if your nozzle was not reduced at all. ”

“ The exhaust pipe from the engine which conducts off the exhaust gases after they have done their work in the cylinder is connected to a peculiarly constructed chamber, called a Silencer, attached to the frame of the car. ”

“ If the secondary circuit is proven to be in good condition, attention should be paid to the carburetor, for a poor mixture, or water in the gasoline, will cause the engine to miss. A badly fitting exhaust valve will permit the burned gases to be drawn back into the cylinder, the fresh charge thus being weakened, and as the valve will shift around on its seat, this may happen irregularly. ”

“ The motor on the outstroke crosses V-shaped parts about from one-sixth to one-seventh from the out end, the displacer charge now passing into the motor cylinder, displacing the exhaust gases by these ports and filling the cylinder and the space at the end of it with the explosive mixture. The introduction of some air in advance of the charge serves the double purpose of cooling down the exhaust gases and preventing direct contact of the inflammable mixture with flame which may linger in the cylinder from the previous stroke. ”

“ The Exhaust Nozzle, as generally constructed, is an elbow attached to the end of the exhaust pipe in the smoke box or smoke stack of the boiler, the end of which points upward, with the opening reduced so that the exhaust steam will be forced up the stack, and thereby produce the same effect as a blower. ”

“ But in the two-cycle Diesel type of engine, the high pressure of the pure air is used for scavenging, and as this is admitted with so large an initial force, the exhaust port may remain uncovered for a longer period than would be the case were the air to rely entirely on the up-stroke of the piston for its compression. ”

“ But a difficulty arises with the internal combustion engine if the supply of mixture is similarly throttled, because a loss of quantity means loss of compression and bad ignition. Many oil engines are therefore governed by apparatus which, when the speed exceeds a certain limit, cuts off the supply altogether, either by throwing the oil-pump temporarily out of action, or by lifting the exhaust valve so that the movement of the piston causes no suction—the "hit-and-miss" method, as it is called. ”

“ Exhaust Piping
From each atmospheric exhaust valve, which is direct-connected to the condensing chamber at each low-pressure cylinder, is run downward a 30-inch riveted-steel exhaust pipe. At a point just under the engine-room floor the exhaust pipe is carried horizontally around the engine foundations, the two from each pair of engines uniting in a 40-inch riser to the roof. This riser is between the pair of engines and back of the high-pressure cylinder, thus passing through the so-called pipe area, where it also receives exhaust steam from the pump auxiliaries. ”

“ The petrol-engine, as now used, emits the products of combustion at a high pressure. If unchecked, they expand violently, and cause a partial vacuum in the exhaust pipe, into which the air rushes back with such violence as to cause a loud noise. ”

“ The waste of energy is clearly evident in the exhaust pipe of an internal combustion engine. The gases after doing their work on the piston rush out [165] with such velocity as to produce a sharp explosive sound. The noise of the exhaust is highly objectionable in automobiles and must be overcome, but instead of utilizing the boisterous energy of the escaping gases and getting a little more useful work out of them, means are provided for hushing their noise. ”

“ A. Nothing is so annoying as to drive a motor which is continually missing fire or has a 'fit of the slows.' The fault is usually with the ignition—the platinum tubes are not hot enough, or are dirty inside or outside, or the passages leading to them are clogged. When exhaust pressure is adopted for feeding the burners with petrol, the pressure-valve sometimes refuses to act and lets the pressure out. ”

“ When the engine is heavily throttled and runs under light load at low speed, the suction on the spray nozzle is small, and consequently the fuel is not finely sprayed. Relatively more heat is needed to ensure the vaporization of the larger globules of fuel, but under these conditions of operation the exhaust does not supply a great amount of heat. A device designed to overcome this difficulty was developed by the Packard Motor Car Co., and is known as the Fuelizer. ”

“ The deterioration of piston-packing, and the rounding of valve-seats, which produce an asthmatic exhaust, may be followed in their downward course if the engineer gets into the habit of listening to the exhaust, and marking its changes. It is very important that he should do so. The man whose ear from long practice has become sensitive to a false tone of the exhaust, needs not to make experiments, by applying steam to the engine while it stands in various positions, in order to find out where a blow comes from,—whether it is in the pistons or in the valves. ”

“ An over-rich mixture will cause the engine speed to fluctuate through more or less regular periods from high to low speeds; the engine will seem to be mis-firing and there will be noticeable a strong odor, as well as, usually, a heavy black smoke from the exhaust.
LEAN MIXTURE
The best adjustment is obtained with the fuel and air valves set as described. It must be remembered that too lean a mixture as well as an over rich mixture causes over-heating and loss of power and is not as economical as an adjustment which provides just the proper proportion of gasoline and air. ”

“ To serve this purpose vehicles must be designed with higher than normal axle ratios, thus requiring greater power from the engine and producing higher exhaust gas temperatures in order to attain any given speed. ”

“ In the [Pg 21] engine house four of Beal's exhausters occupy prominent positions, they are used to exhaust or suck the gas from the retorts and afterwards force it through the vessels for purification; two of these driven by engines of 20 horse power work 150,000 cubic feet per hour each. Two driven by engines of 12 horse power work 100,000 per hour each. Attached to the inlet of each exhauster is one of Wright's exhauster governors, it is made on the principle of pressure or suction elevating or depressing a light cylinder working in a water-lute of sufficient depth. ”

“ The smaller the nozzle, the greater the draft a given amount of steam will create; but the more back pressure there will be, due to the inability of the exhaust steam to get out easily. So the exhaust nozzle should be as large as circumstances will permit. It is a favorite trick with engineers testing the pulling power of their engines to remove the exhaust nozzle entirely for a few minutes when the fire is up. The back pressure saved will at once show in the pulling power of the engine, and every one will be surprised. ”

“ Misfiring, if allowed to continue, will in time injure the engine and the entire mechanism. If you would be known as a good driver you will be satisfied only with a soft, steady purr from the exhaust. If anything goes wrong, stop and fix it if possible—don't wait until you get home. ”

“ It is very important that the pressure of the gases above the piston when it commences to move upwards on the exhaust stroke should be as low as possible, and this can only be secured by opening the exhaust valve towards the end of the explosion or power stroke, thus allowing the bulk of the gases to escape and leaving the piston with little resistance to encounter on its upward exhaust stroke. ”

“ Even the best of mufflers will use up nearly 5 per cent of the engine power. The energy that escapes at the exhaust is not the only loss. All the heat that radiates from the engine represents just so much wasted energy. In our water and air-cooled systems we deliberately abstract heat from the burning gases and throw it away. If we had materials that would stand the intense heat of burning gases and enable us to conserve all the heat developed in the cylinder we could use our fuels much more economically. ”