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Development of High-Efficiency Rotary Engines

2012-05-10
Combustion engines are typically only 20-30% efficient at part-load operating conditions, resulting in poor fuel economy on average. To address this, LiquidPiston has developed an improved thermodynamics cycle, called the High-Efficiency Hybrid Cycle (HEHC), which optimizes each process (stroke) of the engine operation, with the aim of maximizing fuel efficiency. The cycle consists of: 1) a high compression ratio; 2) constant-volume combustion, and 3) over-expansion. At a modest compression ratio of 18:1, this cycle offers an ideal thermodynamic efficiency of 74%. To embody the HEHC cycle, LiquidPiston has developed two very different rotary engine architectures ? called the ?M? and ?X? engines. These rotary engine architectures offer flexibility in executing the thermodynamics cycle, and also result in a very compact package. In this talk, I will present recent results in the development of the LiquidPiston engines. The company is currently testing 20 and 40 HP versions of the ?M?
Technical Paper

Data on Machinability and Wear of Cast Iron

1928-01-01
280022
THE hardness or chemical composition of an iron is, by itself, no indication of the wearing property and machinability of the iron. Irons containing a large amount of free ferrite have been found to wear rapidly, whereas others having considerable pearlite or sorbite in their structure show good wearing properties. The presence in cylinder-blocks of excess-carbide spots or of phosphides of high phosphorus-content is deleterious, because such spots wear in relief and the material ultimately breaks out, acting as an abrasive that scores the surfaces. Causes of wear in cylinder-blocks are discussed, and nickel, or nickel and chromium, intelligently added to the iron is suggested as a means of obtaining the correct microstructure for a combination of good wearing properties and machinability.
Technical Paper

Pistons and Oil-Trapping Rings for Maintaining an Oil Seal

1928-01-01
280054
PROVISION is made, in the piston and rings described by the author, for an adequate flow of heat from all parts of the piston-head to the cylinder-wall by means of adequate cross-section of aluminum alloy in the head and a tongue-and-groove type of piston-ring structure which provides a greater amount of surface than is usual for heat transfer. A labyrinth oil-seal is provided which aids heat transference and prevents leakage past the piston-rings, and the heat transfer is said to be such that the heat does not destroy the oil seal between the piston and the ring. Charts are included that show the effects in reduced temperatures, oil consumption and gas leakage with the construction described. Attention is given also to a skirt construction most suitable to use with the piston-head and rings described.
Technical Paper

Motorcoach-Fleet Maintenance

1929-01-01
290089
METHODS of operation and maintenance pertaining to a small fleet of motorcoaches are described by the author, who outlines the development of this transportation service from July, 1922, when operation was begun. An inspection system was inaugurated in which due consideration was given to the type of equipment, the nature of the service performed, average loads, the speed maintained, and the nature of the roadway over which the vehicles traveled. In this manner preventive-maintenance methods were put into effect, the results being a steady increase in efficiency. In the author's opinion, itemized costs must be kept for each unit of the fleet so that the data will be available for the month, the year to date, the last full year and, if possible, for the last several years. The figures should be embodied in a statement so that comparison can be made between similar items for each unit operated. Units differing in make or type should be grouped and averages shown for each group.
Technical Paper

Powerplant Economics - Piston Displacement versus Horsepower per Dollar

1930-01-01
300004
AN ENDEAVOR is made herein by the author to prove by argument and charts based on data that the greatest result per dollar of car cost is obtained by the greatest piston displacement obtainable per dollar expended rather than by the greatest horsepower per dollar. Maximum result per dollar is a major principle of economics, but horsepower per dollar and piston displacement per dollar are controversial economic fundamentals. The latter is declared to be the accepted principle in the low-price car field, and the author asserts that it should be accepted in the high-price field. Price class controls the cost of the powerplant, and ingenuity of the engineering and manufacturing departments will control piston displacement. The trends in the different price classes as regards car weight, piston displacement, ratio of weight to piston displacement, and potential and actual performance in the items of economy, durability, acceleration and speed, are shown by charts and discussed.
Technical Paper

New Features in Shock Absorbers With Inertia Control

1933-01-01
330012
MANY improvements in shock-absorbing apparatus have been made during the last two years, the most notable being in dash control and devices for temperature compensation. Two types of hydraulic absorbers, the piston and the vane types, have been in use during this period. Both constructions function around the hydraulic principle of forcing a fluid through an orifice of some type. So-called automatic shock-absorbers were much heard of during 1932. The various kinds of control used are examined herewith to determine whether or not some particular type of velocity-load diagram is most desirable. After describing the inertia-controlled shock-absorber, Mr. Kindl enlarges upon its various features. The equipment used for testing purposes is illustrated. In conclusion, he states that future experimental work undoubtedly will increase the perfection of this type of shock absorber.
Technical Paper

Commercial Application of Diesel Engines in Heavy-Duty Motorcoaches and Trucks

1932-01-01
320070
COMPARATIVE tests were made, both on the block and in the same motorcoach chassis, of a 525-cu.-in. gasoline and a 495-cu.-in. Diesel engine. The block tests are reported fully in charts, including curves for torque and power against piston displacement and engine weight. Corrected curves are given on the basis of equal piston displacement and for the Diesel engine throttled enough so that it would not smoke. Road tests included fuel consumption, acceleration, hill climbing and top speed, which are also recorded in charts. Other sections of the paper deal with costs of manufacture and maintenance and present and prospective conditions as to supply and cost of Diesel fuel. Stress is laid on the facts that automotive Diesel engines require a much higher grade of fuel than do the larger and slower Diesel units and that more gasoline than fuel oil can be obtained from a given amount of crude.
Technical Paper

Scavenging by Large Valve-Overlap Increases Power and Economy

1933-01-01
330044
SINCE the power output of an engine is practically proportional to the weight of the charge, the object has been to increase the weight of the charge burned. The weight of charge inducted by an aircraft engine and the supercharger power required to supply this charge depend among other factors upon how completely the engine is scavenged. In the conventional four-stroke-cycle engine only the exhaust gases in the displacement volume are forced out of the cylinder by the piston on the exhaust stroke; consequently, the engine cannot induct a charge of greater volume than that of the displacement volume, whereas if the clearance volume could be scavenged also, the engine could induct a charge equal to the displacement plus the clearance volume.
Technical Paper

The Automobile-Type Engine for Marine Service

1931-01-01
310049
THE SUCCESS attained by marine engines as built by the manufacturer of motor-vehicle engines clearly proves that such engines are entirely suitable for marine service provided rugged automobile, truck or motorcoach engines are used as a basis. However, this involves the necessity of applying the principles of marine design and practices. The author describes and illustrates such an engine developed and built by a leading motor-car-engine manufacturing company. This makes possible the use of cylinder blocks, crankshafts, pistons, valves, tappets and many other minor parts used in the motor-vehicle engines. The outstanding advantage is the use of modern methods of production, equipment, quantity purchasing and the financial resources of the automobile industry.
Technical Paper

Compression-Ignition Characteristics of Injection-Engine Fuels

1932-01-01
320040
NEEDING to study the ignition characteristics of Diesel-engine fuels, the authors developed an idea that was presented at a meeting of the Research Committee of the Society last June. The idea was that engine tests must be the basis of evaluation. A C. F. R. engine was converted into a variable-compression Diesel engine by substituting a new piston and a fuel-injection system for the original piston and ignition system. Test methods that have been developed are reported, together with some results that show the practicability of the procedure and its substantial agreement with data secured in other ways. It is suggested that, as some of the most desirable qualities of gasoline are undesirable for Diesel fuel, and vice versa, fuels may be divided in the future on that basis, and Diesel and gasoline engines may approach each other in compression ratio.
Technical Paper

Development of the Franklin Direct Air-Cooled Engine

1931-01-01
310004
FEATURES of the design of the various cylinders built by the Franklin organization in its development program leading up to the present design are discussed in this paper. The relation of waste heat to cooling-fin areas and cooling-blast velocities is shown and discussed for cylinders up to 3½-in. bore. Characteristics of the cooling system, including fan, fan housing and air housings, are discussed at length, and the authors contend that no more power, if as much, will be absorbed in the cooling system as in that of the indirect air-cooled engine. Results of tests showing the ability of the engine to cool under the severest conditions of load and temperature are given. Since the quietness of any engine is dependent upon constant valve-clearances, the authors describe in detail the method followed in the Franklin design to maintain at less than 0.003 in. any variation in clearance. A careful analysis is made for each part in the valve-gear mechanism that is affected by expansion.
Technical Paper

Combustion and Design Problems of Light High-Speed Diesel Engines

1931-01-01
310011
MORE attention must be paid to light-weight design and to flexible combustion control if the Diesel engine is to become a serious competitor of the gasoline engine. The relative merits of existing types of combustion-chamber and injection systems used in present commercial four-cycle engines are discussed, and it is shown that the single-turbulence-chamber type offers the most promising means to high mean effective pressures at low fuel consumption. Stock high-pressure fuel-pumps and injection-valves, produced in volume by specialists, will have a great influence on the production of high-speed Diesel engines. The interrelation of combustion and injection processes in controlled-turbulence combustion-chambers is explained, and design details and test results are given of the practical application of single-chamber principles and of a stock injection system to flexible combustion control in a recently developed high-speed four-cycle engine.
Technical Paper

Recent Developments in Poppet Valves

1931-01-01
310007
AFTER stating that increased speed, mean effective pressure and piston displacement of engines have made valve conditions more difficult during the last few years, the author recalls the path which development has followed by a brief list of materials and methods of cooling. Where the stem joins the head is the hottest part of the valve. A shield for this point is shown, also a shroud to protect the end of the valve-stem guide. Cooling the valve increases its life. Salt and sodium cooling are compared, and methods of sealing the coolant in place are described. The construction and behavior of copper-cooled valves are illustrated and recounted, and a one-piece hollow-head valve is described. Reasons for valve-seat inserts are given.
Technical Paper

Oil Consumption as Affected by Engine Characteristics

1931-01-01
310009
THE PROBLEM of oil consumption must be solved before the problem of winter starting and winter lubrication can be solved, asserts the author, since winter starting and winter lubrication require light oils, and light oils give poor results as regards oil consumption. Eight factors affecting oil consumption are listed in the order of their importance. Some of the reasons why they affect oil consumption are given and suggestions as to methods of overcoming the difficulties are made. The author concludes that oils of low viscosity, which are required for winter starting, can be made to give satisfactory oil consumption at all engine speeds by necessary changes which probably will involve other mechanical features besides those usually considered in connection with design of the lubrication system. They may include improved bearings, oil-coolers, air-cleaners, oil-filters, better control of cylinder and piston cooling, and other factors.
Technical Paper

Air-Cooled Cylinder-Head Design

1931-01-01
310038
THE TWO MAJOR REQUIREMENTS for good cooling of an air-cooled cylinder-head are (a) adequate conductivity from the zones of maximum heat-flow, that is, the spark-plug bosses and the exhaust-valve seats, elbows and guides, to a sufficient area of finning, and (b) the maintenance of a high-velocity air-flow over the entire length and depth of all fins. Solution of the problem of (b) depends upon many items in the engine installation outside of the cylinder-head. A limit to possible power output of the cylinder is set by detonation, which, with a given fuel, depends upon the cylinder-head temperatures. As these temperatures are the basic index of operating conditions of air-cooled engines, the author states that a head thermocouple instrument should be standard equipment on every airplane, and pilots should be trained to respect head temperatures as much as they now respect oil pressures and temperatures.
Technical Paper

MECHANICAL FRICTION AS AFFECTED BY THE LUBRICANT

1924-01-01
240009
Very few data seem to be available on the frictional losses in automobile engines caused by the failure of the oil to perform its function as a lubricant. The researches of the Lubrication Inquiry Committee in England indicate that the friction of a flooded bearing is proportional to the speed of the engine, the area of the bearing and the viscosity of the lubricant and is independent of the pressure and of the materials of which the opposing surfaces are composed. The principal sources of friction in an engine are the crankshaft, the camshaft and the connecting-rod bearings, which rotate; the pistons and the valves, which slide; and the auxiliaries, such as the generator, the pump and the distributor.
Technical Paper

PRACTICAL BALANCING OF A V-TYPE ENGINE CRANKSHAFT1

1924-01-01
240012
Supplementing a paper by another author that treats of the theoretical balancing of this engine, Mr. Anderson presents the practical methods that have been devised to accomplish the results desired. Since this crankshaft is not in running or in dynamic balance without its piston and its connecting-rod assemblies, it is necessary to apply equivalent weights on each of the crankpins when balancing it on a dynamic balancing-machine, and details are given of how these weights are determined. The selection of parts to obtain equal weights is also necessary; a description is given of how this is made. A combination static and dynamic balancing-machine that can be set for either operation is used for balancing the crankshaft. Details of its operation are presented. Service conditions to secure parts replacements within the weight limits specified are outlined, and flywheel, universal-joint assembly and other unit balancing is discussed. The method of testing the completed work is stated.
Technical Paper

PRACTICAL BALANCING OF ENGINE COMPONENTS

1924-01-01
240010
References to previous theoretical discussions of engine balance are cited prior to consideration of vibrations in four, six or eight-cylinder engines that may either be felt or heard in the car and result from lack of balance. Dynamic arrangement of the engine, unequal forces set up by the unequal weights of moving parts and vibration arising from elasticity or yielding of the parts themselves are the major causes of unbalance, of which the unequal weights of the parts are within the manufacturer's control. Unbalance of the conventional four-cylinder engine is of considerable magnitude, due to the angularity of the connecting-rod that produces unequal piston motion at the upper and lower parts of the stroke, the unbalanced force reversing itself twice per revolution and acting in a vertical direction. The actual magnitude of this force varies directly with the weight of the reciprocating masses and as the square of the speed.
Technical Paper

INTAKE-MANIFOLD DISTRIBUTION

1924-01-01
240005
Definite knowledge as to the behavior of gases and liquids in the manifold of an internal-combustion engine being lacking, an attempt is made to answer the questions: (a) How bad is the distribution, (b) how do the different types of manifold compare, (c) why is the liquid distribution in some manifolds poor and (d) how shall we proceed to correct the trouble? The solution of the problem is affected by the facts that, in extremely cold weather, nearly all fuel is delivered to the engine, at the time of starting, as a liquid; that all cars perform poorly under such conditions, some engines, when cold, “hitting” on only one or two cylinders; and that, because of inferior distribution, many multi-cylinder engines are outperformed by single-cylinder engines of similar design.
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