Suction Stroke Research Articles

Low speed hunting of the pneumatically governed compression ignition engine. (8th Report, Effects of various parameters on the amplitude and frequency of limit cycle: Part II).

For a better understanding of hunting, it is desirable to be able to obtain the amplitude and frequency of hunting analytically. In the author's previous paper as a first step toward nonlinear approximate analysis, the effects of three parameters besides a subventuri pressure lag, i.e. moment of inertia of the crankshaft system, and mass and damping of the governing system, that have a marked influence each on the limit cycle characteristic are estimated as a step to analytically explaining the mechanism of limit cycle evolution. The present report estimates the effects of the other parameters on the limit cycle behavior: (1) the limit cycle lessens with decreasing stiffness of the control rack spring and (2) also with decreasing the slope of engine torque vs. rack displacement, but (3) scarcely depends on the slope of engine torque vs. engine speed, while (4) the calculated amplitude and frequency without considering a component of a higher frequency caused by the suction stroke of each piston do not agree with the experimental.

Research on a screw compressor. Performance analysis based on indicator diagrams.

By means of a small pressure sensor built into the tooth root on the discharge side of the female rotor, the pressure change in the groove can be measured from the midpoint of the suction stroke to the completion of the discharge. Indicator diagrams were collected for a single-stage cycle and the indicated horsepower was calculated. In this manner, we could determine the gas compression conditions inside the groove the thus the data could be analyzed for furthering the studies on high-efficiency profiles.

Experience With Pumpoff Control in the Permian Basin

Shell Western EandP Inc. has installed pumpoff control on more than 2,500 sucker-rod pumping wells in the Permian Basin during the last 12 years. These systems fall into three basic categories: stand-alone analog devices, stand-alone microprocessor units with optional communication capabilities to a central computer, and a centralized system where well data are communicated to a central computer for pumpoff decisions. Evaluation has shown that production can be maintained or slightly increased while energy consumption and maintenance expense are substantially reduced. The pumpoff controllers also provide well data that are beneficial in maintaining good surveillance.

Capacity Self-controllable Rotary Type Compressors for Automotive Air-conditioners : 1st Report, Basic Design Theory

The disadvantage of rotary type compressors for automotive air-conditioners is that the refrigerating capacity increases linearly in proportion to the increase linearly in proportion to the increase in engine speed, and so in the present research, attention was focussed upon the phenomenon of the refrigerating flow in the suction stroke, and the conditions for construction of capacity self-controllable type compressors by selecting suitable parameters were established, In this report, the basic equations which represent all stages of the vane's position in suction passage during the suction stroke have been introduced. By theoretical analysis of the equations, it was found that the capacity self-control characteristics by choosing the area of the suction port and suction groove could be calculated. These results were confirmed by the experiments.

Capacity Self-controllable Rotary Type Compressors for Automotive Air-conditioners : 2nd Report, Design Theory of Multi-vane type

The disadvantage of rotary type compressors for automotive air-conditioners is that the refrigerating capacity increases linearly in proportion to the increase in engine speed, and so in the present research, attention was focused upon the phenomenon of the refrigerating flow in the suction stroke, and the conditions for construction of capacity self-controllable type compressors by selecting suitable parameters were established, In this report, the basic equations which represent all stages of the vane's position in suction passage during the suction stroke are introduced. By theoretical analysis of the equations, it is found that the capacity self-control characteristics by choosing the area of the suction port and suction groove can be calculated. These results are confirmed by the experiments.

Intake noise and behavior of exhaust valve on the condition of exhaust braking in automotive engines.

Using the simulation program, the exhaust manifold and the exhaust valve system to optimize the exhaust brake performance in automotive engines have been investigated on the basis of the evaluations of the exhaust valve behavior, the pumping loss and the intake noise level. It is found that exhaust brake performance can be improved effectively by utilizing the pressure pulsation in the exhaust manifold, and am manifold of the divided type is desirable for this improvement. The intake noise level on the condition of exhaust braking is increased due to two back flows: one is the flow from the exhaust manifold to the intake manifold in the period of the valve over-lap, and the other is the flow from the exhaust manifold to the cylinder due to the re-opening of exhaust valve which occurs on the suction stroke.

An Experimental Study on the Performance of a Multifuel Engine : Part 5, Effect of Exhaust Throttling

In order to improve the multifuel capability o the diesel engine, we operated it by means of the exhaust throttling. By this technique, it was found out that the pressure of the residual gas was increased, and this made it possible to reduce that ignition delay because of a decrease in the quantity of the intake air and the rising temperature in the working gas at the end of compression. According to the experiment, utilizing a low cetane number fuel as automotive gasoline, the same combustibility as we could obtain with utilising gas oil was obtained, because the residual gas pressure was rose to about 3.0 ata. But, with a throttling of the exhaust has, fuel consumption was increased especially in a heavier load range. And yet, the smoke limited output was decreased and the engine noise became louder, because the pumping loss during the suction and exhaust stroke was increased and the charging efficiency was decreased. However, in getting such a combustibility, these are not considerably important. Because, the difficulties in running with a low cetane number fuel occure mainly at the lighter load range.

Starting Aid by Inlet Throttling in a Small Diesel Engine

A well-known phenomenon of the temperature rise due to throttling was applied to a starting aid in a small Diesel engine. Theoretical calculation of the charge temperature at the suction end was carried out for the various throttle ratios. The temperature rise above the ambient increases with the decrease in the mean pressure at the suction stroke and the increase in volumetric efficiency, reaching a maximum at a proper throttle ratio which depends upon the cranking speed. Throttling was performed by two means ; i.e., a throttle plate before the inlet valve and a special cam limiting the opening of the inlet valve to the later part of the stroke. The maximum temperature rise reaches theoretically 21°C in the former while 85°C in the latter. In a practical engine the minimum starting temperature was lowered about 15°C by applying the latter method, which shows an effective aid to cold-starting, but has a drawback of complicating the valve mechanism for the practical use.

Research on the Gasoline-Injection Spark-Ignition Engine : the 4th Report, The Performance of Manifold-Injection Engine

The purpose of the present research is to determine the method of injection, injection pressure, starting period of injection and compression ratio, favourable in the manifoldinjection engine, and also to investigate the anti-knock characteristics and to compare them with those in the carburetor system. With the manifold-injection engine, the direction and the shape of the fuel spray, injection pressure, and the start of injection have not too serious effect on performance as in the cylinder injection engine. Especially, when the spray is directed against the air-flow, very low injection pressure (even 10 atm) can be applied. The start of injection of 90-120°after TDC on the suction stroke is optimum. Manifold-injection is superior to carburetion with respect to anti-knock characteristics. In the manifold-injection engine, slightly later spark is favourable than in the carburetor engine.

Development of a Fuel-Injection Spark-Ignition Oil Engine

Abstract The author describes a fuel-injection spark-ignition oil engine which was designed to operate on the same fuel as a Diesel engine and with approximately the same fuel economy, but with pressures throughout the entire cycle which would not exceed those of a gasoline engine of equal size and speed designed for the same service. In the oil engine only air is admitted to the cylinder during the suction stroke. This air is then compressed to 160 lb per sq in., corresponding to about 6.35 to 1 compression ratio. At the end of the compression stroke, at about 60 deg before top dead center, the fuel is injected into the cylinder in finely atomized state by the fuel pump and injector. The fuel pump and injector are of the same design as those used for Diesel engines. Injection continues until the piston reaches top dead center. The spark occurs 15 deg before top dead center. Due to the time necessary for the vaporization of the injected fuel and its mixing with the air inside the cylinder, not all the fuel injected during the time from the beginning of injection until the spark occurs, will ignite at once, but a rather orderly combustion will take place and the maximum pressure is reached after 10 to 12 deg top dead center, when the engine is running at its rated speed and carries full load. At part-load operation, the beginning of injection is correspondingly later, but the spark timing is fixed. The rate of combustion is controlled by the rate of discharge of the fuel. The expansion and the exhaust strokes have the same functions in this engine as in gasoline and Diesel engines. As in the case of the gasoline engine, the spark can ignite a mixture in the fuel-injection spark-ignition oil engine only when it is constituted of the proper amount of fuel and air necessary to sustain combustion, i.e., a mixture must have the proper air-fuel ratio. In order to maintain this proper air-fuel ratio at all loads, it is necessary that the quantities of fuel and air he controlled in accordance with the momentary load. At full load the total quantity of air available in the engine is utilized and an air-fuel ratio of approximately 16 to 1 is maintained. At part loads the air admitted to the cylinders is reduced in accordance with the momentary load. For metering the fuel, the vacuum of the manifold is used, which acting upon the fuel pump will set the corresponding quantity of fuel. Electric current for the spark plug is supplied from either a magneto or a battery by the customary coil and distributor. The fuel consumption at full load of the production engine amounts to 0.44 lb per bhp-hr, and the part-load fuel economy approaches very closely that of the Diesel engine. The engine can run on gasoline, on fuel oils used in house-heating furnaces, or on regular fuel oils used for Diesel engines. The engine seems to be very insensitive toward its fuel. The engine has a very flat torque characteristic and is highly flexible, therefore, ideal for automotive use. Inasmuch as the maximum pressures are the same as those in gasoline engines, the fuel-injection spark-ignition oil engine is built with the same weight per horsepower as that of the gasoline engine.

The Determination of Mass Flow in the Vapour-Compression Refrigerator

The paper describes an experimental determination of the mass flow of refrigerant per minute and refrigerating effect per minute in a vapour-compression refrigerator, when the state of the refrigerant at the exit from the evaporator was varied over a wide range of superheat temperatures and dryness fractions. The usual methods of measuring the flow of liquids in pipes were not suitable for the present work and a special type of flow meter, described in the text, was developed. The results obtained were not as theory would tend to suggest, but were substantially modified by practical conditions, particularly for dryness fractions between 0·97 and 0·87. The volumetric efficiency changed abruptly over this range from a higher to a lower value. The reduction was attributed to the effect of re-evaporation of. the liquid portion of the refrigerant in the compressor during the suction stroke, as it was found that the higher volumetric efficiency was obtained when the refrigerant was superheated throughout most of the delivery stroke, and the lower volumetric efficiency occurred when the state of the refrigerant on entering the compressor resulted in liquid being present in the cylinder at the end of the delivery stroke. The reduction in the volumetric efficiency resulted in a corresponding reduction in the mass flow, the refrigerating effect, and the heat rejected by the condenser per minute, and in the coefficient of performance for dryness fractions ranging between 0·97 and 0·87.

The Hvid Engine and its Relation to the Fuel Problem

Abstract This paper describes a type of engine, the Hvid, which, it is claimed, has all the advantages and none of the disadvantages of the so-called Diesel type, and which is being produced in units as small as 1½ hp. It can be started cold, has no complicated air-compressor system, and is so economical that it can compete with gasoline engines of the same size. The author outlines the operation of the engine, describing in detail the suction, compression, power and exhaust strokes and presenting a series of indicator cards. Fuel consumption is shown by means of curves obtained as the results of tests performed. The paper concludes with a discussion of the heat balance and torque characteristics of the engine. It is not claimed that this motor has reached its ultimate state of development, but rather that it possesses certain characteristics which, in the author’s opinion, ought to attract many internal-combustion engineers by the possibilities they hold out of helping to solve some of the country’s fuel problems.