Fuel Injection Equipment Research Articles

Fuel Injection in Diesel Engines

In his address the Automobile Division Chairman develops the theme that fuel injection equipment is the heart of the diesel engine. He explains the task that the fuel injection equipment has to carry out and how this has been solved in the past. He describes some present-day systems and sets out the problems in optimizing the injection characteristics. Finally he points to future trends in this field and outlines some recent developments in electronic control of fuel injection.

The generation and properties of boundary films formed by diesel fuel at a steel/steel conjunction

Thin gel-like films are seen on the lubricated surfaces within diesel fuel injection equipment. The formation and properties of these films are investigated, under sliding conditions, using disc-on-plane machines; one steel has been used throughout. The development and maintenance of separation is measured by voltage drop and, during running-in to a high conjunction resistance, films are produced which are similar to those seen in practice. It is shown by static tests that separation is maintained by these films, which behave as quasi-elastic solids. The films are not miscible with diesel fuel and are not produced when the fuel is in static contact with the steel. They exhibit similar electrical properties under static and dynamic conditions: this was unexpected and is not yet understood. It is postulated that the films are produced by chemical reactions, and that the surface polishing observed is due to the same reactions

Noise of diesel engine injection equipment

The investigation presented in the paper deals with the origins of noise of the two major components of the diesel injection equipment, namely the injection pump and “injectors”. It is shown that injection equipment noise is considerably augmented by the mounting system and thus the characteristics of the engine structure become important factors which determine the level and the character of the noise emitted. About 20 dB reduction of injection pump noise and some 25 dB reduction of injector noise has been made possible by relevant design changes of the components themselves, by their mounting arrangements and by the design of the engine structure. The relation between diesel engine and fuel injection equipment noise is considered over the whole range of operating conditions.

Investigation of Diesel Engine and Turbocharger Interaction

The authors are concerned with the proper provisioning of turbochargers and fuel-injection equipment for diesel engines, particularly in the automotive class. Medium-speed engines are run at high mean effective pressures and there is a tendency towards similar outputs in automotive engines. Because of transmission demands these outputs will be required over a wide speed range and the relation of engine air and fuel requirements is examined. The simple turbocharger is not ideally suited to wide range matching and the extent of the compromise inherent in fixed geometry compressors and turbines is discussed. In order to survey engine, turbocharger, and fuel-system interactions tests are reported where turbocharger limitations are avoided by the use of two units in series. Engine operating limits were selected on the basis of safe engine factors and the output assessed with respect to the principal variables of turbocharger pressure ratio and engine compression ratio. The resulting compromise between high cylinder pressures and smoke control tended towards a traction-type torque curve with a higher-than-conventional fall-off in torque with speed. A suggestion was verified that smoke occurred at higher air/fuel ratios as the charge density increased. Nevertheless accepted methods of heat-release prediction from rate of injection characteristics were not affected by variation in charge density.

Paper 12: The Mechanical Design of Fuel Injection Equipment

Loading problems on cam, follower, pump, and tappet are frequently encountered in high-output engines. The main parameters are Hertzian stresses, bouncing tendencies, and cam profile design. Rising speeds, line pressures, and injection rates have brought about major changes in pumping element design, and in this paper plunger and sleeve materials and their failures are discussed. Hydraulic considerations determine the fuel pump delivery valve design, and the chief mechanical problem is fatigue failure. Body redesign has accommodated the increased clamping and sealing loads which higher line pressures demand. Causes and prevention of fuel pipe breakage are described. In the injector assembly the major mechanical problems are the inertia of moving parts, spring stresses, and sealing. As regards future designs, are there ultimate hydraulic or mechanical limitations to conventional jerk pumps and, if so, what are the alternatives ?

The Performance and Quality Control of Diesel Engine Components

This paper outlines methods developed to control the quality of incoming materials and finished components with emphasis on the performance that is ultimately required from them. The examples given are taken from diesel engineering but the basic ideas apply to all industries whose final products consist of an assembly of components which are complete in themselves. The quality control of materials and components fills an important role in ensuring that the technical requirements written into a specification by a designer are met by suppliers. The author outlines various techniques developed in his company to achieve this. The paper has two main sections: ( a) quality control of incoming materials, and ( b) performance control of components. The first part deals with the controls established for cast-iron components of various sizes ranging from bedplates and columns weighing about 20 tons to piston rings weighing less than one pound. Ultrasonic testing is briefly discussed as also is the material specification for white metal bearings. The second part of the paper gives examples of performance testing of a number of diesel engine components together with brief details of some of the test rigs that have been developed to carry out the tests. Some of the components discussed in this section are piston rings, crankshafts, camshafts, cams, and fuel injection equipment.

A Study of Characteristics at the End of Injection in Diesel Engine Fuel System : 1st Report, Analysis of Pressure Drop on Pump Side

The object of this paper which deals with the phenomena at the end of injection of Bosch pump injection system is to show the relation between the design of fuel injection equipment and the pressure drop at the pump side. It was found from experiments that the pressure drop had two features. Pressure at the pump side drops down along a fundamental pressure dropping curve. The fundamental pressure drop is a function of crank angle, injection pipe area, etc., but not of engine speed. The pressure drop along this curve has a maximum value which is decided mainly by the design of the delivery valve of the pump. The theoretical equations of pressure change and flow through the delivery valve port are obtained after reasonable treatment. Assuming suitable factors, the solution of these equations coincided very well with the experimental results.

A Study of Characteristics at the End of Injection in Diesel Engine Fuel System : 1st Report, Analysis of Pressure Drop on Pump Side

The object of this paper which deals with the phenomena at the end of injection of Bosch pump injection system is to show the relation between the design of fuel injection equipment and the pressure drop at the pump side. It was found from experiments that the pressure drop had two features. Pressure at the pump side drops down along a fundamental pressure drop curve. The fundamental pressure drop is a function of cam angle, but not of engine speed. The pressure drop along this curve has a maximum value which is determined mainly by the design of the delivery valve of the pump. The theoretical equations of pressure change and flow through the delivery valve port are obtained after reasonable treatment. Assuming suitable factors, the solution of these equations coincided very well with the experimental results.

Fuel Injection Equipment for Diesel Engines

Fuel Injection Equipment for Diesel Engines

The Change of Viscosity of Oils containing High Polymers when Subjected to High Rates of Shear

The construction and use of an apparatus for the imposition of rates of shear of at least 107 secs-1 on oils containing high polymers is described. The apparatus is constructed from standard fuel injection equipment with minor modifications. A series of typical results is reported, showing that a substantial decrease in the intrinsic viscosity of the polymer, and consequently in the viscosity of the solution, can occur on application of rates of shear of the above order.

Significant Contributions of the Diesel Research Laboratory

This review of Diesel engine development is based on the work carried out at the Diesel Research Laboratory of Caterpillar Tractor Co. under the sponsorship of the author as Director of Research. For many years intensive effort has been made to understand the combustion process in this type of engine by a better knowledge of the fundamentals of ignition and the mechanism of the combustion process, and this study has been developed in the laboratory on a competitive basis. Originally six combustion systems were put to trial and a modified precombustion-chamber engine won the palm of victory on the basis of its ability to maintain uniformity over extended periods of operation. Briefly, the character of the comparative combustion studies followed two general classifications: (1) visual combustion studies; (2) study of combustion-chamber deposits. In order to make extended studies of the combustion phenomena by visual means, a quartz window was designed to achieve maximum cleanliness without the distraction of soot condensation on the cold windows. The author describes the precombustion-chamber process, and deals with the composition of combustion gases, flame duration, temperature distribution, the mechanism of ignition, and combustion-chamber deposits. He also discusses the development of fuel-injection equipment, pretiming, precalibrating, and the evolution of the fuel pump; he describes the characteristics of several types of check valve and fuel valve, and the fuel-pump control of engine torque characteristics. Spray characteristics and the flow through the fuel-valve orifice are also examined. Comments are made upon materials for cylinder liners and piston rings, and the effect of fuel inclusions on cylinder wear; lubrication is also considered. It is believed that excellent performance has been achieved in the precombustion-chamber engine with a minimum of complication in the fuel-injection equipment, and that the development of this principle of combustion has not yet reached its limit of progress.

Wear of Fuel Injection Equipment and Filtration of Fuel for Compression-ignition Engines

The dependence of the wear of fuel injection equipment on abrasive-particle size has been determined using closely graded abrasive prepared by air elutriation. A mechanism of wear is proposed which accounts quantitatively for the wear observed. The particle transmission properties of filters in common use, and of possible alternative filter materials, have been measured using the same preparations of particles. Some information on the nature and particle sizes of solids in fuels is presented. Estimates of the effect of various filters in reducing abrasive wear are made for a particular particle-size distribution of abrasive. These estimates are compared with the results of a review of service experience with current filters, gauze, cloth, and felt, in Great Britain. The choking properties of filter materials have been compared using a waxy sludge obtained from marine Diesel fuel, and a hypothesis of the choking mechanism is proposed which makes it possible to predict choking behaviour from initial resistance and thickness, and to assess, by means of a “figure of merit”, filter materials of different particle-transmission properties and thicknesses. For some services improved filtration is necessary. Papers transmit fewer particles than cloth or felt but choke more readily, necessitating the use of a large filter area; but provided the paper and free volumes on the clean and dirty sides are suitably chosen, a paper filter appears to be practicable giving a greatly improved pump element life with adequate filter element life and reasonable bulk.

The Elbow Combustion Chamber

Abstract A description is given of the “elbow” combustion chamber, developed for use in the gas-turbine power plant designed and built for the United States Navy by the Elliott Company. This type provides extremely high heat-release rates which is an essential characteristic for gas-turbine applications. The fuel-oil-burning system which utilizes standard Diesel fuel-injection equipment has been developed to a high point of efficiency, and may be varied over a range from full load to 1/10 full load without material change in quality of atomization. The paper discusses in detail the air-flow characteristics, fuel supply, ignition and control devices, and analyzes the combustion-chamber performance-test data.

Fuel Injection in Oil Engines in Relation to Combustion

The object of the paper, which deals with the jerk pump injection system, is to show the relationship between the design of fuel injection equipment and the design of the engine on which it is used. First the nozzle is considered as an orifice, in its relation to the combustion chamber, and an account is given of the features of hole type and pintle type nozzles. The action of the differential needle valve is then discussed, and particular reference is made to the design features necessary to ensure quick action of the valve, with good “chattering”. The author then considers the design of “restricting” or “delay” type nozzles, and a description is given of the delivery valve of the pump. The need for “unloading” of the delivery pipe is discussed, together with various types of delivery valve and their action. The delivery pipe itself is treated with reference to ( a) determination of size of pipe; ( b) pipe surges and their effects; ( c) methods of dealing with surges. In addition the action of a pump plunger and barrel of the ported type is considered in relation to its effect on pump output at varying speeds, also the combined effect of pump plunger and delivery valve. The author sets out the points to be considered in the selection of fuel injection equipment for a given engine. Basing his analysis on existing designs, he puts forward a classification of combustion chambers from the viewpoint of fuel injection. He shows that orifice diameter in hole type nozzles depends on the penetration required, and that the total orifice area is also dependent on the piston displacement per unit of time. The selection of a suitable pump to feed the nozzle is discussed, and the author arrives at specific ratios for assessing pump action in relation to the engine and the nozzle. Finally, consideration is given to the limiting capacity of an atomizer of given size, and to the release pressure in an atomizer and the maximum pressure of injection.

Internal Combustion Engine Group: Symposium of Papers on Fuel Injection Equipment: The Conditions of Satisfactory Fuel Injection

Internal Combustion Engine Group: Symposium of Papers on Fuel Injection Equipment: The Conditions of Satisfactory Fuel Injection