Search Results

The potential exists for significantly reducing operating costs by minimizing missing and overlap in successive agricultural field operations, particularly in areas where the equipment is pull-behind and widths of over fifteen meters are common. This paper reports on the development of a sensor, consisting of a video camera and image processing system, to detect the location of the demarcation line between tilled-and-untilled soil and cut-and-standing crop. The development of hardware and software to achieve real-time operation under a variety of crop, soil and ambient lighting conditions is described.

A small, field-scale system has been developed to assess the feasibility of controlling irrigation machine applications by use of an in-situ environmental monitoring system. Presently, the system monitors soil moisture in the root zone by use of Watermark sensors. Development is underway for a soil nitrate sensor. The completed system will monitor soil moisture, plant nutrients and pesticides. Remote, solar-powered sensors periodically update data in a central computer program. The program is being designed to track pollutant concentration and movement in a watershed, control spatial application of large irrigation machines or provide remediation monitoring for federal laboratory sites.

Variable rate nitrogen fertilization (VRNF) is a technique being developed for agricultural applications in recent years. In designing a controller for VRNF system, it is hoped that the process parameters, which are difficult to measure, could be identified on-line so that the model-based digital controllers or adaptive controllers could be used to achieve better system performance. In this paper, the problems associated with the on-line process parameter identification for the control of variable rate nitrogen fertilization are analyzed. Simulation studies and experimental tests were conducted to determine a suitable parameter estimation algorithm and the influence of pseudo random binary signal and external torque disturbance on the parameter identification accuracy. The results from the simulation and experimental studies revealed that the recursive least square algorithm is most suitable for parameter estimation.

A microprocessor based, underspeed draft control has been developed and introduced for use on belted agricultural tractors. This system does not rely on costly, strain sensitive pins for operation. By utilizing engine acceleration and deceleration rates, this system is able to respond quickly to needed changes in implement depth, while remaining stable under all operating conditions. The development process relied heavily on real-time computer simulation, minimizing the amount of actual field operation and substantially reducing the development time and expense.

Electromagnetic compatibility (EMC) design considerations have a vital role in the proper functioning of the electronic circuits and systems of a modern off-highway vehicle (OHV). Careful planning is needed in developing the electronic systems that operate the various functions and tasks on these vehicles. Incorporation of EMC in a system design gives that system the quality of reliability; that is, the system will have reduced emissions and be less susceptible to radiated and conducted electromagnetic energy. This paper provides ideas, concepts, and guidelines that the designer of OHV control circuitry can use for incorporation of EMC at the beginning of a design project.

This paper discusses how active mounts can reduce vibration and noise caused by engine vibration in vehicles. In recent years, vibration and noise problems have been exacerbated by the trend towards lighter, more fuel efficient vehicles. The connection of more powerful engines with fewer cylinders to lighter vehicle frames has resulted in vibration problems that passive elastomeric and hydraulic mounts cannot adequately address. Active mounts, which consist of passive mounts, force generating actuators, sensors, and electronic controllers, can achieve significant performance improvements over passive mounts. The superior vibration isolation capabilities of active mounts may also allow for the elimination of the engine's balance shaft, reducing engine weight, height, and cost, and helping to achieve further fuel efficiencies. In this paper, several different active mount configurations, actuation technologies, and sensor and controller choices are discussed.

This paper describes the communications system used by a microcomputer based monitor / controller designed for the model 2320 and 1720 Air Seeders built by Flexi-Coil. The operational requirements, the various design trade offs and the final design of the system will be presented.

The agricultural combine harvester is one of the most complex of machines used in cereal grain production. It is believed that significant increases in efficiency and productivity could be realized if several of the machine adjustments could be automatically controlled. One of the most important parameters to measure and control is the feedrate, i.e. the mass flow rate of material entering the machine. This paper reports on an investigation of a sensor, using electrical capacitance techniques, to measure feedrate.

A new numerical simulation system has been developed which predicts flow behavior of fuel film formed on intake port and combustion chamber walls of gasoline engines. The system consists of a film flow model employing film thickness as a dependent variable, an air flow model, and a fuel spray model. The system can analyze fuel film flow formed on any arbitrary three-dimensional configuration. Fuel film flow formed under a condition of continuous intermittent fuel injection and steady-state air flow was calculated, and comparison with experimental data showed the system possessing ability of qualitative prediction.

The electronically-governed diesel distributor injection pump, with the proven sleeve control of injection quantity, has been in production at Bosch since 1987. Long-term development resulted in a solenoid-valve controlled injection pump. The function and component assemblies, consisting of the injection pump, solenoid valve and control unit, provide an even more flexible injection system. Of particular advantage with this type of system are the high dynamics of the fuel quantity, matching of each individual injection and the exact pump-specific fuel quantity compensation at numerous map points. Further advantages are the selection of timing and fuel injection rate independent of each other, as well as the ability to provide the correct timing even at cranking speeds. The entire system, with emphasis on the injection pump and the solenoid valve, are described for IDI engines in this paper.

A simple analytic relationship between fuel economy, vehicle parameters and driving cycle characteristics is established. Using publically available information on vehicle characteristics, the model can be used to predict fuel economy with an accuracy of about 5% (standard deviation). The model is based on two approximations: 1) an engine map approximation, and 2) an approximation for tractive energy. This paper emphasizes the second approximation, especially the energy consumed by the brakes. The model reveals the structure of fuel use in a way difficult to achieve with case-by-case numerical results and it enables study of fuel use in modified driving cycles.

The characteristics of a thermal mass airflow sensor are typically reported as response time, or the time delay measured when responding to a step change in airflow rate. However, these measurements do not provide an accurate description of the dynamics that are used to predict system performance. Experimental time response is also difficult to measure and interpret. A number of problems arise in this including difficulty in creating a controlled step change in airflow, effects of flow rate on response time, and non-linear response to mass flow. In order to better explain the dynamic response of the air meter, a frequency domain approach proves useful. A simple model of the meter is a low pass filter with a cut-off frequency determined by the mass airflow rate and the frequency response. When this is combined with a normal static transfer function of mass flow to voltage, the mass airflow sensor is completely characterized.

A prototype multipoint fuel injection system which utilises fluidic injection devices as fuel injectors for spark ignition engines is described in this paper. The unique fluidic injector unit combines four no-moving-part, monostable fluidic devices controlled by a solenoid valve interface and air-fuel mixing nozzles for well atomised air-fuel mixture. The design philosophy and operating characteristics of the novel integrated fluidic injector unit for engine applications are discussed in details in this paper. The initial engine tests on this fluidic injection system show that it provides an extended lean limit of the air/fuel mixture (by 2.2 air/fuel ratio), 7% improvement in fuel economy and 10% reduction in HC emissions compared with a base line carburetted system. These results confirmed that the use of the fluidic fuel injection system resulted in improved fuel distribution, better air/fuel mixture preparation and faster flame propagation speed.

The effect of fuel injection atomization on engine performance has been known to improve fuel economy and to reduce emissions. Hitachi America, Ltd. Research and Development along with Hitachi Research Laboratory in Japan have studied the effects and the operation of the air assist injection system which was developed and studied to help meet future Low Emission Vehicles (LEV) regulations and also Ultra Low Emission Vehicles (ULEV) regulations. The system consisted of newly designed air assist injectors having a spray angle of 15° at 170 kPa (absolute air pressure) with 370 kPa (absolute fuel pressure). The air assist injector generates highly atomized fuel droplets by swirling the fuel clockwise and the air counterclockwise. The fuel and air flowing in opposite directions collide, thereby producing particles around 30 μm in size at 274 kPa air pressure. These characteristics improve cold start, cold coolant conditions and fully warm engine conditions.

In order to improve the atomization capability of a standard port fuel injector, an optimized suggestion for an air shrouded injector is presented. The fluid dynamic part of the retained solution is composed of a special flat seat design for the fuel metering function combined with a post atomization adapter enabling both mono- and multi-spray modes. The concept works equally well in natural manifold gradient mode and with an external pressure pump. The realized concept is tested in both free jet experiments and on two different 2 litre engines, one operated in stoechiometric conditions the other in lean-burn conditions. The experimental work confirms a potential of the concept to increase torque stability and thereby lean-burn limits, decrease required spark advance and enable open inlet valve injection and consequently decrease wall wetting phenomena.

Designers are under increasing pressure to provide powertrain systems which meet tougher market and legislative requirements for:- performance, emissions and economy reliability and durability noise and refinement To meet increasing competition, powertrain products need to be “fast to market and right first time”. This implies the evolution of existing technology, comprising multi cylinder reciprocating engines and gear transmissions, drawing on a database of decades of powerplant design experience. It is with this background that CAE has proven engineering value supporting key areas of powertrain engineering to meet these technological challenges in a cost effective and timely manner. This paper follows the analytical engineering of a four cylinder engine crankshaft from concept to production design. Particular emphasis is placed on the integration of concept design software tools and the combination of finite element analysis and dynamic models with reduced degrees of freedom.

This paper presents a technique for the improvement of the idle stability on a spark ignition engine through the adaptive control of the individual cylinder ignition timing. In many causes that affect the idle stability, the difference in the torque production between cylinders has been a matter of concern. The engine speed has been sampled 220 times per a cycle and the average angular acceleration has been calculated from it. In this research, the average angular acceleration has been characterized by nonuniform torque production among cylinders. The control system has been designed to keep the average angular acceleration constant.

This paper reviews the progress made since the last SAE Congress in the development and testing of the Collins Scotch Yoke crankshaft technology and the demonstrator engine in which it is being proven. New packaging refinements are illustrated, and more detailed internal friction loss data are shown. New fuel consumption data are shown to confirm the low internal friction losses of the demonstrator engine. A study of the potential of supercharging illustrates the power increase that can be achieved with virtually no increase in engine packaging volume. A discussion is also provided of the unique, exact engine balancing that is possible with the scotch yoke technology, due to the pure sinusoidal motion of the pistons and con rods. Finally, a brief discussion is provided of the small crevice volumes that may be achieved with the Collins Scotch yoke technology.

A newly designed opposed free piston internal combustion hydraulic power generator is proposed in this paper. The pressure of the hydraulic power output of the proposed hydraulic power generator is substantially constant and the hydraulic flow rate is variable. The frequency of free piston changes from zero to maximum in response to the hydraulic flow rate and each gas cycle is always performed under an optimum working condition independent of the power output. If the proposed hydraulic power generator is combined with a variable displacement hydraulic motor, it will be possible to obtain excellent torque-speed characteristic, easy operation, and superior fuel economy. A fundamental test apparatus was constructed and tested in this work. The test apparatus uses an opposed free piston, two stroke cycle, direct fuel injection, and compression ignition engine.

Multidimensional computations were made of combustion of natural gas engine via the KIVA-II code to evaluate the combustion and emission characteristics. In the combustion submodel, a two-step kinetic reaction mechanism is employed to account for oxidation of methane. The first of the two global rate equations controls the disappearance of methane, and the second, the oxidation of carbon monoxide. Four types of combustion chamber and a two-spark-plug geometry are considered to achieve quick flame propagation of the lean air-methane mixture. The effect of spark plug locations on the combustion processes is discussed. The calculated results show that the more effective burning process with lower NOx emission could be achieved by proper design of the geometry of the piston bowl and the arrangement of the spark plug by matching of the flame front development with the in-cylinder gas flow.