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In the search for fuel efficiency and emission control in modern gasoline powered automobile engine operation, the single largest problem is the knowledge of the state of the fuel involved. That is, when the fuel is totally liquid it can be handled in much the same way as a hydraulic system. In addition, when the fuel becomes a gas it will function in a manner similar to a pneumatic system. However, in a fuel system the actual state of the fuel depends on the composition of the fuel, the operating conditions, and the ambient conditions. To the authors' knowledge, the analytical model that describes the dynamic time-based performance of a fuel system has not been successfully formulated in the past due to the lack of an adequate time-based fuel state model. This paper will present a complete model of an engine fuel system along with a computer program that is capable of producing a computerized analysis of the dynamic performance for the system.

Every hydraulic system use requires a pump to supply the necessary flow and support the imposed pressure cycle. Therefore the performance of the pump in a hydraulic system is critical to the overall performance of the system. It is a well known fact that the performance of a hydraulic pump is influenced by both the speed at which it is operating and the pressure to which it is subjected. This paper evaluates the volumetric efficiency of a hydraulic pump using both the fundamental expressions which are generally accepted and actual data test data. The widely accepted equation for pump leakage is presented along with an expression that includes the parameter of speed. Results obtained using a pressure-loaded gear pump are used to compare and evaluate the analytical expressions. This comparison reveals a significant influence of speed at high pressures on the volumetric efficiency of the pump.

The design and analysis of most engineered systems involves many and sometimes diverse technical disciplines. For example, in the design of a fluid power system, the input to the system is usually some type of prime mover. In addition, the output may include gears, linkage, etc. The output may be used in a feedback circuit which will normally encompass instrumentation, logic elements, and controllers. In order to evaluate the total performance of such systems analytically, a software package must be available which can unify the interactions of these diverse components. This paper will present a new computer program which will unify hydraulic, pneumatic, electronic, and mechanical components permitting the analysis of complete engineered systems on a P.C. Several example systems will be shown which originate in actual machinery designs. These example systems will be simulated and output type information will be presented.

The selection of a proper fluid to be used in a hydraulic system is an important part of any design effort. The hydraulic fluid must normally transmit, transform, and control the power from the system input to the output. In addition, the fluid is expected to provide lubrication and antiwear protection to many of the other components in the system. Although there are at least 22 parameters which describe a hydraulic fluid, most of these parameters are well defined. However, the antiwear and lubrication properties of a hydraulic fluid deserve more discussion. There are several test methods which have been developed to assess the antiwear properties of liquids. Most of these procedures are intended to evaluate fluids other than those directed toward use in a hydraulic system. This paper will present a bench type wear test method designed to overcome the recognized problems of other wear test procedures.

Separation efficiency, contaminant capacity and operating power consumption are the three major factors in determining the performance of any separator. For an ideal separator, all unwanted material should be removed from the process fluid. In addition, the ideal separator must hold an infinite amount of separated contaminant and consume no power. Unfortunately, such an ideal separator is impossible to attain under the current laws of physics. However, the technology presented here represents a major step closer to these objectives. This paper introduces a new concept, orbital separation, for achieving high performance gas, liquid and solid separation. Orbital separation has nearly unlimited contaminant capacity and requires only a fraction of the input power required by other separation techniques. In this paper, the general principles of filtration and separation mechanics are reviewed. The orbital separation concepts are discussed and illustrated.

This paper discusses a non-intrusive acoustical diagnostic technique for assessing the wear and associated flow degradation of hydraulic pumps. The technique utilizes near-field airborne noise measurements to determine the acoustical energy emitted by the pump at various pumping harmonics. Ratios of the pumping harmonic noise levels are transformed into a Noise Wear Index. Data are presented which show the correlation between the Noise Wear Index and gear pump contaminant induced wear as indicated by a degradation of pump flow performance. The use of the Noise Wear Index for diagnosing system infirmities and improving system reliability is discussed.

REFERENCE: Tessmann, R. K., and G. E. Maroney, “Ferrographic Evaluation of Pump Contaminant Wear,” 1977 SAE National Off-Highway Vehicle Meeting, Milwaukee, Wisconsin, 12-15 September 1977. This paper presents the results of research conducted in contaminant wear of fluid power components. Most of this research and development effort has focused upon hydraulic pumps and pumping type mechanisms. Recently, work was initiated using Ferrographic analysis to correlate the wear debris generated during contaminant wear testing with the degradation in performance of hydraulic pumps. The paper demonstrates the correlation of generated wear debris with the performance degradation of such components.

The multipass filtration performance test which has recently gained industry-wide support offers many fundamental ways of describing the performance characteristics of fluid power filter elements. Some of these descriptions are uniquely qualified to provide the system designer with a practical technique for appraising the capability of filter elements. Important appraisal parameters of a filter element which must be considered by a designer are particle separation capability, contaminant capacity, and pressure loss. In order to specify a filter element properly for a given application, the requirements for the appraisal parameters must reflect the needs of the system components. A practical and fundamental description for the performance of fluid power filters will incorporate appraisal parameters which can be related to the demands of such system components.