• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.8 no.2
• /
• pp.35-43
• /
• 1999

The paper describes an approach for measuring delivery flow ripple generated by oil hydraulic axial piston pumps. In order to reduce pressure ripple which cause to undesirable noise. vibration and fatigue in hydraulic systems it is indispensible measure a delivery flow ripple from pumps. Since the flow ripple measurement of flow pumps is independent of the dynamic characteristics of the connected hydraulic circuit the measurement of flow ripple is most suitable for pump fluid-borne noise rating. The measurement of flow ripple with high frequencies from axial piston pumps is made by applying the remote instantaneous flow rate measurement method which is based on the dynamic characteristics between pressure and flow rate in hydraulic pipeline. The measured flow ripple waveforms are influenced by the configuration of V-shaped triangular relief groove in the valve plate. It can be seen that the appropriate relief groove in valve plate reduces the pressure and flow ripple amplitude and frequency spectrum for high harmonics.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1995.04b
• /
• pp.267-272
• /
• 1995

The paper describes an approach for measuring flow ripple generated by oil hydraulic axial piston pumps. Flow ripple has periodic waveforms due to the cyclic nature of a pump's operation, and interacts with the connected hydraulic systems such as pipes and components to produce a pressure ripple, also known as fluid-borne noise. It is indispensable to measure a flow ripple because increasing of vibration and noise caused by a flow ripple has become a point to be considered and has need of solving these problems. The measurement of flow ripple with high frequencies from oil hydraulic axial piston pumps is msde by using the remote instantaneous flow rate measurement method. As a result, the reverse flow through the relief groove in valve plate has an important effect upon a flow ripple generated by a pumps.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.8 no.6
• /
• pp.70-78
• /
• 2000

A balanced vane pump for the use of automotive power steering systems generates a flow ripple which is imposed upon the mean flow rate. The flow ripple interacts with the characteristics of the connected pipes, valves and steering gear in a complex manner to produce a pressure ripple, also known as fluid-borne noise. In order to reduce vibration level and produce quieter and more reliable power steering systems, it is important to measure the flow ripple produced by a pump with high accuracy and fast response. In this paper, the flow ripple generated by a vane pump in automotive power steering systems is measured by the remote instantaneous flow rate measurement method (RIFM) using hydraulic pipeline dynamics. In experiment, flow and pressure ripple wave forms are measured under various operating conditions. Also, the parameters affected upon the flow and pressure ripple are investigated by the frequency analysis.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.10 no.1
• /
• pp.120-126
• /
• 2001

This study deals with a flow and pressure ripple characteristics for a hydrostatic transmission(HST) consisting of a vari-able axial piston pump connected in an open loop to a fixed displacement axial piston motor. These flow ripples produced by pump and motor in HST interacts with the source impedances of the pump or motor and dynamic characteristics of the connected pipeline, and results in a pressure ripples, Pressure ripples. Pressure ripples in HSP is major source of vibration, which can lead to fatigue failure of components and cause noise. In this paper, the flow ripples generated by a swash plate type axial piston pump or motor in HST are measured by making use of hydraulic pipeline dynamics and the measured pressure data at two points along the pipeline. By using the self-checking functions, the validity of the method us investigated by comparison with the measured and estimated pressure ripples at the halfway section of the pipeline, and good agreement is achieved.

• Transactions of The Korea Fluid Power Systems Society
• /
• v.4 no.3
• /
• pp.22-27
• /
• 2007

The source flow ripple and the source impedance in hydraulic pump are characteristic values showing fluid-borne vibration characteristics decisively. We cannot measure these two characteristic values directly, but can measure them by some indirect methods. One representative indirect measuring method is ISO 10767-1. The authors constructed a hardware and a software for the measuring method based on ISO 10767-1. Through the error evaluation of the measured results, accuracy of the measuring method using ISO 10767-1 was examined in detail.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.13 no.6
• /
• pp.48-55
• /
• 2004

Design for quite operation of fluid power system requires the understanding of noise and vibration characteristics of the system. This paper presents a dynamic response of design of hydraulic circuit. Experimental investigations on the attenuation of pressure ripple in automotive power steering hydraulic pipe line is examined. Also, a mathematical model of hydraulic pipe is p개posed to support a design of the hydraulic circuit. and the impedance characteristics of pressure ripple is analyzed. It is experimentally shown that power steering hydraulic pipe attenuates pressure ripple with high frequency.

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.23 no.1
• /
• pp.174-179
• /
• 2009

Arterial pulse palpation is an important diagnostic method in Oriental Medicine, particularly for obtaining information about a patient's health conditions or illness, or for confirming a diagnostic conclusion based on the patient's pulsation. The pulse analyzer is both a leading Oriental Medical equipment and a promising tool with such a strong industrial ripple effect that it was selected as one of the four strategic tools for world Oriental Medical instrument market domination at a recent survey. Although various pulse analyzers had been developed, however, most of these were not widely used for clinical diagnosis, due perhaps to lack of the appliance's reliability caused by its inability to reflect the requirements of the clinicians. Thus, in this thesis, the clinical requirements for the pulse analyzer were identified and analyzed by conducting a questionnaire survey among Oriental Medicine clinicians. By looking into the basic functions of a pulse analyzer, the required measurement time, and the medical insurance fee required were determined and among others, the appliance's specific requirements were determined. Moreover, by investigating on the latest patent trend, the technical elements that are needed for the development of a next-generation pulse analyzer were identified. Through these processes, the flow of the technology that must be developed for the pulse analyzer was determined, and the direction for the development of the specific pulse analyzer hardware, sensor, and diagnostic algorithm was identified and proposed.