• Journal of the Korea Society for Simulation
• /
• v.25 no.4
• /
• pp.53-63
• /
• 2016

This study aims to verify the feasibility of design by developing pressure flow-controlled swash plate type pump with the use of SimulationX, a computer analysis program. Developing analysis model based on design drawing data has a cost-saving effect because it is possible to figure out the effectiveness of design through the work and it never falls into repeated inaccuracies in the production process. Analysis model is developed in the following order. First, the structure of each part such as valve and rotating unit which have dynamic factor is analyzed and the modeling of single component is carried out, reflecting drawing data. Second, the modeling of pump assembly is carried out with the combination of each analysis model and a work is conducted to determine whether the modeling can perform pressure flow control function according to load condition smoothly based on design intent. At the end of the modeling process, the feasibility of design is verified by showing the parts which are moving as expected mechanism.

• Journal of Mechanical Science and Technology
• /
• v.18 no.10
• /
• pp.1700-1711
• /
• 2004

Piston friction is one of the important but complicated sources of energy loss of a hydraulic axial piston machine. In this paper, two formulas are derived for estimating instantaneous piston friction force and average piston friction moment loss. The derived formula can be applicable for piston guides with or without bushing as well as for axial piston machines of motoring and pumping operations. Through the formula derivation, a typical curve shape of friction force found from several experimental measurements during one revolution of a machine is clearly explained in this paper that it is mainly due to the equivalent friction coefficient dependent on its angular position. Stribeck curve effect can easily be incorporated into the formula by replacing outer and inner friction coefficients at both edges of a piston with the coefficient given by Manring (1999) considering mixed/boundary lubrication effects. Novel feature of the derived formula is that it is represented only by physical dimensions of a machine, hence it allows to estimate the piston friction force and loss moment of a machine without hardworking experimental test.

• Journal of Drive and Control
• /
• v.12 no.2
• /
• pp.21-26
• /
• 2015

In order to design a swash plate type pump for electro-hydrostatic actuators the performance of the hydrostatic piston shoe bearings in the low speed range needs to be examined, since the pump operates frequently at low speeds, compensating for position control errors as a control element. As a common practice, piston shoes are equipped with inner rings as an auxiliary element to enhance their tribological performance. In this paper, the effects of the inner rings of the piston shoes on the frictional loss and leakage flow rate were investigated, where three piston shoe models, with different inner ring shapes and different inlet orifice sizes, were integrated. The test results showed that a large inner ring and small inlet orifice were advantageous for reducing both the frictional loss and leakage flow rate; this could also be confirmed by computational analyses.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.4
• /
• pp.2424-2429
• /
• 2015

In an oil hydraulic piston pump, the cylinder block and valve plate in high speed relative sliding motion have the characteristics which should be extremely controlled for the optimization of leakage and friction losses, and pressure-resistance design of them is very important for high pressure performance. But the studies on the stress analysis of those parts have not been performed briskly. Therefore, in this paper, the stress and displacement distributions of the cylinder block and valve plate in the oil hydraulic piston pump with a swash plate type are discussed through the static stress analysis using CATIA V5. The stress and displacement of the cylinder block are more influenced by the axial pressure than by the radial pressure, and are larger by approximately 66% and 30%, respectively. The results show that a review of the material and shape of the valve plate is required.

• Tribology and Lubricants
• /
• v.14 no.4
• /
• pp.15-22
• /
• 1998

Recently, the importance of variable displacement piston pump is increasing in industrial world. Especially, most consumers require various range of pressures and flow rates. Pressure compensator is a system controlling flow rate in piston pump at low cost and, therefore, satisfies the need of consumers. However, the system has serious problems, such as response and leakage. The response and leakage are affected by clearance between actuator piston and cylinder, roughness of surface, and spool overlap. In this paper, these effects are investigated experimentally, and optimal clearance and chamfer is obtained. While diameter of cylinder is fixed and diameter of actuator piston is changed in this experiment, response and leakage are measured. Also parameters such as roughness and processing accuracy are changed for piston of fixed clearance. Experimental setup modelled into several parts of actuator piston, cylinder, spool, and swash plate. Input pressure is changed by function generator and proportional valve. The result of this experiment shows that leakage increases very much in proportion to the increase of clearance, and especially leakage occurs enormously when clearance is more than 0.002. The response is not good because as clearance increases leakage increases and as clearance decreases viscous damping effect increases. Accordingly, it is found out that optimal clearance range exists for tile response, within about 0.0012∼0.0014, at this time. Futhermore, the better roughness and geometrical accuracy of actuator piston are, the smaller are leakage and friction. The paper informs that response and leakage are influenced by and geometrical accuracy of actuator piston, roughness of surface, and the clearance between actuator piston and cylinder, and that optimal design of actuator piston in the pressure compensator is possible.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.14 no.4
• /
• pp.293-303
• /
• 2002

For successful design of component, performances of one-tank plate type evaporator, gas-liquid separation type condenser, swash plate type compressor and thermostatic expansion valve for automotive air conditioner are investigated experimentally. Heat transfer characteristics in the evaporator are examined by means of air temperature, relative humidity, air volume flow, outlet refrigerant pressure and superheat, and heat transfer characteristics in the condenser are examined by means of air temperature, air velocity and inlet refrigerant pressure. Pressure drops for both evaporator and condenser are measured arid empirical correlations are derived. Volumetric efficiencies and isentropic efficiencies for trio types of compressors with different capacity are measured and compared. Thermostatic expansion valve is tested to investigate the pressure variation according to temperature changes.

• Transactions of The Korea Fluid Power Systems Society
• /
• v.2 no.3
• /
• pp.12-17
• /
• 2005

This paper presents a theoretical study of the delivery flow ripple produced by a swash plate type hydraulic piston pump for the purpose of developing a computer simulation program capable of predicting the pump source flow ripple accurately at the design stage. Particular attention has been paid to the development of the theoretical model by clarifying quantitatively the design influences of key parts of valve plate such as relief groove and pre-compression/expansion.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.20 no.3
• /
• pp.68-75
• /
• 2021

The fuel economy is a key issue for the automotive industry due to environmental concerns. In particular, only 5-20% of the energy generated in a car using an internal combustion engine is used as power, and the remaining energy is dissipated due to friction with other parts. The main components in the reciprocating piston type compressors commonly used in general vehicles include shafts, swash plates, pistons, and cylinders, and severe friction loss occurs due to the contact of these components. Generally, the wear contact is the maximum between the shaft and cylinder and between the piston and swash plate. The friction of these parts may cause quality problems and deteriorate the durability. In this study, to reduce the frictional loss, a prototype with additional coating agents was produced. Moreover, an optimized design was generated, and performance, noise, and durability tests were conducted. A more durable product was successfully obtained.

• The KSFM Journal of Fluid Machinery
• /
• v.9 no.2 s.35
• /
• pp.13-18
• /
• 2006

This paper was studied to design Process considered flexibility and reliability of suction and discharge valves. Flexibility and reliability of valves are main important factors in compressor valves design. And they are incompatible with efficiency of compressor. In this study, we have performed the optimal design of CO2 compressor valves to consider these factors. At first, we analyzed performance simulation of compressor to obtain optimal flexibility level of valves. From this simulation, we could get some important data at valve design like the optimal natural frequency and the height of retainer. After that we studied to reliability of valves corresponding to optimal flexibility level by finite element method. For each case bending stress and natural frequency were obtained by it. Also we investigated the fatigue stability to obtain optimal valve shape that ensured to reliability.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.9 no.1
• /
• pp.88-95
• /
• 2000

In this paper, an expansion-resonator type pulsation attenuator is proposed to absorb and attenuate flow an pressure ripple with high frequencies generated from hydraulic control systems. The basic principle of a pulsation attenuator proposed here is applied to propagation, reflection, absorption of pressure waves at the cross section of discontinuity and resonance in the pipeline. It has advantage of the compact size and high degree fo freedom for installation in hydraulic systems. The design scheme based on distributed parameter pipeline system with dissipative viscous compressible model is developed. To investigate the reduction of flow and pressure ripple with high frequencies produced by swash plate type axial piston pump, two kinds of attenuators are manufactured. It is experimently confirmed that the spectral intensity of flow and pressure ripple with high frequencies from the pump are reduced up to about 20$^{\circ}$~30dB by using attenuators proposed here. The calculated results were in good agreement with the measured values. From there sults of this study, it is shown that an expansion-resonator type pulsation attenuator is effective in a wide frequency ranges to attenuate the flow and pressure ripple from hydraulic components.