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New Boston, MI, United States

A stepped capillary tube consisting of two serially connected capillary tubes with different diameters is invented to replace the conventional expansion device. The mass flow rate of refrigerant R410A in stepped capillary tubes with different size were tested. The model of stepped capillary tube is proposed, and its numerical algorithm for tube length and mass flow rate is developed. The experimental results show that the performance comparing between stepped capillary tube system and capillary tube assembly system, the cooling capacity is reduced by 0.3%, the energy efficiency ratio(EER) is equal to each other, the heating capacity is increased by 0.3%, the coefficient of performance(COP) is decreased by 0.3%. That is to say, the performance index of the two kinds of throttle mechanism is almost identical. It indicates that the stepped capillary tube can replace the capillary tube assembly in the R410A heat pump type air conditioner absolutely. The model is validated with experimental data, and the results show that the model can be used for sizing and rating stepped capillary tube. © (2014) Trans Tech Publications, Switzerland.


Xu Y.S.,Pump Engineering
Advanced Materials Research | Year: 2014

In order to calculate the structure size of stepped capillary tube, the experiments of flow characteristic of it were performed. The experience benchmark model of flow characteristics of R22 was set up through experimental method in specific reference conditions based on the impedance calculation method. The variable working condition model suitable for a range of conditions was obtained through fixing the condition based on the reference model. The mass flow rate of refrigerant R22 in two stepped capillary tubes with different size was tested. The experimental results show that the stepped capillary tube model has a high precision and working condition of certain flexibility. The deviation of cooling and heating flow between the calculated values and measured values are less than±10%. The model can meet the need of matching for stepped capillary tube on the heat pump type air conditioner with R22. © (2014) Trans Tech Publications, Switzerland.


Inaguma Y.,Pump Engineering
Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science | Year: 2012

This article presents a practical approach to the investigation of the influence of oil temperature on the friction torque in various types of hydraulic pumps using a mathematical model. Currently, an external gear, an internal gear or a vane pump is commonly used for an automatic transmission. These pumps have their own friction torque characteristics, which depend not only on pump-operating conditions such as operating pressures, pump speeds and oil temperature but also on structures and dimensions of the pumps. For various pumps, however, the friction torque characteristics can be represented by an identical mathematical model. In the pump-operating conditions, the oil temperature significantly and complicatedly affects them. The pump should be operated under conditions to obtain a higher mechanical efficiency, and the mathematical model is helpful to analyse how the oil temperature influences the friction torque. It is found that with an increase in oil temperature, the friction torque at a high pump speed decreases in a low oil temperature region, but it would not decrease in a high oil temperature region for all the tested pumps. This fact suggests that the pump overall efficiency would not improve at a high oil temperature, even if the volumetric efficiency does not go down. © IMechE 2011.


Inaguma Y.,Pump Engineering
Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science | Year: 2010

This paper presents a method of reducing friction torque in a hydraulic vane pump through a short-period pump operation by using physical vapour deposition (PVD)-coated vanes. It is well known that the friction torque in a vane pump as well as in other hydraulic machines can be reduced by running-in through a long-time pump operation. This paper revealed that the reduction in the friction torque was derived from lowered friction between a cam contour and vane tips owing to the smoothed surface of a cam contour. Commonly, it was difficult to obtain such an effect through a short-period pump operation. The author has attempted to lessen the surface roughness of the cam contour and to decrease the friction torque of a vane in a short period of time by using vanes coated with an extremely hard PVD layer on their tips. In this study, three kinds of coatings of chromium nitride (CrN), titanium carbonitride (TiCN), and diamond-like carbon (DLC) by PVD were examined. It was found that the TiCN-coated vane was excellent in smoothing the surface roughness of the cam contour and in reducing the friction torque of the vane in a short period of time. It was also shown that the reduced friction torque of the vane depended essentially on the smoothness of the cam contour surface. In addition, the difference of the friction at the vane tip between an ordinary vane and coated vanes was indistinct for the same surface roughness of the cam contour below 0.8 μ m Rz. © Authors 2010.


Inaguma Y.,Pump Engineering
Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science | Year: 2011

This paper describes the influence of pump operating conditions, such as operating pressures, pump speeds, and oil temperatures, on the friction torque characteristics of internal gear pumps for automobiles. Additionally, it presents a new mathematical model reflecting the influence of the oil temperature on the friction torque. In an internal gear pump, the friction torque was affected by oil temperature as well as operating pressure and pump speed. When the operating pressure was high, the influence of oil temperature on friction torque at a pump speed of less than 1000 r/min was contrary to that at a pump speed of greater than 1000 r/min. It was considered that the friction torque is fundamentally composed of three components: the component dependent on the operating pressure, dependent on the pump speed, and independent of both the operating pressure and the pump speed. However, the component dependent on the operating pressure was affected significantly by not only the pump speed but also the oil temperature. In addition, another factor besides the viscosity of the oil existed in the component dependent on the pump speed. A mathematical model for the friction torque characteristic of the internal gear pump was newly established by adding factors including the oil temperature to the Wilson's model. The new model was able to represent with accuracy the experimental friction torque characteristic in the internal gear pump under various pump operating conditions. © Authors 2011.

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