Research On The Discharge Process And Working Characteristics Of The Reed Valve In A Scroll Compressor Based On The Coupled Compressor-Valve Numerical Model

Scroll compressors were widely used in refrigeration and air conditioning,vacuum,food and medical fields because of their compact structure and small size and light weight.In recent years,with the development of electric vehicles,the requirements of high cooling and heat production in the car make the scroll compressor gradually applied to small passenger cars.However,due to the small installation space in the cabin of the car,the size of the vehicle scroll compressor was small and its design internal pressure ratio was low.In order to achieve a given pressure ratio,the discharge port was mostly equipped with a reed valve.Under the action of the reed valve,the compressor exhaust process was shortened and the resistance is increased,but the exhaust backflow is also weakened.At the same time,the operating characteristics of the reed valve were also influenced by the compressor discharge pulsation.Therefore,it was important to study the transient coupling operating characteristics of the compressor-reed valve to improve the efficiency of the compressor and the reliability of the reed.In this paper,a numerical model of the compressor-reed valve coupling was established to study the characteristics of the compressor discharge process and the dynamic operating characteristics of the reed valve under the action of the machine valve coupling.The main work was as follows:(1)A numerical model of the compressor-reed valve coupling non-stationary state was developed and validated against experimental results.The results showed that the cyclic opening and closing of the reed valve leads to the formation of multiple vortices in the discharge chamber,resulting in enhanced discharge mass flow pulsation.As the fluid in the valve chamber needs to overcome the preload torque and elastic torque of the reed valve,the maximum pressure in the valve chamber exceeded the discharge pressure by 8.8%,thus forming a large pressure gradient at the clearance and a pair of approximately centrosymmetric leakage vortices,and the leakage flow also caused asymmetric axial temperature distribution in the chamber.(2)In the early stage of valve opening,the valve clearance cross-section was small,the flow resistance was large,and the pressure distribution on the lower surface of the reed shows a trend that the center of the valve chamber was the high pressure area and decreases outward in a circular pattern.With the spindle rotation,the valve chamber volume decreases,the valve chamber fluid thrust on the reed continues to rise,the reed lift increases,and its upper pressure distribution was more concentrated.After the valve was closed,the pressure in the valve chamber decreases continuously,and the maximum pressure difference between the two cavities can reach 0.378 MPa,and the fluid leaks into the valve chamber through the valve clearance by the discharge chamber.(3)As the reed preload torque increases,the reed opening pressure and the maximum pressure in the valve chamber increase,but the maximum pressure difference between the valve chamber and the discharge chamber decreases,and the maximum leakage from the discharge chamber to the valve chamber was reduced by 52.5%.The increase in the reed preload torque leads to an increase in the fluid torque on the reed,but the combined torque on the reed decreases,resulting in a 46.1%decrease in the maximum lift of the reed,an 8.8%decrease in the valve opening time,and a decrease in the spring torque.(4)The increase in speed causes the leakage in the working chamber to decrease and the pressure in the chamber to rise slowly,resulting in the delayed opening of the reed,but the reed opening angle interval was maintained at about 230°.The mass flow rate of suction and discharge increases,and the degree of pulsation increases,but the number of pulsation decreases.When the spindle speed was doubled,the maximum fluid torque on the reed increases by 48.1%,the maximum lift of the reed increases by 76.8%,the fluid flow rate was faster,and the vortex formed at the valve clearance was larger.Also,the maximum pressure difference between the discharge chamber and the valve chamber increased by 41.2%during the valve closing period,and the leakage from the discharge chamber to the valve chamber increased by 6.45%.