The key to affect the power of the sliding valve pump is the exhaust pressure of the pump, and the size of the exhaust pressure of the sliding valve pump depends on the design of the exhaust system.
The first is the structural design of the exhaust valve. The exhaust system of single stage slide valve pump can be made of composite structure of floating valve and spring valve. When the inlet pressure of the slide valve pump is very high, because of the large flow of gas, it can discharge large flow of gas through the combined action of floating valve and spring valve; when the inlet pressure is low, only a small amount of gas can be discharged through the action of floating valve. For a two-stage spool pump, when working near the limit pressure, the exhaust system of the two-stage spool pump can not adopt the structure of the floating valve because the flow rate of the gas extracted by the pump is too small to operate accurately by the floating valve.
The second is the reset device of the exhaust valve. Floating valve is operated by differential pressure without reset device. The spring valve is reset by spring force. On the premise that the exhaust valve can close in time at the end of exhaust, the spring elasticity coefficient of the exhaust valve should be smaller. Under the same exhaust pressure, the exhaust valve has a larger stroke, and the exhaust valve has better conductivity, which is conducive to reducing the exhaust pressure of the pump and reducing the slide valve. Pump power.
The third is the design of exhaust passage. From the point of view of reducing the power of the slide valve pump, when designing the exhaust passage, it is necessary to ensure that the compressed part of the pump is always connected with the exhaust passage during the exhaust process, so as to avoid ineffective compression and lubricant compression, which is conducive to reducing the power of the pump; secondly, the exhaust passage must have sufficient conductivity to ensure the rapid discharge of gas. It is helpful to reduce the exhaust pressure of the pump.
The viscosity of lubricating oil has great influence on pump power. The viscosity of the lubricating oil makes the moving parts of the pump suffer additional resistance in the course of operation. The higher the viscosity of the oil, the greater the resistance and the greater the power consumption. With the increase of temperature, the viscosity of lubricating oil decreases, the resistance caused by lubricating oil decreases, and the power consumption decreases. For example, when the inlet pressure of the H-150 slide valve pump is 3.3 *104 Pa, the power is 12.2 kW and 11.2 kW when the temperature of the pump is 50 centigrade and the temperature of the pump is 75 centigrade. The effect of lubricant viscosity on starting power of sliding valve pump is more obvious. For example, starting power of 412H sliding valve pump (normal operation with 7.5 kW motor) is 32 kW at 8 C and 34.5 kW at 4 C. This phenomenon can lead to difficulty in starting sliding valve pump in winter.
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