Abstract: A method was proposed for measuring the speeds of hermetic reciprocating compressors based on discharge pressure pulsations.The suction and discharge valves of the hermetic reciprocating compressors were opened and closed with the reciprocating movements of pistons,resulting in pressure pulsations of compressor suctions and discharges,and the discharge pressure pulsations are more obvious than the suction pressure pulsations.The amplitudes of the pressure pulsations in the discharge chambers are higher than that in discharge pipes,and the speeds of compressor equal to the pressure pulsation frequencies with CZT after detrending.Therefore,the pressures in discharge pipes may be taken as the sampling signals for compressor speed measurements.Under different compression ratios,the speeds measured by this method were compared with the actual rotational speeds of the compressors.Experimental results show the effectiveness of the measuring method herein under different load conditions with the accuracy of ±1 r/min and the measuring time of 1 s.

Key words: discharge pressure fluctuation, compressor speed, Chirp-Z transform（CZT）, spectrum thinning, compression ratio

摘要： 提出一种基于排气压力脉动的全封闭往复式压缩机转速测量的新方法。全封闭往复式压缩机的吸排气阀片伴随着活塞的往复运动而开启与关闭,使压缩机吸排气产生压力脉动,排气压力脉动比吸气压力脉动明显。排气阀室较排气管出口压力脉动幅值明显,去除趋势项后经CZT变换得到的脉动频率和转速一致,故可将排气管出口压力作为新方法的采样信号。在不同压缩比工况下,新方法测得转速与压缩机实际转速进行对比,实验表明新方法在不同负载工况下都有效,精度为±1 r/min；测量时间为1 s。

关键词: 排气压力脉动, 压缩机转速, 线性调频Z变换, 频谱细化, 压缩比