Centrifuge is an instrument for separating samples. It is widely used in the fields of dry biomedicine, petrochemicals, agriculture, food hygiene, etc. It uses the difference in precipitation speed of different substances in the centrifugal force field to achieve the analysis and separation of samples. Since the advent of the centrifuge, it has undergone changes of low speed, adjustment and overspeed, and its progress is mainly reflected in two aspects of centrifugal equipment and centrifugal technology, which complement each other. From the perspective of rotation speed, desktop centrifuges basically belong to the category of low-speed and high-speed centrifuges, so they have the technical characteristics of low-speed and high-speed centrifuges, and their structure is mainly composed of motor drive systems, refrigeration systems, mechanical systems, rotors, and system control. Compared with the floor centrifuge, the composition is only a little smaller in size and capacity. The development of universal desktop centrifuges has blurred the boundaries of low-speed, high-speed, micro- and large-capacity centrifuges, and many rotors provide researchers with a wide range of applications, becoming the first choice for scientific research laboratories.
We combine the popular desktop centrifuges at home and abroad. Focusing on the functional structure, the key technology of desktop centrifuge and its application are introduced, and we hope to provide useful selection suggestions through the technical summary and comparison of popular models at home and abroad.
、交流变频调速将逐步取代直流调速 1.AC variable frequency speed regulation will gradually replace DC speed regulation
The speed regulation system is the core part of the centrifuge. It consists of three major elements: control, power drive and motor. It mainly controls the speed of the motor. In the development of centrifuges, DC speed regulation is indispensable. Its main characteristics are good starting and braking, wide speed regulation range, simple structure, low cost, and mature theory and practice. Centrifuges are widely used and mature, so they were widely used in centrifuges before the 1980s.
Heraeus 、 Hettich 等，我国也将变频调速离心机列为攻关计划，部分厂家已经推出变频调速离心机，如上海安亭科学仪器厂， 上海博翎仪器设备有限公司 等。 Although DC speed regulation has a long history and mature technology, the commutator commutation of DC motors is its fatal weakness. After the 1990s, almost all of the major foreign centrifuge manufacturers' products adopted frequency conversion speed regulation technology, regardless of overspeed and high speed. , Or low-speed centrifuges, such as Heraeus , Hettich , Germany , etc., China also listed variable frequency speed governing centrifuges as a key project, some manufacturers have launched variable frequency speed governing centrifuges, such as Shanghai Anting Scientific Instrument Factory, Shanghai Bo Yi Instrument Equipment Co., Ltd. Company, etc. According to the different AC motors, the frequency conversion speed regulation is also different. At present, there are mainly three types of motors used in frequency conversion speed regulation centrifuges: asynchronous induction motors, brushless DC motors and variable reluctance motors. 年 SORVALL 应用无刷直流电机首次推出 RC － 285 亚超速离心机， Beckman 应用可变磁阻电机生产出转速高达三万转的 Avanti 系列离心机，其起制动加减速率比同类离心机快一倍，但目前应用最普及和最成熟还是异步感应电机。 In 1988 , SORVALL applied a brushless DC motor for the first time to launch the RC - 285 sub-super centrifuge. Beckman applied a variable reluctance motor to produce an Avanti series centrifuge with a speed of up to 30,000 rpm . Its acceleration and deceleration rates are faster than similar centrifuges. Double, but currently the most popular and mature application is asynchronous induction motors.
、多功能、自动化和微机控制 2.Multi-function, automation and microcomputer control
With the development of centrifuge manufacturing and application technology, centrifuges have not only made progress in speed regulation technology, but also made great progress in multi-function and automation aspects, such as variable rate braking, program shifting, direct input of centrifugal force, and operation procedures. Storage and recall, automatic diagnosis of the instrument status, requirements to display the centrifuge parameters and status information as fully as possible, more comprehensive safety protection functions, etc. Some functions are not only icing on the cake, but also directly affect the centrifuge effect, such as variable rate control Movement and program speed can improve the centrifugal effect and shorten the centrifugation time.
With the use of microcomputer technology, software can replace hardware functions or perform functions that are difficult to achieve in hardware, such as centrifuge program control and motor control. This not only greatly simplifies the structure of the hardware, but also multi-function and automation become a reality. The core of a centrifugal microcomputer control system is a single-chip microcomputer. The hardware system includes: an operation interface, a motor control interface, a temperature control interface, a safety protection monitoring interface, and a system monitoring. ， VBG7Z) ，离心机和离心管的工业标准 (DIN58970 ， PARTI ， 2 ， 3and4) 。 Improper use of centrifuges, such as overspeed, overload, imbalance, etc., may damage the instrument and even explode the head, threatening personal safety. Therefore, manufacturers pay special attention to safety design, and international and national countries have also formulated corresponding safety standards, such as Germany Standards for Accident Protection of Centrifuges (UVV , VBG7Z) , Industry Standards for Centrifuges and Centrifuge Tubes (DIN58970 , PARTI , 2 , 3and4) .
3. Environmental protection is mainly manifested in two aspects,
制冷，但目前采用半导体制冷的离心机尚不多见；二是降噪音，一般通常谈话声为 60 分 p ，公共气车行驶声为 70 至 80 分贝，医学研究表明， 70 分贝以上的噪音能干扰谈话，造成心烦意乱，影响工作，甚至引起事故，根据我国产品质量检验机构计量认证技术考核规范 (fiG102 一 90) ，测试实验室的噪音不得大于 70dBo 通常离心机采用的降噪音措施有：外壳和转动头腔体加吸音涂层；采用坚固稳重的抗震底座与机械框架用弹性减震器隔离；应用无整流子电机等。 The first is that the refrigeration system uses fluorine-free refrigerants or semiconductors (Peltier) for refrigeration, but centrifuges that use semiconductors for refrigeration are currently rare; the second is to reduce noise. Generally speaking, the conversation sound is 60 minutes p , and the public air vehicle is 70 To 80 decibels, medical research shows that noise above 70 decibels can interfere with conversations, cause upsets, affect work, and even cause accidents. According to China's product quality inspection agency measurement certification technology assessment specifications (fiG102-90 ) , the test laboratory The noise should not be greater than 70dBo . The noise reduction measures commonly used in centrifuges are: shell and rotating head cavity with sound-absorbing coating; a solid and stable seismic base is used to isolate the mechanical frame with an elastic shock absorber; and no commutator motor is used. 60 分贝以内。 After the shock absorption process, the noise of the centrifuge can be limited to 60 decibels.