VF-0.850空气压缩机的设计（整体设计编程一、二级缸设计）【说明书+CAD】

购买设计请充值后下载，资源目录下的文件所见即所得，都可以点开预览，资料完整，充值下载可得到资源目录里的所有文件。【注】：dwg后缀为CAD图纸，doc,docx为WORD文档，原稿无水印，可编辑。具体请见文件预览，有不明白之处，可咨询QQ:12401814 中文译文供油系统和多供油系统螺杆式压缩机的润滑方法关谷；吉光(日本 守屋)摘要油液制冷压缩机应用于制冷等系统，在其系统中，由于高温和润滑剂粘度降低而造成的轴承材料强度降低和轴承材料寿命降低的问题已经得到解决。压缩机体的供油系统是由轴承供油系统（在低压下，为压缩机体的每个轴承进行润滑）和油液温控系统（在高压下，为压缩机体进行温度控制）组成。轴承供油系统是一个由油箱、油冷却器和油泵组成的闭环供油系统，油液温控系统是一个由隔油池和油冷却器组成的闭环供油系统。发明的最佳方案以相应的附图，现在将详细说明本发明的最佳的体现形式。然而，其目的是，除非特别指定发明中零部件的尺寸、材料和相对位置等等，不可仅仅解释为本发明的适用范围受限。图1 是依据本发明中螺杆式压缩机润滑油路的一个透视图示例。在图1中，引用数字 I 是温控油路，润滑油透过这条线路注入通向由图形转子和凹形转子组成的螺杆转子b的滑阀中，从而控制压缩液体时从中溢出的压缩液体温度。引用数字 II 是轴承润滑油油路，润滑油由这条油路到达转子轴c的滑动轴承d 和止推轴承e、减轻轴向载荷的平衡活塞g 和油封h，然后通过油路II流回图中未显示的油箱中。引用数字 III 是供油线路，它为驱动滑阀a的液压活塞p供油。这条线路是一条由本发明涉及到的线路I和II独立供油的闭合回路。线路III 与本发明不相关，因而解释从略。通过本发明中供油线路I和II的单独供油，压缩机便可以在温度、压力和经各线路供应润滑油流量最佳的条件下运转，从而使本发明的目标便得以实现。另外，本发明首要体现在如图2中的润滑油供应系统，引用数字1是螺杆式压缩机，2 是一对阴阳螺杆转子中的一个，它用来支撑压缩机1旋转的转子箱，3是在转子箱中为转子2注入润滑油的滑阀。引用数字1a是将液体f进行压缩的吸入口，1b是压缩液体f的卸料口，2a是转子轴2的一部分。压缩液体f由吸入口1a吸入压缩机1并被压缩，像转子2旋转一样，并与润滑油一起在加压状态下泄出。混合润滑油在隔油池4中与压缩气体分离。分离出的润滑油油冷却器5中冷却，透过过滤器6滤去杂质重新流回滑阀3。此闭环回路由温度控制和供油线路I组成并用虚线表示。引用数字7是的装有润滑油的供油槽，储备在供油槽7中的油液由供油泵8 通过油冷却器和过滤器供应到压缩机转子轴承的部件中，供应到转子轴承部件中的润滑油流经线路L.sub.3分支回路又重新回到供油槽7中。这个回路是由轴承润滑油油路II组成的并用实线表示。供油槽7中有用来监测油位的液面测量计13和油位发射器11，它们将被监测到的油位信号经液面测量计13发送给油位控制操作员12。温度控制阀14为上游的油冷却器9，由温度控制阀14分出的支路 L.sub.1，再由支路L.sub.1分出的支路L.sub.2装有调压阀15 允许一部分润滑油从供油泵8流回供油槽7。含有压力控制阀16的油路L.sub.4 与在供油槽上部的气带相连为吸油口附近的一个位置1a供油，含有调速阀17的油路 L.sub.5，在油路II中润滑油为吸油口1a附近的位置提供润滑。油路L.sub.6将通往供油槽7的一部分润滑油供应给温控油路I，在油路L.sub.6中有过滤器18和调速阀19。温度控制阀20在油冷却器5下游，由温度控制阀20分支出油路L.sub.7这一支路。隔油池4 的油位测量计22用来探测油位，当探测到液位低于下限时液控开关21发出警报。引用数字23、24和25 是温度探测器用来监测和发射监测到的温度信号，应用数字26、27、28和29是压力检波器用来探测和发射各条油路的压力信号。引用数字30是流量计，31是控制操作员依据供油泵8上游和下游区域的压力差和温度控制油路I和轴承润滑油路II的压力差来为轴承润滑油路II指定适当或最佳油压，同时通过调节控制调压阀15使轴承润滑油路II实现上述油压。引用数字32、33、34和35是单向阀，36是手控阀。图3A显示了转子和图1中第一个体现轴承零件的布局，在图中，如I所述润滑油注入转子空间内来控制压缩液f的温度，如II所属润滑油为轴承润滑。在图3A中，引用数字2 是一对阴阳转子，每个转子2由其轴上部件2a两端伸出滑动轴承42支撑。引用数字41是油封，43是止推轴承。引用数字44是机械油封。图3B和图3C分别是滑动轴承的放大截面视图，在图3A中用箭头B和箭头C指明。在图3B和图3C中，油槽45、46为每一个滑动轴承供油润滑并通过回油路L.sub.3使润滑油流回供油槽7。这种类型的轴承，可连同油封 41或无油密封件41。第一个体现了润滑油供应通过温控油路I和轴承润滑油路II 如图2和图3A所示，二无可避免地混合，因此宁可用相同种类的润滑油用于线路I和II中。润滑油的温控可以利用卸料口1b处的出口压力与压缩过程中转子室的压力的压差注入转子室。至于油的温度，油的温度来自于由温控油路I 和由轴承润滑油路II是不同的，由于这两条线路是两条相互独立的线路。例如，提高油注入转子的温度是有效的，为避免发生压缩气体在压缩机中的冷凝，可以通过减少或停止油的流动来实现，同时，降低油温以保证轴承润滑油适当的粘度。因此，先前的技术问题在于滑动轴承的强度的降低源于由于摩擦发热性和由于润滑油黏性的降低导致轴承寿命的降低，这些都是可以预防的。根据这种现象，转子室的注射油会使油温升高或者流量降低，为了避免压缩液体冷凝现象，那么液体中掺入润滑油的量润滑油可以有所减少。因此在温控油路I中的供油槽尺寸可以减小从而有的分离效率会有所增强。另外，混入液体f的外界杂质经压缩进入轴承润滑油油路II可被抑制到最低限度。此外，转子轴承润滑油的流量可降低到最低限度而且它的温度也会降到轴承润滑容许温度以下。因此，通过低粘度的润滑油已成为了可能（例如：矿物油），同样通过冲入高温压缩气体便无需润滑油的过渡冷却。此外，用轴承润滑油路II中的油路 L.sub.3 来回收为压缩机1轴承润滑的润滑油将其送入供油槽7中，用温控润滑油路I中的油路L.sub.6来隔油池4中一些个别的润滑油并用油冷却器5冷却，两条线路的润滑油包括漏油最终都会回到轴承润滑油路II的供油槽7中，所以这两条线路允许的润滑油一定量的泄漏。由于两条油路的润滑油会混在一起，所以所用的润滑油必须相同。如图3中所示，采用滑动轴承支撑旋转转子2，将润滑油通过低压油路L.sub.3分别引入在转子端面一侧在每个滑动轴承尾部一侧的槽45和46 中，是润滑油堆积在哪里，从而使润滑油在流动中做了暂态积累以便于润滑油的回收，这样润滑轴承润滑油的供油和回油可以轻松顺利的完成，从转子室到转子箱或者相反从转子箱到转子室润滑油的泄漏可以压缩至最低，同时允许的润滑油一定量的泄漏。换句话说，润滑油的泄漏可以通过润滑油在流动中做暂态积累后，在另一条恢复油路中形成另一种低压油的方式抑制，这时，在油路I和II上的泄漏可降至最低。此外，通过连入调压阀16的油路L.sub.4将轴承润滑油路II中供油槽7的气带连接到吸油口1a 附近的位置，轴承润滑油路II中供油槽7内气带的压力可以做到与被压缩的进口液体f或者在进出油口之间的中间压力一样，因此当启动压缩机1时，轴承润滑油路II中的供油槽7的压力上升可以避免，这就使得在压力检波器(26)监测到的出口压力与压力检波器(28)监测到的进口压力之间的压差作用下油喷入转子室的现象成为可能，即可以采用运转时的压差供油。此外，控制操作员31依据油泵8上游和下游的之间的压差(压力检波器27监测到的压力与压力检波器28监测到的压力之间的压差)和温控油路I中的废气压力(压力检波器26监测到的压力)与油泵8下游的油压 (压力检波器27监测到的压力)之间的压差控制开口压力的调压阀15，通过连入调压阀15的支路L.sub.2把油泵8下游的回油输送到供油槽7中，当启动压缩机时润滑油回路L.sub.2快速升压会得到缓解。此外，将油位发射器11接入轴承润滑油路II的供油槽7中，通过接入调速阀17的油路L.sub.5将循环润滑油从供油槽7通入温度控制油路I，通过接入调速阀19的温度控制油路I中的油路L.sub.6 将部分润滑油输送回供油槽7中，其中，调速阀17和19依据油位发射器11所监测到的油位进行控制。控制操作员12 负责监控供油槽7 中的油位保持在一定的预定范围之内，使得供油槽7中的油位可保持在预定范围之内，同时由于轴承润滑油路II与温控油路I等之间的漏油所引起油位的变化会得到抑制。此外，转子轴承可采用低温高黏度的润滑油，通过分支油路L.sub.1使卸出的润滑油从油泵8绕过轴承润滑油路II中的油冷却器9，接入温度控制阀14来控制进入支路L.sub.1的润滑油的温度，并且用温度控制阀14的开口来调节供给轴承转子润滑油的油温。此外，通过采用使供油槽7上方的气带保持与压缩机1的进油压力或者在吸油和卸油之间的中间压力相同的操作方法，在运转过程中利用压缩机进口和出口的压力差将油注入转子室并保持供油槽7中的气压与进油压力或者进出口之间的中间压力相同，压力差是由于压缩机的出口压力与轴承润滑油路II的供油压力而产生的。这使得采用压差供油成为可能，从而使轴承润滑油路II中的压力的异常上升得以避免。虽然阀16、17和19是关闭的，当运转的系统停止时，温控供油回路I中的润滑油不会与轴承润滑回路II中的润滑油混合在一起，但是转子室向轴承漏油是不可避免的。有人认为，供油槽7中的压力变得与工业气体的压力(换言之液体f的出口压力)相同。通过控制温控供油回路I与轴承润滑供油回路II之间的压差，当供油泵8在系统再次启动被驱动时，轴承润滑供油回路II中油压的快速上升是可以避免的。此外，调压阀16是受控的以便在空转并伴随着开机后的最低负载，供油槽7中的压力逐渐变为额定压力。在本方案中，用平衡活塞来避免来自止推轴承过大的推力，当运转时，滑阀3 处于最低负载位置来减小启动力矩，甚至当平衡活塞的共有压力较低时可以避免过大的推力。因此，轴承润滑油的压力（压力检波器27监测到的压力）也很容易确定 ，从而有的流量可以在所需最小流量。当供给平衡活塞的必要油压在正常运转时，提供一个来自另一轴承润滑油路的油路为平衡活塞独立的供油将会十分有效。在这种情况下，另一轴承润滑油路中的流量当被严格控制在所需最小流量。当启动运转时，假设转子室没有润滑油。如前面的假设，凭借压缩机进口和出口的压力差将油喷射乳转子室，尽管转子室内发生无润滑状况，压缩机仍然可以做短暂启动。因此，人们担心发热导致阴阳转子发生接触，除非是用定式齿轮精确控制转子类型的压缩机，在启动时适当的将调速阀17微微打开。为了使压缩机不完全启动后从转子室到轴承润滑油路II的高压气体和高压油的泄漏降至最低，在螺杆式压缩机和隔油池4之间安装单向阀或者自动阀是十分有效的，从而就会尽量阻止高压气体就侵入压缩机的内部。尽管所有的油路基本上都是闭合回路，但是各个管路之间也可能漏油，供油槽7和隔油池4中的油位可以被受油位控制操作员12控制的调速阀17和19 控制。但是，螺杆式压缩机压缩的开环压缩气体，之所以喷油回路中的油会慢慢减少至耗尽是因为一部分油与压缩气体一并被送入油路中去。当喷射油路中的油耗尽时，别无选择的从轴承润滑油路II里调速阀19的缝隙中供油。当连续启动时，一些从轴承至转子室的漏油像喷射油一样是可以预料的。有人认为，在温控油路I中即使缺油仍然可能照常运转。然而，像轴承润滑回路II，缺油是不允许的。因此，至于被控制操作员31控制的，正常的连续运转中供油槽7中的油位控制优先被控制操作员12控制是十分有效的。有一种方法提供低位警报就像喷射油路I中所有的油，但由于喷射油路仅仅对压缩机工业废气的温度有影响，当废气温度高于规定温度时，压缩机的运转会因温度过高跳闸而停止运转。图4是依据本发明螺杆式压缩机的润滑油供应系统第二方案的部分阻滞简图。在图4中，其中的器件及零部件与图2和图3中注明的引用数字相同。在图4中，油路L.sub.8 是来自轴承供油润滑油路II的供油支路，为平衡活塞51供油，引用数字52和53分别是调速阀和监测轴承润滑油路II中流量与发射监测信号的流量探测器。在结构上除了那些添加的器件和零部件都与方案一中相同。在第二方案中，油泵8为平衡活塞51和为轴承及油封加压供油，加压供油分为两条线路以便把高压油供给平衡活塞（平衡活塞需要供应高压油），并且压力方面使油减少源于轴承/油封，对于他们油量很重要而不是压力。供油泵8打出的压力油，即供给到平衡活塞51油压力的控制是由控制操作员31完成的，控制操作员首先依据压力检波器26检测到的废气压力和压力检波器29检测到的吸气压力估算施加到阳转子上的推力，然后确定施加到平衡活塞51上的反抗力并且通过控制压力控制阀15来控制平衡活塞供油压力的大小，从而通过供给到平衡活塞上的压力油将适当的反抗力施加到平衡活塞上。轴/油封的油料供应流由流量调节阀52调节，因此始终需要流量探测器53对流速进行探测。当压缩机轻负荷运行时，对于轴可以使用较低的润滑油压，但是必须设定最小允许流速以确保安全。根据第二个发明，将轴润滑油供应线II分为两条线路，即通过油料供应线L.sub.8 为平衡阀51供油通过另一条线路为轴承/油封供油，采用流量控制阀52控制上述的另一条线路为轴承/油封供油，可以分别为平衡活塞和轴承/油封保持适当的油流量和流速。当平衡阀51的压力（由压力检测器26和27监测压差）达到最小压力时，即当平衡阀的需求流量不能超过对于轴承/油封的最小允许流量时，流量调节阀52开始进行调节，致使流量调节阀53对流速进行调节使其超过上面给定的下限。工业应用以在冷却系统中的应用为例，此发明将为螺旋式压缩机供应润滑油的润滑油供应系统划分为压缩机转子供油的低压润滑油供油线和通过与压缩机压缩进程中的流体相连来控制压缩机压缩空气的温度的高压温度控制供油线。轴承润滑油经油冷却器冷却并变得黏稠，通过供油罐的润滑油供应泵为轴承提供持续供应。因此，可以避免卡死现象和和轴承耐磨性降低且轴承寿命得以延长。此外，转子的轴承润滑油流量可减少到最低，压缩机压缩气体的排气温度允许达到很高的温度，轴承润滑的润滑油的供应温度可以比轴承允许温度更低，轴承的润滑在低压力与低黏度下进行使润滑油供应系统得以实现。 另外，可以缩小诸如隔油池这样的仪器部件的体积，这样不仅可以提高油的分离效率而且可以减小外来因子对润滑油液体的扰乱。此外，它可以缓解压缩机开机时，避免由于轴承润滑油路供油槽内压力过度上升带来的轴承润滑油油路的润滑油压力的急剧上升，并可通过压缩机输送压力和吸进压力之间的压力差向转子室注入润滑油。在这个案例中采用了平衡活塞，可以持续维持平衡活塞和每一个轴承（正常工作）所必须的油的供应压力。英文原文Lubricant supply system and operating method of multisystem lubrication screw compressorSekiya; Yoshimitsu (Moriya, JP)Abstract An oil refrigeration screw compressor being applied to a refrigeration system etc., in which the problem of strength reduction of a bearing material under high temperatures and that of lifetime reduction of the bearing material due to viscosity lowering of lubricant are solved. A lubricant supply system to a compressor body is divided into a bearing oil supply system for supplying lubricant to each bearing of the compressor body at low pressure and into a temperature control oil supply system for supplying lubricant into the compressor body at high pressure. The bearing oil supply system is a closed circuit oil supply system comprising an oil supply tank, an oil cooler, and an oil supply pump, and the temperature control oil supply system is a closed circuit oil supply system comprising an oil separator and an oil cooler. BEST MODE FOR EMBODIMENT OF THE INVENTION Preferred embodiment of the present invention will now be detailed with reference to the accompanying drawings. It is intended, however, that unless particularly specified, dimensions, materials, relative positions and so forth of the constituent parts in the embodiments shall be interpreted as illustrative only not as limitative of the scope of the present invention. FIG. 1 is a schematic illustration of an example of lube oil supply line of the screw compressor according to the present invention in a perspective view. In FIG. 1, reference numeral I is an oil supply line for controlling temperature, lube oil is supplied through this line to be injected from a slide valve toward screw rotors b consisting of a male rotor and a female rotor in order to control temperature of the compressed fluid discharged from the compressor together with the compressed fluid. Reference numeral II is a bearing lubricating oil supply line, lube oil is supplied through this line to sleeve bearings d and thrust bearings e of rotor shafts c, to a balance piston g for reducing thrust load, and to an oil seal h, and flows out to a return path II which communicates to an oil supply tank not shown in the drawing. Reference numeral III is an oil supply line for supplying oil to a hydraulic piston p for driving the slide valve a. This line is a closed line provided separately from the line I and II which are related to the present invention, The line III is not related to the invention, so explanation is omitted. By providing the oil supply lines I and II separately from each other in the invention, the compressor can be operated at optimal conditions concerning temperature, pressure, and flow rate of lube oil supplied via each of the oil supply lines, and the objects of the present invention can be attained. Next, in FIG. 2 showing the lube oil supply system of the first embodiment of the invention, reference numeral 1 is a screw compressor, 2 is a screw rotor of a pair of male and female screw rotors supported rotatably in the rotor casing of the compressor 1, 3 is a slide valve for injecting lube oil to the rotor 2 in the rotor casing. Reference numeral 1a is a suction port of fluid f to be compressed, 1b is a discharge port of compressed fluid f, and 2a is a shaft part of the rotor 2. The fluid f to be compressed is sucked from the suction port 1a into the compressor 1 and compressed as the rotors 2 rotate to be discharged in a pressurized state together with lube oil mixed in it. The mixed lube oil is separated from the compressed gas in an oil separator 4. The separated lube oil is cooled in an oil cooler 5, filtered through a filter 6 to remove foreign matter, and again returned to the slide valve 3. This closed circulation circuit composes the temperature control, oil supply line I and shown by a broken line. Reference numeral 7 is an oil supply tank in which lube oil is reserved, the oil reserved in the oil supply tank 7 is supplied by means of an oil supply pump 8 to rotor bearing parts of the compressor via an oil cooler and a filter 10. The lube oil supplied to the rotor bearing parts is recovered to the oil supply tank 7 passing through a return path L.sub.3. This closed circuit composes the bearing lubricating oil supply line II and shown by a solid line. The oil supply tank 7 is provided with a liquid-level meter 13 for detecting oil levels and a liquid level transmitter 11 for sending oil levels detected by the liquid-level meter 13 to an oil-level control operator 12. A temperature control valve 14 is provided in the upstream of the oil cooler 9, a branch path L.sub.1 branches from the temperature control valve 14, and a branch path L.sub.2 equipped with a pressure regulator valve 15 branches from the branch path L.sub.1 for allowing a part of the lube oil from the oil supply pump 8 to be returned to the oil supply tank 7. A path L.sub.4 is provided which communicates the gas zone in the upper part of the oil supply tank 7 to a position near the suction port 1a, a pressure regulator valve 16 is provided in the path L.sub.4, and a path L.sub.5 having a flow regulator valve 17 is provided for allowing the lube oil in the oil supply line II to be supplied to the position near the suction port 1a. A path L.sub.6 is provided to the temperature control oil supply line I for supplying a part of the lube oil to in the line to the oil supply tank 7, and a filter 18 and a flow regulator valve 19 are provided in the path L.sub.6. A temperature control valve 20 is provided in the downstream of the oil cooler 5, and a path L.sub.7 branches from the temperature control valve 20. The oil separator 4 is provided with a liquid-level meter 22 for detecting oil levels and a liquid-level switch 21 for allowing an alarm to be sounded when the detected oil level has lowered to a limit level. Reference numerals 23, 24, and 25 are temperature detectors for detecting and transmitting signals of detected temperatures, and reference numeral 26, 27, 28, and 29 are pressure detectors for detecting pressure and transmitting signals of detected pressures provided to each of the paths respectively. Reference numeral 30 is a flow detector, 31 is a control operator for determining oil pressure adequate or optimal for the bearing lubricating oil supply line II based on the pressure difference between the upstream and downstream zone of the oil supply pump 8 and on the pressure difference between the temperature control oil supply line I and bearing lubricating oil supply line II, and for controlling the pressure regulator valve 15 so that said adequate oil pressure is realized in the bearing lubricating oil supply line II. Reference numerals 32, 33, 34, and 35 are non-return valves, and 36 is a manual valve. FIG. 3A shows arrangement of rotors and bearing parts of the first embodiment shown in FIG. 1. In the drawing, lube oil injected into the rotor room to control temperature of compressed fluid f is indicated by I, and lube oil supplied to lubricate bearings is indicated by II. In FIG. 3A, reference numeral 2 is a pair of male and female rotors, each of the rotors 2 is supported by journal bearings 42 at its shaft parts 2a extending from both ends thereof. Reference numerals 41 are oil seals, 43 are thrust bearings. Reference numeral 44 is a mechanical oil seal. FIG. 3B and FIG. 3C are respectively an enlarged sectional view of the journal bearing indicated by an arrow B and arrow C in FIG. 3A. In FIG. 3B and FIG. 3C, an oil groove 45, 46 is provided in each of the journal bearings for returning lube oil to the oil supply tank 7 via the oil return path L.sub.3. Journal bearings of this type may be used together with the oil seals 41 or without the oil seals 41. In the first embodiment shown in FIG. 2 and FIG. 3A, lube oil supplied via the temperature control oil supply line I and via the bearing lubricating oil supply line II inevitably mix with each other, so preferably lube oil of the same kind is used for the lines I and II. Lube oil for controlling temperature can be injected into the rotor room by utilizing pressure difference between the discharge pressure at the discharge port 1b and the pressure in the rotor space under compression process. As to temperature of oil, temperature of the oil supplied via the temperature control oil supply line I and that supplied via the bearing lubricating oil supply line II can be made different, for the two lines I and II are separate lines. It is effective, for example, to raise the temperature of the oil injected into the rotor room for temperature control in order to prevent occurrence of condensation of the gas compressed in the compressor by decreasing or stopping oil flow and decrease the temperature of the oil supplied to the bearings in order to secure proper viscosity of the lube oil. Herewith, aforementioned problems in the prior art, that is, reduction in strength of slide bearings due to heat generation by friction and reduction in bearing life due to lowering in viscosity of lube oil, can be prevented. According to the embodiment, injection oil supplied to the rotor room can be raised in temperature or decreased in flow rate for the purpose of preventing occurrence of condensation of compressed fluid, so the amount of lube oil mixed in the fluid can be reduced. Therefore, the oil separator in the temperature control oil supply line I can be small sized and oil separation efficiency can be increased. Further, intrusion of foreign matter contained in the fluid f to be compressed to the bearing lubricating oil supply line II can be suppressed to the minimum. On the other hand, the amount (flow rate) of lube oil for lubricating rotor bearings can be reduced to the minimum and its temperature can be lowered below permissible temperature for bearing lubrication. Therefore, it is made possible to adopt low viscosity lube oil, for example, mineral oil, and also to maintain the compressed gas in high temperature without excessively cooled by lube oil. Further, by providing the path L.sub.3 in the bearing lubricating oil supply line II in order to recover the lube oil after lubricating bearings of the compressor 1 to the oil supply tank 7 and the path L.sub.6 in the temperature control oil supply line I in order to supply a part of the lube oil separated in the oil separator 4 and cooled by the oil cooler 5, lube oil in both lines including lube oil leaked between both lines can be eventually recovered to the oil supply tank 7 in the bearing lubricating oil supply line II, so a little leakage between both lines is acceptable. The same lube oil must be used for both lines, for lube oil in both lines mixes with each other.As shown in FIG. 3, by adopting slide bearings for supporting rotatably the rotors 2 and providing grooves 45 and 46 respectively near the rotor end face side end of each slide bearing to allow lube oil to be accumulated therein so that the lube oil accumulated in the groove is introduced to the lube oil recovery path L.sub.3 of low pressure, supply and recovery of lube oil for lubricating the bearings can be performed easily and positively, and leakage of lube oil from bearing space into the rotor casing or on the contrary from the rotor casing into the bearing space can be suppressed to the minimum while allowing the leakage of a certain amount of lube oil. That is, leakage of lube oil can be suppressed by allowing lube oil to accumulate transiently in the grooves and recovering again to another low pressure lube oil recovering path. By this, lube oil leakage between both lines I and II can be minimized. Further, by providing the path L.sub.4 for communicating the gas zone in the oil supply tank 7 in the bearing lubricating oil supply line II to a position near the suction port 1a and attaching the pressure regulator valve 16 to the path L.sub.4, pressure of the gas zone in the oil supply tank 7 in the bearing lubricating oil supply line II can be made to be at a pressure the same as suction pressure of fluid f to be compressed or intermediate pressure between suction and discharge pressure, so pressure rise in the oil supply tank 7 in the bearing lubricating oil supply line II when starting operation of the compressor 1 can be prevented, and it is made possible that oil injection into the rotor room can be performed by pressure difference between discharge pressure detected by the pressure detector (26) and suction pressure detected by the pressure detector (28), that is, oil supply by pressure difference in operation can be adopted. Further, by providing the branch path L.sub.2 for returning lube oil in the downstream of the oil supply pump 8 to the oil supply tank 7, attaching the pressure regulator valve 15 to the branch path L.sub.2, and providing the control operator 31 for controlling the opening of the pressure regulator valve 15 based on the pressure difference between oil pressure in the downstream and upstream of the oil supply pump 8 (pressure difference between the pressure detected by the pressure detector 27 and that detected by the pressure detector 28) and the pressure difference between discharge gas pressure in the temperature control oil supply line I (pressure detected by the pressure detector 26) and oil pressure in the downstream of the oil supply pump 8 (pressure detected by the pressure detector 27), a rapid pressure rise in the lube oil recovery path L.sub.2 when staring operation of the compressor can be alleviated. Further, by providing the oil-level meter 11 to the oil supply tank 7 in the bearing lubricating oil supply line II, providing the path L.sub.5 for returning lube oil from the oil supply tank 7 to the temperature control oil supply line I, providing the flow regulator valve 17 to the path L.sub.5, providing the flow regulator valve 19 to the path L.sub.6 in the temperature control oil supply line I to recover a part of lube oil to the oil supply tank 7, the flow regulator valves 17 and 19 being controlled based on the oil level detected by the oil-level meter 11, and providing the control operator 12 for controlling the level of the oil in the oil supply tank 7 in a predetermined range, the level of the oil in the oil supply tank 7 can be maintained in a prescribed range and variation of the oil level caused by oil leak between the bearing lubricating oil supply line II and temperature control oil supply line I etc. can be suppressed. Further, by providing the branch path L.sub.1 for allowing the lube oil discharged from the oil pump 8 to bypass the oil cooler 9 in the bearing lubricating oil supply line II, attaching the temperature control valve 14 for controlling lube oil temperature to the branch path L.sub.1, and controlling temperature of lube oil supplied to the bearings of the rotors by controlling the opening of the temperature control valve 14, lube oil of low temperature and high viscosity can be supplied to the bearings of the rotors. Further, by adopting an operating method with which the gas zone in the upper part of the oil supply tank 7 is maintained at the same pressure as suction pressure of the compressor 1 or intermediate pressure between suction and discharge pressure, pressure difference is produced between the discharge pressure of the compressor and the oil supply pressure of the bearing lubricating oil supply line II, and it is made possible to adopt oil supply by pressure difference in operation to inject oil into the rotor room toward the rotors by pressure difference between the discharge and suction pressure of the compressor, and by maintaining the gas pressure in the oil supply tank 7 to be the same as suction pressure or intermediate pressure between suction and discharge pressure, abnormal rise in pressure in the bearing lubricating oil supply line II can be prevented. Although the valves 16, 17, and 19 are closed so that the lube oil in the temperature control oil supply line I does not mix with the lube oil in the bearing lubricating oil supply line II when operation of the system is halted, occurrence of oil leak from the rotor room to bearings can no be evaded, and it is thought that the pressure in the oil supply tank 7 becomes the same as pressure of process gas, i.e. discharge pressure of the fluid f. By controlling pressure difference between the pressure in the temperature control oil supply line I and that in the bearing lubricating oil supply line II, a rapid rise in oil pressure in the bearing lubricating oil supply line II can be prevented when the oil supply pump 8 is driven by starting operation of the system next time. Further, the pressure regulator valve 16 is controlled so that pressure in the oil supply tank 7 gradually becomes a prescribed pressure in idle operation with a minimum load after starting of operation of the system. In the embodiment, a balance piston is provided to avoid excessive thrust force from exerting on the thrust bearing, and when starting, the slide valve 3 is positioned at a low load position for reducing starting torque, so occurrence of excessive thrust force can be avoided even when pressure of oil supplied to the balance piston is low. Therefore, it is also possible to determine bearing lubricating oil pressure which is detected by the pressure detector 27 so that the flow rate of the oil is at a minimum necessary flow rate. When oil pressure required to be supplied to the balance piston in ordinary operation, it will be effective to provide an oil supply line for supplying oil to the balance piston separately from the other bearing lubricating oil supply line. In such a case, the flow rate in the other bearing lubricating oil supply line is controlled for securing a minimum necessary flow of lube oil. When starting operation, it is supposed that there exists no lube oil in the rotor room. As oil injection into the rotor room by pressure difference between discharge pressure and suction pressure of the compressor, a state of no lubrication occurs in the rotor room although for a short period at the start of operation of the compressor. Therefore, heat generation is feared to occur by the contact of the male rotor with female rotor unless the compressor is of a type in which engagement of the rotors is defined by timing gears, so it is suitable to open the flow regulator valve 17 a little when starting. In order to minimize leakage of high-pressure gas and oil from the rotor room to the bearing lubricating oil supply line II just after halting operation of the compressor, it is also effective to provide a non-return valve or automatic valve between the screw compressor and the oil separator 4 so that high pressure gas does not intrude into the inside of the compressor as far as possible. All of the oil supply lines are basically closed circuits although oil leak may occur between each of the lines, oil levels in the oil supply tank 7 and oil separator 4 can be controlled by controlling the flow regulator valves 17 and 19 by the oil-level control operator 12. However, in an open cycle of compressing gas by a screw compressor, the oil in the injection oil supply line reduces in amount by little and little and will eventually be exhausted, for a part of the oil is sent out of the line together with the compressed gas. When the oil in the injection supply line is exhausted, there is no choice but to supply oil from the bearing lubricating oil supply line II by opening the flow regulator valve 19. When operating continuously, some amount of oil leaking from the bearings into the rotor room can be expected to serve as injected oil, and it is thought that operation may be able to be continued even if oil is deleted in the temperature control oil supply line I. However, as to the bearing lubr