Hydraulic system and the typical fault mechanism analysisAbstract: the article to hydraulic system working principle as the foundation, study the hydraulic system failure form, described the methods for solving this kind fault. Keywords: hydraulic cylinder Control valvesHydraulic pump 1.Working principle Hydraulic transmission is based on liquid medium for work, through the energy conversion to implement executive agency needs a kind of movement transmission mode. First of all, hydraulic pump will motor (or other prime mover) mechanical energy into liquid pressure can, and then, through the hydraulic cylinder (or hydraulic motor) will with liquid pressure can be transformed into mechanical energy to drive the load movement. 2.Hydraulic system composition Hydraulic transmission system is usually the following five parts. （1）The power plant parts. Its role is to motor (or other prime mover) provide mechanical energy into liquid pressure. Say simply, it is to the system to provide the pressure oil device. Such as all kinds of hydraulic pump. （2）Control adjusting device parts. Including pressure, flow rate, direction control valves, is to control and adjustment of the hydraulic system the fluid flow pressure, flow and flow direction, in order to meet the required force working parts (or torque), speed (or speed) and the movement direction (or movement cycle) requirements. （3）Actuators parts. Its role is to pressure liquid into mechanical energy to drive the working parts of sports. Including hydraulic cylinder and hydraulic pressure motor. （4）Automatic control parts. Is mainly refers to the electrical control device. （5）Auxiliary devices parts. In addition to the four other than most of the oil tank, oil tube, integrated blocks, oil filters, accumulator, pressure gauge, heater, cooler, and so on. They work to ensure the reliability of hydraulic system and stability is indispensable, has the vital role. 3.Hydraulic cylinderThe hydraulic cylinder is put into mechanical energy of hydraulic actuators. The hydraulic cylinder common faults are: hydraulic cylinder, hydraulic external leakage, crawling hydraulic cylinder mechanical strength, hydraulic cylinder don't air intake, hydraulic cylinder impact, etc. 3.1The hydraulic cylinder crawling failure analysis and processing (1) cylinder or conduit memory with air, processing methods: set exhaust device; If not exhaust device can start the hydraulic system to the largest travel reciprocating several times, eliminate air force; On the system and line seal. (2) cylinder somewhere form negative pressure, and processing methods: to find the hydraulic cylinder formation in negative pressure to seal; And exhaust. (3) pressure sealing ring too tight and processing methods: adjust the sealing ring, make its not loose not tight, ensure the piston rod can by hand pull back and forth. (4) the piston and axial piston rod, processing methods: both pack together, in V piece of correction, make with degrees in error within 0.04 mm; Change new piston. (5) the piston rod is not straight (have curve), processing methods: a single or together with the pistons on V block, with pressure straight and equipped with dial indicators correction to the upright. (6) guide or the slider clip too tight or is not parallel with hydraulic cylinder, processing methods: adjust guide or slide block pressure (a) the tightness of rewinding, not only ensure the precision of moving parts, and ensure the sliding resistance to small; If the adjustment is invalid, should check cylinder and guide rail parallel degree, and blow the interface to correction. (7) two piston rod ends and nuts too tight and processing methods: adjust tightness of rewinding, keep the piston rod in a natural state. (8) cylinder wall or the piston surface is pulled, the local badly worn or corrosion, processing methods: boring hole in cylinder, heavy with the pistons. 3.2The impact of the hydraulic cylinder fault analysis and processing (1) does not have a buffer device, processing methods: adjusting the commutation time ( 0.2 seconds), reduce speed hydraulic cylinder power; Add buffer device. (2) buffer installations in the piston and the hole large clearance, processing methods: to replace delay of piston or in holes set in the set, and clearance to regulations; Check the throttle valve. (3) end of the buffer fitting reverse, processing methods: repair, grind with one-way valve seat or replace with. 3.3Hydraulic cylinder of the leak fault analysis and treatment (1) the piston rod surface damage, processing methods: repair the piston rod damage. (2) sealing ring edge injuries or aging, processing methods: replace the sealing ring. (3) pipe joint seal lax, processing methods: check the sealing ring and contact surfaces have scars, try to repair or replacement. (4) in the cylinder head seal lax, processing methods: check the surface machining accuracy and sealing ring aging, to replace or repair. (5) with exhaust bad, make the gas adiabatic compression leading local high temperature and damage the sealing ring, processing methods: check the exhaust device, or add exhaust device; Timely exhaust. (6) buffer device sealing in lax, processing methods: cylinder rod surface machining accuracy and sealing ring aging, change in time or trim. 3.4Hydraulic cylinder of fault analysis and treatment in the leak (1) cylinder piston wear for the hole and with increasing gap of tolerance, processing methods: the piston wear serious when, should be boring cylinder hole, the piston car is small, and the car a few way worse loaded on sealing ring seal or new match the piston. (2) on the piston seal ring abrasion or aging, processing methods: sealing ring abrasion or aging should change in time. (3) the piston and cylinder install different heart or bear with eccentric load, make the piston tilt or partial grinding, processing methods: check the cylinder piston and cylinder, piston rod with holes of concentricity, and trimmed to. (4) cylinder aperture processing straight sex differences or local wear leading local YaoGu form boring cylinder hole, processing methods: heavy with the pistons. 3.5Sound and noise The adiabatic compressed air piston, processing methods: will the piston slow motion, reciprocating several times, each time all walk to the top, to rule out of gas cylinder, can eliminate the serious noise, still can prevent 4.Hydraulic control valvesHydraulic control valves is hydraulic transmission system of control regulation components, it control the oil flow direction, pressure, and flow rate in order to meet the need of the actuator pressure, direction and speed requirements, and drives the execution for achieving the load of the action. 4.1The performance requirements of hydraulic valves In the hydraulic system, the performance requirements of hydraulic valve, basically have the following points. (1) action quick, reliable operation, the work of the impact and vibration to small and long service life. (2) the oil flow through hydraulic pressure loss to small, sealed performance is better, internal leakage to small, no outside leakage. (3) compact structure, installation, maintenance, easy to adjust, excellent versatility. 4.2 Hydraulic classification (1) pressure control valves (hereinafter referred to as pressure valve). Is used to control the pressure in the hydraulic system to meet the execution element required force (or torque) requirements. Including the relief valve, pressure reducing valve, order valve, pressure relay, etc. (2) the direction control valves (hereinafter referred to as the direction valve). Is used to control the hydraulic system in the direction of oil, in order to meet the requirements of the actuator movement direction. Including the check valve, reversing valves, etc. (3) flow control valves (hereinafter referred to as flow valve). Is used to control the hydraulic system of flow, to meet the requirements of the speed of executive element movement. Including the throttle valve, speed control valves, etc. (4) composite valve (also called multiple valve). Is used to control the hydraulic system of direction, pressure, and flow rate three parameters of two or all. For example, one-way pressure reducing valve, can not only control the oil direction, and also control the oil pressure. 4.3The relief valve common fault analysis and processing Hydraulic valve to overflow valve as an example, introduces simply. Fault content processing method The relief valve adjusting device problems disassemble, replace the appropriate pressure regulating spring Electromagnetic valve core of the directional control valve stuck. After electrify, electromagnetic force can't make directional control valve core are in place so that the tiny opening mouth have disassemble, cleaning, the grinding electromagnetic valve core The relief valve pilot valve cone valve core bad (1) disassemble, the grinding conical valve core seal surface. Serious damage, should be replaced with a new qualified parts. (2) apart and check the hydraulic oil is washing pollution levels, according to the circumstances of oil or oil filter Relief valve of the directional control valve of the electromagnetic valve core badly worn, internal leakage aggravate disassemble, cleaning hydraulic components and systems, eliminate the cause hydraulic components not normal wearing of factors, and then replace new directional control valves Relief valve of the directional control valve of the electromagnetic valve core badly worn, internal leakage aggravate disassemble, cleaning hydraulic components and systems, eliminate the cause hydraulic components not normal wearing of factors, and then replace new directional control valves The main valve failure disassemble, cleaning, trim valves and valve core hole. When necessary check the oil pollution, filter or replace the oil, assembling keep valve core and valve of concentricity hole 5.Hydraulic pump Hydraulic pump is hydraulic components, it is will motor (or other prime mover) input mechanical energy into a hydraulic energy conversion devices. Its function is to provide the hydraulic system pressure oil. 5.1Hydraulic pump classification: (1) the gear pump (the meshing gear pump and internal meshing gear pump) (2) vane pump (single function and dual action vane pump vane pump) (3) piston pump (axial piston pump and radial piston pump) 5.2The gear pump common fault analysis and processing The gear pump is common in the production line of the hydraulic pump. In this, the only fault aperture and treatment gear pump is introduced as follows: (1) the oil pump gear and pump shell with clearance of more than the specified limit, processing methods: replacement pump shell or use set set repair method, ensure top gear pump and shell with clearance in a set area. (2) gear collar and gear end excessive wear, make discharging pressure sealing ring the compression is enough and lose the sealing function, leading to high pressure oil chamber pump to low voltage oil chamber in collusion, inside the severe leakage, processing methods: under the collar and compensation gasket (compensation shim thickness should not be commonly more than 2 mm) and to ensure that the sealing ring of compression was laid. (3) disassembling the oil pump, in 2 bushings (spiral oil groove sleeves) combined with surface place, will be loaded in the wrong direction oriented steel wire, processing methods: ensure oriented steel wire can at the same time will be two collar passive gear rotating direction according to deflect a Angle, make two collar plane joint closely. (4) in the disassembly oil pump, the pressure seal aging damage, discharging pressure piece of gasket was wrong, processing methods: if the pressure seal aging, should replace new thing: discharging pressure piece of gasket must be packed in oil absorption cavity (mouth) side (low pressure chamber), and ensure that there is a certain pre-tightened stress. Such as into pressure oil chamber side, gasket will soon damage, cause high pressure chamber and low pressure chamber are interlinked, make the oil pump to lose working ability. 6.Summary The hydraulic system on the parts of the common faults and processing method of simple introduction, is our long-term practice shows results. It may help us to avoid detours, fast and accurately find fault, and in a short time to solve it. So as to improve the production efficiency, reduce production cost; Can create good economic benefit.