When stop rotary vane vacuum pumps, oil hole and pump chamber are inter linked or surface of exhaust valve, shaft seal, pump cover, air inlet pipe, air valve, such as untight seal, as a result of the existence of liquid level difference and gravity are in a vacuum tank and pump cavity and differential pressure of the pump cavity, oil will be back into the pump chamber, oil amount is large enough, the oil will return to the air intake duct, form next time starting resistance is big, rotary vane and rotor bearing, exhaust valve force big, difficult starting, affecting the service life of parts, reduce the pump of sex.Therefore, should try to avoid stopping to return oil pump.Its principle is that when the pump stop cutting oil, eliminate negative pressure pump chamber, the lower level is poor, decrease back into the oil.
Detailed measures commonly used are:
1. The vent is full of oil and other oil, oil level is only slightly higher than the partition.
2. Move the fuel tank and exhaust valve in the side, to reduce oil level, decrease oil.
3. The seat plane to level off, the valve plate and elastic.
4. Shaft freeze-up static sealing parts to secure, timely change.
5. Add the pipe to the oil hole, make the oil level is only slightly higher than the inlet.
6. Set the check valves, stop the pump automatically shut down when the oil hole.
7. Set the oil pump and auxiliary mechanism, when the pump is going to cut off the oil.
8. Pump inlet air charging valve.
9. Entrance to the container.
My company produces 2 xz-c series type pump adopts the first check valve, is used by oil pump work impeller reaction as a CAM mechanism, promote open check valve stem oil hole.Valve lever must be adjusted to a reasonable position, make the stem of the force line of action of the impeller and transmission center has a gap, so as to stop the pump, oil fading reaction force of the impeller.The elastic deflection can make the impeller on the valve stem and valve stem off, close the oil hole.Adjust the point is the biggest opening of valve head on oil hole plane height is 0.8 ~ 1.2 mm, up a dead point is present.
A modified structure is to use alternative tension spring leaf spring, can prevent the assembly and repair when not careful provoked deformation failure.To constitute the CAM contour with centripetal force.Eccentric block whereabouts evil resistance is small, close more secure.
Optimal defects compared: pump electromagnetic cutoff air inlet valve, such as air bleeder increases capital, increase the valve, reduce the pumping speed.About the oil hole through, the exhaust valve closed lax pump, valve can only delay the return oil and prevent oil pump housing outside is pumped into the valve system.For manufacturing, the structure of the pump is simple, manufacture is easy, avoid pollution outside the valve by the pumping system is relatively stable.
Check valves and dynamic seals and static sealing structure, even meet all of a sudden power failure and not to pump in air, can also be in a long time makes the pump chamber in the vacuum state, no significant return oil.But its strong manufacturing, assembly, oil seal, to the quality of the exhaust valve and other static seals.If equipped with a entry containers, so, even if the attack back to oil, also only into the container, the match, the user can choose measures.
Points out, by the way, check valves have the effect of the control input.Per revolution, for example, only about a quarter of the time open the oil hole.Oil is too much noise is big, because the oil gas bearing, full pressure limit is also likely to land.Too small oil hole processing is more difficult, the check valve can restrain this difficult.In addition, one thousand check valve parts damaged, after the removal of check valve rod pump can still be used.But stop the vacuum pump to pump immediately after aeration, in case of return oil, therefore, to timely maintenance, for important USES, can be mounted to the relief valve or by air bleed valve.
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