Improvement of metering pump stroke adjustment mechanismTraditional transmission structure of the metering pump
metering pump flow can be changed by trips, speed or stroke and speed changes to regulation, through travel agencies connected to pump electric servo or pneumatic servo control realizes the automatic regulation of electricity and gas metering pump flow. Figure 1 shows a typical n-axis stroke adjustment mechanism.
metering pump working principle: connected by a coupling of motor and worm after worm gear turns the sleeve under deceleration, driven through the sleeve under the sliding key n to rotate, and rotate with the shaft and the n axis eccentric sleeve, which will drive connecting rod for reciprocating motion.
eccentric sets eccentric from Regulation: using manual, and electric or pneumatic turned pump body top of regulation rod, for regulation rod and regulation seat Zhijian for thread joins, regulation seat not moving, so makes regulation Rod along axis to mobile, regulation Rod through thrust ball bearing led n axis in Shang sleeve, and Xia sleeve within mobile, to arrived change eccentric from of purpose, eventually achieved pump of trip regulation. N axis is sheathed with eccentric, eccentric offset for maximum stroke length of Central 1/4,N axis's eccentricity is zero, and the upper and lower ends of the n axis eccentricity the same (for maximum stroke length of 1/4). N-axis eccentricity and eccentric offset when you cancel each other out, General eccentricity of zero, that is Center of the eccentric and the n axis of rotation Center, stroke length is zero. N-axis eccentricity and eccentricity of the eccentric wheel on one side completely overlap, the radius of the eccentric shaft eccentric and n 1/2 stroke length, namely pumps for 100% stroke. Due to the length of stroke. 100% stroke length changes, so as to realize the metering pump flow in 0-100% within the rated flow adjustment 2.
&Nbsp; figure 1 n axial stroke adjustment mechanism schematic
1. Lower sleeve; 2. Connecting rod sets; 3. Eccentric; 4. Thrust ball bearing 5. Crimp ring 6. Adjusting lever 7. On the sleeve; 8. N axis; 9. Eccentric, 10. Connecting rod, 11. Worm, 12. Worm gear, 13. Deep groove ball bearings, 14. Adjusting axis stroke adjustment mechanism
at present, the domestic production of medium and large metering pumps, mostly n-axial stroke adjustment mechanism, but n-axial stroke adjustment mechanism also has some shortcomings:
(1), a complex structure. N shaft center line axis of both ends of the shaft head n. Metering pump flow control by n-axis shifted the eccentric in an n-location on the shaft neck, in order to achieve a change.
(2) less n-axis machining process. Specialized machine tools or special tooling machining is needed in order to ensure the accuracy of its type and size, which increases the cost of pump products.
(3) stress concentration. Because n-axis structural reasons, are prone to stress concentration in the process, so as to produce n-axis fracture, greatly reducing the reliability of the product. In addition, the n axis stroke adjustment mechanism in the transmission mode is determined by the worm and worm wheel drive Adjustable eccentricity of eccentric circular motion into reciprocating motion, n-axis relies on upper and lower sleeve bearing, when processing sleeve, two Bush concentricity tolerances exist error, cannot be the same, leading to less neutral. Upper and lower sleeve with deep groove ball bearings, axial positioning precision lower worm gear easy axial movement, making worm and worm wheel wear, affecting the transmission efficiency and reliability of the pump.
3 new oblique slot axis trip regulation structure
for above measurement pump trip regulation institutions exists of problem, proposed has a measurement pump with core parts of new structure that using
oblique slot axis replaced original n type axis of trip regulation institutions, to improved its work State, solution original n type crankshaft easy fatigue, and fracture, technology problem, then improve measurement pump of reliability and using life, expanded its using range. Figure 2 shows the skew axis stroke adjustment mechanism.
&Nbsp; figure 2 slot shaft structure schematic
1. Connecting rod; 2. Bush, 3. Eccentric; 4. Adjust Rod 5. Skew axis 6, chute bushings; 7. PIN 8. Cylindrical pin 9. Support rings, 10. Worm; 11. Worm;
12. Angular contact ball bearings
is a new metering pump consists of a driving box, cover plates, skew axis adjustment mechanism, adjust the seats, motor bracket, hydraulic cylinder brackets, connecting rod, cross first class composition. And one of the core institutions--skew axis adjustment device the cylinder pin, PIN, eccentric, inclined trough axis, chute bushings, bearing and bearing rings and so on. Its features:
(1) drive turned moment and trip regulation of passed is through 2 a obviously separation of parts completed of, power directly from motor drive axis by rigid connection of worm, and worm parts passed to eccentric; all drive parts of connection are is by its static conditions by decided, ensure has the pump has minimum of mechanical beat, high of overload security;
(2) Trip adjustment and trip length Zhijian of relationship is linear of, convenient has pump flow of regulation;
(3) through regulation rod to for trip regulation not passed any drive turned moment, so only need manual imposed a is small of torque can completed trip regulation;
(4) all of movement parts are is in not continuous oil bath lubrication conditions Xia work of, wear, and consumption work small, drive efficiency high, run reliable. And traditional n-axis stroke adjustment mechanism (see Figure 1) compared, advantages of a new skew axis stroke adjustment mechanism:
(1) is rather simple in structure, process good chutes of cylindrical shaft ends, symmetrical rectangular plane has skewed hole in the Middle, simple technology and easy to manufacture.
(2) oil gap even, good lubrication of bearing rings used to support link, preventing the link from dead at work declined, resulting in uneven Rod-bearing clearance, lubrication, wear, failure.
(3) axial position replaced the original high precision angular contact ball bearings deep groove ball bearings. Due to the axial position to prevent axial movement beyond the scope of design, ensures the position of worm and worm, preventing a worm and worm wheel due to axial movement arising excessive wear and improves product reliability.
(4) radial axis the high positioning accuracy
chute is equipped with a chute sleeve, the chute sleeve is a whole, and the n-type sleeve is made up of upper and lower bushings. In contrast, chute bushings improve stiffness and strength of the overall support, ensure the axiality of upper and lower bearings, improved the skew axis force and support, to prevent the turn changes or the wear of axial and radial movement of. Skew axis stroke adjustment mechanism works: bushings rotate the drive motor through worm parts chute, led in the chute on the sleeve's eccentric synchronous rotation, eccentric drive the big swing, and through connected to the connecting rod small end of the connecting rod crosshead, eccentric rotary motion into reciprocating motion. When adjusting Rod axial moving, chute helical groove in the PIN and cylinder pin has moved, through a cylindrical pin which is connected to the eccentric move both radial eccentricity change. Which pump performance by adjusting the itinerary, change the pump flow, achieve the purpose of metering and delivery. Motor driven worm and worm gears, helical groove sleeve and eccentric rotation, eccentricity with drive connecting rod bearing the swinging, and connected to the connecting rod crosshead, reciprocating motion, with the plunger, the discharge valve. In the case shown in Figure 2, eccentric offset is zero, so travel is also zero. When you need to adjust the piston stroke length, by hand, in the direction perpendicular to the figure 2 clockwise (assuming) turn the adjusting sleeve, then move the adjusting lever up and drive the chute along with axial axial movement. At this point, chute helical groove in the cylinder pin and the chute move, their eccentricity increases. Piston stroke length is determined by the eccentricity, meaning piston stroke length will increase with increasing eccentricity.