A brief analysis of the failure of air compressors in the latest category to reduce wear and tear

A double-acting rotary of a four-slide is pressed into a sealing line. At the same time, the root of the slider drives the flying block to rotate together, and the flying block generates centrifugal force and acts on the inner end of the other pair of sliding blades through the pulling rope, thereby forming a centripetal pulling force, which is opposite to the centrifugal force of the sliding piece, and part of it It offsets the force of the slide on the wall of the cylinder bore, thus reducing friction and wear between them. However, due to the reduction of the contact force, the sealing ability of the sliding piece and the cylinder hole in the contact line is also weakened, so the weight of the flying block needs to be carefully designed.

One of the necessary conditions for the normal operation of the vane compressor is that the top of the vane and the cylinder profile must maintain a reliable contact seal to form a closed working volume. The phenomenon that the sliding piece leaves the inner surface of the cylinder for a short time is called the phenomenon of the sliding of the sliding piece. The void will cause the slide and the cylinder to collide and generate noise, which will damage the internal leakage of the working elements on both sides of the slide, which may result in the compressor not working properly.

In the exhaust phase, as the rotor angle increases, the sliding plate is gradually retracted into the chute under the forcing action of the cylinder bore profile, and generally no voiding occurs. In the suction phase, as the rotor angle increases, the vane and cylinder

The contact point B of the profile line is longer and longer than the center of the cylinder bore O. If the outward movement of the slider under the action of the centrifugal force cannot keep up with the growth rate of the radial diameter, between the slider and the cylinder bore surface There will be a void, that is, the contact fails.

In order to prevent the vane from being emptied, it is necessary to make =Fncos

Fr=ma where h is the radial height of the slider and m is the mass of the slider, which is the pressure angle. In addition, the pullback force of the drawstring: Fs=Fmtg=kmL2tg, where k is the ratio of the mass of the fly block to the mass of the slide (k<1), and L is the distance from the center of mass of the flyweight to the center O of the rotor. Substituting (1) and finishing: Fn=mcos

(2) Obviously, in order to keep the sliding piece in contact with the cylinder hole type line, the contact reaction force Fn must be greater than zero. Note that the pressure angle is <90, so the condition that the sliding plate and the cylinder bore wall surface are not emptied is: (-h2-kLtg)2-a>0(3) since a=d2dt2=2d2d2=2E2cos2(4) and tg=- hL(5), therefore, the formula (3) can be rewritten as: -h2-k(-h)>2Ecos2(6) The above equation is the constraint equation for the vane compressor not to cause void when the gas pressure and friction are not considered. According to this formula, the maximum allowable weight of the flying block can be determined. A design example is: r=31mm, E=8mm, h=16mm, then substituting (4) for finishing: 7-15k+(40-8k)sin2>0(7) note k<1 and 0%sin2 For %1, take k<7/15 to ensure that the sliding plate and the cylinder bore wall are not emptied. If the gas pressure and the friction of the chute are taken into consideration, the value of k is smaller, and the installation space of the flying block must also be considered. The results show that <6>, the value of k is in the range of 0.250.35.

Conclusion The slide type compressor with the flying block friction reducing device has a reduced contact force between the sliding piece and the cylinder hole profile, so the friction and wear between them are also inevitably reduced. However, if one-sided pursuit of anti-friction effect increases the mass of the flying block, the sealing force between the sliding piece and the cylinder hole may be invalid due to insufficient contact force, and even the vane void phenomenon may occur, thereby affecting the normal operation of the compressor. Therefore, for this type of compressor, the weight of the flyweight must be strictly controlled.

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