RU2499161C1 - Axially diagonal screw pump with rotor automatic radial load release unit - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: pump comprises housing with inlet and outlet and rotor. The latter comprises the shaft running in radial and radial thrust ball bearings and auger wheel with helical blades and hollow taper bush fitted on said shaft. Said bush adjoins the outlet at larger diameter via radial and end grooves of slotted stepwise clearance to make release chamber with bypass channels on outer side of wheel space. Said channels communicate the chamber with auger wheel inlet cavity. Radial thrust ball bearing outer race is fitted in the housing with end clearance not smaller than end clearance of said slotted stepwise seal. Shroud is fixed at the auger wheel blades, at wheel outer line taper section, to abut on inlet via slotted seal end clearance equal thereto.

EFFECT: higher reliability, longer life.

1 dwg

Description

The invention relates to the field of pump engineering and can be used in the development of designs of axial-diagonal screw pumps with increased requirements for reliability and durability of the running gear. Osediagonal screw pumps are indispensable in emergency characteristics for pumping viscous contaminated liquids, in spills of oil and oil products; for basic works at oil depots, bulk racks, in systems of industrial drains and industrial waste; when pumping from buried tanks.

The closest in the set of essential features is, adopted for the prototype, known (RU, patent No. 2342564, published December 27, 2008) osediagonal screw pump with automatic rotor unloading from axial force, comprising a housing consisting of a supply and a discharge, and a rotor including a shaft rotating in a radial and thrust bearings installed in the housing and screw mounted on the shaft with helical blades and a hollow cone-shaped sleeve adjacent to the housing on a large diameter through the radial and end gaps of the slotted stupa of the seal and forming with it from the outside, with respect to the flow part, the unloading chamber with bypass channels, the thrust bearing along the outer ring is installed in the housing with the end gap so that its value is greater than the size of the end gap in the gap-type step seal .

The rotor is unloaded from the axial force in the known pump as a result of automatic regulation with negative feedback of the pressure plot in the discharge chamber, and consequently, of the component of the axial force generated on the hollow cone-shaped sleeve and directed towards the entrance to the screw wheel, causing the rotor to move into axial direction within the end gap along the outer ring of the thrust bearing installed in the housing, while changing the size of the end gap in the slotted upenchatom seal until the balance with oppositely acting axial force component generated on the tapered section of the outer contour of the blades at the diagram unregulated pressure, and hence the magnitude of said axial force component.

The disadvantage of the rotor unloading machine from axial force in the known axial-diagonal screw pump is that there is a possibility that a situation arises in which the balance of counter-acting components of the axial forces is achieved (as calculations show and confirmed in practice), with relatively small values of the end gap (δ _x ≤0.2-0.3 mm) in a gap-type stepped seal, which can lead, given the dynamic nature of the machine, to touch and even wear the working surfaces of the parts forming the end gap in slotted stepped seal.

The objective of the claimed invention is the modernization of the existing design of an axial diagonal screw pump.

The technical result obtained by the implementation of the present invention is to eliminate the contact and wear of the working surfaces of the parts forming the end gap in the slotted stepped seal, to increase reliability and increase the service life of the running gear of the axial diagonal screw pump.

The specified technical result is achieved by the fact that in an axial-diagonal screw pump containing a housing consisting of inlet and outlet, and a rotor including a shaft rotating in radial and angular contact ball bearings mounted in the housing and a screw wheel with screw blades and a hollow cantilever mounted on the shaft cone-shaped sleeve adjacent to the body outlet on a large diameter through the radial and end gaps of the slotted step seal and forming the discharge side from the outside, relative to the flowing part, an access chamber with bypass channels communicating with the cavity at the inlet of the auger wheel flow path, in which an angular contact ball bearing along the outer ring is installed in a housing with an end gap, the value of which is not less than the end gap of the aforementioned gap seals, and on the blades, at the beginning of the conical section of the outer contour of the screw wheel, a bandage is fixedly fixed adjacent to the supply of the housing at a smaller diameter through the end gap of the gap seal, the value Otori equal to the mechanical gap in the aforementioned slit stepped compaction.

When the rotor rotates, there is a pressure drop of the pumped liquid between the outlet and the inlet of the auger wheel, leading to the appearance of counter-axial axial forces acting on the external contour of the auger wheel:

a) a component of the axial force A1 acting on the conical section of the outer contour of the blades in the direction from the entrance to the exit of the screw wheel (from the flow part):

$$A\mathrm{one}=2\times \pi \times {\displaystyle {\int }_{r_{\mathrm{one}}}^{r_2}{p}_{\mathrm{one}}(r)\times r\times d}$$

b) a component of the axial force A2 acting on the inner surface of the hollow cone-shaped sleeve in the direction from the exit to the entrance of the screw wheel (from the discharge chamber):

$$A2=2\times \pi \times {\displaystyle {\int }_{r_{\mathrm{one}}}^{r_2}{p}_2(r)\times r\times d}$$

Where

r is the current radius of the auger wheel, varying from the value of the outer radius of the auger wheel at the outlet (r ₂ ) to the size of the radius of the location of the bypass holes (r ₁ );

p ₁ (r) and p ₂ (r) are analytical expressions of the diagram of static pressure along the radius of the screw wheel,

acting, respectively, on the conical section of the outer contour of the blades on the side of the flowing part and on the inner surface of the hollow cone-shaped sleeve on the side of the discharge chamber, determined by the dependences known for example in the theory of hydromechanics of turbomachines, for example, see (A.A. Lomakin. Centrifugal and Axial Pumps . "Engineering" Moscow, Leningrad, 1966, p. 157 - "the distribution of pressure between the wheel and the housing").

Moreover, due to the fact that the annular cross-sectional area on the sleeve (between r ₂ and r ₁ ), which is affected by the pressure diagram P ₂ (r), and therefore the magnitude of the axial force component (A2) from the outlet side, is larger than the annular cross-sectional area on the conical section of the blades, which is affected by the pressure diagram P ₁ (r) and, accordingly, the magnitude of the axial force component (A1) from the inlet side, there is axial displacement of the rotor within the end gap along the outer ring installed radially in the housing thrust ball bearing scheesya decrease in the clearance of face, respectively, in the stepped slit seal sleeve with a tap casing and impeller shroud housing with inlet. As a result of the indicated change in the end clearances: a) the pressure on the conical section of the outer contour of the blades increases due to a decrease in the amount of leakage through the radial clearance between the blades and the body inlet; b) the pressure in the discharge chamber is reduced by reducing the amount of leakage through the slotted stepped seal and dumping it through the bypass channels into the cavity at the inlet of the flowing part of the auger wheel. As a result, the pressure drop on the surfaces of the outer contour of the auger wheel, and therefore the value of the total axial force (A _po ) acting on the rotor, is equal to the difference between the counter-acting axial forces

A _po = A2-A1,

decreases until a balance of components (A1 and A2) is reached when equality occurs

A1 = A2.

Since the integral value of the pressure on the conical section of the outer contour of the auger blades depends on the amount of leakage through the radial clearance between the blades and the housing inlet and when they decrease, the pressure increases, and the end gap between the bandage and the housing inlet, limiting their size, decreases with the axial movement of the rotor , there is an additional increase in pressure, and hence the component of the axial force (A1). And this means that the balance of the component axial forces (A1 = A2) occurs earlier (compared with the prototype) with a larger value of the end gap in the gap-type stepped seal. As a result of this effect, the possibility of touching and wear of the working surfaces of the parts forming the end gap in the slotted step seal is eliminated, which increases the reliability and service life of the running gear of the axial diagonal screw pump

That is, a device is obtained that regulates pressure distribution diagrams with negative feedback, and, consequently, the magnitude of axial forces acting on the rotor in opposite directions from two directions: a) from the inlet side of the screw wheel to the conical section of the outer contour of the blades (in the flow part) due to changes in the size of the end gap between the bandage and the inlet of the housing; and b) from the side of the exit of the screw wheel to the inner surface of the hollow cone-shaped sleeve (in the unloading chamber) due to the change in the end gap Ora in slotted stepped seal. The device itself, characterized as a combination of a housing consisting of inlet and outlet and a rotor including a shaft rotating in radial and angular contact ball bearings mounted in the housing and cantilevered on the shaft of a screw wheel with helical blades and a hollow cone-shaped sleeve adjacent to the body outlet on a large diameter, through the radial and end gaps of the slotted stepped seal, forming from the outside, with respect to the flow part, the discharge chamber with bypass channels, with communicating with the cavity at the inlet of the flowing part of the auger wheel, with a bandage attached to the blades at the beginning of the conical section of the outer contour of the auger wheel adjoining the housing supply through the end gap of the gap seal equal in size to the end gap of the gap step seal, while the angular contact ball bearing the outer ring is installed in the housing with an end gap, the value of which is not less than the end gap of the slotted stepped seal, can be considered as bilateral minutes automatic unloading of the rotor of the axial force.

Thus, increasing the reliability and durability of the running gear of the axial diagonal screw pump occurs by expanding the control range of the rotor unloading machine from axial force by increasing the end gap in the slotted stepped seal when the balance of axial force components acting on the external contour of the screw wheel is reached : from the inlet side (flow part) to the conical section of the outer contour of the blades and from the outlet side (discharge chamber) to the inner turn Xenia hollow cone-shaped sleeve.

To clarify the essence of the claimed invention is a drawing (figure 1), which shows the meridional section of the axial diagonal screw pump with a two-sided rotor unloading machine from axial force, where:

r ₁ and r ₂ , respectively, the inner and outer radii of the outer annular cross-section of the screw wheel, forming the formation of components of the axial force (the radius of the bypass holes and the outer radius of the screw wheel at the exit);

P ₁ (r) and P ₂ (r) - respectively, pressure plots on the outer annular sections of the auger wheel, acting on it from the input side and the output side;

δ _x -, respectively, the current value of the end gap in the slotted stepped seal of the sleeve and the outlet of the housing, in the slotted seal of the bandage and the supply of the housing and in the installation of the angular contact ball bearing along the outer ring in the housing.

The Osediagonal screw pump contains: a housing consisting of inlet 1 (conical inlet pipe) and outlet 2 (cochlea), and a rotor including shaft 3, and a screw wheel cantileverly mounted on it with screw blades 4 and a hollow cone-shaped sleeve 5. The shaft rotates in ball bearings 6 (radial) and 7 (angular contact) installed in the housing 8, mounted in the branch 2 of the pump housing using a flange connection.

The outer surface of the blades 4 has a conical section 9 on the inlet side and a cylindrical section 10 at the exit on a large diameter, passing to the sleeve 5 in the form of a cylindrical surface 11 and ending with the end surface 12 on the disk 13 of the sleeve 5.

The blades 4 at the beginning of the conical section 9 have a bandage 14 fixed on them, which abuts on a small diameter through the end surface 15 to the counter surface of the supply lead 1 of the housing, with the formation of the end gap 16 of the gap seal, and on the large diameter of the cylindrical section 10 through the cylindrical 11 and end 12 of the surface of the sleeve 5, adjacent to the mating surfaces of the spiral outlet 2 of the housing, with the formation of radial 17 and end 18 clearances of the gap stepped seal.

The specified sealing gap-type step seal between the screw sleeve 5 and the outlet of the pump housing 2 serves to separate the cavities of high pressure (EXIT of the flow part) and low (discharge chamber 19 with bypass channels 20 communicating with the cavity 21 at the inlet of the flow path of the screw wheel).

Moreover, the angular contact ball bearing 7 on the outer ring is installed in the pump housing 8 with an end gap 22, the value of which is not less than the end face clearances 16 and 18 of the auger wheel, respectively, in the gap seal of the bandage with the inlet and in the gap seal of the sleeve with a challenge.

Thus, when the shaft 3 rotates on the conical section 9 of the outer contour of the blades 4, a pressure differential occurs between the OUTPUT and the INPUT of the screw wheel, which causes the axial force component A1 to appear on it in the direction from the INPUT to the OUTPUT, as well as a pressure drop and an axial component forces A2 on the hollow cone-shaped sleeve 5 - in the direction from the EXIT to the ENTRANCE. Moreover, due to the fact that the area of the annular section between r ₂ and r ₁ on the sleeve 5, which is affected by the pressure diagram P ₂ (r), and therefore the magnitude of the component of the axial force from the OUT (A2) side, is larger than the area of the annular the cross-section in the conical section 9, which is affected by the pressure diagram P ₁ (r), and accordingly the magnitude of the axial force component from the INPUT side (A1), axial displacement of the rotor occurs within the end clearance 22 along the outer ring of the angular contact ball bearing 7, accompanied by a decrease end face values new gaps 16 and 18, respectively, in the gap seal of the bandage 14 with the inlet 1 of the housing and in the gapwise stepped seal of the sleeve 5 with the outlet 2 of the housing, as a result of which the pressure on the conical section 9 of the outer contour of the blades 4, due to the reduction of leakage through the radial the gap between the blades 4 and the inlet 1, and therefore the axial force component (A1) from the ENTRANCE of the auger wheel, increases, and in the discharge chamber 19, by reducing the amount of leaks and their discharge through the bypass channels 20 into the cavity 21 to the inlet of the flowing part and, consequently, the axial force component (A2) from the EXIT side of the auger wheel decreases until the onset of balance (A1 = A2) of the counter-acting axial forces components. In general, there is automatic regulation with negative feedback, pressure plots and the total axial force (A _pom ) acting on the external contour of the screw wheel, leading to unloading of the rotor and angular contact ball bearing 7 from the action of axial force, which increases reliability and durability operating resource of the running gear of the osediagonal screw pump.

Claims (1)

An axial diagonal screw pump, comprising a housing consisting of inlet and outlet, and a rotor including a shaft rotating in radial and angular contact ball bearings mounted in the housing, and a screw wheel cantileverly mounted on the shaft with screw blades and a hollow cone-shaped sleeve adjacent to the housing outlet on a large diameter through the radial and end gaps of the slotted stepwise seal with the formation of an unloading chamber with bypass channels communicating with it from the outer side relative to the flow part of the side with an entrance cavity to the flow part of the screw wheel, while the angular contact ball bearing along the outer ring is installed in the housing with an end gap, the value of which is not less than the end gap of the slotted step seal, characterized in that on the blades at the beginning of the conical section of the outer contour of the screw wheel the bandage fixed adjacent to the supply of the housing through the gap seal with an end gap equal in size to the gap of the gap in the gap step seal.