CN103486023B - Screw pump and screw rod - Google Patents

Abstract

The invention discloses a kind of screw pump and screw rod, wherein in the inlet end face of screw rod, be provided with streamlined structure, by this streamlined structure, the axial velocity that liquid flows into screw rod confined space can be increased, thus strengthen the suction stream ability of screw pump, improve its volumetric efficiency.

Description

Screw pump and screw rod

Technical field

The present invention relates to a kind of screw pump and screw rod.

Background technique

In screw pump, driving screw and from screw rod when engagement rotation, the confined space that spatial volume constantly changes can be formed, when the confined space of entrance point constantly becomes large, to form low pressure area in inlet, the liquid in such pump chamber, due to the effect of pressure reduction, obtains initial velocity by making the screw rod end face liquid being originally in laminar motion state on screw axial, thus flow into screw rod confined space entrance, reach the continuity of screw rod transmission liquid.

By analysis, the suction stream ability of screw pump is that the confined space ingress liquid level speed caused by pressure reduction determines, when the axial velocity that liquid flows into screw rod confined space increases, the suction stream ability of pump will increase, and the axial velocity therefore improving liquid inflow screw rod confined space increases the effective means that screw pump inhales stream ability.

Summary of the invention

In view of this, the invention provides a kind of screw pump and screw rod, suction stream ability and the volumetric efficiency of screw pump can be improved.

The invention provides a kind of screw pump, comprising: screw rod, the inlet end face of described screw rod is provided with streamlined structure.

Further, the different radii R that described streamlined structure is corresponding _iplace's cross sectional coordinate meets following constraint conditio:

$\left(\begin{array}{c}{x}_c\\ y_c\end{array}\right)=\left[\begin{array}{cc}\cos {\mathrm{\θ}}_{\mathrm{bc}}& \sin {\mathrm{\θ}}_{\mathrm{bc}}\\ -\sin {\mathrm{\θ}}_{\mathrm{bc}}& \cos {\mathrm{\θ}}_{\mathrm{bc}}\end{array}\right]\left[\begin{array}{cc}\cos {\mathrm{\θ}}_{\mathrm{ab}}& \sin {\mathrm{\θ}}_{\mathrm{ab}}\\ -\sin {\mathrm{\θ}}_{\mathrm{ab}}& \cos {\mathrm{\θ}}_{\mathrm{ab}}\end{array}\right]\left(\begin{array}{c}{x}_{a0}\\ y_{a0}\end{array}\right),$

${\mathrm{\θ}}_{\mathrm{ab}}=\frac{l_{\mathrm{AB}}}{R_i}=\frac{x_a-x_{a0}}{R_i},$

${\mathrm{\θ}}_{\mathrm{bc}}=\arccos \left(\frac{2R_i^2-{(x_{b0}-x_{c0})}^2-{(y_{b0}-y_{c0})}^2}{2R_i^2}\right),$

Wherein, x _a0, y _a0for tooth shape of screw end face starting point coordinate; x _c, y _cfor transforming the coordinate of corresponding points on rear streamlined end face; θ _abfor the angle of point in straight line-arc-coordinate transfer process between any point and starting point; θ _bcfor point carries out changing the angle produced in circular arc-profile of tooth coordinate; l _aBfor the length in straight line-arc-coordinate between any point and starting point; R _ihalf path length corresponding to any point; x _b0, y _b0for the coordinate of starting point in circular arc-profile of tooth coordinate; x _c0, y _c0for on tooth shape of screw with the coordinate of the point corresponding to starting point.

Present invention also offers a kind of screw rod, the inlet end face of described screw rod is provided with streamlined structure.

Further, the corresponding different radii R of described streamlined structure _iplace's cross sectional coordinate meets following constraint conditio:

$\left(\begin{array}{c}{x}_c\\ y_c\end{array}\right)=\left[\begin{array}{cc}\cos {\mathrm{\θ}}_{\mathrm{bc}}& \sin {\mathrm{\θ}}_{\mathrm{bc}}\\ -\sin {\mathrm{\θ}}_{\mathrm{bc}}& \cos {\mathrm{\θ}}_{\mathrm{bc}}\end{array}\right]\left[\begin{array}{cc}\cos {\mathrm{\θ}}_{\mathrm{ab}}& \sin {\mathrm{\θ}}_{\mathrm{ab}}\\ -\sin {\mathrm{\θ}}_{\mathrm{ab}}& \cos {\mathrm{\θ}}_{\mathrm{ab}}\end{array}\right]\left(\begin{array}{c}{x}_{a0}\\ y_{a0}\end{array}\right),$

${\mathrm{\θ}}_{\mathrm{ab}}=\frac{l_{\mathrm{AB}}}{R_i}=\frac{x_a-x_{a0}}{R_i},$

${\mathrm{\θ}}_{\mathrm{bc}}=\arccos \left(\frac{2R_i^2-{(x_{b0}-x_{c0})}^2-{(y_{b0}-y_{c0})}^2}{2R_i^2}\right),$

Wherein, x _a0, y _a0for tooth shape of screw end face starting point coordinate; x _c, y _cfor transforming the coordinate of corresponding points on rear streamlined end face; θ _abfor the angle of point in straight line-arc-coordinate transfer process between any point and starting point; θ _bcfor point carries out changing the angle produced in circular arc-profile of tooth coordinate; l _aBfor the length in straight line-arc-coordinate between any point and starting point; R _ihalf path length corresponding to any point; x _b0, y _b0for the coordinate of starting point in circular arc-profile of tooth coordinate; x _c0, y _c0for on tooth shape of screw with the coordinate of the point corresponding to starting point.

Beneficial effect of the present invention:

The embodiment of the present invention, in the inlet end face of screw rod, by smooth end face being arranged to the entrance face of streamlined structure, such liquid is cannot keeping parallelism running state after nonplanar streamlined structure, and the speed along screw axial direction can be produced, the liquid at such screw rod entrance face place is when entering confined space, not only there is the axial velocity produced due to differential pressure action, and also have the axial component velocity produced owing to streaming motion, thus the speed making liquid enter confined space increases substantially, increase suction stream ability and the volumetric efficiency of screw pump, especially the conveying capacity of the high-end screw pumps such as big-flow high-pressure can be ensured.

Accompanying drawing explanation

Below in conjunction with drawings and Examples, the invention will be further described:

Fig. 1 is the structural representation of the embodiment of screw rod provided by the invention.

Fig. 2 is the plan view of Fig. 1.

Fig. 3 is the structural representation of the embodiment of streamlined structure.

Fig. 4 is that A-A in Fig. 3 is to structural representation.

Fig. 5 is peripheral flow illustraton of model.

Fig. 6-(a) is inlet end face ichthyoid projection view after optimizing.

Fig. 6-(b) is the projection view of Fig. 6-(a) after straight line-arc-coordinate conversion.

Fig. 6-(c) is the projection view of Fig. 6-(b) after circular arc-profile of tooth Coordinate Conversion.

Fig. 7 is straight line-arc-coordinate transition diagram.

Fig. 8 is circular arc-profile of tooth Coordinate Conversion schematic diagram.

Embodiment

Fig. 1 is the structural representation of the embodiment of screw rod provided by the invention, Fig. 2 is the plan view of Fig. 1, and Fig. 3 is the structural representation of the embodiment of streamlined structure, and Fig. 4 is that A-A in Fig. 3 is to structural representation, wherein reference character 1 represents " rotor ", and reference character " 2 " represents streamlined structure.

The screw pump of the embodiment of the present invention, mainly the inlet end face structure of its screw rod is improved, the inlet end face of screw rod is in the past flat configuration, and the inlet end face of the screw rod of the embodiment of the present invention is provided with streamlined structure 2, like this when screw rod is in rotation process, because streamlined structure and screw rod are an entirety, therefore streamlined structure also rotates thereupon, according to motion composition, situation equivalence now can be converted to screw rod and keep state of rest, the liquid of screw rod entry end rotates around screw axis, now can according to flow around body principle, liquid is cannot keeping parallelism motion state after nonplanar streamlined body, but flow along the surface of ichthyoid, after fluid walks around ichthyoid, a velocity component along screw axial direction can be produced in the inlet of confined space, the liquid at such screw rod entrance face place is when entering confined space, not only there is the axial velocity produced due to differential pressure action, and also have the axial component velocity produced owing to streaming motion, thus make liquid enter the speed of confined space than front raising, to realize the raising of the suction stream ability of pump.

Concrete, the reduction formula that screw pump inhales stream ability η is

$\mathrm{\η}=\frac{Q}{\mathrm{\ΔV}}=\frac{Q_p+Q_v}{\mathrm{\ΔV}}$

Wherein Q is end face inlet flow rate; Δ V is the Volume Changes of confined space; Q _pfor only depending on differential pressure action and entering the flow of pump confined space; Q _vfor entering the flow of pump confined space owing to having axial velocity.Q _v=u ₀s, u ₀the speed obtained for liquid after streaming through streamlined structure is at the component of axis; Face area when S is the formation of screw rod confined space, when there is no streamlined body, u ₀=0.Therefore, when there is no streamlined structure, when being provided with streamlined structure, clearly η _before< η _after, therefore, after increasing streamlined structure, the suction stream ability of screw pump is significantly improved.

Further, the optimization form of streamlined structure is made a concrete analysis of below.

In order to the component velocity making the fluid of screw rod inlet end face have an initial y direction when entering the confined space that pump meshing zone is formed, the separation point in its boundary layer, inlet end face place should be in Cylindrical symmetry line go flow side, and the slope at fluid this some place when departing from separation point can be made to reach minimum, i.e. the velocity attitude of separation point fluid and vertical direction angle theta _sepminimum, as shown in Figure 5.

The Optimized model of screw pump inlet end face streamlined structure can be obtained according to the relation of peripheral flow streamline and boundary layer separation:

$\min :{\mathrm{\&theta;}}_{\mathrm{sep}}=\arctan \left(\frac{2x(\mathrm{\&Psi;}-\mathrm{Uxy})}{U(x^2+3y^2-R^2)-2\mathrm{\&Psi;y}}\right)-\frac{\mathrm{\&pi;}}{2}$

$s.t.:\left\{\begin{array}{c}\mathrm{\&Psi;}=\mathrm{Uy}(1-\frac{R^2}{x^2+y^2})\\ \tan {\mathrm{\&alpha;}}_{\mathrm{sep}}=\frac{2x(\mathrm{\&Psi;}-\mathrm{Uy})}{U(x^2+3y^2-R^{2}y-R^2)-2\mathrm{\&Psi;y}}\\ \frac{\&PartialD;p_t}{\&PartialD;x}=<0\\ {\mathrm{\&theta;}}_t=\mathrm{\&pi;}-{\mathrm{\&alpha;}}_{\mathrm{sep}}\\ \mathrm{\&Psi;}>0,U>0,x>0,y>0\\ x^2+y^2>R^2\end{array}\right.$

Wherein, θ _sepfor the angle of liquid speed direction, separation point place and vertical direction; X, y are the coordinate value at separation point place; U is the linear velocity of corresponding different radii place screw rod end face; R is Root radius; α _sepfor the angle of separation point place liquid speed in the other direction and between substantially horizontal.

For screw pump teethed end faces geometric parameter, use the same method to calculate and optimize rear inlet end face ichthyoid projection view as shown in Fig. 6-(a) to Fig. 6-(c).

In conjunction with the ichthyoid layout of tooth shape of screw, in order to obtain tooth shape of screw inlet end face ichthyoid, in conjunction with tooth shape of screw parameter, use coordinate transformation relation, by the corresponding conversion of ichthyoid Fig. 6-(a) Suo Shi to tooth shape of screw end face as Fig. 6-(c).As shown in FIG. 7 and 8, following coordinate transformation relation is needed.

(1) straight line-arc-coordinate conversion.

${\mathrm{\&theta;}}_{\mathrm{ab}}=\frac{l_{\mathrm{AB}}}{R_i}=\frac{x_a-x_{a0}}{R_i}$

Wherein rotational coordinates closes and is:

$\left\{\begin{array}{c}{x}_b=x_{a0}\cos {\mathrm{\&theta;}}_{\mathrm{ab}}+y_{a0}\sin {\mathrm{\&theta;}}_{\mathrm{ab}}\\ y_b=-x_{a0}\sin {\mathrm{\&theta;}}_{\mathrm{ab}}+y_{a0}\cos {\mathrm{\&theta;}}_{\mathrm{ab}}\end{array}\right.$

Wherein, x _a0, y _a0for tooth shape of screw end face starting point coordinate; θ _abfor the angle of point in straight line-arc-coordinate transfer process between any point and starting point; l _aBfor the length in straight line-arc-coordinate between any point and starting point; x _a, y _afor the coordinate of any point on straight line before Coordinate Conversion; x _b, y _bfor the coordinate of the point of any point on straight line after Coordinate Conversion.

(2) circular arc-profile of tooth Coordinate Conversion

${\mathrm{\&theta;}}_{\mathrm{bc}}=\arccos \left(\frac{2R_i^2-l_{\mathrm{AD}}^2}{2R_i^2}\right)$

Wherein $l_{\mathrm{AD}}=\sqrt{{\left(x_{b0}-x_{\mathrm{vc}0}\right)}^2+{(y_{b0}-y_{c0})}^2},$ Obtain for people's above formula

${\mathrm{\&theta;}}_{\mathrm{bc}}=\arccos \left(\frac{2R_i^2-{(x_{b0}-x_{c0})}^2-{(y_{b0}-y_{c0})}^2}{2R_i^2}\right)$

The coordinate transformation relation that arc section AC forwards arc section DE to is:

$\left\{\begin{array}{c}{x}_c=x_b\cos {\mathrm{\&theta;}}_{\mathrm{bc}}+y_b\sin {\mathrm{\&theta;}}_{\mathrm{bc}}\\ y_c=-x_b\sin {\mathrm{\&theta;}}_{\mathrm{bc}}+y_b\cos {\mathrm{\&theta;}}_{\mathrm{bc}}\end{array}\right.$

Finally, can obtain the coordinate transformation relation that Fig. 6-(a) is transformed into Fig. 6-(c), being write as matrix form is:

$\left(\begin{array}{c}{x}_c\\ y_c\end{array}\right)=\left[\begin{array}{cc}\cos {\mathrm{\&theta;}}_{\mathrm{bc}}& \sin {\mathrm{\&theta;}}_{\mathrm{bc}}\\ -\sin {\mathrm{\&theta;}}_{\mathrm{bc}}& \cos {\mathrm{\&theta;}}_{\mathrm{bc}}\end{array}\right]\left[\begin{array}{cc}\cos {\mathrm{\&theta;}}_{\mathrm{ab}}& \sin {\mathrm{\&theta;}}_{\mathrm{ab}}\\ -\sin {\mathrm{\&theta;}}_{\mathrm{ab}}& \cos {\mathrm{\&theta;}}_{\mathrm{ab}}\end{array}\right]\left(\begin{array}{c}{x}_{a0}\\ y_{a0}\end{array}\right)$

Wherein, ${\mathrm{\&theta;}}_{\mathrm{ab}}=\frac{l_{\mathrm{AB}}}{R_i}=\frac{x_a-x_{a0}}{R_i},{\mathrm{\&theta;}}_{\mathrm{bc}}=\arccos \left(\frac{{2R}_i^2-{(x_{b0}-x_{c0})}^2-{(y_{b0}-y_{c0})}^2}{2R_i^2}\right).$

X _c, y _cfor transforming the coordinate of corresponding points on rear streamlined end face; θ _bcfor point carries out changing the angle produced in circular arc-profile of tooth coordinate; R _ihalf path length corresponding to any point; x _b0, y _b0for the coordinate of starting point in circular arc-profile of tooth coordinate; x _c0, y _c0for on tooth shape of screw with the coordinate of the point corresponding to starting point.

What finally illustrate is, above embodiment is only in order to illustrate technological scheme of the present invention and unrestricted, although with reference to preferred embodiment to invention has been detailed description, those of ordinary skill in the art is to be understood that, can modify to technological scheme of the present invention or equivalent replacement, and not departing from aim and the scope of technical solution of the present invention, it all should be encompassed in the middle of right of the present invention.

Claims (4)

1. a screw pump, comprising: screw rod, it is characterized in that: the inlet end face of described screw rod is provided with streamlined structure.

2. screw pump as claimed in claim 1, is characterized in that: the different radii R that described streamlined structure is corresponding _iplace's cross sectional coordinate meets following constraint conditio:

$\left(\begin{array}{c}{x}_c\\ y_c\end{array}\right)=\left[\begin{array}{cc}\cos {\mathrm{\&theta;}}_{\mathrm{bc}}& {\sin \mathrm{\&theta;}}_{\mathrm{bc}}\\ -\sin {\mathrm{\&theta;}}_{\mathrm{bc}}& \cos {\mathrm{\&theta;}}_{\mathrm{bc}}\end{array}\right]\left[\begin{array}{cc}{\cos \mathrm{\&theta;}}_{\mathrm{ab}}& {\sin \mathrm{\&theta;}}_{\mathrm{ab}}\\ {-\sin \mathrm{\&theta;}}_{\mathrm{ab}}& {\cos \mathrm{\&theta;}}_{\mathrm{ab}}\end{array}\right]\left(\begin{array}{c}{x}_{a0}\\ y_{a0}\end{array}\right),$

${\mathrm{\&theta;}}_{\mathrm{ab}}=\frac{l_{\mathrm{AB}}}{R_i}=\frac{x_a-x_{a0}}{R_i},$

${\mathrm{\&theta;}}_{\mathrm{bc}}=\arccos \left(\frac{{2\mathrm{ar}}_i^2-{(x_{b0}-x_{c0})}^2-{(y_{b0}-y_{c0})}^2}{{2R}_i^2}\right),$

Wherein, x _a0, y _a0for tooth shape of screw end face starting point coordinate; x _c, y _cfor transforming the coordinate of corresponding points on rear streamlined end face; θ _abfor the angle of point in straight line-arc-coordinate transfer process between any point and starting point; θ _bcfor point carries out changing the angle produced in circular arc-profile of tooth coordinate; l _aBfor the length in straight line-arc-coordinate between any point and starting point; R _ihalf path length corresponding to any point; x _b0, y _b0for the coordinate of starting point in circular arc-profile of tooth coordinate; x _c0, y _c0for on tooth shape of screw with the coordinate of the point corresponding to starting point.

3. a screw rod, is characterized in that: the inlet end face of described screw rod is provided with streamlined structure.

4. screw rod as claimed in claim 3, is characterized in that: the corresponding different radii R of described streamlined structure _iplace's cross sectional coordinate meets following constraint conditio:

$\left(\begin{array}{c}{x}_c\\ y_c\end{array}\right)=\left[\begin{array}{cc}\cos {\mathrm{\&theta;}}_{\mathrm{bc}}& {\sin \mathrm{\&theta;}}_{\mathrm{bc}}\\ -\sin {\mathrm{\&theta;}}_{\mathrm{bc}}& \cos {\mathrm{\&theta;}}_{\mathrm{bc}}\end{array}\right]\left[\begin{array}{cc}{\cos \mathrm{\&theta;}}_{\mathrm{ab}}& {\sin \mathrm{\&theta;}}_{\mathrm{ab}}\\ {-\sin \mathrm{\&theta;}}_{\mathrm{ab}}& {\cos \mathrm{\&theta;}}_{\mathrm{ab}}\end{array}\right]\left(\begin{array}{c}{x}_{a0}\\ y_{a0}\end{array}\right),$

${\mathrm{\&theta;}}_{\mathrm{ab}}=\frac{l_{\mathrm{AB}}}{R_i}=\frac{x_a-x_{a0}}{R_i},$

${\mathrm{\&theta;}}_{\mathrm{bc}}=\arccos \left(\frac{{2\mathrm{ar}}_i^2-{(x_{b0}-x_{c0})}^2-{(y_{b0}-y_{c0})}^2}{{2R}_i^2}\right),$

Wherein, x _a0, y _a0for tooth shape of screw end face starting point coordinate; x _c, y _cfor transforming the coordinate of corresponding points on rear streamlined end face; θ _abfor the angle of point in straight line-arc-coordinate transfer process between any point and starting point; θ _bcfor point carries out changing the angle produced in circular arc-profile of tooth coordinate; l _aBfor the length in straight line-arc-coordinate between any point and starting point; R _ihalf path length corresponding to any point; x _b0, y _b0for the coordinate of starting point in circular arc-profile of tooth coordinate; x _c0, y _c0for on tooth shape of screw with the coordinate of the point corresponding to starting point.