CN1648457A - Cycloidal screw tooth form of large flow double screw pump - Google Patents

Abstract

The present invention discloses a kind of screw cycloid profile for large flow double screw pump. The screw profile includes addendum circle connected via prolonged cycloid to one end of the dedendum circle, pitch circle with one end connected via prolonged cycloid to the other end of the dedendum circle, and the other end of the pitch circle connected via epicycloid to the other end of the addendum circle. The screw pump with the screws has less leakage, high output pressure, smooth running, great specific flow rate, high bearing capacity and easy manufacture.

Description

A kind of cycloidal screw profile of tooth of big flow two screw pump

Technical field

The present invention relates to the Course Exercise in Machinery Elements Design processing technique field, especially, relate to a kind of cycloidal screw profile of tooth of big flow two screw pump.

Background technique

The profile of tooth of two screw pump screw rod have cycloidal tooth profile (patent No.: 99201251.1), 96236524.6) and involute profile etc. the spiral of Archimedes tooth shape of screw (patent No.:.All these profiles of tooth are formed by two kinds of curves, and therefore processing owes convenient.Compare with above-mentioned various profiles of tooth, profile of tooth of the present invention only is made up of a kind of profile of tooth of cycloid, and it is convenient relatively to process.

Summary of the invention

The objective of the invention is at the deficiencies in the prior art, a kind of cycloidal screw profile of tooth of big flow two screw pump is provided.By superior trochoid, pitch circle one end and the root circle the other end be by superior trochoid between top circle and root circle one end, the screw rod of a kind of tooth that the pitch circle the other end and the top circle the other end are made up of epicycloid.Be used in the screw pump and leak for a short time, the delivery pressure height operates steadily, and specific discharge is big, and bearing capacity is strong, processes easier.

In order to achieve the above object, the technical solution used in the present invention is as follows: a kind of cycloidal screw profile of tooth of big flow two screw pump, the screw rod radial cross section is made up of top circle camber line ed, superior trochoid cd, root circle camber line bc, superior trochoid ab, pitch circle circular arc line af, epicycloid ef.Wherein, top circle camber line ed, root circle camber line bc and pitch circle circular arc line af have the same center of circle and radius is respectively R, r, R ₀Circular arc.

The present invention with respect to the beneficial effect of prior art is:

1. only need a pitch just can form Seal cage, compact structure, rigidity height.

2. the store oil space is big, so specific discharge is big, and good seal performance, pressure height.

3. form by cycloid owing to each section profile of tooth, and cycloid processing is ripe, so technology is simple relatively.

4. significantly increase helix angle, therefore, can significantly shorten spiro rod length.

Description of drawings

Fig. 1 is a structural representation of the present invention;

Fig. 2 is a longitudinal section view of the present invention;

Fig. 3 is two screw rods engagement figure when making pure rolling;

Fig. 4 is two screw rods pitch curve figure when making pure rolling;

Fig. 5 is the side view of two screw rods pitch curve when making pure rolling.

Embodiment

The shape of screw rod radial cross section, the top circle curve is the arc line, the root circle curve of the opposite side of top circle is the arc line, the pitch circle curve of a side is the arc line in the middle of top circle and the root circle, form by superior trochoid between tooth top arc line one end points and tooth root arc line one end points, form by superior trochoid between another end points of tooth root arc line and pitch circle arc line one end points, form by epicycloid between another end points of tooth top arc line and another end points of pitch circle arc line; Number n 〉=1 of screw rod, the length of screw rod is greater than the length of two pitch.

Describe the present invention in detail below in conjunction with accompanying drawing.

As shown in Figure 1 and Figure 2, the shape of screw rod radial cross section, the top circle curve is arc line de, the root circle curve of the opposite side of top circle is arc line bc, the pitch circle curve of a side is arc line af in the middle of top circle and the root circle, form by superior trochoid cd between tooth top arc line de 1 end points d point and tooth root arc line bc 1 end c point, form by superior trochoid ab between tooth root arc line bc the other end b point and pitch circle arc line af 1 end points a point, form by epicycloid ef between tooth top arc line de the other end e point and pitch circle arc line af the other end f point; Number n 〉=1 of screw rod, the length of screw rod is greater than the length of two pitch.

When the pitch circle II of screw rod 2 when the pitch circle I of screw rod 1 makes pure rolling, as shown in Figure 3, on the screw rod 2 with screw rod 1 on the track of d point corresponding points d ' be superior trochoid cd, equally, the track of putting e ' on the screw rod 2 is superior trochoid ab, and the track of putting a ' on the screw rod 2 is epicycloid ef, and the equation that each section tooth curve forms is as follows:

1. the formation of superior trochoid cd:

x＝Rsin2ψ-2R ₀sinψ

y＝2R ₀cosψ-Rsin2ψ

$\mathrm{\ρ}=\sqrt{x^2+y^2}$

$\mathrm{\β}={\cos }^{-1}\frac{{\mathrm{\ρ}}^2+4R_0^2-R^2}{4R_0\mathrm{\ρ}}$

$\mathrm{\ψ}={\cos }^{-1}\frac{4R_0^2+R^2-{\mathrm{\ρ}}^2}{4R_{0}R}$

＝β-ψ

In the formula: in the formula: x, y---the right angled coordinates of any point on the flank profil

ρ, ---the polar radius vector and the corner of any point on the flank profil

R, r, R ₀---top circle, root circle and Pitch radius

ψ---pitch circle II is with respect to the corner of pitch circle I

The angle of β---utmost point footpath and the two screw rods line of centres

2. the formation of top circle de:

ρ＝R

3. the formation of root circle bc:

ρ＝r

4. the formation of pitch circle af:

ρ＝R ₀

5. the formation of superior trochoid ab:

＝ψ-β- ₀

In the formula: ₀--the radian of tooth top circular arc de and tooth root circular arc bc

6. the formation of epicycloid ef:

＝ ₁+ ₀-(γ-α)

$\mathrm{\α}={\cos }^{-1}\frac{3R_0^2+{\mathrm{\ρ}}^2}{4R_0\mathrm{\ρ}}$

$\mathrm{\γ}={\cos }^{-1}\frac{{5R}_0^2+R^2}{4R_0^2}$

In the formula:

As shown in Figure 1, as given tip circle radius R and Root radius r, just can determine superior trochoid dc, as the radian of given tip circle circular arc de and the round arc bc of root again ₀( ₀Can 0 when ultimate state), then b point and e point also provide immediately.Because utmost point footpath oa and oe determine that according to superior trochoid and epicycloidal character, the contained angle ∠ eof of angle ∠ aob that superior trochoid ab is contained and epicycloid ef just can try to achieve respectively, promptly superior trochoid ab and epicycloid ef can determine.In other words, in case Outside radius R, root radius r, the radian Ψ of top circle circular arc and root circle circular arc _OGive regularly, the tooth curve abcdef that Fig. 1 provides is unique.

The meshing relation of two screw rods correspondence is as shown in Figure 3: the pitch curve that screw rod 2 top circle d ' e ' are corresponding is the tooth root circular arc bc of screw rod 1, point d ' is corresponding to superior trochoid cd, tooth root circular arc b ' c ' is corresponding to tooth top circular arc de, and some a ' is corresponding to epicycloid ef, and e ' is corresponding to superior trochoid ab.Pitch circle circular arc a ' f ' is corresponding to pitch circle circular arc af.Vice versa.

As Fig. 4, shown in Figure 5, when two screw rods rolled relatively, bar 2 will form space pitch curve 1-2-3-4-5-6-7-8-9 on bar 1.

Equally, screw rod 1 also can form corresponding pitch curve on screw rod 2.Because it is continuous rolling, these two pitch curves have been blocked the input cavity and the output cavity of pump, and constantly push ahead, thereby have produced pressure fluid.

The formation of above-mentioned pair of meshing curve needs a pitch length, for input cavity and output cavity are isolated all the time, before the pair of meshing curve interrupts, must form another to pitch curve in the whole service process, therefore, the length of whole screw rod should be greater than two pitch.

The foregoing description is used for the present invention that explains, rather than limits the invention, and in the protection domain of spirit of the present invention and claim, any modification and change to the present invention makes all fall into protection scope of the present invention.

Claims (2)

1. the cycloidal screw profile of tooth of a big flow two screw pump is characterized in that, the screw rod radial cross section is made up of top circle camber line ed, superior trochoid cd, root circle camber line bc, superior trochoid ab, pitch circle circular arc line af, epicycloid ef.Wherein, top circle camber line ed, root circle camber line bc and pitch circle circular arc line af have the same center of circle and radius is respectively R, r, R ₀Circular arc.

2. the cycloidal screw profile of tooth of big flow two screw pump according to claim 1 is characterized in that,

The curvilinear equation of described superior trochoid cd is:

x＝Rsin2ψ-2R ₀sinψ

y＝2R ₀cosψ-Rsin2ψ

$\mathrm{\ρ}=\sqrt{x^2+y^2}$

$\mathrm{\β}={\cos }^{-1}\frac{{\mathrm{\ρ}}^2+{4R}_0^2-R^2}{4R_0\mathrm{\ρ}};$

$\mathrm{\ψ}={\cos }^{-1}\frac{4R_0^2+R^2-{\mathrm{\ρ}}^2}{4R_{0}R}$

＝β-ψ

The curvilinear equation of described top circle camber line de is:

ρ＝R；

The curvilinear equation of described root circle camber line bc is:

ρ＝r；

The curvilinear equation of described pitch circle circular arc line af is:

ρ＝R ₀；

The curvilinear equation of described superior trochoid ab is:

＝ψ-β- ₀；

The curvilinear equation of described epicycloid ef is:

＝ ₁+ ₀-(γ-α)

$\mathrm{\α}={\cos }^{-1}\frac{3R_0^2+{\mathrm{\ρ}}^2}{4R_0\mathrm{\ρ}}$

$\mathrm{\γ}={\cos }^{-1}\frac{5R_0^2+R^2}{4R_0^2}$

In the formula, x, y are the right angled coordinates of any point on the flank profil, and ρ, are the polar radius vector and the corner of any point on the flank profil, R, r, R ₀Be top circle, root circle and Pitch radius, ψ is the corner of pitch circle II with respect to pitch circle I, and β is utmost point footpath and the angle of the two screw rods line of centres, and is the radian of tooth top circular arc de and tooth root circular arc bc.

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