CN1648456A - Involute line screw tooth shape of large flow double screw pump - Google Patents

Abstract

The present invention discloses a kind of screw involute 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 and involute to the other end of the dedendum circle, and the other end of the pitch circle connected via involute 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 and easy manufacture.

Description

A kind of involute tooth shape of screw 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 tooth shape of screw 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.:.Though it is hermetically sealed that these profiles of tooth can keep, thereby pressure is bigger, main shortcoming is that specific discharge is less than normal, and is too huge at the application volume of big flow.Profile of tooth of the present invention is compared with above-mentioned various profiles of tooth, is keeping on the former pressure-based, and specific discharge obviously increases, and volume reduces, and processing is still more convenient.

Summary of the invention

The objective of the invention is at the deficiencies in the prior art, a kind of involute tooth shape of screw of big flow two screw pump is provided.The top circle of this screw rod is connected by superior trochoid with root circle one end, and pitch circle circular arc one end is connected with involute by superior trochoid with the root circle the other end, and the pitch circle circular arc the other end and the top circle the other end are connected to form by involute.Be used in the screw pump and leak for a short time, the delivery pressure height operates steadily, and specific discharge is big, processes easier.

In order to achieve the above object, the technical solution used in the present invention is as follows:

The present invention with respect to the beneficial effect of prior art is: a kind of involute tooth shape of screw of big flow two screw pump, and the screw rod radial cross section is made up of top circle camber line ef, superior trochoid ed, root circle camber line cd, superior trochoid bc, involute ab, pitch circle circular arc line ag, involute fg; Wherein, top circle camber line ef, root circle camber line cd and pitch circle circular arc line ag have the same center of circle and radius is respectively R, r, R ₀Circular arc; The tooth root of formed involute part and tooth top part when involute ab and fg are respectively and are basic circle with the root circle.

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

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

3. 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.

Fig. 1, Fig. 2 show the shape of screw rod radial cross section, the top circle curve is circular arc line ef, the root circle curve of the opposite side of top circle is circular arc line cd, the pitch circle curve of a side is circular arc line ag in the middle of top circle and the root circle, form by superior trochoid ed between top circle camber line ef 1 end points e point and root circle camber line cd 1 end d point, form by involute ab and superior trochoid bc between root circle camber line cd the other end c point and pitch circle circular arc line ag 1 end points a point, form by involute fg between top circle camber line ef the other end f point and pitch circle circular arc line ag the other end g point; Number n 〉=1 of screw rod, the length of screw rod is greater than the length of two pitch.

As shown in Figure 3, when the pitch circle II of screw rod 2 when the pitch circle I of screw rod 1 makes pure rolling, the track of the some e ' corresponding with e point on the screw rod 1 is superior trochoid de on the screw rod 2, and is same, the track of putting f ' on the screw rod 2 is superior trochoid bc, and the equation that each section tooth curve forms is as follows:

1. the formation of superior trochoid ed:

x＝Rsin2 _ψ-2R ₀sinψ

y＝2R ₀cosψ-Rcos2ψ

$\mathrm{\ρ}=\sqrt{x^2+y^2}$

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

$\mathrm{\χ}={\cos }^{-1}\frac{{4R}_0^2+R^2-{\mathrm{\ρ}}^2}{{4R}_{0}R}$

In =β-ψ 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 root circle ef:

ρ＝R

3. the formation of root circle cd:

ρ＝r

4. the formation of pitch circle ag:

ρ＝R ₀

5. the formation of superior trochoid bc:

x＝-Rsin(2ψ- ₀)+2R ₀?sin(ψ- ₀)

y＝-Rcos(2ψ- ₀)+2R ₀?cos(ψ- ₀)

＝ψ-β

(ρ β ψ is with superior trochoid ed)

₀: the radian of tooth root circular arc ed.

6. the formation of involute fg:

$\mathrm{\ρ}=\frac{r}{\cos \mathrm{\α}}$

In the formula: α---the pressure angle of involute fg.

7. the formation of involute ab:

$\mathrm{\ρ}=\frac{r}{\cos \mathrm{\α}}$

$\mathrm{ob}=\sqrt{r^2+{(2\sqrt{R_0^2-r^2}-\sqrt{R^2-r^2})}^2}$

As shown in Figure 1, as given tip circle radius R and Root radius r, just can determine superior trochoid de, as the radian of given tip circle circular arc ef and the round arc cd of root again ₀( ₀Selected arbitrarily, when ultimate state, can be 0), then c point and f point also provide immediately.Because utmost point footpath oa and of determine that ob also can obtain again, according to the character of superior trochoid and involute, the angle ∠ boc that superior trochoid bc is contained, angle ∠ aob and ∠ fog that involute ab and fg are contained all can try to achieve respectively, i.e. superior trochoid bc, and involute ab and fg can determine.In other words, in case Outside radius R, root radius r and top circle circular arc and root circle circular arc ₀Given, then the tooth curve abcdefg that provides of Fig. 1 is unique.

Fig. 3 shows the meshing relation of two screw rods correspondence: the pitch curve that screw rod 2 top circle e ' f ' are corresponding is the tooth root circular arc cd of screw rod 1, point e ' is corresponding to superior trochoid de, tooth root circular arc c ' d ' is corresponding to tooth top circular arc ef, point f ' is corresponding to superior trochoid bc, and pitch circle circular arc a ' g ' is corresponding to pitch circle circular arc ag.

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.

Vice versa, 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 involute tooth shape of screw 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 ef, superior trochoid ed, root circle camber line cd, superior trochoid bc, involute ab, pitch circle circular arc line ag, involute fg.Wherein, top circle camber line ef, root circle camber line cd and pitch circle circular arc line ag have the same center of circle and radius is respectively R, r, R ₀Circular arc.The tooth root of formed involute part and tooth top part when involute ab and fg are respectively and are basic circle with the root circle.

2. the involute tooth shape of screw of big flow two screw pump according to claim 1 is characterized in that, the curvilinear equation of described superior trochoid ed is:

x＝Rsin2 _ψ-2R ₀sinψ

y＝2R ₀cosψ-Rcos2ψ

$\mathrm{\ρ}=\sqrt{x^2+y^2}$

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

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

＝β-ψ

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

ρ＝R；

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

ρ＝r；

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

ρ＝R ₀；

The curvilinear equation of described superior trochoid bc is:

x＝-Rsin(2ψ- ₀)+2R ₀sin(ψ- ₀)

y＝-Rcos(2ψ- ₀)+2R ₀cos(ψ- ₀)

＝ψ-β

The curvilinear equation of described involute fg is:

$\mathrm{\ρ}=\frac{r}{\cos \mathrm{\α}}$

The curvilinear equation of described involute ab is:

$\mathrm{\ρ}=\frac{r}{\cos \mathrm{\α}}$

$\mathrm{ob}=\sqrt{r^2+(2\sqrt{R_0^2-r^2}-\sqrt{R^2-r^2}{)}^2}$

Wherein, 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, ₀Be the radian of tooth root circular arc ed, α is the pressure angle of involute fg.

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