CN217270815U - Screw rotor and screw vacuum pump - Google Patents

Abstract

An embodiment of the utility model provides a screw rotor and screw vacuum pump relates to the screw rotor field. The end face profile of the screw rotor comprises: a basic curve L, which comprises a cycloid AB, a root circle arc BC, an arc envelope line CD, an arc DE and an addendum circle arc EA which are connected in sequence, wherein the arc DE is a lobe crest circle arc, and the center O of the lobe crest circle ₂ And the center O of addendum circle ₁ A distance of b, center of circle O ₂ To the center of circle O ₁ The included angle of the extension line of the line connecting the straight line and the point A and the point B of the cycloid AB is w, the arc envelope line CD and the addendum circle arc EA are tangent to the arc DE, the arc envelope line CD and the cycloid AB are tangent to the dedendum circle arc BC, the arc envelope line CD is tangent to the dedendum circle without a sharp point, and the arc DE is tangent to the addendum circle without a sharp point.

Description

Screw rotor and screw vacuum pump

Technical Field

The utility model relates to a screw rotor field particularly, relates to a screw rotor and screw vacuum pump.

Background

The vacuum pump refers to a device or equipment for obtaining vacuum by pumping a pumped container by using a mechanical, physical, chemical or physicochemical method. In popular terms, vacuum pumps are devices that use various methods to improve, create and maintain a vacuum in an enclosed space. Vacuum pumps can be basically classified into two types, i.e., a gas trap pump and a gas transfer pump, according to the operating principle of the vacuum pump. It is widely used in metallurgy, chemical industry, food, electronic coating and other industries. Common vacuum pumps include dry screw vacuum pumps, water ring pumps, reciprocating pumps, slide valve pumps, rotary vane pumps, roots pumps, diffusion pumps, and the like.

In the prior art, the molded line of the end face of the screw rotor has a sharp point, so that the air tightness is poor in the working process after the screw rotor is meshed, and the ultimate vacuum degree and the pumping speed of the screw vacuum pump are influenced.

SUMMERY OF THE UTILITY MODEL

The utility model provides a screw rotor and screw vacuum pump, it can avoid causing screw rotor meshing back, at the in-process of work, and the gas tightness is not good, influences screw vacuum pump's ultimate vacuum and pumping speed.

The embodiment of the utility model discloses a can realize like this:

an embodiment of the utility model provides a screw rotor, screw rotor's terminal surface molded lines includes:

the basic curve L comprises a cycloid AB, a root circle arc BC, an arc envelope line CD, an arc DE and an addendum circle arc EA which are sequentially connected;

the parametric equation for cycloid AB is:

X1＝Rm*sin(2*t)-2A*sin(t)

y1 ═ 2A × cos (t) -Rm × cos (2 × t), where X1 and Y1 are rectangular coordinates of points on the cycloid AB, Rm is the radius of the addendum circle, a is half the center distance between the end face rotor profiles of the two meshing screw rotors, and t is a preset parameter value;

the circular arc DE is a circular arc of the blade crest, and the center O of the blade crest circle ₂ And the center O of the addendum circle ₁ A distance of b, the center of the circle O ₂ To the center of the circle O ₁ The included angle between the straight line of the cycloid AB and the extension line of the connecting line of the point A and the point B is w, and the value range of the included angle w is as follows: [90 °, 180 ° ]]；

The parameter equation of the circular arc envelope CD is as follows:

X2＝2*A*cos(t)-b*cos(2*t)-(r+δ)*(A*cos(t)+b*cos(2*t))/((A^2+b^2+2*A*b*cos(t))^(1/2))

Y2＝2*A*sin(t)-b*sin(2*t)+(r+δ)*(b*sin(2*t)-A*sin(t))/((A^2-b^2+2*A*b*cos(t))^(1/2))，

wherein b + r ═ Rm, b ═ r (Rm ^2-a ^2)/(2 ^ r (r + Rm ^ cos (pi/2 z))), X2 and Y2 are rectangular coordinates of points on a circular arc envelope CD, r is a leaf peak circle radius, and delta is a screw rotor clearance;

the arc envelope line CD and the addendum circle arc EA are tangent to the arc DE, and the arc envelope line CD and the cycloid AB are tangent to the dedendum circle arc BC.

Optionally, in the parametric equation of the cycloid AB, t has a value in a range of [0, arccos (2A/(2 × Rm)) ].

Optionally, in the parameter equation of the circular arc envelope CD, a value range of t is [0, pi/(2 × z) ], and a parameter z is a design coefficient.

Optionally, the number of the basic curves L is two, and the two basic curves L are connected end to end in sequence.

Optionally, the number of the basic curves L is three, and the three basic curves L are connected end to end in sequence.

Optionally, the number of the basic curves L is four, and the four basic curves L are connected end to end in sequence.

Optionally, the number of the basic curves L is five, and the five basic curves L are connected end to end in sequence.

Optionally, the value of z is 5.

Optionally, the value of z is 4.

The embodiment of the utility model also provides a screw vacuum pump, which comprises a pump body and the screw rotors, wherein the two screw rotors are mutually meshed;

the point a, the root circle arc BC and the arc envelope CD of one of the screw rotors are respectively used to engage the cycloid AB, the root circle arc EA and the arc DE of the other screw rotor.

The utility model discloses screw rotor and screw vacuum pump's beneficial effect includes, for example:

an embodiment of the utility model provides a screw rotor, screw rotor's terminal surface molded lines includes: a basic curve L, which comprises a cycloid AB, a root circle arc BC, an arc envelope line CD, an arc DE and an addendum circle arc EA which are connected in sequence, wherein the arc DE is a lobe crest circle arc, and the center O of the lobe crest circle ₂ And the center O of addendum circle ₁ B from center O2 to center O ₁ The included angle of the extension lines of the connecting lines of the straight line and the point A and the point B of the cycloid AB is w, the circular arc envelope line CD and the addendum circle circular arc EA are tangent with the circular arc DE, the circular arc envelope line CD and the cycloid AB are tangent with the dedendum circle circular arc BC, the circular arc envelope line CD and the dedendum circle are tangent without sharp points, the circular arc DE and the addendum circle are tangent without sharp points, the end surface molded lines are in smooth transition, and the smooth transition of the end surface molded lines can be avoided when the screw rotors are meshed and work after the screw rotors are meshedIn the process, the air tightness is poor, and the ultimate vacuum degree and the pumping speed of the screw vacuum pump are influenced.

The embodiment of the utility model provides a screw vacuum pump is still provided, including the pump body and foretell screw rotor, two screw rotor intermeshing, point A, the root of tooth circle circular arc BC and the circular arc envelope CD of one of them screw rotor are used for meshing cycloid AB, root of tooth circle circular arc EA and the circular arc DE of another screw rotor respectively, and it can avoid causing screw rotor meshing back, at the in-process of work, and the gas tightness is not good, influences screw vacuum pump's ultimate vacuum and take out speed.

Drawings

In order to more clearly illustrate the technical solution of the embodiments of the present invention, the drawings which are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention, and therefore should not be considered as limiting the scope, and it is also possible for those skilled in the art to obtain other related drawings based on the drawings without inventive efforts.

Fig. 1 is a schematic view of a single-end screw rotor end-face profile provided in an embodiment of the present invention;

fig. 2 is a schematic view of the end-face profile meshing of a single-end screw rotor provided in an embodiment of the present invention;

fig. 3 is a schematic view of end face profile meshing of a double-headed screw rotor provided in an embodiment of the present invention;

fig. 4 is a schematic view of the engagement of the end-face profile of the three-headed screw rotor provided in the embodiment of the present invention;

fig. 5 is a schematic view of end-face profile meshing of a four-head screw rotor provided in an embodiment of the present invention;

fig. 6 is a schematic view of end-face profile meshing of a five-screw rotor according to an embodiment of the present invention.

Detailed Description

To make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the attached drawings in the embodiments of the present invention are combined to clearly and completely describe the technical solution in the embodiments of the present invention, and obviously, the described embodiments are part of the embodiments of the present invention, rather than all embodiments. The components of embodiments of the present invention, as generally described and illustrated in the figures herein, may be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the present invention, presented in the accompanying drawings, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by a person of ordinary skill in the art without creative efforts belong to the protection scope of the present invention.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

It should be noted that the features of the embodiments of the present invention may be combined with each other without conflict.

The vacuum pump refers to a device or apparatus for obtaining vacuum by evacuating a container to be evacuated by using a mechanical, physical, chemical or physicochemical method. In general, a vacuum pump is a device for improving, generating and maintaining a vacuum in a certain closed space by various methods. Vacuum pumps can be basically classified into two types, i.e., a gas trap pump and a gas transfer pump, according to the operating principle of the vacuum pump. It is widely used in metallurgy, chemical industry, food, electronic coating and other industries. Common vacuum pumps include dry screw vacuum pumps, water ring pumps, reciprocating pumps, slide valve pumps, rotary vane pumps, roots pumps, diffusion pumps, and the like. In the prior art, the molded line of the end face of the screw rotor has a sharp point, so that the air tightness is poor in the working process after the screw rotor is meshed, and the ultimate vacuum degree and the pumping speed of the screw vacuum pump are influenced.

In view of this, the screw rotor and the screw vacuum pump provided in the embodiments of the present invention can solve this problem.

Referring to fig. 1-6, the present embodiment provides a screw rotor and a screw vacuum pump, which will be described in detail below.

Referring to fig. 1 and 2, an embodiment of the present invention provides a screw vacuum pump, specifically a twin-screw vacuum pump, which includes a pump body and screw rotors, wherein the screw rotors are single-head screw rotors, the two screw rotors are engaged with each other, and a point a, a tooth root circle arc BC and an arc envelope CD of one screw rotor are respectively used for engaging a cycloid AB, a tooth root circle arc EA and an arc DE of the other screw rotor.

Specifically, a point a, a root circle arc BC and an arc envelope CD on the end face profile of the single-headed screw rotor are used to engage a cycloid AB, a root circle arc EA and an arc DE on the end face profile of the other single-headed screw rotor, respectively.

The end face molded line of the screw rotor comprises a basic curve L, the basic curve L comprises a cycloid AB, a tooth root circular arc BC, an arc envelope line CD, an arc DE and an addendum circular arc EA which are sequentially connected, and the cycloid AB, the tooth root circular arc BC, the arc envelope line CD, the arc DE and the addendum circular arc EA are sequentially connected end to form the end face molded line of the single-head screw rotor. The arc DE is the arc of the blade crest circle, the center O of which ₂ And the center O of addendum circle ₁ A distance of b from the center of circle 02 to the center of circle O ₁ The included angle between the straight line of the cycloid curve A and the extension line of the connecting line of the point A and the point B of the cycloid curve AB is w, the circular arc envelope line CD and the addendum circle circular arc EA are tangent to the circular arc DE, and the circular arc envelope line CD and the cycloid curve AB are tangent to the dedendum circle circular arc BC.

Therefore, the arc envelope CD is tangent to the tooth root circle and does not have a sharp point, the arc DE is tangent to the tooth top circle and does not have a sharp point, the phenomenon that a cutter jumps and poor transition occurs in the machining process of a screw rotor is avoided, and meanwhile, the phenomenon that the screw rotor is meshed and then the air tightness is poor in the working process and the limit vacuum degree and the pumping speed of the screw vacuum pump are influenced can be avoided.

Wherein, the parameter equation of cycloid AB is:

X1＝Rm*sin(2*t)-2A*sin(t)

y1 ═ 2A × cos (t) -Rm × cos (2 × t), where X1 and Y1 are rectangular coordinates of points on the cycloid AB, Rm is the radius of the addendum circle, a is half the center distance between the end face rotor profiles of the two meshing screw rotors, i.e., the radius of the pitch circle of Ra, and t is a preset parameter value.

Wherein, the arc DE is the arc of the blade crest circle, the radius of the blade crest circle is r, and the center O of the blade crest circle ₂ And the center O of addendum circle ₁ A distance of b, a center of a circle O ₂ To the center of circle O ₁ The included angle of the straight line and the extension line of the connecting line of the point A and the point B of the cycloid AB is w, and the value range of the included angle w is as follows: [90 °, 180 ° ]]Specifically, in this embodiment, the value of the included angle w is 135 °. In addition, the circle center 02 is located in the end face rotor profile of the single-head screw rotor.

In addition, the parameter equation of the circular arc envelope CD is:

X2＝2*A*cos(t)-b*cos(2*t)-(r+δ)*(A*cos(t)+b*cos(2*t))/((A^2+b^2+2*A*b*cos(t))^(1/2))

Y2＝2*A*sin(t)-b*sin(2*t)+(r+δ)*(b*sin(2*t)-A*sin(t))/((A^2-b^2+2*A*b*cos(t))^(1/2))，

in the present embodiment, b + r ═ Rm, b ═ Rm ^2-a ^2)/(2 ^ r + Rm ^ cos (pi/2 z))), X2 and Y2 are orthogonal coordinates of points on the circular arc envelope CD, r is the radius of the lobe circle, δ is the screw rotor clearance, that is, δ is the meshing clearance of the end surface molded lines of the two screw rotors, and δ may be, for example, 0.1mm to 0.2 mm.

In this example, in the parameter equation of the cycloid AB, the value range of t is [0, arccos (2A/(2 × Rm)) ], in the parameter equation of the circular arc envelope CD, the value range of t is [0, pi/(2 × z) ], the parameter z is a design coefficient, the value of z can be 2, 3, 4, and 5, the value of z can be selected according to specific situations, and when the value of z is larger, the area utilization coefficient of the end surface profile of the screw rotor is also larger.

Also, in this embodiment, the profile of the end faces of the two intermeshing screw rotors is the same, which can be transmitted using a synchronizing gear.

With continued reference to fig. 3 to fig. 6, the number of the basic curves L may be other numbers to form a multi-head screw rotor, which can solve the dynamic balance problem of the single-head screw rotor and reduce the vibration, for example, the number of the basic curves L is two, the two basic curves L are sequentially connected end to form a double-head screw rotor, the number of the basic curves L is three, the three basic curves L are sequentially connected end to form a three-head screw rotor, the number of the basic curves L is four, the four basic curves L are sequentially connected end to form a four-head screw rotor, the number of the basic curves L is five, and the five basic curves L are sequentially connected end to form a five-head screw rotor.

In summary, the end profile of the screw rotor includes: a basic curve L, which comprises a cycloid AB, a root circle arc BC, an arc envelope line CD, an arc DE and an addendum circle arc EA which are connected in sequence, wherein the arc DE is a lobe crest circle arc, and the center O of the lobe crest circle ₂ And the center O of addendum circle ₁ A distance of b, a center of a circle O ₂ To the center of circle O ₁ The included angle of the extension lines of the connection lines of the straight line and the point A and the point B of the cycloid AB is w, the arc envelope line CD and the addendum circle arc EA are tangent to the arc DE, the arc envelope line CD and the cycloid AB are tangent to the dedendum circle arc BC, the arc envelope line CD and the dedendum circle arc are tangent to each other without a sharp point, the arc DE and the addendum circle arc are tangent to each other without a sharp point, and after the screw rotors are meshed, the limit vacuum degree and the pumping speed of the screw vacuum pump are influenced due to poor air tightness in the working process.

Meanwhile, the area of a leakage triangle is reduced, interstage backflow of the pump is reduced, and when the screw rotor is produced, the detection mode can be used for detecting the concave tooth surface and the inclined tooth surface by a common three-axis three-coordinate equipped measuring pin joint, so that the detection difficulty is reduced.

The screw vacuum pump comprises a pump body and the screw rotors, wherein the two screw rotors are meshed with each other, a point A, a tooth root circular arc BC and an arc envelope CD of one screw rotor are respectively used for meshing a cycloid AB, a tooth root circular arc EA and an arc DE of the other screw rotor, and the screw vacuum pump can avoid the influence on the limit vacuum degree and the pumping speed of the screw vacuum pump due to poor air tightness in the working process after the screw rotors are meshed.

The above description is only for the specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims (10)

1. A screw rotor, characterized in that a face profile of the screw rotor comprises:

the basic curve L comprises a cycloid AB, a root circle arc BC, an arc envelope line CD, an arc DE and an addendum circle arc EA which are sequentially connected;

the parametric equation for cycloid AB is:

wherein X1 and Y1 are rectangular coordinates of points on the cycloid AB, Rm is the radius of an addendum circle, A is half of the center distance of end face rotor profiles of two meshed screw rotors, and t is a preset parameter value;

the circular arc DE is a circular arc of a blade peak, and the center O of the blade peak circle ₂ To the center O of the addendum circle ₁ The included angle between the straight line of the cycloid AB and the extension line of the connecting line of the point A and the point B is w, and the value range of the included angle w is as follows: [90 °, 180 ° ]]；

The parameter equation of the circular arc envelope CD is as follows:

wherein X2 and Y2 are rectangular coordinates of points on the circular arc envelope CD, r is the radius of a blade peak circle, delta is the clearance of a screw rotor, and b is the center O of the blade peak circle ₂ And the center O of the addendum circle ₁ B + r ═ Rm, b ═ (Rm ^2-a ^2)/(2 ^ r + Rm ^ cos (pi/2 z)));

the arc envelope line CD and the addendum circle arc EA are tangent to the arc DE, and the arc envelope line CD and the cycloid AB are tangent to the dedendum circle arc BC.

2. Screw rotor according to claim 1, characterized in that t in the parametric equation of cycloid AB has a value in the range of [0, arccos (2A/(2 x Rm)) ].

3. The screw rotor according to claim 1, characterized in that in the equation of the parameters of the circular arc envelope CD, t has a value in the range of [0, pi/(2 x z) ], and z is a design coefficient.

4. Screw rotor according to claim 3, characterised in that z has a value of 5.

5. Screw rotor according to claim 3, characterised in that z has a value of 4.

6. Screw rotor according to claim 1, characterized in that the number of base curves L is four, the four base curves L being connected end to end in sequence.

7. The screw rotor of claim 1, characterized in that the number of the basic curves L is five, and five basic curves L are connected end to end in sequence.

8. Screw rotor according to claim 1, characterized in that the number of base curves L is two, the two base curves L being connected end to end in sequence.

9. Screw rotor according to claim 1, characterized in that the number of elementary curves L is three, the three elementary curves L being connected end to end in sequence.

10. A screw vacuum pump comprising a pump body and two screw rotors according to any one of claims 1 to 9, the two screw rotors being intermeshed;

the point a, the root circle arc BC and the arc envelope CD of one of the screw rotors are respectively used to engage the cycloid AB, the root circle arc EA and the arc DE of the other screw rotor.

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