CN1328513C - Method for designing molded lines of rotor of helical lobe compressor - Google Patents

Abstract

The present invention discloses a designing method for a type line of a rotor of a screw compressor. One or a plurality of secondary curves are selected first to form a tooth curve according to the general requirements and the practical using occasions of the type line of the rotor of the screw compressor and the specific requirements, wherein the secondary curve comprises a circular arc, an ellipse and a conjugate envelope line of the secondary curve; the tooth curve has no point, straight line or conjugate cycloid of the tooth curve. Next, the geometric character value of the tooth curve is calculated out through quantitative calculation, and the integral performance of the screw compressor is predicated, so that the combination of the tooth number and the structure parameters of the type line are adjusted and optimized. Thereby, the resultant moment of a vapor body of a female rotor of a designed type line approaches to zero. The engaging gap is determined by using an element limiting method to specifically analyze and calculate the deformation of each part of the type line, and the driving side and the non-driving side near to a pitch circle are respectively provided with a driving belt. Therefore, the present invention ensures that the female rotor and a male rotor only contact and transfer moment near a pitch circle in a pure rolling mode when the compressor works. The rotor designed by the method of the present invention is suitable for being processed by a grinding method, and has the advantages of performance improvement and noise reduction.

Description

A kind of method for designing molded lines of rotor of helical lobe compressor

Technical field

The invention belongs to Machine Design and manufacture field, particularly a kind of method for designing molded lines of rotor of helical lobe compressor.

Background technique

Helical-lobe compressor has the advantage of a series of uniquenesses, at home, all have very big development potentiality on the international market.That helical-lobe compressor has is simple in structure, reliability is high and the advantage of a series of uniquenesses such as convenient operating maintenance, can be widely used in refrigeration, air-conditioning and the kinds of processes flow process.

In the design process of helical-lobe compressor, the overall performance of the machine that the design of molded lines of rotor often determines.Can sum up from molded lines patent both domestic and external and developing history: screw molded lines is divided into symmetrical molded lines and asymmetric molded lines, and monolateral molded lines and bilateral molded lines.The identical symmetric form that is called in tooth top center line both sides, and the asymmetrical type that is called inequality; Only in the inside of rotor pitch circle or outsidely have monolateral molded lines of being called of molded lines on one side, all has the bilateral molded lines of becoming of molded lines at pitch circle inside and outside.Screw molded lines has experienced symmetrical circular arc molded lines, asymmetric molded lines, new asymmetric molded lines three generations's development.Along with the development of computer level, the molded lines of exhaust end base of oil injection threaded bolt is with bilateral asymmetrical molded lines (Arc Cycloid, envelope cycloid are main flow), and the result who adopts this molded lines is that the efficient of machine is more and more higher, and performance is become better and better.Several representative molded lines are:

1.X molded lines: the X molded lines is to form on the basis of the asymmetric monolateral molded lines that Arc Cycloid is formed, and gear ratio is 4: 6.Belonging to monolateral asymmetric molded lines, is to be proposed by the Atlas company of Sweden.

2.Sigma molded lines: the Sigma molded lines is 5: 6 a gear ratio molded lines by the Kaeser company release of Germany.

3.CF molded lines: the CF molded lines is to be proposed by the GHH company of Germany, and it has the characteristics of X molded lines and Sigma molded lines, and structurally more reasonable.

The helical-lobe compressor production and the application of China are started late, after entering this century,, energy-conservation and environmental protection are had higher requirement along with the development of Chinese national economy, the helical-lobe compressor of domestic original co-design is because noise is big, energy consumption is high, can not satisfy market demands.In addition, the fast development along with China's refrigeration, air-conditioning industry also presses for high performance helical-lobe compressor on the market.In this case, China has to from external a large amount of import helical-lobe compressors, has caused very big adverse effect for the development of China's national industry.Though China has had the process equipment of production high quality rotor, improve the performance level and the workmanship of homemade helical-lobe compressor, key is to improve designing technique.And the design of molded lines of rotor is the core technology of helical-lobe compressor, and molded lines of rotor has decisive influence to the noise and the performance of helical-lobe compressor.

Summary of the invention

According to above-mentioned domestic and international helical-lobe compressor molded lines designs situation, the objective of the invention is to, a kind of new method of molded lines of rotor of helical lobe compressor design is provided, the helical-lobe compressor molded lines processing of this method design is simple, processing cost is low, be fit to adopt the method processing of grinding, guarantee high machining accuracy easily, improve the performance of helical-lobe compressor and reduce noise.

The function of helical-lobe compressor is to compress all kinds of gas working mediums cost-effectively, for this reason, the screw rotor molded lines should satisfy the requirement of general gear motion, and promptly the respective teeth half-interval contour must satisfy the fundamental law of flank profil engagement, and asks for the conjugate curve of known curve by conjugate condition.In addition, because the rotor end-face molded lines also has decisive influence to the aspects such as efficient, volume and processing cost of helical-lobe compressor, therefore no matter be in the design process of new molded lines, still when analyzing more different molded lines, all also will consider the basic demand of following several respects.At first be requirement, promptly require molded lines that compressor is had axially and tightness radially sealing.Particularly, except that require the rotor Line of contact continuously, also require the leakage triangle area as far as possible little, Line of contact is as far as possible short.And in fact, this is the factor of a pair of mutual restriction, can not reach the most satisfied index simultaneously.When the design molded lines, key is the relation that will match the two.Secondly, be that the requirement molded lines has bigger area utilization factor, so not only the size of machine can be smaller, and the leakage loss of unit capacity also will lack, and efficient is improved relatively.In addition, also require the molded lines streaming, reduce noise, also will be convenient to processing to reduce the gas flow loss.In view of satisfying as above all requirements, the molded lines of rotor of helical lobe compressor is generally multistage curve end-to-end to be formed, and wherein mainly contains cycloid, circular arc, ellipse and parabola etc.In general, the employing cycloid can effectively reduce the area of leakage triangle, but contact line length will increase.Adopt circular arc that Line of contact is shortened, but also increased the leakage triangle area simultaneously.

To achieve these goals, the present invention adopts following technological scheme:

A kind of method for designing molded lines of rotor of helical lobe compressor is characterized in that, may further comprise the steps:

1) at first according to the molded lines of rotor of helical lobe compressor designing requirement, according to the definite tooth curved segments that is adopted of following theory shaped wire equation, wherein quadratic curve comprises circular arc, ellipse and conjugation envelope thereof, the tooth curve does not contain point, straight line and conjugation cycloid thereof, it is tangent that the tie point of each tooth curve keeps, be that single order can be led and derivative equates, to guarantee the smooth connection of tooth curve;

The cd section: $\left\{\begin{array}{c}{x}_2=R_{2t}-{\mathrm{<figure-callout\; id="3"\; label="R"\; filenames="C20051009639100181.png"\; state="\{\{state\}\}">R</figure-callout>}}_3\mathrm{<figure-callout\; id="2"\; label="cos\; t\; y"\; filenames="C20051009639100181.png"\; state="\{\{state\}\}">cos</figure-callout>}t& \\ y_{}{}_2=-R_3\sin t\end{array}\right.(0\&le;t\&le;t_1)$

The de section: $\left\{\begin{array}{c}{x}_2=R_8\cos t_2-R_4\cos (t+t_2)\\ y_2=R_8\sin t_2-R_4\sin (t+t_2)\end{array}\right.(t_8\&le;t{\&le;t}_5)$

Ea ₂Section: $\left\{\begin{array}{c}{x}_2=(R_{2t}-R_5)\mathrm{<figure-callout\; id="3"\; label="cos\; t"\; filenames="C20051009639100181.png"\; state="\{\{state\}\}">cos</figure-callout>}{t}_{}{}_3+R_5\cos (t-t_2-t_5)\\ {\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="C20051009639100181.png"\; state="\{\{state\}\}">y</figure-callout>}}_2=-(R_{2t}-R_5)\sin t_3-R_5\sin (t-t_2-t_5)\end{array}\right.(0\&le;t\&le;t_9)$

a ₂a ₁Section: $\left\{\begin{array}{c}{x}_2=R_{2t}\mathrm{<figure-callout\; id="2"\; label="cos\; t\; y"\; filenames="C20051009639100181.png"\; state="\{\{state\}\}">cos</figure-callout>}t& \\ y_{}{}_2=R_{2t}\sin t\end{array}\right.({\mathrm{<figure-callout\; id="3"\; label="t"\; filenames="C20051009639100181.png"\; state="\{\{state\}\}">t</figure-callout>}}_3\&le;t\&le;{\mathrm{<figure-callout\; id="3"\; label="t"\; filenames="C20051009639100181.png"\; state="\{\{state\}\}">t</figure-callout>}}_3+t_0)$

a ₁The b section: $\left\{\begin{array}{c}{x}_2=R_7\cos (t-t_4)+(R_{2t}-R_7)\cos t_4\\ {\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="C20051009639100181.png"\; state="\{\{state\}\}">y</figure-callout>}}_2=-R_7\sin (t-t_4)+(R_{2t}-R_7)\sin t_4\end{array}\right.(0\&le;t\&le;t_7)$

The bc section:

Wherein, a ₁B, cd, de, ea ₂, a ₂a ₁Be circular curve, bc is an arc envelope line,

x ₂, y ₂Be respectively the coordinate of female rotor composing type line segment each point,

t ₀: circular arc a in the expression molded lines ₂a ₁The central angle of being striden;

t ₂: used auxiliary angle when circular arc de is calculated in expression is its center of circle Q and female rotor center O ₂Line and rotor centerline O ₁O ₂Angle between the line;

t ₄: circular arc a is calculated in expression ₁Used auxiliary angle during b is its center of circle s and female rotor center O ₂Line and rotor centerline O ₁O ₂Angle between the line;

R ₃Be cd section sweep, R ₄Be de section sweep, R ₅Be ea ₂The section sweep, R ₆Be bc section sweep, R ₇Be a ₁B section sweep, R _2tBe a ₂a ₁The section sweep, R ₈For calculating the auxiliary materials of de section curve;

R _1tBe the male rotor Pitch radius,

R _2tBe the female rotor Pitch radius,

D ₁Be the male rotor external diameter,

K=i+1, i are the rotor gear ratio,

A is a centre distance,

 ₁Be the male rotor corner,

Cd section curve plays angle and whole angle and is respectively 0 and t ₁, de section curve plays the angle and whole angle is respectively t ₈And t ₅, ea ₂The section curve plays angle and whole angle and is respectively 0 and t ₉, a ₂a ₁The section curve plays the angle and whole angle is respectively t ₃And t ₃+ t ₀, a ₁B section curve plays angle and whole angle and is respectively 0 and t ₇, t forms the angle parameter of curve for each;

2) determined after the female rotor molded lines equation,, obtained male rotor molded lines equation according to following transformation of coordinates relation according to the theory of engagement:

In the formula: k=i+1, i are yin, yang rotor gear ratio,

x ₁, y ₁Be respectively the coordinate of male rotor composing type line segment each point;

3) then by the contact line length that quantitatively calculates the tooth curve, the geometrical property value of revealing triangle area, area utilization factor, vent ports area, and the prediction helical-lobe compressor whole can, adjust and optimize number of teeth combination and molded lines structural parameter, wherein,

I) determine the number of teeth:

Along with increasing of the number of teeth, determine the molded lines of number of teeth 5+6 combination by the geometrical property value of more several number of teeth combinations;

Ii) select parameter as follows:

R ₃＝0.1577D ₁，R ₅＝0.0571D ₁，R ₆＝0.0604D ₁，R ₇＝0.0143D ₁；

4) calculate moment distribution and bearing load between rotor again, make the gas resultant moment of force on the female rotor approaching zero,

The computational methods of female rotor moment are as follows:

Female rotor axial gas forces: F _Gaa=∑ Δ p _iΔ S _i

In the formula: F _GaaBe axial gas forces, Δ p _iBe the gas pressure difference of i between cog volume Line of contact both sides, Δ S _iOn corresponding contact groove section, flank of tooth area of contour poor on end face in the upper and lower high pressure of bottom land helix district determined by the molded lines equation;

The female rotor moment of torsion is: $M_{\mathrm{ga}}={\&Integral;}_{\left(f\right)}d{M}_{\mathrm{ga}}=\frac{\mathrm{<figure-callout\; id="2"\; label="T"\; filenames="C20051009639100181.png"\; state="\{\{state\}\}">T</figure-callout>}}{2\mathrm{\&pi;}}{F}_{\mathrm{gaa}},$

T is the female rotor helical pitch in the formula;

5) utilize finite element method that the distortion of whole molded lines of rotor is analyzed and calculated at last, determine not equidistant back lash, select each parameter, the driving side and the non-drive side formation length that make it near pitch circle are the rotating band of 2～4mm, thereby guarantee when compressor operating, the yin, yang rotor only near pitch circle the mode with pure rolling contact and carry-over moment.

Owing in molded lines of rotor design of the present invention, adopted the method and the criterion of a series of novelties, obtained brand-new molded lines of rotor design result, the result of calculation of SCCAD software shows, the female rotor gas resultant moment of force of the monolateral asymmetric cycloid of domestic original co-design-pin tooth circular arc molded lines is for negative, and its size is about 15% of a compressor input torque.The female rotor gas resultant moment of force of SRM-D molded lines that application is also arranged at home is for just, and its size is 10%～15% of a compressor input torque.In method for designing molded lines of rotor of the present invention, then consciously with the gas resultant moment of force on the female rotor approaching zero.Like this, when compressor operating, male rotor only need overcome the frictional resistance moment that acts on the female rotor, can drive female rotor, very helps to reduce noise and improves performance.Utilize the helical-lobe compressor performance of this method design to improve more than 5%, the noise 5～10dB (A) that descends has reached the international most advanced level of like product.The machine of a plurality of models has dropped into to be produced in batches and uses, and has obtained huge economic benefit and good social benefit.

Description of drawings

Fig. 1 at the designed bilateral asymmetric wholecircle camber line of opening type Spiral Lobe Refrigeration Compressor, is called for short the X molded lines for utilizing method of the present invention.

Fig. 2 is the partial enlarged drawing of X molded lines shown in Figure 1.

Fig. 3 is the influence of female rotor addendum to female rotor gas resultant moment of force.

Fig. 4 is rotor engaged gap distribution figure.

Embodiment

For a more clear understanding of the present invention, the present invention is described in further detail below in conjunction with accompanying drawing and data sheet and specific embodiment.

The technology used in the present invention principle and scheme are described in detail as follows:

1) when the design molded lines, at first will be according to the fitness for purpose of molded lines of rotor of helical lobe compressor and the specific (special) requirements of actual use occasion, preliminary earlier selected one or more curves are formed the tooth curve, then by quantitatively calculating its geometrical property value and its performance of prediction, adjusting and combination of optimization such as the number of teeth and molded lines structural parameter etc., finally is the superior new molded lines of availability.The present invention is significantly improved at the common molded lines of composition tooth curve ratio of screw rotor molded lines, do not adopt a little and straight line in the design because usually molded lines of rotor form contain in the tooth curve a bit, straight line and conjugation cycloid thereof, cause having in the molded lines shortcoming of a plurality of cusps.The existence of these cusps can cause bigger flow perturbation loss, and bring out higher noise.In addition, form in the tooth curve and contain straightway, rotor also is not suitable for adopting the method processing of grinding.

2) computational geometry characteristic value and primary election molded lines structural parameter

The geometrical property value of so-called rotor of helical lobe compressor, be on face type line computation result's basis, consider Structural Parameters of its Rotor (as slenderness ratio, torsion angle) and aperture parameter, further calculate geometrical properties such as Changing Pattern such as contact line length, leakage triangle area, area utilization factor, suction and discharge orifice area and element volume.When designing or analyzing new molded lines, can come the quality of preliminary judgement molded lines or the structural parameter of initial shaping line by comparing the geometrical property value of molded lines.In addition, the calculating of geometrical property value also is the basis and the prerequisite of helical-lobe compressor operation process simulation and performance prediction.

3) prediction of helical-lobe compressor overall performance and molded lines parameter optimization

The overall performance prediction of helical-lobe compressor is exactly on the basis that aforementioned geometrical property value is calculated, utilize engineering thermodynamics, thermal conduction study and hydromechanical knowledge, consider the various leakages in the helical-lobe compressor comprehensively, losses such as flow resistance, set up compressor from beginning the mathematical model of the air-breathing entire work process that finishes to exhaust process, adopt suitable algorithm then, utilize computer to find the solution this model, obtain the element volume internal pressure, temperature, microscopic characteristics and air displacement that quality etc. change with angle of rotor, air horsepower, adiabatic efficiency, macro properties such as volumetric efficiency, thereby the volumetric efficiency of the different molded lines of energy quantitative comparison, performance index such as adiabatic efficiency, realize the optimization of molded lines structural parameter, and design the molded lines of performance the best in light of the circumstances.Consider Structural Parameters of its Rotor and aperture parameter simultaneously, further conventional geometrical property parameter in the Changing Pattern of calculating such as contact line length, leakage triangle area, area utilization factor, suction and discharge orifice area and element volume and the compressor design.When designing or analyzing new molded lines, can come the quality of preliminary judgement molded lines or the structural parameter of initial shaping line by comparing the geometrical property value of molded lines.In addition, the calculating of geometrical property value also is the basis and the prerequisite of helical-lobe compressor operation process simulation and performance prediction.

4) in method for designing molded lines of rotor of the present invention, noticed not only that from the angle preferred parameter that reduces to leak also further having noticed has the influence of related parameter to moment distribution and bearing load between rotor.When helical-lobe compressor was worked, the female rotor flank of tooth was touched line and is divided into two-part that effect has high and low pressure refrigeration agent gas pressure.Along with the composition tooth curve kind of molded lines of rotor employing and the difference of parameter variation range thereof, its gas resultant moment of force might also might be negative (promptly driving the female rotor rotation) for just (promptly hindering the female rotor rotation).This explanation though male rotor and prime mover link, when compressor operating, might be the male rotor drive female rotor in helical-lobe compressor, also might be the female rotor drive male rotor.Obviously, the moment between this rotor divides the noise and the performance of pairing compressor that material impact is all arranged, and the moment of transmitting between rotor is more little, and compressor performance is just good more.

5) the crucial optimisation technique of another in the method for designing molded lines of rotor is the setting of back lash between rotor.Stress deformation and expanded by heating when compensating machining error and working rotor need be set the gap of each point, and carry out the processing of rotor according to the actual molded lines that obtains thus on the basis of theoretical molded lines.Traditional gap establishing method is isometric type collimation method and equidistant profile method, and two kinds of methods are not all considered the difference of molded lines each several part amount of deformation.In molded lines of the present invention back lash is set, then utilize Finite Element Method that the distortion of molded lines each several part is analyzed and calculated, formed the not equidistant of back lash.In addition, because on pitch circle, the yin, yang rotor is a pure rolling, does not have relative sliding velocity between rotor, in the back lash of this project is set, near pitch circle driving side and non-drive side all further reduce the gap consciously again, are provided with the rotating band that length is 2～4mm, thereby guaranteed when compressor operating, the yin, yang rotor only near pitch circle the mode with pure rolling contact and carry-over moment, to further reduction noise with improve compressor performance, played help.

Above-mentioned correct performance prediction program and geometrical property value computer program and series of optimum method have been arranged, just can calculate molded lines performance with different structure parameter, and the final on this basis selected structural parameter that can obtain top performance.

Through making great efforts for many years, Xi'an Communications University has successfully developed the complete helical-lobe compressor computer-aided design(CAD) system SCCAD of a cover, this software mainly carries out geometrical property, thermodynamic property analysis and prediction to the helical-lobe compressor of different molded lines, a series of difficult problems that exist in this class compressor design have been solved, helical-lobe compressor computer-aided design(CAD) system SCCAD optimizes, in the novel line development process of helical-lobe compressor, need quantitatively to calculate specific molded lines the geometrical property value, and simulate the working procedure of new molded lines helical-lobe compressor on this basis.Obviously, these work can not be finished with traditional design of twin screw compressor method.

Below provide concrete design example:

1) the theory shaped wire equation is determined: as example, Fig. 1 illustrates the tooth curve X molded lines of superior performance.According to the specific (special) requirements of fitness for purpose and actual use occasion, the tooth curved segments of employing is respectively: a ₁B, cd, de, ea ₂, a ₂a ₁Be circular curve, bc is an arc envelope line, and preliminary selected this new molded lines equation is as follows:

The cd section: $\left\{\begin{array}{c}{x}_2=R_{2t}-{\mathrm{<figure-callout\; id="3"\; label="R"\; filenames="C20051009639100181.png"\; state="\{\{state\}\}">R</figure-callout>}}_3\cos t\\ {\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="C20051009639100181.png"\; state="\{\{state\}\}">y</figure-callout>}}_2=-{\mathrm{<figure-callout\; id="3"\; label="R"\; filenames="C20051009639100181.png"\; state="\{\{state\}\}">R</figure-callout>}}_3\sin t\end{array}\right.(0\&le;t\&le;t_1)$

The de section: $\left\{\begin{array}{c}{x}_2=R_8\cos t_2-{\mathrm{<figure-callout\; id="4"\; label="R"\; filenames="C20051009639100181.png"\; state="\{\{state\}\}">R</figure-callout>}}_4\cos (t+t_2)\\ {\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="C20051009639100181.png"\; state="\{\{state\}\}">y</figure-callout>}}_2=R_8\sin t_2-{\mathrm{<figure-callout\; id="4"\; label="R"\; filenames="C20051009639100181.png"\; state="\{\{state\}\}">R</figure-callout>}}_4\sin (t+t_2)\end{array}\right.(t_8\&le;t\&le;t_5)$

Ea ₂Section: $\left\{\begin{array}{c}{x}_2=(R_{2t}-R_5)\mathrm{<figure-callout\; id="3"\; label="cos\; t"\; filenames="C20051009639100181.png"\; state="\{\{state\}\}">cos</figure-callout>}{t}_{}{}_3+{\mathrm{<figure-callout\; id="5"\; label="R"\; filenames="C20051009639100181.png"\; state="\{\{state\}\}">R</figure-callout>}}_5\cos (t-t_2-t_5)\\ {\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="C20051009639100181.png"\; state="\{\{state\}\}">y</figure-callout>}}_2=-(R_{2t}-R_5)\sin t_3-{\mathrm{<figure-callout\; id="5"\; label="R"\; filenames="C20051009639100181.png"\; state="\{\{state\}\}">R</figure-callout>}}_5\sin (t-t_2-t_5)\end{array}\right.(0\&le;t\&le;t_9)$

a ₂a ₁Section: $\left\{\begin{array}{c}{x}_2=R_{2t}\cos t\\ {\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="C20051009639100181.png"\; state="\{\{state\}\}">y</figure-callout>}}_2=R_{2t}\sin t\end{array}\right.({\mathrm{<figure-callout\; id="3"\; label="t"\; filenames="C20051009639100181.png"\; state="\{\{state\}\}">t</figure-callout>}}_3\&le;t\&le;{\mathrm{<figure-callout\; id="3"\; label="t"\; filenames="C20051009639100181.png"\; state="\{\{state\}\}">t</figure-callout>}}_3+t_0)$

a ₁The b section: $\left\{\begin{array}{c}{x}_2=R_7\cos (t-t_4)+(R_{2t}-R_7)\cos t_4\\ {\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="C20051009639100181.png"\; state="\{\{state\}\}">y</figure-callout>}}_2=-R_7\sin (t-t_4)+(R_{2t}-R_7)\sin t_4\end{array}\right.(0\&le;t\&le;t_7)$

The bc section:

Determined after the male rotor molded lines equation,, can obtain male rotor molded lines equation according to following transformation of coordinates relation according to the theory of engagement.

In the formula: k=i+1, i are yin, yang rotor gear ratio, and A is a centre distance,  ₁Be the male rotor corner.

2) computation of geometric property and molded lines structure parameter optimizing:

Determine after the yin, yang molded lines of rotor, need further to determine parametric equation, come initial optimization molded lines structural parameter by calculating to its computational geometry characteristic value.

1. the number of teeth is determined

The negative and positive rotor number of teeth is extremely important for the molded lines of rotor Effect on Performance, table 1 provided have identical theoretical displacement, same composition tooth curve, but the geometrical property value of the different molded lines of number of teeth combination.

The geometrical property of the different number of teeth combinations of table 1

The number of teeth		Contact line length (mm)	Leakage triangle area (mm 2)	Area utilization factor	Vent ports area (mm 2)
						Male rotor	Female rotor
4	5							349	0.538	0.434	2213
		4	6	369	0.528	0.441	2237
5	5							402	0.548	0.429	2570
		5	6	423	0.534	0.436	2574
5	7							530	0.604	0.388	2971

As can be seen from the table, along with increasing of the number of teeth, contact line length and vent ports area all increase, and area utilization factor and leakage triangle area then vary.Relatively the geometrical property value of these several number of teeth combinations can be judged, the scheme of number of teeth 5+7 combination is except that having the big slightly and rotor rigidity of vent ports area preferably the advantage, because its long Line of contact, excessive leakage triangle area and too small area utilization factor, efficient is not high, should avoid using.Number of teeth 4+5 combination and number of teeth 5+5 combination are with respect to number of teeth 5+6 combination, and except the short advantage of Line of contact, the leakage triangle area is bigger, and area utilization factor and vent ports area are all little, therefore neither optimum number of teeth combination.Number of teeth 4+6 combination is made up with respect to number of teeth 5+6, though make moderate progress at aspects such as Line of contact, leakage areas, but the vent ports area reduces, increased the exhaust process loss, and along with the number of teeth of male rotor increases, actual leakage rate by tooth top can increase with the number of teeth and reduce, and the while is along with the increase (rising of rotating speed) of male rotor top circle circular velocity, the performance of number of teeth 4+6 combination can be worse and worse, so number of teeth 5+6 combination is more superior number of teeth combination.

2. parameter is selected

In this molded lines parameter, except number of teeth combination, also has the main molded lines structural parameter tooth depth radius R that compressor performance is had significant impact in addition ₃, radius of arc R ₅, R ₆And R ₇Deng.R ₃Value be directly connected to area utilization factor, R ₅Value mainly consider contact line length, R ₆And R ₇Then directly have influence on the size of leakage triangle area.Therefore these Parameter Optimization combinations just can make the molded lines performance obtain optimum the embodiment.Utilize the computational analysis of SCCAD software to show, when the value of these parameters is following, can obtain desirable molded lines.

R ₃=0.1577D ₁R ₅=0.0571D ₁R ₆=0.0604D ₁R ₇=0.0143D ₁D in the formula ₁Be the male rotor external diameter.

3) calculating of moment distribution and bearing load between rotor

When helical-lobe compressor was worked, the female rotor flank of tooth was touched line and is divided into two-part that effect has high and low pressure refrigeration agent gas pressure.Along with the composition tooth curve kind of molded lines of rotor employing and the difference of parameter variation range thereof, its gas resultant moment of force might also might be negative (promptly driving the female rotor rotation) for just (promptly hindering the female rotor rotation).This explanation though male rotor and prime mover link, when compressor operating, might be the male rotor drive female rotor in helical-lobe compressor, also might be the female rotor drive male rotor.Obviously, the moment between this rotor divides the noise and the performance of pairing compressor that material impact is all arranged, and the moment of transmitting between rotor is more little, and compressor performance is just good more.Fig. 3 illustrates the influence of the female rotor addendum of certain molded lines to female rotor gas resultant moment of force.The result of calculation of SCCAD software shows that the female rotor gas resultant moment of force of the monolateral asymmetric cycloid of domestic original co-design-pin tooth circular arc molded lines is for negative, and its size is about 15% of a compressor input torque.The female rotor gas resultant moment of force of SRM-D molded lines that application is also arranged at home is for just, and its size is 10%～15% of a compressor input torque.

In method for designing molded lines of rotor of the present invention, then consciously with the gas resultant moment of force on the female rotor approaching zero.Like this, when compressor operating, male rotor only need overcome the frictional resistance moment that acts on the female rotor, can drive female rotor, very helps to reduce noise and improves performance.The computational methods of female rotor moment are as follows:

Female rotor axial gas forces: F _Gaa=∑ Δ p _iΔ S _i

In the formula: F _GaaBe axial gas forces, Δ p _iBe the gas pressure difference of i between cog volume Line of contact both sides, Δ S _iOn corresponding contact groove section, the upper and lower high pressure of bottom land helix district flank of tooth area of contour poor on end face, this is determined by the molded lines equation.

The female rotor moment of torsion is: $M_{\mathrm{ga}}={\&Integral;}_{\left(f\right)}d{M}_{\mathrm{ga}}=\frac{\mathrm{<figure-callout\; id="2"\; label="T"\; filenames="C20051009639100181.png"\; state="\{\{state\}\}">T</figure-callout>}}{2\mathrm{\&pi;}}{F}_{\mathrm{gaa}}$

T is the female rotor helical pitch in the formula.

4) setting of back lash between rotor

Traditional gap establishing method is isometric type collimation method and equidistant profile method, and two kinds of methods are not all considered the difference of molded lines each several part amount of deformation.Stressed and expanded by heating distortion when compensating machining error and working rotor is set the gap of each point according to theory shaped wire, and is obtained actual molded lines thus.In molded lines of the present invention back lash is set, then utilize Finite Element Method that the distortion of molded lines each several part is analyzed and calculated, formed the not equidistant of back lash.In addition, because on pitch circle, the yin, yang rotor is a pure rolling, does not have relative sliding velocity between rotor, in back lash of the present invention is set, near pitch circle driving side and non-drive side all further reduce the gap consciously again, are provided with the rotating band that length is 2～4mm, thereby guaranteed when compressor operating, the yin, yang rotor only near pitch circle the mode with pure rolling contact and carry-over moment, to further reduction noise with improve compressor performance, played help.Its concrete design can be consulted Xing Ziwen professor's monograph: " helical-lobe compressor---theory, design and application " and finite element correlation theory.

The molded lines of rotor that is designed to as shown in Figure 4.

As stated above, semiclosed and dependency structure parameters opening type two type line are optimized, finally obtained the new molded lines of better performances.

Its main structure parameters and geometrical property value are as shown in table 2.

The geometrical property value and the structural parameter of the different molded lines of table 2

Molded lines	Geometrical property value main structure parameters				Main structure parameters
										Contact dimension mm	Leakage triangle area mm 2	Area utilization factor	Vent ports area mm 2	The number of teeth		Diameter mm		Length m m
	Male rotor	Female rotor	Male rotor	Female rotor
					The X molded lines	340.3	0.540	0.435	2231					5	6	105	89		129.4
GB	444.8	0.146	0.469	2475						4	6	105	96					120.0

As a comparison, also calculated the geometrical property value of the monolateral asymmetric pendulum-pin tooth circular arc molded lines (abbreviation GB) of NBS JB2780-79 regulation.

Table 3 illustrates the test performance data of the helical-lobe compressor of different molded lines.

The compressor performance of the different molded lines of table 3 relatively

Molded lines	Working medium and operating mode	Refrigerating capacity kW	COP value kW/kW	Noise dB (A)
					The X molded lines	R717 -6.7/35℃	856.5	4.31	82
GB	722.8	4.08	87

As can be seen from Table 3, two kinds of new molded lines efficient are all than NBS molded lines height, and performance improves more than 5%, and the noise 5～10dB (A) that descends has reached the international most advanced level of like product.

The foregoing description is a concrete example, and also available certainly ellipse and circular arc and conjugation envelope thereof constitute the tooth curve by method of the present invention, and it is tangent that the tie point of each tooth curve keeps, and promptly single order can be led and derivative equates; Can guarantee the smooth connection of tooth curve; Do not contain traditional point, straight line and conjugation cycloid thereof in the tooth curve.Designed molded lines of rotor of helical lobe compressor all can reach purpose of the present invention.

Claims (1)

1. a method for designing molded lines of rotor of helical lobe compressor is characterized in that, may further comprise the steps:

1) at first according to the molded lines of rotor of helical lobe compressor designing requirement, according to the definite tooth curved segments that is adopted of following theory shaped wire equation, wherein quadratic curve comprises circular arc, ellipse and conjugation envelope thereof, the tooth curve does not contain point, straight line and conjugation cycloid thereof, it is tangent that the tie point of each tooth curve keeps, be that single order can be led and derivative equates, to guarantee the smooth connection of tooth curve;

Wherein, a ₁B, cd, de, ea ₂, a ₂a ₁Be circular curve, bc is an arc envelope line,

x ₂, y ₂Be respectively the coordinate of female rotor composing type line segment each point,

t ₀: circular arc a in the expression molded lines ₂a ₁The central angle of being striden;

t ₂: used auxiliary angle when circular arc de is calculated in expression is its center of circle Q and female rotor center O ₂Line and rotor centerline O ₁O ₂Angle between the line;

t ₄: circular arc a is calculated in expression ₁Used auxiliary angle during b is its center of circle s and female rotor center O ₂Line and rotor centerline O ₁O ₂Angle between the line;

R ₃Be cd section sweep, R ₄Be de section sweep, R ₅Be ea ₂The section sweep, R ₆Be bc section sweep, R ₇Be a ₁B section sweep, R _2tBe a ₂a ₁The section sweep, R ₄For calculating the auxiliary materials of de section curve;

R _1tBe the male rotor Pitch radius,

R _2tBe the female rotor Pitch radius,

D ₁Be the male rotor external diameter,

K=i+1, i are the rotor gear ratio,

A is a centre distance,

 ₁Be the male rotor corner,

Cd section curve plays angle and whole angle and is respectively 0 and t ₁, de section curve plays the angle and whole angle is respectively t ₈And t ₅, ea ₂The section curve plays angle and whole angle and is respectively 0 and t ₉, a ₂a ₁The section curve plays the angle and whole angle is respectively t ₂And t ₃+ t ₀, a ₁B section curve plays angle and whole angle and is respectively 0 and t ₇, t forms the angle parameter of curve for each;

2) determined after the female rotor molded lines equation,, obtained male rotor molded lines equation according to following transformation of coordinates relation according to the theory of engagement:

In the formula: k=i+1, i are yin, yang rotor gear ratio,

x ₁, y ₁Be respectively the coordinate of male rotor composing type line segment each point;

3) then by the contact line length that quantitatively calculates the tooth curve, the geometrical property value of revealing triangle area, area utilization factor, vent ports area, and the prediction helical-lobe compressor whole can, adjust and optimize number of teeth combination and molded lines structural parameter, wherein,

I) determine the number of teeth:

Along with increasing of the number of teeth, determine the molded lines of number of teeth 5+6 combination by the geometrical property value of more several number of teeth combinations;

Ii) select parameter as follows:

R ₃＝0.1577D ₁，R ₅＝0.0571D ₁，R ₆＝0.0604D ₁，R ₇＝0.0143D ₁；

4) calculate moment distribution and bearing load between rotor again, make the gas resultant moment of force on the female rotor approaching zero,

The computational methods of female rotor moment are as follows:

Female rotor axial gas forces: F _Gaa=∑ Δ p ₁Δ S ₁

In the formula: F _GaaBe axial gas forces, Δ p ₁Be the gas pressure difference of i between cog volume Line of contact both sides, Δ S ₁On corresponding contact groove section, flank of tooth area of contour poor on end face in the upper and lower high pressure of bottom land helix district determined by the molded lines equation;

The female rotor moment of torsion is: $M_{\mathrm{ga}}={\&Integral;}_{\left(f\right)}{\mathrm{dM}}_{\mathrm{ga}}=\frac{T}{2\mathrm{\&pi;}}{F}_{\mathrm{gaa}},$

T is the female rotor helical pitch in the formula;

5) utilize finite element method that the distortion of whole molded lines of rotor is analyzed and calculated at last, determine not equidistant back lash, select each parameter, the driving side and the non-drive side formation length that make it near pitch circle are the rotating band of 2～4mm, thereby guarantee when compressor operating, the yin, yang rotor only near pitch circle the mode with pure rolling contact and carry-over moment.

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