阅读说明：本技术 一种正时齿形链系统的设计方法 (Design method of timing tooth-shaped chain system ) 是由 汤乐超 卢炳武 何洪源 刘英杰 于 2019-10-28 设计创作，主要内容包括：本发明属于汽车技术领域,具体的说是一种正时齿形链的设计方法。该设计方法包括对链片、链轮导轨的关键参数进行设计；对参数生成对应的链片及链轮齿形、导轨轮的装配直观查看设计结果是否合理即是否存在干涉、长度不够、链片与链轮传动啮合是否干涉,并且通过不断调整对应设计参数的办法快速高效的确定出设计结果。本发明可以对各种布局型式的正时齿形链传动系统进行设计,可以大大降低在对正时齿形链传动系统开发设计时对设计经验的依赖,使一般的工程技术人员也能够对正时齿形链系统进行开发设计,并提高了设计效率和开发产品质量。(The invention belongs to the technical field of automobiles, and particularly relates to a design method of a timing toothed chain. The design method comprises the steps of designing key parameters of a chain sheet and a chain wheel guide rail; the assembly of the chain sheet, the tooth form of the chain wheel and the guide rail wheel corresponding to the parameter generation visually checks whether the design result is reasonable or not, namely whether the design result is interfered or not, the length is not enough, and whether the transmission meshing of the chain sheet and the chain wheel is interfered or not, and the design result is determined quickly and efficiently by a method of continuously adjusting the corresponding design parameter. The invention can design timing tooth chain transmission systems with various layout types, can greatly reduce the dependence on design experience when the timing tooth chain transmission systems are developed and designed, enables general engineering technicians to develop and design the timing tooth chain transmission systems, and improves the design efficiency and the quality of developed products.)

1. A design method of a timing toothed chain system is characterized by comprising the following steps:

step one, designing key parameters of the chain sheet;

the key parameters of the chain sheet comprise the pitch of the chain plate, namely the distance p between two pin shaft holes, the edge center distance f and the tooth form angle 2 a;

secondly, designing key parameters of the chain wheel;

the key parameters of the chain wheel comprise a chain wheel pressure angle alpha, a deflection coefficient x, a tooth crest circle radius da, a tooth root circle radius df, a base circle diameter db, a pitch circle diameter d, and a tooth crest and tooth root circle transition fillet;

thirdly, designing key parameters of the guide rail;

key parameters of the guide rail include guide plate curvature;

generating corresponding chain sheet, chain wheel tooth form and guide rail contour results according to the parameters designed in the first step to the third step, wherein the results are stored in an editable graphic format, and visually checking whether the design results are reasonable or not, namely whether interference exists or not, the length is insufficient, and whether the chain sheet is interfered with the chain wheel transmission meshing or not through assembling the mounting positions of all parts of the wheel system from a graphic file, if not, the design results can be quickly and efficiently determined through a method of continuously adjusting the corresponding design parameters;

step five, when designing a multilayer chain, after completing the design of the initial layout of a single-layer chain system, assembling the chain systems with different layers, displaying the system layout corresponding to the whole timing chain transmission system in a pattern mode, giving the corresponding number of links, and correspondingly adjusting unreasonable design parameters until obtaining a satisfactory layout and a proper number of links;

and step six, determining a design scheme, and sorting and filing the determined design parameters and the generated design result to complete development and design.

2. The method for designing a timing toothed chain system according to claim 1, wherein the specific method of the first step is as follows: firstly, it is determined how large the link plate pitch is to be designed, the edge center distance f is 35% -45% of the link plate pitch, and the tooth profile angle 2a is 30 °.

3. The method for designing the timing toothed chain system according to claim 1, wherein the specific method of the second step is as follows: the reference circle diameter d is obtained by solving the following formula:

d＝p/sin(π/z)；

wherein p is the chain pitch; z is the sprocket tooth number;

the base circle diameter db is obtained by solving the following formula:

db＝m z cosα；

wherein m is modulus, and m is p/pi; z is the sprocket tooth number; p is the chain pitch; alpha is a sprocket pressure angle;

the selection of the sprocket pressure angle alpha is related to the number of teeth, when the number of teeth is less than or equal to 25, the sprocket pressure angle alpha is 31.5 degrees, and when the number of teeth is more than 25, the sprocket pressure angle alpha is taken to be 30 degrees;

the addendum circle radius da and the dedendum circle radius df are selected to meet the requirement that interference does not occur after meshing, the requirement that da is less than d-d1 and the requirement that df is less than d-d2 are met, and the specific value can be solved according to the following formula.

da＝d-d1-c1·m

df＝d-d2-c2·m

Wherein d is the reference circle diameter; d1 is the distance between the reference circle and the bottom of the chain sheet; d2 is the distance between the reference circle and the lowest end of the chain sheet; m is a modulus; c1 is the addendum circle clearance coefficient; c2 is the root circle clearance coefficient; d1 and d2 are variable values, the radius of the reference circle is increased along with the increase of the number of teeth of the chain wheel, the value of d1 is gradually reduced, and the value of d2 is not changed;

the displacement coefficient x is obtained by solving the following formula:

in the formula, p₂Normal tooth pitch of the chain wheel hob; z is the sprocket tooth number; alpha is alpha₂Taking a tooth form angle of 30 degrees for the normal direction of the hob; f. of₀Is hypothetical corresponds to p₀The initial edge-to-center distance of the chain; p is a radical of₀The chain is an imaginary chain initial pitch, and the size of the chain initial pitch is equal to the normal tooth pitch of the hob; f. of₀Solving according to the following formula to obtain:

in the formula, f is the edge center distance of the chain plate; z is the sprocket tooth number; p is the chain pitch; p is a radical of₂Normal tooth pitch of the chain wheel hob;

the transition fillet of the tooth top and the tooth root circle is 0.4mm-2 mm.

4. The design method of the timing toothed chain system according to claim 1, characterized in that the specific method of the third step is as follows: the chain wheel pressure angle alpha, the connecting line of the crankshaft rotation central point and the arc circle center of the chain motion track and the included angle beta between the connecting lines of the two chain wheel centers are obtained by solving according to the following formula:

according to the geometric relationship diagram, the inner concave quantity C of the tight edge₁The relationship with the curvature radius of the chain motion track is represented by the following formula:

wherein r1 and r2 are respectively the pitch circle of the meshing of the crankshaft sprocket and the left idler sprocket with the chain, namely the pitch circle radius; a is₁The distance between the rotation center of the crankshaft chain wheel and the rotation center of the left idle wheel chain wheel; r₁The radius of curvature of the motion trail of the chain is the radius of curvature of the chain after the fixed guide plate is installed;

C₁＝(2-10)％a₁(ii) a When in useInner concave amount C of chain₁When the value is determined, the curvature radius R of the chain motion track under the condition that the chain is tangent to the two chain wheels at the same time can be obtained₁Radius of curvature R of the stationary guide_fgThe following values are taken:

R_fg＝(0.95～0.98)R₁-h₁

in the formula, h₁The chain plate design parameter is the height of the back side of the chain plate, namely the distance from the center of the chain plate hole to the back side of the chain plate.

Technical Field

The invention belongs to the technical field of automobiles, and particularly relates to a design method of a timing toothed chain.

Background

Chain transmission has the advantages of same service life as an engine, high transmission efficiency and the like, so that the chain transmission is widely applied, and a toothed chain is favored due to the characteristic of low noise. However, the timing tooth chain system has different layouts and has an important influence on the dynamic performance of the engine, the development and design of the timing tooth chain system are difficult, and only a few experienced technicians can design and develop the timing tooth chain system by experience, so that mastering a design and development method of the timing tooth chain system becomes one of core technologies which are of great concern to engine host manufacturers.

The timing tooth-shaped chain transmission system works under severe working conditions of high rotating speed, variable load and the like, has strict requirements on the service life, the noise characteristic and the like of the system, and has different layout types aiming at different engine specifications, such as single overhead, double overhead, V-shaped, multi-shaft type, multi-layer type and the like. Therefore, no effective design guidance method is provided for the design of the timing chain transmission system, the dependency of the design of the timing chain transmission system of the engine on the design experience is very large, the foundation of the field in China is weak, corresponding technical means and methods are lacked, and no program method capable of guiding enterprises to design and develop the timing toothed chain system is provided at the present stage.

Disclosure of Invention

The invention provides a simple method for designing a timing toothed chain, which can be used for designing timing toothed chain transmission systems of various layout types, greatly reduce the dependence on design experience during the development and design of the timing toothed chain transmission system and fill the blank of the timing toothed chain design in the prior stage.

The technical scheme of the invention is described as follows by combining the attached drawings:

a design method of a timing toothed chain system comprises the following steps:

step one, designing key parameters of the chain sheet;

the key parameters of the chain sheet comprise the pitch of the chain plate, namely the distance p between two pin shaft holes, the edge center distance f and the tooth form angle 2 a;

secondly, designing key parameters of the chain wheel;

the key parameters of the chain wheel comprise a chain wheel pressure angle alpha, a deflection coefficient x, a tooth crest circle radius da, a tooth root circle radius df, a base circle diameter db, a pitch circle diameter d, and a tooth crest and tooth root circle transition fillet;

thirdly, designing key parameters of the guide rail;

key parameters of the guide rail include guide plate curvature;

generating corresponding chain sheet, chain wheel tooth form and guide rail contour results according to the parameters designed in the first step to the third step, wherein the results are stored in an editable graphic format, and visually checking whether the design results are reasonable or not, namely whether interference exists or not, the length is insufficient, and whether the chain sheet is interfered with the chain wheel transmission meshing or not through assembling the mounting positions of all parts of the wheel system from a graphic file, if not, the design results can be quickly and efficiently determined through a method of continuously adjusting the corresponding design parameters;

step five, when designing a multilayer chain, after completing the design of the initial layout of a single-layer chain system, assembling the chain systems with different layers, displaying the system layout corresponding to the whole timing chain transmission system in a pattern mode, giving the corresponding number of links, and correspondingly adjusting unreasonable design parameters until obtaining a satisfactory layout and a proper number of links;

and step six, determining a design scheme, and sorting and filing the determined design parameters and the generated design result to complete development and design.

The specific method of the first step is as follows: firstly, determining the pitch of a chain plate to be designed, wherein the edge center distance f is 35-45% of the pitch of the chain plate, and the tooth profile angle 2a is 30 degrees;

the specific method of the second step is as follows: the reference circle diameter d is obtained by solving the following formula:

d＝p/sin(π/z)；

wherein p is the chain pitch; z is the sprocket tooth number;

the base circle diameter db is obtained by solving the following formula:

db＝m z cosα；

wherein m is modulus, and m is p/pi; z is the sprocket tooth number; p is the chain pitch; alpha is a sprocket pressure angle;

the selection of the sprocket pressure angle alpha is related to the number of teeth, when the number of teeth is less than or equal to 25, the sprocket pressure angle alpha is 31.5 degrees, and when the number of teeth is more than 25, the sprocket pressure angle alpha is taken to be 30 degrees;

the addendum circle radius da and the dedendum circle radius df are selected to meet the requirement that interference does not occur after meshing, the requirement that da is less than d-d1 and the requirement that df is less than d-d2 are met, and the specific value can be solved according to the following formula.

da＝d-d1-c1·m

df＝d-d2-c2·m

Wherein d is the reference circle diameter; d1 is the distance between the reference circle and the bottom of the chain sheet; d2 is the distance between the reference circle and the lowest end of the chain sheet; m is a modulus; c1 is the addendum circle clearance coefficient; c2 is the root circle clearance coefficient; d1 and d2 are variable values, the radius of the reference circle is increased along with the increase of the number of teeth of the chain wheel, the value of d1 is gradually reduced, and the value of d2 is not changed;

the displacement coefficient x is obtained by solving the following formula:

in the formula, p₂Normal tooth pitch of the chain wheel hob; z is the sprocket tooth number; alpha is alpha₂Taking a tooth form angle of 30 degrees for the normal direction of the hob; f. of₀Is hypothetical corresponds to p₀The initial edge-to-center distance of the chain; p is a radical of₀The chain is an imaginary chain initial pitch, and the size of the chain initial pitch is equal to the normal tooth pitch of the hob; f. of₀Solving according to the following formula to obtain:

in the formula, f is the edge center distance of the chain plate; z is the sprocket tooth number; p is the chain pitch; p is a radical of₂Normal tooth pitch of the chain wheel hob;

the transition fillet of the tooth top and the tooth root circle is 0.4mm-2 mm.

The chain wheel pressure angle alpha, the connecting line of the crankshaft rotation central point and the arc circle center of the chain motion track and the included angle beta between the connecting lines of the two chain wheel centers are obtained by solving according to the following formula:

according to the geometric relationship diagram, the inner concave quantity C of the tight edge₁The relationship with the curvature radius of the chain motion track is represented by the following formula:

wherein r1 and r2 are respectively the pitch circle of the meshing of the crankshaft sprocket and the left idler sprocket with the chain, namely the pitch circle radius; a is₁The distance between the rotation center of the crankshaft chain wheel and the rotation center of the left idle wheel chain wheel; r₁The radius of curvature of the motion trail of the chain is the radius of curvature of the chain after the fixed guide plate is installed;

C₁＝(2-10)％a₁(ii) a When the chain indent amount C₁When the value is determined, the curvature radius R of the chain motion track under the condition that the chain is tangent to the two chain wheels at the same time can be obtained₁Radius of curvature R of the stationary guide_fgThe following values are taken:

R_fg＝(0.95～0.98)R₁-h₁

in the formula, h₁The chain plate design parameter is the height of the back side of the chain plate, namely the distance from the center of the chain plate hole to the back side of the chain plate.

The invention has the beneficial effects that:

the invention can design timing tooth chain transmission systems with various layout types, can greatly reduce the dependence on design experience when the timing tooth chain transmission systems are developed and designed, enables general engineering technicians to develop and design the timing tooth chain transmission systems, and improves the design efficiency and the quality of developed products.

Drawings

FIG. 1 is a schematic view of a chain sheet;

FIG. 2 is a schematic view of the chain link and sprocket after engagement;

FIG. 3 is a schematic view of a crankshaft sprocket and left idler fixed rail calculation parameter geometry.

Detailed Description

A design method of a timing toothed chain system is characterized by comprising the following steps:

referring to fig. 1, step one, designing key parameters of a link;

the key parameters of the chain sheet comprise the pitch of the chain plate, namely the distance p between two pin shaft holes, the edge center distance f and the tooth form angle 2 a;

the specific method comprises the following steps: firstly, determining the pitch of a chain plate to be designed, and then determining the edge center distance f and the tooth profile angle 2a according to the pitch of the chain plate, wherein the edge center distance is 35-45% of the pitch, and the conventional tooth profile angle 2a can be designed according to 30 degrees. When the system has special requirements, 35 degrees or other angles can be selected. And calculating according to the design space and the reliability of the chain, and then carrying out detailed design adjustment.

Referring to fig. 2, step two, designing key parameters of the chain wheel;

the design of the chain wheel is mainly to design the involute tooth profile of the chain wheel, and follows the design method of the gear, and the key parameters of the chain wheel comprise a chain wheel pressure angle alpha, a deflection coefficient x, an addendum circle radius da, a dedendum circle radius df, a base circle diameter db, a reference circle diameter d, an addendum and dedendum circle transition fillet;

the specific method comprises the following steps: the reference circle diameter d is obtained by solving the following formula:

d＝p/sin(π/z)；

wherein p is the chain pitch; z is the sprocket tooth number;

the base circle diameter db is obtained by solving the following formula:

db＝m zcosα；

wherein m is modulus, and m is p/pi; z is the sprocket tooth number; p is the chain pitch; alpha is a sprocket pressure angle;

the selection of the sprocket pressure angle alpha is related to the number of teeth, when the number of teeth is less than or equal to 25, the sprocket pressure angle alpha is generally 31.5 degrees, and when the number of teeth is more than 25, the sprocket pressure angle alpha is taken to be 30 degrees;

the addendum circle radius da and the dedendum circle radius df are selected to meet the requirement that interference does not occur after meshing, the requirement that da is less than d-d1 and the requirement that df is less than d-d2 are met, and the specific value can be solved according to the following formula.

da＝d-d1-c1·m

df＝d-d2-c2·m

Wherein d is the reference circle diameter; d1 is the distance between the reference circle and the bottom of the chain sheet; d2 is the distance between the reference circle and the lowest end of the chain sheet; m is a modulus; c1 is the addendum circle clearance coefficient; c2 is the root circle clearance coefficient; d1 and d2 are distances between two arcs and are variable values, the radius of a reference circle is increased along with the increase of the number of teeth of the sprocket, the value of d1 is gradually reduced, and the value of d2 is hardly changed;

the displacement coefficient x is obtained by solving the following formula:

in the formula, p₂Normal tooth pitch of the chain wheel hob; z is the sprocket tooth number; alpha is alpha₂The normal tooth form angle of the hob can be 30 degrees; f. of₀Is hypothetical corresponds to p₀The initial edge-to-center distance of the chain; p is a radical of₀The chain is an imaginary chain initial pitch, and the size of the chain initial pitch is equal to the normal tooth pitch of the hob; f. of₀Solving according to the following formula to obtain:

in the formula, f is the edge center distance of the chain plate; z is the sprocket tooth number; p is the chain pitch; p is a radical of₂Normal tooth pitch of the chain wheel hob;

the transition fillet of the tooth top and the tooth root circle is 0.4mm-2 mm.

Referring to fig. 3, step three, designing key parameters of the guide rail;

key parameters of the guide rail include guide plate curvature;

the specific method comprises the following steps: the chain wheel pressure angle alpha, the connecting line of the crankshaft rotation central point and the arc circle center of the chain motion track and the included angle beta between the connecting lines of the two chain wheel centers are obtained by solving according to the following formula:

according toGeometric relation graph, inner concave quantity of tight edge C₁The relationship with the curvature radius of the chain motion track is represented by the following formula:

wherein r1 and r2 are respectively the pitch circle of the meshing of the crankshaft sprocket and the left idler sprocket with the chain, namely the pitch circle radius; a is₁The distance between the rotation center of the crankshaft chain wheel and the rotation center of the left idle wheel chain wheel; r₁The radius of curvature of the motion trail of the chain is the radius of curvature of the chain after the fixed guide plate is installed;

C₁＝(2-10)％a₁(ii) a When the chain indent amount C₁When the value is determined, the curvature radius R of the chain motion track under the condition that the chain is tangent to the two chain wheels at the same time can be obtained₁Radius of curvature R of the stationary guide_fgThe following values are taken:

R_fg＝(0.95～0.98)R₁-h₁

in the formula, h₁The chain plate design parameter is the height of the back side of the chain plate, namely the distance from the center of the chain plate hole to the back side of the chain plate.

Generating corresponding chain sheet, chain wheel tooth form and guide rail contour results according to the parameters designed in the first step to the third step, wherein the results are stored in an editable graphic format, and visually checking whether the design results are reasonable or not, namely whether interference exists or not, the length is insufficient, and whether the chain sheet is interfered with the chain wheel transmission meshing or not through assembling the mounting positions of all parts of the wheel system from a graphic file, if not, the design results can be quickly and efficiently determined through a method of continuously adjusting the corresponding design parameters; the parameters can be adjusted continuously by using a trial and error method when being adjusted;

step five, when designing a multilayer chain, after completing the design of the initial layout of a single-layer chain system, assembling the chain systems with different layers, displaying the system layout corresponding to the whole timing chain transmission system in a pattern mode, giving the corresponding number of links, and correspondingly adjusting unreasonable design parameters until obtaining a satisfactory layout and a proper number of links; the parameters can be adjusted continuously by using a trial and error method when being adjusted;

and step six, determining a design scheme, and sorting and filing the determined design parameters and the generated design result to complete development and design.