Composite internal meshing tooth profile for timing tooth-shaped chain of engine and design method of composite internal meshing tooth profile

Abstract

The invention relates to a composite internal meshing tooth profile for an engine timing tooth-shaped chain and a design method of the composite internal meshing tooth profile. The design method mainly solves the technical problem that interference between a chain plate inner meshing tooth profile and a chain wheel involute tooth profile cannot be solved in an existing design method of the inner-outer composite meshing tooth-shaped chain for the engine. According to the technical scheme, the composite internal meshing tooth profile is formed by connecting a transition arc tooth profile and an involute type tooth profile or an involute-like tooth profile. The involute type tooth profile design method comprises the following steps: calculating a reference circle radius, a base circle radius and a positioning circle radius of a crankshaft chain wheel according to known basic parameters of an automobile engine timing system and a tooth-shaped chain; according to the design method of the involute-like tooth profile, the curvature radius and the curvature center of the involute-like tooth profile are obtained by constructing an auxiliary circle based on a calculation result of involute-like tooth profile design. The meshing impact between the chain and the chain wheel can be effectively reduced, so that the overall abrasion resistance of the chain is improved, and the service life is prolonged.

Description

Technical Field

[0001] The invention belongs to the technical field of automobile engine parts, and in particular relates to a composite internal meshing tooth profile for an engine timing toothed chain and a design method thereof. Background Art

[0002] Toothed chains are widely used in the field of mid-to-high-end automotive engine timing systems due to their long life, stable operation, light weight, and high transmission efficiency. Especially with the vigorous development of new energy vehicles in recent years, toothed chains have become the only choice for engine timing transmission in hybrid passenger cars.

[0003] According to the different meshing mechanisms, toothed chains can be divided into external meshing toothed chains and internal-external compound meshing toothed chains. Compared with external meshing toothed chains, internal-external compound meshing toothed chains have the advantages of lower meshing impact, smaller system loose edge vibration, and more stable camshaft speed output, so they have higher stability, longer life, lower transmission noise, and easier to achieve precise valve control. Therefore, internal-external compound meshing toothed chains are an effective technical means to improve engine performance and passenger car comfort. Especially for hybrid passenger cars, in order to improve fuel economy, their engines need to be in the medium and high speed range for a long time. Under this operating range, the vibration and noise of the engine are both large, which seriously affects its ride comfort.

[0004] However, the performance of the traditional internal-external compound meshing toothed chain is not stable. Due to the lack of a reliable and scientific design method as a support, during the operation of the timing system, the internal meshing tooth profile of the internal-external compound meshing toothed chain often interferes with the involute tooth profile of the sprocket, which not only fails to meet the original technical expectations, but also aggravates the vibration and noise of the chain, thereby seriously shortening the chain life and reducing the comfort that the passenger car should have. Therefore, the internal-external compound meshing toothed chain has not been widely used in the timing system of passenger car engines, thus limiting the further development of passenger car engine technology towards the high-level technical field of low energy consumption, low noise and low vibration.

[0005] The existing publication number CN116882092A discloses a design method for an internal-external compound meshing toothed chain for an engine, but the method cannot solve the problem of interference between the internal meshing tooth profile of the chain plate and the involute tooth profile of the sprocket, and also does not propose a specific calculation method for the internal meshing tooth profile. Therefore, the method cannot solve the problem of interference between the internal meshing tooth profile of the chain plate and the involute tooth profile of the sprocket. Summary of the invention

[0006] The purpose of the present invention is to solve the technical problem that the existing design method of internal-external composite meshing toothed chain for engine cannot solve the interference between the internal meshing tooth profile of the chain plate and the involute tooth profile of the sprocket, and to provide a composite internal meshing tooth profile for engine timing toothed chain and its design method.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] A composite internal meshing tooth profile for an engine timing toothed chain, wherein the composite internal meshing tooth profile (1.1) is composed of a transition arc tooth profile (1.1.1) and an involute tooth profile (1.1.2); the composite internal meshing tooth profile (1.1) is located on the left and right sides of the interior of a chain plate (1) and is symmetrical with the chain plate (1) about the symmetry axis in the vertical direction; the length of the transition arc tooth profile (1.1.1) and the involute tooth profile (1.1.2) accounts for 1 / 2 of the composite internal meshing tooth profile. The total length ratio of the internal meshing tooth profile (1.1) ranges from 40% to 60%. When the chain plate (1) is positioned on the intake camshaft sprocket (4) or the exhaust camshaft sprocket (5), the transition arc tooth profile (1.1.1) cannot interfere with the intake camshaft sprocket involute tooth profile (4.1) or the exhaust camshaft sprocket involute tooth profile (5.1), and the chain plate crotch arc (1.2) must ensure the tensile strength of the chain plate (1). At the same time, the toothed chain meshing parameters must meet the following requirements:

[0009]

[0010] In formula (1), α is the tooth profile half angle of chain plate (1), α 11 is the crankshaft sprocket (3) pressure angle, α 21 is the pressure angle of the intake camshaft sprocket (4) or the exhaust camshaft sprocket (5), p is the chain pitch, i.e. the pitch of the chain plate (1), p 11 is the pitch of the crankshaft sprocket (3), p 21 The pitch of the intake camshaft sprocket (4) or the exhaust camshaft sprocket (5).

[0011] Furthermore, the involute tooth profile (1.1.2) can also be replaced by a quasi-involute tooth profile (1.1.3), wherein the quasi-involute tooth profile (1.1.3) is a circular arc tooth profile that is similar to the involute tooth profile (1.1.2).

[0012] The design method of the composite internal meshing tooth profile for the engine timing toothed chain, wherein the design method steps of the involute tooth profile (1.1.2) are as follows:

[0013] S1. Based on the known basic parameters of the automobile engine timing system and the toothed chain, calculate the pitch circle radius r1 and base circle radius r of the crankshaft sprocket (3). b1 and the radius of the positioning circle r p1 ;

[0014] The basic parameters of the automobile engine timing system include: the number of teeth z1 of the crankshaft sprocket (3) and the radius R of the chain tight side track 12 ;

[0015] The basic parameters of the toothed chain include: a pitch p of the chain plate (1), a center distance f of the chain plate (1), a half-height H of the teeth of the chain plate (1), and a half-angle α of the tooth profile of the chain plate (1);

[0016] S2. Determine the involute parameters of the involute tooth profile (1.1.2), that is, determine its base circle radius r bin and the displacement coefficient χ in , the above parameters are determined by the following formula:

[0017]

[0018] In formula (2), R 12 is the radius of the chain tight side track, r p1 is the radius of the positioning circle of the crankshaft sprocket (3), r1 is the radius of the pitch circle of the crankshaft sprocket (3), α is the tooth profile half angle of the chain plate (1), z1 is the number of teeth of the crankshaft sprocket (3), f is the side-to-center distance of the chain plate (1), and p is the pitch of the chain plate (1);

[0019] If the crankshaft sprocket (3) parameters r1, r b1 、r p1 All are replaced with the pitch circle radius r2 and base circle radius r of the intake camshaft sprocket (4) or the exhaust camshaft sprocket (5). b2 and the radius of the positioning circle r p2 Parameters, design results are still valid.

[0020] Another design method for a composite internal meshing tooth profile, the arc tooth profile similar to the involute tooth profile (1.1.2), that is, the quasi-involute tooth profile (1.1.3), needs to be designed based on the calculation results of steps S1 to S2, and the specific design steps are as follows:

[0021] D1, with the curvature center of the chain tight side O 12 As the center of the circle, with R 12 +H / 2 is the radius, a first auxiliary circle is made, and the pressure angle of the involute tooth profile (1.1.2) on the first auxiliary circle is obtained;

[0022] D2, according to the radius r of the first auxiliary circle m1 Pressure angle α with the involute tooth profile (1.1.2) on the first auxiliary circle m1 , calculate the arc curvature radius ρ of the involute-like tooth profile (1.1.3);

[0023] D3. Establish an absolute coordinate system S(xO1y) with the rotation center O1 of the crankshaft sprocket (3) as the reference, and calculate the coordinate position (x) of the meshing point M on the first auxiliary circle on S(xO1y). M ,y M ); taking the rotation center O1 of the crankshaft sprocket (3) as the center and O1M as the radius, make a second auxiliary circle, and obtain the relevant parameters on the second auxiliary circle;

[0024] The relevant parameters on the second auxiliary circle specifically include: the radius of the second auxiliary circle r m2 , the pressure angle α of the crankshaft sprocket (3) on the second auxiliary circle m2 , the tooth thickness s of the crankshaft sprocket (3) on the second auxiliary circle m2 ;

[0025] D4. Using the center of the right pin (2) of the chain plate as a reference, establish the design coordinate system S1 (x1O1'y1), and calculate the relative coordinate O of the center of curvature of the arc of the quasi-involute tooth profile (1.1.3) in S1 (x1O1'y1). ρ (x ρ ,y ρ );

[0026] If the crankshaft sprocket (3) parameters r1, r b1 、r p1 All replaced with intake camshaft sprocket (4) or exhaust camshaft sprocket (5) parameters r2, r b2 、r p2 , the design results are still valid.

[0027] Furthermore, the arc curvature radius of the involute-like tooth profile (1.1.3) is determined by the following formula:

[0028] ρ=r m1 ·sinα m1 (3);

[0029] In formula (3), r m1 is the radius of the first auxiliary circle, α m1 is the pressure angle of the involute tooth profile (1.1.2) on the first auxiliary circle. The above parameters are determined by the following formula:

[0030]

[0031] In formula (4), R 12 is the radius of the chain tight side track, H is the half height of the chain plate (1), r bin is the base circle radius of the involute tooth profile (1.1.2), r m1 is the radius of the first auxiliary circle.

[0032] Furthermore, the y-axis of the absolute coordinate system S(xO1y) is 12 coincident, where O1 is the rotation center of the crankshaft sprocket (3), O 12 is the curvature center of the chain tight side. At this time, the coordinate value of the meshing point M on the first auxiliary circle in the absolute coordinate system S (xO1y) is obtained by the following formula:

[0033]

[0034] In formula (5), r p1 R is the radius of the crankshaft sprocket (3) positioning circle, 12 is the radius of the chain tight side track, r b1 is the base circle radius of the crankshaft sprocket (3), α is the tooth profile half angle of the chain plate (1), and α m1 is the pressure angle of the involute tooth profile (1.1.2) on the first auxiliary circle;

[0035] A second auxiliary circle is made with the rotation center O1 of the crankshaft sprocket (3) as the center and O1M as the radius. The radius of the second auxiliary circle satisfies:

[0036]

[0037] In formula (6), x M and M They are the horizontal and vertical coordinates of the meshing point M in the absolute coordinate system S (xO1y) respectively;

[0038] The pressure angle of the crankshaft sprocket (3) on the second auxiliary circle is determined by the following formula:

[0039]

[0040] In formula (7), r b1 is the base circle radius of the crankshaft sprocket (3), r m2 is the radius of the second auxiliary circle;

[0041] The tooth thickness s of the crankshaft sprocket (3) on the second auxiliary circle m2 Determined by the following formula:

[0042]

[0043] In formula (8), r1 is the pitch circle radius of the crankshaft sprocket (3), r m2 is the radius of the second auxiliary circle, α m2 is the pressure angle of the crankshaft sprocket (3) on the second auxiliary circle, α is the tooth profile half angle of the chain plate (1); wherein s is the standard tooth thickness, which can be calculated by the following formula:

[0044]

[0045] In formula (9), p is the pitch of the chain plate (1), α is the tooth profile half angle of the chain plate (1); wherein χ1 is the displacement coefficient of the crankshaft sprocket (3), which satisfies χ1=-χ in .

[0046] Furthermore, in step D4, the auxiliary parameter is first calculated Auxiliary parameters Determined by the following formula:

[0047]

[0048] In formula (10), r1 is the pitch circle radius of the crankshaft sprocket (3), r p1 R is the radius of the crankshaft sprocket (3) positioning circle, 12 is the radius of the chain tight side track, x M and M are the horizontal and vertical coordinates of the meshing point M in the absolute coordinate system S (xO1y), s m2 is the tooth thickness of the crankshaft sprocket (3) on the second auxiliary circle, r m2 is the radius of the second auxiliary circle;

[0049] The relative coordinate O of the center of curvature of the arc of the quasi-involute tooth profile (1.1.3) in S1(x1O1'y1) ρ (x ρ ,y ρ ), calculated by the following formula:

[0050]

[0051] In formula (11), r bin is the base circle radius of the involute tooth profile (1.1.2), α is the tooth profile half angle of the chain plate (1), is the auxiliary parameter for calculation, p is the pitch of the chain plate (1), R 12 is the radius of the chain tight side track.

[0052] The beneficial effects of the present invention are:

[0053] First, the technical solution of the present invention can effectively reduce the meshing impact between the chain and the sprocket, thereby improving the overall wear resistance and life of the chain, and further improving the stability of the engine operation. Secondly, the technical solution of the present invention can effectively reduce the speed fluctuation of the intake camshaft and the exhaust camshaft, thereby reducing the overall polygonal effect of the timing system, and further improving the accuracy of the engine valve control. Third, the technical solution of the present invention can effectively reduce the loose edge amplitude of the chain, thereby improving the overall life of the timing system, and further reducing the transmission noise of the timing system. Fourth, the technical solution of the present invention is a complete parameter design process, which can realize design automation through computer programming, significantly reducing the design threshold and the workload of engineering personnel. The technical solution of the present invention is applicable to most passenger car engines, especially to four-cylinder engines for hybrid vehicles, thereby providing a feasible technical means for improving the comfort and fuel economy of hybrid vehicles. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 Schematic diagram of the composite internal meshing tooth profile of the present invention;

[0055] Figure 2 It is the design requirement diagram of the transition arc tooth profile of the present invention;

[0056] Figure 3 It is a parameter diagram of the involute-like tooth profile of the present invention;

[0057] Figure 4 It is a structural diagram of the timing system of a four-cylinder engine;

[0058] Figure 5 This is a meshing effect diagram of the composite internal meshing tooth profile of the present invention;

[0059] Figure 6 It is a schematic diagram of meshing interference of traditional tooth profile;

[0060] Figure 7 A schematic diagram of the timing system parameters required by the present invention;

[0061] Figure 8 This is a comparison diagram of the meshing force between the present invention and the conventional tooth profile when the rotation speed is 3000r / min;

[0062] Fig. 9 This is a comparison diagram of the maximum meshing force of the tooth profile of the present invention and the traditional tooth profile at different speeds;

[0063] Fig.10 This is a comparison diagram of the camshaft sprocket speed when the tooth profile speed of the present invention and the conventional one is 3000r / min;

[0064] Fig.11A comparison diagram of the camshaft sprocket speed fluctuations at different speeds between the present invention and the conventional tooth profile;

[0065] Fig.12 This is a comparison diagram of the tensioner vibration when the tooth profile speed is 3000r / min between the present invention and the conventional one;

[0066] Fig.13 A comparison diagram of the maximum vibration of the tensioner at different speeds between the present invention and the conventional tooth profile;

[0067] In the figure: 1-chain plate, 1.1-compound internal meshing tooth profile, 1.1.1-transition arc tooth profile, 1.1.2-involute tooth profile, 1.1.3-quasi-involute tooth profile, 1.2-chain plate crotch arc, 2-pin shaft, 3-crankshaft sprocket, 3.1-crankshaft sprocket involute tooth profile, 4-intake camshaft sprocket, 4.1-involute tooth profile of intake camshaft sprocket, 5-exhaust camshaft sprocket, 5.1-exhaust camshaft sprocket involute tooth profile, 6.1-guide rail, 6.2-auxiliary guide rail, 6.3-tensioning guide plate, 7-tensioner. DETAILED DESCRIPTION

[0068] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0069] like Figure 1 As shown, in this embodiment, a composite internal meshing tooth profile is used for an engine timing toothed chain, wherein the composite internal meshing tooth profile 1.1 is composed of a transition arc tooth profile 1.1.1 and an involute tooth profile 1.1.2, and the composite internal meshing tooth profile 1.1 is located on the left and right sides of the chain plate 1, and is symmetrical with the symmetry axis of the chain plate 1 in the vertical direction; the length of the transition arc tooth profile 1.1.1 and the involute tooth profile 1.1.2 accounts for 40% to 60% of the total length of the composite internal meshing tooth profile 1.1; when the chain plate 1 is positioned at the intake camshaft sprocket 4 or the exhaust camshaft sprocket 5, the transition arc tooth profile 1.1.1 cannot interfere with the intake camshaft sprocket involute tooth profile 4.1 or the exhaust camshaft sprocket involute tooth profile 5.1, and the chain plate crotch arc 1.2 must ensure the tensile strength of the chain plate 1; at the same time, the toothed chain meshing parameters must meet:

[0070]

[0071] In formula (1), α is the half angle of the tooth profile of chain plate 1, α 11 is the pressure angle of crankshaft sprocket 3, α 21 is the pressure angle of the intake camshaft sprocket 4 or the exhaust camshaft sprocket 5, p is the chain pitch, that is, the pitch of the chain plate 1, p 11 is the pitch of crankshaft sprocket 3, p 21 It is the pitch of the intake camshaft sprocket 4 or the exhaust camshaft sprocket 5.

[0072] For example, if the chain plate tooth profile half angle α = π / 6 and the chain plate pitch p = 6.38 mm, then it is necessary to: α 11 =α 21 =π / 6, p 11 =p 21 =6.38mm. This is a necessary condition of the present invention.

[0073] The involute tooth profile 1.1.2 can also be replaced by a quasi-involute tooth profile 1.1.3, wherein the quasi-involute tooth profile 1.1.3 is a circular arc tooth profile that is similar to the involute tooth profile 1.1.2.

[0074] The design method of the composite internal meshing tooth profile for the engine timing toothed chain mentioned above, wherein the design method steps of the involute tooth profile 1.1.2 are as follows:

[0075] S1. Calculate the pitch circle radius r1 and base circle radius r1 of the crankshaft sprocket 3 based on the known basic parameters of the automobile engine timing system and the toothed chain. b1 and the radius of the positioning circle r p1 ;

[0076] The basic parameters of the automobile engine timing system include: the number of teeth z1 of the crankshaft sprocket 3 and the radius R of the chain tight side track 12 ;

[0077] The basic parameters of the toothed chain include: the pitch p of the chain plate 1, the edge distance f of the chain plate 1, the half height H of the chain plate 1 teeth and the half angle α of the chain plate 1 teeth;

[0078] For example, taking a four-cylinder inline engine as an example, the basic parameters of the timing system satisfy: z1 = 23, R 12 =885mm. The basic parameters of the toothed chain are: p = 6.38mm, f = 2.55mm, H = 3.92mm, α = π / 6.

[0079] First, the pitch circle radius r1 of crankshaft sprocket 3 is solved by the following formula:

[0080] r1=pz1 / 2π;

[0081] Where p is the pitch of chain plate 1, and z1 is the number of teeth on crankshaft sprocket 3.

[0082] From this, it can be concluded that the pitch circle radius r1 of crankshaft sprocket 3 is 23.354 mm.

[0083] Second, the base circle radius r of the crankshaft sprocket 3 b1 Solve it by the following formula:

[0084] r b1 = r1cosα;

[0085] Where r1 is the pitch circle radius of crankshaft sprocket 3, and α is the tooth profile half angle of chain plate 1.

[0086] From this, the base circle radius of the crankshaft sprocket 3 is obtained as r b1 =20.225mm.

[0087] Third, the radius r of the positioning circle of the crankshaft sprocket 3 p1 Solve it by the following formula:

[0088] r p1 =p / [2sin(π / z1)];

[0089] Where p is the pitch of chain plate 1, and z1 is the number of teeth on crankshaft sprocket 3.

[0090] The radius of the positioning circle of the crankshaft sprocket 3 is obtained as r p1 =23.427mm.

[0091] S2. Determine the involute parameters of the involute tooth profile 1.1.2, that is, determine its base circle radius r bin and the displacement coefficient χ in , the above parameters are determined by the following formula:

[0092]

[0093] In formula (2), R 12 is the radius of the chain tight side track, r p1 is the radius of the positioning circle of the crankshaft sprocket 3, r1 is the radius of the pitch circle of the crankshaft sprocket 3, α is the half angle of the tooth profile of the chain plate 1, z1 is the number of teeth of the crankshaft sprocket 3, f is the edge center distance of the chain plate 1, and p is the pitch of the chain plate 1;

[0094] From this, the base circle radius of the involute tooth profile 1.1.2 can be obtained as r bin =766.496mm, its displacement coefficient is χ in =1.223.

[0095] If the crankshaft sprocket 3 parameters r1, r b1 、r p1 All are replaced by the pitch circle radius r2 and base circle radius r of the intake camshaft sprocket 4 or the exhaust camshaft sprocket 5. b2 and the radius of the positioning circle r p2 Parameters, the design results are still valid.

[0096] When the involute tooth profile 1.1.2 is used, the composite internal meshing tooth profile 1.1 is not convenient to manufacture, so the present invention also provides a design method for a quasi-involute tooth profile 1.1.3 similar to the involute tooth profile 1.1.2, the projection of which is a circular arc, such as Figure 3The arc curvature radius of the involute-like tooth profile 1.1.3 is ρ, and the curvature center in the design coordinate system S1 (x1O1'y1) is O ρ (x ρ ,y ρ ).

[0097] The design of the quasi-involute tooth profile 1.1.3 needs to be based on the calculation results of the above steps S1 to S2. The specific design steps are as follows:

[0098] D1, with the curvature center of the chain tight side O 12 As the center of the circle, with R 12 +H / 2 is the radius, a first auxiliary circle is made, and the pressure angle of the involute tooth profile 1.1.2 on the first auxiliary circle is obtained;

[0099] First, the radius of the first auxiliary circle is:

[0100]

[0101] The radius of the first auxiliary circle is obtained as r m1 =886.960mm.

[0102] Second, the pressure angle α of the involute tooth profile 1.1.2 on the first auxiliary circle m1 It can be calculated by the following formula:

[0103] α m1 =arccos(r bin / r m1 ) (4);

[0104] The pressure angle of the involute tooth profile 1.1.2 on the first auxiliary circle is obtained as α m1 =0.527rad.

[0105] D2, according to the radius r of the first auxiliary circle m1 Pressure angle α with the involute tooth profile 1.1.2 on the first auxiliary circle m1 , calculate the arc curvature radius ρ of the involute-like tooth profile 1.1.3;

[0106] The arc curvature radius of the involute-like tooth profile 1.1.3 can be determined by the following formula:

[0107] ρ=r m1 ·sinα m1 (3);

[0108] From this, it can be obtained that the curvature radius of the involute-like tooth profile 1.1.3 is ρ=446.298 mm.

[0109] D3. Establish an absolute coordinate system S(xO1y) with the rotation center O1 of the crankshaft sprocket 3 as the reference, and calculate the coordinate position (x M ,y M ); Make a second auxiliary circle with the rotation center O1 of the crankshaft sprocket 3 as the center and O1M as the radius, and obtain the relevant parameters on the second auxiliary circle;

[0110] The relevant parameters on the second auxiliary circle specifically include: the radius of the second auxiliary circle r m2 , the pressure angle α of the crankshaft sprocket 3 on the second auxiliary circle m2 , the tooth thickness s of crankshaft sprocket 3 on the second auxiliary circle m2 ;

[0111] First, establish an absolute coordinate system S(xO1y) with its y axis at right angles to O1O 12 coincident, where O1 is the rotation center of crankshaft sprocket 3, O 12 is the curvature center of the chain tight side. At this time, the coordinate value of the meshing point M on the first auxiliary circle in the absolute coordinate system S (xO1y) is obtained by the following formula:

[0112]

[0113] In formula (5), r p1 R is the radius of the positioning circle of crankshaft sprocket 3 12 is the radius of the chain tight side track, r b1 is the base circle radius of crankshaft sprocket 3, α is the tooth profile half angle of chain plate 1, α m1 is the pressure angle of the involute tooth profile 1.1.2 on the first auxiliary circle;

[0114] The coordinates of the meshing point M in the absolute coordinate system S(xO1y) are obtained as follows (x M ,y M )=(-3.258mm,21.473mm).

[0115] Second, make a second auxiliary circle with the rotation center O1 of the crankshaft sprocket 3 as the center and O1M as the radius. The radius of the second auxiliary circle satisfies:

[0116]

[0117] In formula (6), x M and M They are the horizontal and vertical coordinates of the meshing point M in the absolute coordinate system S (xO1y) respectively;

[0118] From this, the radius of the second auxiliary circle is r m2 =21.719mm.

[0119] Third, the pressure angle of the crankshaft sprocket 3 on the second auxiliary circle is determined by the following formula:

[0120]

[0121] In formula (7), r b1 is the base circle radius of crankshaft sprocket 3, r m2 is the radius of the second auxiliary circle;

[0122] The pressure angle of the crankshaft sprocket 3 on the second auxiliary circle is obtained as α m2 =0.373rad.

[0123] Fourth, the tooth thickness s of the crankshaft sprocket 3 on the second auxiliary circle m2 Determined by the following formula:

[0124]

[0125] In formula (8), r1 is the pitch circle radius of crankshaft sprocket 3, r m2 is the radius of the second auxiliary circle, α m2 is the pressure angle of the crankshaft sprocket 3 on the second auxiliary circle, α is the tooth profile half angle of the chain plate 1; where s is the standard tooth thickness, which can be calculated by the following formula:

[0126]

[0127] In formula (9), p is the pitch of chain plate 1, α is the tooth profile half angle of chain plate 1; χ1 is the displacement coefficient of crankshaft sprocket 3, which satisfies χ1=-χ in .

[0128] The standard tooth thickness is s = 0.332 mm, and the tooth thickness of the crankshaft sprocket 3 on the second auxiliary circle is s. m2 =1.839mm.

[0129] D4. Establish the design coordinate system S1 (x1O1'y1) with the center of the pin 2 on the right side of the chain plate as the reference, and calculate the relative coordinate O of the center of curvature of the arc of the quasi-involute tooth profile 1.1.3 in S1 (x1O1'y1). ρ (x ρ ,y ρ );

[0130] First, calculate the auxiliary parameters Auxiliary parameters Determined by the following formula:

[0131]

[0132] In formula (10), r1 is the pitch circle radius of crankshaft sprocket 3, r p1R is the radius of the positioning circle of crankshaft sprocket 3 12 is the radius of the chain tight side track, x M and M are the horizontal and vertical coordinates of the meshing point M in the absolute coordinate system S (xO1y), s m2 is the tooth thickness of crankshaft sprocket 3 on the second auxiliary circle, r m2 is the radius of the second auxiliary circle;

[0133] The auxiliary parameters are obtained to satisfy

[0134] Second, the relative coordinate O of the center of curvature of the arc of the quasi-involute tooth profile 1.1.3 in S1(x1O1'y1) ρ (x ρ ,y ρ ), calculated by the following formula:

[0135]

[0136] In formula (11), r bin is the base circle radius of the involute tooth profile 1.1.2, α is the tooth profile half angle of the chain plate 1, is an auxiliary parameter, p is the pitch of chain plate 1, R 12 is the radius of the chain tight side track.

[0137] From this we can get O ρ (x ρ ,y ρ )=(383.436mm,223.151mm).

[0138] If the crankshaft sprocket 3 parameters r1, r b1 、r p1 All replaced with intake camshaft sprocket 4 or exhaust camshaft sprocket 5 parameters r2, r b2 、r p2 . Then the design of compound internal meshing tooth profile 1.1 is still valid.

[0139] For example, in this timing chain drive system, the basic parameter of the intake camshaft sprocket 4 or the exhaust camshaft sprocket 5 is z2=46. According to step S1, it can be obtained that: r2=46.708 mm, r b2 =40.451mm, r p2 =46.745mm. According to step S2, we can get r bin =766.465mm, x in =1.187. According to steps D1 to D4, we can get ρ=447.842mm, O ρ (x ρ ,y ρ)=(384.795mm, 223.984mm). At this time, the meshing between the composite internal meshing tooth profile 1.1 and the crankshaft sprocket involute tooth profile 3.1 (or the intake camshaft sprocket involute tooth profile 4.1 or the exhaust camshaft sprocket involute tooth profile 5.1) still satisfies Figure 5 shown.

[0140] like Figure 5 As shown, if the technical solution of the present invention is adopted, the composite internal meshing tooth profile 1.1 of the chain plate 1 can perfectly mesh with the crankshaft sprocket involute tooth profile 3.1 (or the intake camshaft sprocket involute tooth profile 4.1 or the exhaust camshaft sprocket involute tooth profile 5.1) without any interference, so that the chain can be transmitted according to its ideal trajectory.

[0141] In order to verify the beneficial effects of the present invention, the composite internal meshing tooth profile of the present invention was compared with the traditional tooth profile. The experimental results are as follows: Figure 8 to Figure 13 shown.

[0142] First, the composite internal meshing tooth profile of the present invention can effectively reduce the meshing impact between the chain plate 1 and the crankshaft sprocket 3 (or the intake camshaft sprocket 4 or the exhaust camshaft sprocket 5), thereby improving the wear resistance and life of the entire chain, and further improving the stability of engine operation. Figure 8 It can be seen that the composite internal meshing tooth profile of the present invention can reduce the maximum meshing force by (546.439–412.186) / 546.439=24.57% under the working condition of 3000 r / min; Fig. 9 It can be seen that the composite internal meshing tooth profile of the present invention can effectively reduce the maximum meshing force between the chain plate 1 and the crankshaft sprocket 3 at any rotation speed.

[0143] Secondly, the composite internal meshing tooth profile of the present invention can effectively reduce the speed fluctuation of the intake camshaft sprocket 4 (or the exhaust camshaft sprocket 5), thereby reducing the overall polygonal effect of the transmission system, thereby further improving the accuracy of the engine valve control. Fig.10 It can be seen that the composite internal meshing tooth profile of the present invention can reduce the speed fluctuation of the intake camshaft sprocket 4 (or the exhaust camshaft sprocket 5) from 157.538-156.606=0.903rad / s to 157.337-156.718=0.619rad / s under the working condition of 3000r / min, which is reduced by (0.903-0.619) / 0.903=31.45%; Fig.11 It can be seen that the composite internal meshing tooth profile of the present invention can effectively reduce the maximum speed fluctuation of the intake camshaft sprocket 4 (or the exhaust camshaft sprocket 5) at any speed.

[0144] Third, the composite internal meshing tooth profile of the present invention can effectively reduce the loose edge amplitude of the chain, thereby increasing the overall life of the timing system and further reducing the transmission noise of the timing system. Fig.12 It can be seen that the composite internal meshing tooth profile of the present invention can reduce the maximum vibration of the tensioner 7 from 0.7303–0.7167=0.0136mm to 0.7466–0.7348=0.0118mm under the working condition of 3000r / min, which is a total reduction of (0.0136–0.0118) / 0.903=13.23%; Fig.13 It can be seen that the composite internal meshing tooth profile of the present invention can effectively reduce the maximum vibration of the tensioner 7 at any rotation speed.

[0145] Fourth, the design method of the present invention is a complete parameter design process, which can realize design automation and platformization through computer programming, significantly reducing the design threshold and the workload of engineers. The design method of the present invention is applicable to most passenger car engines, especially to four-cylinder engines for hybrid vehicles, thus providing a feasible technical means for improving the comfort and fuel economy of hybrid vehicles.

[0146] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A composite internal meshing tooth profile for an engine timing toothed chain, characterized in that: The composite internal meshing tooth profile (1.1) is composed of a transition circular arc tooth profile (1.1.1) and an involute tooth profile (1.1.2); the composite internal meshing tooth profile (1.1) is located on the left and right sides of the chain plate (1) and is symmetrical with the chain plate (1) about the symmetry axis in the vertical direction; the length of the transition circular arc tooth profile (1.1.1) and the involute tooth profile (1.1.2) accounts for 100% of the length of the composite internal meshing tooth profile (1.1). The total length ratio ranges from 40% to 60%; when the chain plate (1) is positioned on the intake camshaft sprocket (4) or the exhaust camshaft sprocket (5), the transition arc tooth profile (1.1.1) cannot interfere with the intake camshaft sprocket involute tooth profile (4.1) or the exhaust camshaft sprocket involute tooth profile (5.1), and the chain plate crotch arc (1.2) must ensure the tensile strength of the chain plate (1); at the same time, the toothed chain meshing parameters must meet the following requirements: In formula (1), α is the tooth profile half angle of chain plate (1), α 11 is the crankshaft sprocket (3) pressure angle, α 21 is the pressure angle of the intake camshaft sprocket (4) or the exhaust camshaft sprocket (5), p is the chain pitch, i.e. the pitch of the chain plate (1), p 11 is the pitch of the crankshaft sprocket (3), p 21 The pitch of the intake camshaft sprocket (4) or the exhaust camshaft sprocket (5).

2. The composite internal meshing tooth profile for an engine timing toothed chain according to claim 1, characterized in that: The involute tooth profile (1.1.2) can also be replaced by a quasi-involute tooth profile (1.1.3), wherein the quasi-involute tooth profile (1.1.3) is a circular arc tooth profile that is similar to the involute tooth profile (1.1.2).

3. The design method of a composite internal meshing tooth profile for an engine timing toothed chain according to claim 1, characterized in that: The steps of the involute tooth profile (1.1.2) design method are as follows: S1. Based on the known basic parameters of the automobile engine timing system and the toothed chain, calculate the pitch circle radius r1 and base circle radius r of the crankshaft sprocket (3). b1 and the radius of the positioning circle r p1 ; The basic parameters of the automobile engine timing system include: the number of teeth z1 of the crankshaft sprocket (3) and the radius R of the chain tight side track 12 ; The basic parameters of the toothed chain include: a pitch p of the chain plate (1), a center distance f of the chain plate (1), a half-height H of the teeth of the chain plate (1), and a half-angle α of the tooth profile of the chain plate (1); S2. Determine the involute parameters of the involute tooth profile (1.1.2), that is, determine its base circle radius r bin and the displacement coefficient χ in , the above parameters are determined by the following formula: In formula (2), R 12 is the radius of the chain tight side track, r p1 is the radius of the positioning circle of the crankshaft sprocket (3), r1 is the radius of the pitch circle of the crankshaft sprocket (3), α is the tooth profile half angle of the chain plate (1), z1 is the number of teeth of the crankshaft sprocket (3), f is the side-to-center distance of the chain plate (1), and p is the pitch of the chain plate (1); If the crankshaft sprocket (3) parameters r1, r b1 、r p1 All are replaced with the pitch circle radius r2 and base circle radius r of the intake camshaft sprocket (4) or the exhaust camshaft sprocket (5). b2 and the radius of the positioning circle r p2 Parameters, design results are still valid.

4. The design method of a composite internal meshing tooth profile for an engine timing toothed chain according to claim 2, characterized in that: The arc tooth profile similar to the involute tooth profile (1.1.2), i.e., the quasi-involute tooth profile (1.1.3), needs to be designed based on the calculation results of steps S1 to S2, and the specific design steps are as follows: D1, with the curvature center of the chain tight side O 12 As the center of the circle, with R 12 +H / 2 is the radius, a first auxiliary circle is made, and the pressure angle of the involute tooth profile (1.1.2) on the first auxiliary circle is obtained; D2, according to the radius r of the first auxiliary circle m1 Pressure angle α with the involute tooth profile (1.1.2) on the first auxiliary circle m1 , calculate the arc curvature radius ρ of the involute-like tooth profile (1.1.3); D3. Establish an absolute coordinate system S(xO1y) with the center O1 of the crankshaft sprocket (3) as the reference, and calculate the coordinate position (x M ,y M ); taking the rotation center O1 of the crankshaft sprocket (3) as the center and O1M as the radius, make a second auxiliary circle, and obtain the relevant parameters on the second auxiliary circle; The relevant parameters on the second auxiliary circle specifically include: the radius of the second auxiliary circle r m2 , the pressure angle α of the crankshaft sprocket (3) on the second auxiliary circle m2 , the tooth thickness s of the crankshaft sprocket (3) on the second auxiliary circle m2 ; D4. Using the center of the right pin (2) of the chain plate as a reference, establish the design coordinate system S1 (x1O1'y1), and calculate the relative coordinate O of the center of curvature of the arc of the quasi-involute tooth profile (1.1.3) in S1 (x1O1'y1). ρ (x ρ ,y ρ ); If the crankshaft sprocket (3) parameters r1, r b1 、r p1 All replaced with intake camshaft sprocket (4) or exhaust camshaft sprocket (5) parameters r2, r b2 、r p2 , the design results are still valid.

5. The design method according to claim 4, characterized in that: The arc curvature radius of the involute-like tooth profile (1.1.3) is determined by the following formula: p=r m1 ·sina m1 (3); In formula (3), r m1 is the radius of the first auxiliary circle, α m1 is the pressure angle of the involute tooth profile (1.1.2) on the first auxiliary circle. The above parameters are determined by the following formula: In formula (4), R 12 is the radius of the chain tight side track, H is the half height of the chain plate (1), r bin is the base circle radius of the involute tooth profile (1.1.2), r m1 is the radius of the first auxiliary circle.

6. The design method according to claim 4, characterized in that: The y-axis of the absolute coordinate system S(xO1y) is 12 coincident, where O1 is the rotation center of the crankshaft sprocket (3), O 12 is the curvature center of the chain tight side; at this time, the coordinate value of the meshing point M on the first auxiliary circle in the absolute coordinate system S (xO1y) is obtained by the following formula: In formula (5), r p1 R is the radius of the crankshaft sprocket (3) positioning circle, 12 is the radius of the chain tight side track, r b1 is the base circle radius of the crankshaft sprocket (3), α is the tooth profile half angle of the chain plate (1), and α m1 is the pressure angle of the involute tooth profile (1.1.2) on the first auxiliary circle; A second auxiliary circle is made with the rotation center O1 of the crankshaft sprocket (3) as the center and O1M as the radius. The radius of the second auxiliary circle satisfies: In formula (6), x M and M They are the horizontal and vertical coordinates of the meshing point M in the absolute coordinate system S (xO1y) respectively; The pressure angle of the crankshaft sprocket (3) on the second auxiliary circle is determined by the following formula: In formula (7), r b1 is the base circle radius of the crankshaft sprocket (3), r m2 is the radius of the second auxiliary circle; The tooth thickness s of the crankshaft sprocket (3) on the second auxiliary circle m2 Determined by the following formula: In formula (8), r1 is the pitch circle radius of the crankshaft sprocket (3), r m2 is the radius of the second auxiliary circle, α m2 is the pressure angle of the crankshaft sprocket (3) on the second auxiliary circle, α is the tooth profile half angle of the chain plate (1); wherein s is the standard tooth thickness, which can be calculated by the following formula: In formula (9), p is the pitch of the chain plate (1), α is the tooth profile half angle of the chain plate (1); wherein χ1 is the displacement coefficient of the crankshaft sprocket (3), which satisfies χ1=-χ in .

7. The design method according to claim 4, characterized in that: In step D4, the auxiliary parameters are first calculated. Auxiliary parameters Determined by the following formula: In formula (10), r1 is the pitch circle radius of the crankshaft sprocket (3), r p1 R is the radius of the crankshaft sprocket (3) positioning circle, 12 is the radius of the chain tight side track, x M and M are the horizontal and vertical coordinates of the meshing point M in the absolute coordinate system S (xO1y), s m2 is the tooth thickness of the crankshaft sprocket (3) on the second auxiliary circle, r m2 is the radius of the second auxiliary circle; The relative coordinate O of the center of curvature of the arc of the quasi-involute tooth profile (1.1.3) in S1(x1O1'y1) ρ (x ρ ,y ρ ), calculated by the following formula: In formula (11), r bin is the base circle radius of the involute tooth profile (1.1.2), α is the tooth profile half angle of the chain plate (1), is the auxiliary parameter for calculation, p is the pitch of the chain plate (1), R 12 is the radius of the chain tight side track.

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