Method and device for acquiring fatigue life of driving half shaft

Abstract

The invention discloses a method and a device for acquiring the fatigue life of a driving half shaft, which are used for determining the fatigue life of the driving half shaft in a catapult starting mode and acquiring a first torque and a working angle corresponding to the driving half shaft in the catapult starting mode. And if the working angle is not zero, determining a new torque, namely the second torque, again by using the first torque and the working angle. Wherein the driving half shaft realizes the working angle of 0 corresponding to ejection starting under the action of the second torque. And determining a second fatigue life corresponding to the driving half shaft in the ejection starting mode by utilizing the first torque, the second torque and the first fatigue life. Wherein the first fatigue life refers to the fatigue life of the driving half shaft capable of being used for ejection starting under the action of the first torque under the condition that the fatigue life is reserved. Namely, when the fatigue life of the driving half shaft in the ejection starting mode needs to be determined, the fatigue life can be quickly calculated and obtained through the calculation model provided by the invention, rack testing is not needed, the optimization cost is reduced, and the development period is shortened.

Description

Technical Field

[0001] The present application relates to the field of data processing technology, and in particular to a method and device for obtaining the fatigue life of a driving half-shaft. Background Art

[0002] In order to improve the power of the vehicle and the driving experience of the user, a launch start mode is usually added during the development of the electric drive assembly control strategy. Launch start means that when the vehicle control system detects that the driver has the intention of launching and determines that the launch start function needs to be activated, the electric drive assembly can output power far exceeding its normal torque, so as to significantly improve the vehicle's starting acceleration performance and overtaking acceleration performance, thereby improving the driving experience.

[0003] However, due to the large power output in the launch mode, it will cause excessive fatigue damage to the power system parts including the drive axle. At present, the fatigue life of the drive axle under the impact torque of the launch mode can only be obtained through bench testing. Because the output torque of the electric drive assembly in the launch mode will be continuously optimized and adjusted during the development process, the drive axle needs to complete multiple rounds of bench testing based on different torques, which will bring a lot of additional verification costs and verification cycles. Summary of the invention

[0004] In view of this, the present application provides a method and device for obtaining the fatigue life of a driving half-shaft, so as to quickly obtain the fatigue life of the driving half-shaft in the launch start mode, reduce development costs, and shorten the development cycle.

[0005] To solve the above problems, the technical solutions provided by this application are as follows:

[0006] In a first aspect of the present application, a method for obtaining the fatigue life of a driving half shaft is provided, the method comprising: obtaining a first torque and a working angle corresponding to the driving half shaft in a launch start mode; if the working angle is not 0, determining a second torque according to the first torque and the working angle, and the working angle corresponding to the driving half shaft under the second torque is 0; determining a second fatigue life corresponding to the driving half shaft in the launch start mode according to the first torque, the second torque and a first fatigue life, the first fatigue life referring to the fatigue life of the driving half shaft that can be used for launch start under the condition of reserving fatigue life, and the first fatigue life is the fatigue life of the driving half shaft determined under the condition that the first torque is applied and the working angle is 0.

[0007] In one possible implementation, determining the second torque based on the first torque and the working angle includes: determining the second torque based on the first torque and the working angle based on the principle that the force exerted on the driving half-shaft by the first torque and the working angle is equal to the force exerted on the driving half-shaft by the second torque.

[0008] Wherein, the driving half shaft may include a fixed universal joint and a mobile universal joint, and the determining of the second torque based on the first torque and the working angle includes: obtaining a third torque corresponding to the fixed universal joint, the force of the third torque on the fixed universal joint is equal to the force of the first torque and the working angle on the fixed universal joint; obtaining a fourth torque corresponding to the mobile universal joint, the force of the fourth torque on the mobile universal joint is equal to the force of the first torque and the working angle on the mobile universal joint; and determining the maximum torque between the third torque and the fourth torque as the second torque.

[0009] The action force may be a normal contact force on the ball track of the universal joint. Specifically, for a fixed universal joint, the action force is a normal contact force on the ball track of the fixed universal joint; for a mobile universal joint, the action force is a normal contact force on the ball track of the mobile universal joint.

[0010] In a possible implementation, obtaining the first fatigue life includes:

[0011] Obtaining a third fatigue life according to reference data and the first torque, wherein the third fatigue life refers to the total fatigue life of the driving half shaft corresponding to the first torque without considering the reserved fatigue life, and the reference data includes a reference torque and a fatigue life corresponding to the reference torque;

[0012] Obtaining a fourth fatigue life according to the demand data corresponding to the reserved fatigue life and the first torque, wherein the fourth fatigue life refers to the reserved fatigue life corresponding to the driving half shaft under the action of the first torque, and the demand data includes the reserved torque and the reserved fatigue life corresponding to the reserved torque;

[0013] A difference between the third fatigue life and the fourth fatigue life is determined as the first fatigue life.

[0014] In a possible implementation, obtaining a fourth fatigue life according to demand data corresponding to the reserved fatigue life and the first torque includes:

[0015] Based on the principle that the damage caused to the driving half shaft under the action of the demand data is equivalent to the loss caused to the driving half shaft under the action of the first torque and the fourth fatigue life, the fourth fatigue life is obtained according to the demand data and the first torque.

[0016] In a possible implementation, the method further includes:

[0017] If the working angle is 0, the first fatigue life is determined as the fatigue life corresponding to the driving half shaft in the launch mode.

[0018] In a second aspect of the present application, a device for obtaining fatigue life of a driving half shaft is provided, the device comprising:

[0019] An acquisition unit, used for acquiring a first torque and a working angle corresponding to the driving half shaft in the launch start mode;

[0020] A first determining unit is used to determine a second torque according to the first torque and the working angle if the working angle is not 0, and the working angle corresponding to the driving half shaft under the action of the second torque is 0;

[0021] a second determination unit, for determining a second fatigue life corresponding to the drive half shaft in the launch mode according to the first torque, the second torque and a first fatigue life, wherein the first fatigue life refers to a fatigue life of the drive half shaft that can be used for launch under the condition of reserving fatigue life, and the first fatigue life is a fatigue life determined under the condition that the drive half shaft is under the action of the first torque and the working angle is 0.

[0022] In a third aspect of the present application, a vehicle is provided, the vehicle comprising a driving half shaft and the acquisition device according to the second aspect;

[0023] The driving half shaft is used to provide power to the vehicle;

[0024] The acquisition device is used to acquire the fatigue life of the driving half shaft in the launch start mode.

[0025] In a fourth aspect of the present application, an electronic device is provided, comprising: a processor, a memory;

[0026] The memory is used to store computer-readable instructions or computer programs;

[0027] The processor is used to read the computer-readable instructions or the computer program so that the device implements the method described in the first aspect or any possible manner of the first aspect.

[0028] In a fifth aspect of the present application, a computer-readable storage medium is provided, wherein instructions are stored in the computer-readable storage medium. When the instructions are executed on a device, the device executes the method described in the first aspect or any possible manner of the first aspect.

[0029] It can be seen that this application has the following beneficial effects:

[0030] In order to determine the fatigue life of the driving half shaft in the ejection start mode in this application, the first torque and working angle corresponding to the driving half shaft in the ejection start mode are first obtained, that is, the driving half shaft can achieve ejection start under the action of the first torque and working angle. If the working angle is not 0, a new torque, that is, the second torque, is re-determined using the first torque and working angle. Among them, the working angle corresponding to the ejection start of the driving half shaft under the action of the second torque is 0. That is, the effectiveness of the driving half shaft under the first torque and working angle is equal to the effectiveness under the second torque. The second fatigue life corresponding to the driving half shaft in the ejection start mode is determined using the first torque, the second torque and the first fatigue life. Among them, the first fatigue life refers to the fatigue life of the driving half shaft that can be used for ejection start under the action of the first torque when the fatigue life is reserved. That is, when it is necessary to determine the fatigue life of the driving half shaft in the ejection start mode, it can be quickly calculated by the calculation model provided in this application, without the need for bench testing, thereby reducing the optimization cost and development cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic diagram of a driving half-shaft structure provided in an embodiment of the present application;

[0032] Figure 2 A flow chart of a method for obtaining fatigue life of a drive half shaft provided in an embodiment of the present application;

[0033] Figure 3 A schematic diagram of the internal structure of a fixed universal joint provided in an embodiment of the present application;

[0034] Figure 4 A schematic diagram of a radial cross-section of a fixed universal joint raceway provided in an embodiment of the present application;

[0035] Figure 5 A schematic diagram of a geometric model of steel ball control distribution provided in an embodiment of the present application;

[0036] Figure 6 A two-dimensional coordinate analysis diagram of a steel ball 1 provided in an embodiment of the present application;

[0037] Figure 7 A two-dimensional coordinate analysis enlarged diagram of a steel ball 1 provided in an embodiment of the present application;

[0038] Figure 8 A steel ball provided in an embodiment of the present application is 0n Coordinate system projection diagram;

[0039] Fig. 9 A schematic diagram of the relationship between normal contact force and working angle / rotation angle provided in an embodiment of the present application;

[0040] Fig.10 A schematic diagram of the relationship between normal contact force and rotation angle provided in an embodiment of the present application;

[0041] Fig.11 A schematic diagram of the internal structure of a mobile universal joint provided in an embodiment of the present application;

[0042] Fig.12 A schematic diagram of the force of a mobile universal joint provided in an embodiment of the present application;

[0043] Fig.13 A schematic diagram of the relationship between a normal contact force and a working angle / rotation angle provided in an embodiment of the present application;

[0044] Fig.14 A schematic diagram of an application framework provided for an embodiment of the present application;

[0045] Fig.15 A structural diagram of a device for acquiring fatigue life of a drive half-shaft provided in an embodiment of the present application. DETAILED DESCRIPTION

[0046] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the embodiments of the present application are further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0047] During the development of electric vehicles, the launch mode will be added to the electric drive control strategy based on the acceleration performance of the vehicle. As one of the important components of the powertrain system, the launch mode brings many challenges to the fatigue life of the drive axle. The drive axle must not only meet the daily fatigue life requirements of car users, but also meet the additional high torque and high angle impact fatigue life requirements of the launch mode. The structure of the drive axle is as follows: Figure 1 As shown, the electric drive assembly outputs power to the mobile universal joint, and the mobile universal joint outputs power to the fixed universal joint through the shaft, and the fixed universal joint is fixedly connected to the wheel hub bearing and the tire through fasteners.

[0048] However, the electric drive assembly outputs different torques in different launch modes. Under different torques, the ground adhesion transmitted to the drive wheels through the drive axle is different. This adhesion will cause the axle load of the entire vehicle to transfer and the front of the vehicle to lift, which will cause the electric drive assembly to move up with the mobile universal joint of the drive axle, which will cause the working angle of the drive axle to change. Both torque and working angle have an impact on the fatigue life of the drive axle. Moreover, launch control is only an additional working condition. The drive axle also needs to meet the fatigue life requirements of the drive axle under daily vehicle use (that is, non-launch control mode).

[0049] Therefore, while reserving fatigue life to meet the fatigue life requirements of the drive axle in non-launch start mode, the fatigue life that can be used in launch start mode is determined to avoid system safety risks caused by excessive fatigue damage to the drive axle due to excessive use of launch start. At present, the fatigue life of the drive axle in launch start mode is mainly obtained through actual bench testing. When it is necessary to obtain the fatigue life of the drive axle that can be used for launch start under different torques and working angles, multiple bench tests will be required, increasing development costs and cycles.

[0050] Based on this, this application constructs a calculation model for the fatigue life of the drive half-shaft under different launch torques based on the SN curve, linear damage theory, etc., so that the calculation model can be used to quickly obtain the fatigue life of the drive half-shaft under the launch mode, thereby reducing development costs and cycles.

[0051] Among them, the SN curve is also called the stress-life curve, which refers to the relationship curve between the stress level applied during the fatigue process and the number of cycles of failure, i.e., life, with the logarithm of the fatigue load of the standard material specimen lgS as the ordinate and the logarithm of the fatigue life 1gN as the abscissa. Among them, S represents the stress level and N represents the life. Linear damage means that the damage caused by each load cycle can be accumulated linearly, and failure occurs when the accumulation reaches a certain level.

[0052] To facilitate understanding of the technical solution of the present application, the present application will be described below in conjunction with the accompanying drawings.

[0053] See also Figure 2 , which is a flow chart of a method for obtaining fatigue life of a drive half shaft provided in an embodiment of the present application. The method may include:

[0054] S201: Obtaining a first torque and a working angle corresponding to a driving half shaft in a launch mode.

[0055] In this embodiment, in order to obtain the fatigue life of the driving half shaft in the launch mode, the torque (first torque) required to be loaded on the driving half shaft and the working angle of the driving half shaft to achieve the launch mode are first obtained. For example, the launch mode requires the torque loaded on the driving half shaft to be 2000Nm and the working angle to be 20°.

[0056] S202: If the working angle is not 0, determine a second torque according to the first torque and the working angle.

[0057] After obtaining the first torque and working angle corresponding to the drive half shaft for launch control, it can be determined whether the working angle is 0. If it is not 0, the second torque is determined according to the first torque and the working angle. That is, a virtual torque, i.e., the second torque, is synthesized using the first torque and the working angle. The working angle corresponding to the drive half shaft under the action of the second torque is 0.

[0058] In this embodiment, the second torque is determined according to the first torque and the working angle based on the principle that the force exerted on the driving half shaft by the first torque and the working angle is equal to the force exerted on the driving half shaft by the second torque. The above-mentioned force can be the normal contact force between the parts. In the specific implementation, according to the principle of linear damage, the working angle δ of the driving half shaft cannot directly affect the fatigue life of the universal joint. When the torque T T When the working angle δ changes, the normal contact force Q between the sub-parts of the universal joint caused by the same torque is N is different, and the normal contact force Q N It is the direct cause of fatigue damage to the universal joint. Normal contact force Q N The difference will lead to different damage caused by each load, and finally lead to different fatigue life.

[0059] Among them, the torque T acting on the driving half shaft T , the working angle δ of the driving half shaft, the normal contact force Q N The following formula (1) is satisfied.

[0060] Q N =F(T T ,δ) (1)

[0061] The second torque T' T , where T′ T T T and δ, as shown in formula (2).

[0062] T′ T =f(T T ,δ) (2)

[0063] Wherein, the second torque T TNormal contact force Q′ between the sub-components of the universal joint caused by 0 angle N , as shown in formula (3), and T T The normal contact force Q caused at angle δ N Therefore, the damage caused by each load is also equivalent, so (T T ′,0) instead of (T T ,δ) to calculate the fatigue life.

[0064] Q′ N =F(T T ′,0) (3)

[0065] Among them, the focus of this application is to establish formula (2) to ensure that the Q calculated by formula (1) N And Q′ calculated by formula (3) N equal.

[0066] Since the driving half shaft includes a fixed universal joint and a movable universal joint, the internal structures of the two are different, and the torque and working angle loaded on the driving half shaft have different effects on the two. Among them, the above-mentioned normal contact force refers to the normal contact force for the universal joint ball track, such as the normal contact force for the fixed universal joint ball track or the normal contact force for the movable universal joint ball track.

[0067] Specifically, obtain the third torque corresponding to the fixed universal joint, the force exerted by the third torque on the fixed universal joint is equal to the force exerted by the first torque and the working angle on the fixed universal joint; obtain the fourth torque corresponding to the mobile universal joint, the force exerted by the fourth torque on the mobile universal joint is equal to the force exerted by the first torque and the working angle on the mobile universal joint; determine the maximum torque of the third torque and the fourth torque as the second torque. Generally, the greater the force corresponding to the torque, the greater the loss caused to the component, and the shorter the corresponding fatigue life of the component, so the maximum torque of the third torque and the fourth torque is used as the second torque. Among them, the working angle corresponding to the fixed universal joint under the action of the third torque is 0, and the working angle corresponding to the mobile universal joint under the action of the fourth torque is 0.

[0068] For ease of understanding, the impact on fixed universal joints and mobile universal joints will be introduced separately below.

[0069] 1. About fixed universal joints

[0070] The internal structure of the fixed universal joint is as follows Figure 3 As shown, in order to ensure the uniform velocity of the universal joint, the outer spherical surface of the star sleeve is centered at O2. N The inner sphere of the outer shell is centered at o1. WThe steel ball is located exactly between the two spherical surfaces. Since O0O2=o0O1, the center P of the steel ball is located on the angular bisector of the axis of the outer shell and the axis of the star sleeve.

[0071] Cut the fixed universal joint along O2P or O1P to obtain the radial cross-section diagram of the universal joint raceway as shown in the figure. Figure 4 As shown. The normal contact force Q of the star sleeve acting on the steel ball N , the normal contact force Q acting on the outer shell by the steel ball w , and the circumferential force Q on the ball f Satisfies the following equations (4) and (5).

[0072] Q f =Q N sinα2 (4)

[0073] Q f =Q W sinα1 (5)

[0074] According to formula (4) and (5), we can get Q N and Q w There is a fixed proportional relationship between them as shown in the following formula (6), so when calculating the influence of the working angle on the normal contact force of the fixed universal joint sub-parts, it is only necessary to calculate Q N That's it.

[0075] Q N sinα2=Q w sinα1 (6)

[0076] For the sake of calculation simplicity, it is assumed that the normal contact forces on the six steel balls are equal, that is:

[0077] Q N =Q N1 =Q N2 =Q N3 =Q N4 =Q N5 =Q N6 (7)

[0078] Combining formulas (4) and (7), we get:

[0079] Q N sinα2*(r1+r2+r3+r4+r5+r6)=T N (8)

[0080] Among them, r1, r2, r3, r4, r5, and r6 are the distances from the six steel balls to the axis centerline. The digital model of the fixed universal joint is removed by removing the outer shell and the shaft rod, and the spatial distribution of the six steel balls is obtained as follows: Figure 5 As shown ( Figure 5 The star-shaped sleeve in the figure is only a simplified model to indicate the spatial position of the steel ball. Figure 5 Based on the digital model, two planes are cut out and the internal spline hole for fixing the shaft is processed).

[0081] in, Figure 5 The star sleeve can be regarded as a sphere with 6 grooves on the surface (the groove diameter is equal to the steel ball diameter). When the working angle of the fixed universal joint changes, the steel ball slides in the groove to adapt to the change of angle, so the center of the steel ball is always located on the arc with the star sleeve center O2 as the center, O2P as the radius and passing through the groove bisector. And the centers of the 6 steel balls are located on the angle bisector plane of the outer shell axis and the star sleeve axis. This plane passes through the joint center O0 and is rotated by an angle of δ / 2 relative to the position at 0 angle.

[0082] In order to calculate the spatial position of the steel ball, we need to establish five coordinate systems as shown in Table 1.

[0083] Table 1 Steel ball calculation coordinate system

[0084]

[0085]

[0086] The X0 coordinate system and X2 coordinate system in Table 1 are coordinate systems passing through the center of the universal joint O0 and the center of the star sleeve O2. 0nn The coordinate system is z 0nn The three coordinate systems are fixed coordinate systems. In the actual working process of the driving half shaft, as the car moves forward, the universal joint will rotate around its own axis. Assuming that the rotation angle is ψ, the X0 coordinate system and the X2 coordinate system are fixed on the universal joint and rotated with it, and two rotating coordinate systems X0 and X2 can be obtained. 0n , X 2n .

[0087] Among them, a cross section is made through the center of the steel ball 1 and the ball track bisector plane, and the two-dimensional coordinate analysis diagram of the steel ball 1 is obtained as follows Figure 6 As shown, because X 0n , X 2n Both coordinate systems rotate with the universal joint, so the z-axis of these two coordinate systems must be located at Figure 6 On the cross section shown.

[0088] Will Figure 6 Zooming in with the center of the steel ball and the origin of the coordinate system as the center, we can get Figure 7 ,according to Figure 7 The calculation formula of r1 in formula (8) can be obtained as shown in formula (9):

[0089] r1=|R*cosλ| (9)

[0090] At the same time by Figure 7 It can be concluded that:

[0091] λ=β+η (10)

[0092]

[0093] In formulas (9)-(11), R is the distance from the center of the star sleeve O2 to the center of the steel ball P, and e is the distance from the center of the star sleeve O2 to the center of the universal joint O0. These two values ​​are constants and depend on the structural design dimensions of the universal joint.

[0094] The angle η is the coordinate axis z 0n and plane y 0nn z 0nn The negative number of the angle between X and 0n The coordinate system is along z 0n Coordinate axes as unit vectors And map this unit vector to X 0nn In the coordinate system.

[0095] From Table 1, we can see that:

[0096] X 0n =X0rot(x0,ψ ) (12)

[0097]

[0098] According to formula (12) (13), we can get:

[0099]

[0100] So the unit vector In X 0nn The coordinates in the coordinate system are:

[0101]

[0102] Since the angle η is and plane y 0nn z 0nn The negative of the angle, so:

[0103]

[0104] Combining formulas (10), (11), (16), we get:

[0105]

[0106] Combining formulas (9) and (17), we get the distance r1 from the steel ball 1 to the rotation axis as:

[0107]

[0108] like Figure 8 As shown, because the 6 steel balls are at X 0n The projections in the coordinate system are 60° to each other, so:

[0109]

[0110]

[0111] …

[0112]

[0113] According to the working characteristics of the universal joint (δ≤45°), the six steel balls and z 2n The angle between the coordinate axes is definitely less than 90°, that is, -90°<λ<90°. Therefore, the absolute value signs in formulas (18)-(21) can be directly removed, and then formulas (8)(18)-(21) are combined to obtain:

[0114]

[0115] Let the constant Q in formula (22) be N sinα2R=1, and the normal contact force Q of the ball track can be obtained. N The calculation relationship between the driving half-shaft working angle δ and the rotation angle ψ. The relationship diagram of the three is drawn using Python as follows Fig. 9 As shown, let δ = 30° to plot the normal contact force Q N The relationship between the rotation angle ψ is as follows Fig.10 shown.

[0116] comprehensive Fig. 9 , Fig.10 It can be concluded that the normal contact force Q N It increases nonlinearly with the increase of working angle δ, and fluctuates up and down with the increase of rotation angle ψ. When ψ=0°, 60°, 120°…, the normal contact force is the largest. Whether in the actual vehicle or on the test bench, the rotation angle ψ of the driving half shaft will change at any time, so this paper directly takes ψ as 0° to calculate the worst working condition (according to Fig.10 It can be concluded that the influence of the rotation angle ψ on the normal contact force is small, not exceeding 1%).

[0117] Simplifying formula (22) we can get:

[0118]

[0119] make:

[0120]

[0121] Substituting into formula (23), we can get:

[0122]

[0123] Therefore, for a fixed universal joint, the virtual torque T′ applicable to formula (2) is T The calculation formula is shown in formula (26):

[0124]

[0125] 2. The influence of angle on mobile universal joint

[0126] The internal structure of the driving half-shaft movable universal joint is as follows Fig.11 As shown, the force diagram of the mobile universal joint is as follows Fig.12 As shown in the figure, the normal contact force Q1 acting on the mobile universal joint ball track is decomposed into the normal contact force P1 acting on the tripod pin and the friction force f1 between the roller and the tripod pin, so:

[0127] Q1=P1 / cosλ (27)

[0128] For the sake of simplicity in calculation, we assume that the normal contact forces of the three rollers on the tripod pin are equal, that is:

[0129] P1=P2=P3 (28)

[0130] The calculation formula of P1 is as follows (29):

[14] :

[0131]

[0132] In formula (29), R is the distance from the center of the raceway to the center of the tripod housing axis. This value is a constant and depends on the structural design dimensions of the universal joint. e is the distance from the center of the tripod O2 to the center of the tripod housing axis. The calculation formula is:

[0133]

[0134] like Fig.12 As shown, the angle between the normal contact force Q1 and the normal contact force P1 is λ. In order to establish the calculation formula of λ, it is necessary to establish four coordinate systems as shown in Table 2.

[0135] Table 2 Coordinate system for calculation of tripod pins

[0136]

[0137]

[0138] The X1 coordinate system and X2 coordinate system in Table 2 are coordinate systems passing through the center O1 of the tripod housing and the center O2 of the tripod pin. Both coordinate systems are fixed coordinate systems. In the actual working process of the driving half shaft, as the car moves forward, the mobile universal joint will rotate around its own axis. Assuming that the rotation angle is ψ, the X1 coordinate system and the X2 coordinate system are fixed on the tripod housing and the tripod pin and rotate together with them, and two rotating coordinate systems X 1n , X 2n .

[0139] The λ in formula (27) is the coordinate axis x 1n and the coordinate axis x 2n To obtain this angle, we only need to 2n Coordinate system inner edge x 2n Coordinate axes as unit vectors And map this unit vector to X 1n In the coordinate system.

[0140] From Table 2, we can see that:

[0141] X 1n =X1rot(z1,ψ ) (31)

[0142] X 2n =X2rot(z2,ψ ) (32)

[0143] X2=X1rot(x1,δ) (33)

[0144] Combining formulas (31)-(33) we get:

[0145] X 1n =X 2n rot(z2,-ψ)rot(x2,-δ)rot(z1,ψ) (34)

[0146] So the unit vector In X 1n The coordinates in the coordinate system are:

[0147]

[0148] Therefore, the angle λ between the normal contact force Q1 and the normal contact force P1 is:

[0149] cosλ=cos 2 ψ+sin 2 ψcosδ (36)

[0150] Combining formulas (27), (29), (36), we get:

[0151]

[0152] Python is used to draw the relationship between the normal contact force Q1 of the ball lane and the driving half-axis working angle δ and rotation angle ψ as shown below: Fig.13 As shown. According to formula (37) and Fig.13 It can be seen that the normal contact force Q1 increases nonlinearly with the increase of the working angle δ, and fluctuates periodically with the increase of the rotation angle ψ. When ψ=90° or 270°, the normal contact force is the largest. Whether on the actual vehicle or on the test bench, the rotation angle ψ of the drive half shaft will change at any time, so this article directly takes ψ as 90° to calculate the worst working condition.

[0153] Simplifying formula (37) we can get:

[0154]

[0155] Combining formulas (30) and (38) we get:

[0156]

[0157] Therefore, for the mobile universal joint, the virtual torque T′ applicable to formula (2) is N The calculation formula of is shown in formula (40):

[0158]

[0159] That is, when determining the second torque according to the first torque and the working angle, the present application will use the above formula (26) to obtain the third torque corresponding to the fixed universal joint when the first torque and the working angle act, and use formula (40) to obtain the fourth torque corresponding to the mobile universal joint when the first torque and the working angle act, and determine the maximum torque of the third torque and the fourth torque as the second torque. That is, when actually calculating the influence of the angle on the fatigue life of the driving half shaft, it is only necessary to calculate formulas (26) and (40) respectively and take the maximum value.

[0160] S103: Determine a second fatigue life corresponding to the driving half shaft in the launch mode according to the first torque, the second torque and the first fatigue life.

[0161] In this embodiment, after the second torque is determined according to the first torque and the working angle, the fatigue life of the driving half shaft in the launch mode is determined according to the first torque, the second torque and the first fatigue life. The first fatigue life refers to the fatigue life of the driving half shaft that can be used for the launch mode under the condition of reserved fatigue life, and the first fatigue life is the fatigue life determined when the driving half shaft is under the action of the first torque and the working angle of the driving half shaft is 0. The reserved fatigue life refers to the fatigue life of the driving half shaft of the vehicle under non-launch mode conditions.

[0162] It should be noted that the second fatigue life determined in this embodiment is also the result of considering the fatigue life requirement of the user in the non-elastic launch mode. Specifically, the second fatigue life can be calculated using the following formula:

[0163]

[0164] Among them, N′ N represents the second fatigue life, N′ T represents the first fatigue life, T L and T H Refers to the reference torque, N L and N H Refers to the fatigue life, T L Indicates small torque, T H Indicates high torque, T T represents the first torque, T′ T It should be noted that the reference torque and the fatigue life corresponding to the reference torque may be data obtained through a small amount of bench tests or may be empirical data, which is not limited in this embodiment.

[0165] Among them, the first fatigue life can be obtained by the following method:

[0166] 1) Obtain a third fatigue life according to the reference data and the first torque.

[0167] In this example, reference data and the torque (first torque) applied to the driving half shaft in the launch mode are first obtained, and the third fatigue life is obtained according to the first torque and the reference data. The third fatigue life is the total fatigue life of the driving half shaft under the first torque without considering the reserved fatigue life, and the reference data includes the reference torque and the fatigue life corresponding to the reference torque. The reference torque and the fatigue life corresponding to the reference torque can be data obtained through a small number of bench tests or empirical data, which is not limited in this embodiment.

[0168] If the fatigue life margin is not considered, the torque applied to the drive half shaft in the launch mode is T TWhen the fatigue life N of the drive half shaft can be calculated by the following formula (42): T :

[0169]

[0170] Among them, N T Represents the third fatigue life.

[0171] 2) Obtaining a fourth fatigue life according to the demand data corresponding to the reserved fatigue life and the first torque.

[0172] In this embodiment, if a reserved fatigue life is required to meet the user's fatigue life requirement for the driving half shaft in the non-launch start mode, the reserved fatigue life corresponding to the driving half shaft under the first torque is determined according to the requirement parameter corresponding to the reserved fatigue life and the first torque, that is, the fourth fatigue life. The requirement data includes the reserved torque and the reserved fatigue life corresponding to the reserved torque. The fourth fatigue life is obtained based on the principle that the damage caused to the driving half shaft under the requirement data is equivalent to the loss caused to the driving half shaft under the first torque and the fourth fatigue life.

[0173] For example, the required data corresponding to the reserved fatigue life is: the torque applied to the drive half shaft is T Y When the fatigue life of the driving half shaft is not less than N Y Then we need to first use the following formula (43) to convert T according to the principle of linear damage: Y Life expectancy under torque N Y , converted to T T Life expectancy under torque N Y ′.

[0174]

[0175] Among them, N Y ' represents the fourth fatigue life.

[0176] It should be noted that N calculated according to formula (43) Y ' means that when the torque loaded on the driving half shaft is T T And the number is N Y ′, and the loading torque is T Y And the number is N Y When the fatigue damage to the drive axle is equivalent, it can be replaced equivalently. Therefore, to meet the user's fatigue life requirements for non-launch start mode, only N Y ' times will do.

[0177] 3) The difference between the third fatigue life and the fourth fatigue life is determined as the first fatigue life.

[0178] After the total fatigue life of the drive axle shaft (third fatigue life) and the fatigue life of the non-launch mode (fourth fatigue life) that meets the user's requirements are determined through the above steps, the fatigue life (first fatigue life) of the drive axle shaft that can be used in the launch mode can be obtained under the condition of reserved fatigue life. Specifically, refer to the following formula:

[0179] N T ′=N T -N Y v (44)

[0180] It should be noted that the above steps 1)-3) refer to the influence of torque on the fatigue life of the driving half shaft when the working angle is 0 degrees.

[0181] In addition, when the working angle obtained in step S101 is 0 angle, the first fatigue life is determined as the fatigue life corresponding to the driving half shaft in the launch mode, that is, the second fatigue life.

[0182] To understand the specific implementation of this application, see Fig.14 As shown in the implementation framework diagram. Fig.14 As shown, firstly, the parameter data, the torque and angle required in the launch mode are obtained, and the total fatigue life of the drive half shaft under the launch torque is calculated.

[0183] If fatigue life needs to be reserved to meet the life requirement of the drive half shaft in the non-launch start mode, the fatigue life 2 required to be reserved under the launch start torque is calculated based on the reserved torque and the reserved fatigue life. The fatigue life 3 of the drive half shaft under the launch start torque is obtained by subtracting the difference between fatigue life 1 and fatigue life 2.

[0184] It should be noted that, since the fatigue life 1 and the fatigue life 2 are calculated based on the working angle of the driving half shaft in the launch mode being 0, the obtained fatigue life 3 also does not take the working angle into consideration.

[0185] Then, it is determined whether the working angle in the launch mode is 0. If so, the fatigue life 3 is directly output; if not, according to the principle of equal normal contact force, the virtual torque is calculated using the torque loaded to the driving half-shaft in the launch mode and the working angle of the driving half-shaft. Under this virtual torque, the working angle of the driving half-shaft is 0.

[0186] Then, the fatigue life 4 of the drive half shaft is calculated according to the fatigue life 3, the torque required in the launch mode, and the virtual torque.

[0187] Based on the above method embodiment, the embodiment of the present application also provides a data transmission device, which will be described below in conjunction with the accompanying drawings.

[0188] See also Fig.15 , which is a structural diagram of a fatigue life acquisition device for a drive half shaft provided in an embodiment of the present application, such as Fig.15 As shown, the device 1500 includes: an acquisition unit 1501 , a first determination unit 1502 , and a second determination unit 1503 .

[0189] Specifically, the acquisition unit 1501 is used to acquire the first torque and working angle corresponding to the driving half shaft in the launch start mode;

[0190] A first determining unit 1502 is configured to determine a second torque according to the first torque and the working angle if the working angle is not 0, and the working angle corresponding to the driving half shaft under the action of the second torque is 0;

[0191] The second determination unit 1503 is used to determine the second fatigue life corresponding to the driving half shaft in the launch mode according to the first torque, the second torque and the first fatigue life, the first fatigue life refers to the fatigue life of the driving half shaft that can be used for launch under the condition of reserving fatigue life, and the first fatigue life is the fatigue life of the driving half shaft determined under the condition that the first torque is applied and the working angle is 0.

[0192] In a specific implementation, the first determination unit 1502 is specifically used to determine the second torque according to the first torque and the working angle based on the principle that the force generated by the first torque and the working angle on the driving half-shaft is equal to the force generated by the second torque on the driving half-shaft.

[0193] In a specific implementation, the driving half-shaft includes a fixed universal joint and a mobile universal joint, and the first determination unit 1502 is specifically used to obtain a third torque corresponding to the fixed universal joint, and the force of the third torque on the fixed universal joint is equal to the force of the first torque and the working angle on the fixed universal joint; obtain a fourth torque corresponding to the mobile universal joint, and the force of the fourth torque on the mobile universal joint is equal to the force of the first torque and the working angle on the mobile universal joint; determine the maximum torque between the third torque and the fourth torque as the second torque.

[0194] In a specific implementation, the action force is a normal contact force with respect to the ball track of the universal joint.

[0195] In a specific implementation, the acquisition of the first fatigue life includes: obtaining a third fatigue life based on reference data and the first torque, the third fatigue life refers to the total fatigue life corresponding to the driving half shaft under the action of the first torque without considering the reserved fatigue life, and the reference data includes a reference torque and a fatigue life corresponding to the reference torque; obtaining a fourth fatigue life based on demand data corresponding to the reserved fatigue life and the first torque, the fourth fatigue life refers to the reserved fatigue life corresponding to the driving half shaft under the action of the first torque, and the demand data includes a reserved torque and a reserved fatigue life corresponding to the reserved torque; and determining the difference between the third fatigue life and the fourth fatigue life as the first fatigue life.

[0196] In a specific implementation, the fourth fatigue life is obtained according to the demand data corresponding to the reserved fatigue life and the first torque, including: based on the principle that the damage caused to the driving half shaft under the action of the demand data is equivalent to the loss caused to the driving half shaft under the action of the first torque and the fourth fatigue life, the fourth fatigue life is obtained according to the demand data and the first torque.

[0197] In a specific implementation, the device further includes: a third determining unit;

[0198] The third determining unit is configured to determine the first fatigue life as the fatigue life corresponding to the driving half shaft in the launch control mode if the working angle is 0.

[0199] It should be noted that the specific implementation of each unit in this embodiment can refer to the relevant description in the above method embodiment, and this embodiment will not be repeated here.

[0200] In addition, the embodiment of the present application further provides a vehicle, including a driving half shaft and an acquisition device 1500;

[0201] The driving half shaft is used to provide power to the vehicle;

[0202] The acquisition device 1500 is used to acquire the fatigue life of the driving half shaft in the launch mode.

[0203] An embodiment of the present application provides an electronic device, including: a processor, a memory;

[0204] The memory is used to store computer-readable instructions or computer programs;

[0205] The processor is configured to read the computer-readable instructions or the computer program to enable the device to implement the method.

[0206] An embodiment of the present application provides a computer-readable storage medium, including instructions or computer programs, which, when executed on a computer, enable the computer to execute the above-described method.

[0207] It should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same or similar parts between the various embodiments can be referred to each other. For the system or device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description.

[0208] It should be understood that in the present application, "at least one (item)" means one or more, and "plurality" means two or more. "And / or" is used to describe the association relationship of associated objects, indicating that three relationships may exist. For example, "A and / or B" can mean: only A exists, only B exists, and A and B exist at the same time, where A and B can be singular or plural. The character " / " generally indicates that the objects associated before and after are in an "or" relationship. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, at least one of a, b or c can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, c can be single or multiple.

[0209] It should also be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0210] The steps of the method or algorithm described in conjunction with the embodiments disclosed herein may be implemented directly using hardware, a software module executed by a processor, or a combination of the two. The software module may be placed in a random access memory (RAM), a memory, a read-only memory (ROM), an electrically programmable ROM, an electrically erasable programmable ROM, a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.

[0211] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for obtaining fatigue life of a driving half shaft, characterized in that: The method comprises: Obtaining a first torque and a working angle corresponding to the driving half shaft in the launch mode; If the working angle is not 0, a second torque is determined according to the first torque and the working angle, and the working angle corresponding to the driving half shaft under the action of the second torque is 0; The second fatigue life of the driving half shaft in the launch mode is determined according to the first torque, the second torque and the first fatigue life, the first fatigue life refers to the fatigue life of the driving half shaft that can be used for launch under the condition of reserving fatigue life, and the first fatigue life is the fatigue life of the driving half shaft determined under the condition that the first torque is applied and the working angle is 0.

2. The method according to claim 1, characterized in that The determining the second torque according to the first torque and the working angle comprises: Based on the principle that the force exerted on the driving half shaft by the first torque and the working angle is equal to the force exerted on the driving half shaft by the second torque, the second torque is determined according to the first torque and the working angle.

3. The method according to claim 1 or 2, characterized in that: The driving half shaft includes a fixed universal joint and a movable universal joint, and the second torque is determined according to the first torque and the working angle, including: Acquire a third torque corresponding to the fixed universal joint, wherein the force exerted by the third torque on the fixed universal joint is equal to the force exerted by the first torque and the working angle on the fixed universal joint; Acquire a fourth torque corresponding to the mobile universal joint, wherein the force exerted by the fourth torque on the mobile universal joint is equal to the force exerted by the first torque and the working angle on the mobile universal joint; A maximum torque of the third torque and the fourth torque is determined as a second torque.

4. The method according to claim 2 or 3, characterized in that: The force is the normal contact force on the ball track of the universal joint.

5. The method according to claim 1, characterized in that: The acquisition of the first fatigue life comprises: Obtaining a third fatigue life according to reference data and the first torque, wherein the third fatigue life refers to a total fatigue life of the driving half shaft under the action of the first torque without considering a reserved fatigue life, and the reference data includes a reference torque and a fatigue life corresponding to the reference torque; Obtaining a fourth fatigue life according to demand data corresponding to the reserved fatigue life and the first torque, wherein the fourth fatigue life refers to the reserved fatigue life corresponding to the driving half shaft under the action of the first torque, and the demand data includes the reserved torque and the reserved fatigue life corresponding to the reserved torque; A difference between the third fatigue life and the fourth fatigue life is determined as the first fatigue life.

6. The method according to claim 5, characterized in that Obtaining a fourth fatigue life according to the required data corresponding to the reserved fatigue life and the first torque includes: Based on the principle that the damage caused to the driving half shaft under the action of the demand data is equivalent to the loss caused to the driving half shaft under the action of the first torque and the fourth fatigue life, the fourth fatigue life is obtained according to the demand data and the first torque.

7. The method according to claim 1, characterized in that The method further comprises: If the working angle is 0, the first fatigue life is determined as the fatigue life corresponding to the driving half shaft in the launch mode.

8. A device for obtaining fatigue life of a driving half shaft, characterized in that: The device comprises: An acquisition unit, used for acquiring a first torque and a working angle corresponding to the driving half shaft in the launch start mode; A first determining unit is used to determine a second torque according to the first torque and the working angle if the working angle is not 0, and the working angle corresponding to the driving half shaft under the action of the second torque is 0; a second determination unit, for determining a second fatigue life corresponding to the drive half shaft in the launch mode according to the first torque, the second torque and a first fatigue life, wherein the first fatigue life refers to a fatigue life of the drive half shaft that can be used for launch under the condition of reserving fatigue life, and the first fatigue life is a fatigue life determined under the condition that the drive half shaft is under the action of the first torque and the working angle is 0.

9. A vehicle, characterized in that: The vehicle comprises a driving half shaft and the acquisition device according to claim 8; The driving half shaft is used to provide power to the vehicle; The acquisition device is used to acquire the fatigue life of the driving half shaft in the launch start mode.

10. An electronic device, characterized in that: Including: processor, memory; The memory is used to store computer-readable instructions or computer programs; The processor is configured to read the computer-readable instructions or the computer program so that the device implements the method according to any one of claims 1 to 7.

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